ABSTRACT. This research analyzes two stator design features as structural solutions to reduce noise and vibration in permanent magnet synchronous machines (PMSM). The study was focused on a surface mounted PMSM with 12-stator slots and 10-rotor poles where vibration is a well-known issue. The structural-harmonic analysis was used to quantify the vibration by analyzing the radial deformation and acceleration on the outer face of the motor housing. The acoustics-harmonic analysis was also carried out to quantify the airborne noise radiated from the motor.

ABSTRACT. In order to reduce noise and vibration in SRM, many kinds of commutation methods have been proposed. One of them is well-known as 2-stage commutation method. But it has also some defects which are revealed particularly when SRM is operated at high speed and high load condition. In this study, through the magnetic-structural coupled analysis using FEM and the mathematical analysis of exciting force in 4-phase 8/6 SRM, the reason why vibration reduction based on the 2-stage commutation does not work is investigated. According to the investigations, a modified method to reduce vibration and noise independent from operating condition is proposed.

ABSTRACT. Efficient condition monitoring can diagnose the inception of fault mechanisms in induction motors, thus avoiding failure and expensive repairs. Therefore, there is a strong need to develop a more efficient condition monitoring. The main target is to achieve a relatively low cost and/or non-invasive system which is still powerful in terms of monitoring for online detection of developing faults. The presented digest addresses rotor eccentricity faults and studies conventional monitoring techniques for induction motors. The radial forces in an induction motor are calculated, and the characteristics of unbalanced magnetic pull are described.

ABSTRACT. This paper investigates the influence of slot and pole number combinations and magnet thickness on unbalanced magnetic force in PM machines with different rotor eccentricity and magnetization. It shows the machines with different magnetizations have different behavior as for unbalanced magnetic force with rotor eccentricity when magnet thickness and slot/pole combination vary. The machine with Halbach array is most sensitivity to these two parameters.

ABSTRACT. This paper provides a detailed investigation of the influence mechanism on vibration and noise of permanent magnet synchronous motors with skewed stators. Several skewed stator structures are researched to show the features of the flux and force. The finite element method is used to analyze the motor vibrations, displacements of deformation, and modals considering the mechanism of skewed stator. The displacements are converted to the sound pressure level which can reveal the characteristics of acoustic noise. The noise performance of motors with different stator skew factors is compared to choose a best stator structure. At last, the testing motor with skewed stator was experimentally demonstrated the validity of the theoretical research.

ABSTRACT. The traction motor for Electric Vehicle requires space saving, fault tolerant operation, and high efficiency driving. This research proposes a dual winding multi- phase motor which achieves variable speed-torque characteristics. This paper reveals the proposed motor characteristics by simulation results and experimental results.

ABSTRACT. The permanent magnet synchronous motor (PMSM) driver system for electric vehicle applications is developing to high voltage, high speed, high power density and efficiency. The rotor design needs to meet many requirements. In this paper, A PMSM for electric vehicle driver system(named as EV motor) with 35 kW, 8-pole / 48-slots/ single-layer winding as an example, the optimal groove and magnetic bridge design on rotor surface is studied, the feasibility of this proposed rotor structure is confirmed by the simulation results compared with the motor in Camry (named as Camry motor).

ABSTRACT. Motor control system is a most important part of electric vehicles. To implement its control strategies, a lot of practical problems need to be taken into account. In this paper, an induction motor control system for electric bus is developed based on DSP. The control strategy is based on field-oriented control (FOC) and space vector pulse width modulation (SVPWM). Over-modulation, field weakening control, PI controller and fault diagnosis are also applied in this DSP algorithm. As a practical product running on a real electric bus with a 100 kW induction motor, communication with vehicle control unit (VCU) by Controller Area Network (CAN bus), control system safety and PC software designed for experiment at lab are also discussed. The transient and steady-state performance of this motor control system is both analyzed by Simulink and experiments. Its performance is also satisfactory when applied to the real electric bus.

ABSTRACT. A bridge-like piezoelectric energy harvester which can be used for energy harvesting on large force load occasions is proposed in this paper. The harvester consists of two parts: piezoelectric stack and a bridge-like amplification mechanism. Finite element analysis based design is introduced in this paper to achieve higher output power as well as higher energy transmission efficiency. In order to realize an optimized structure, many influencing factors such as material parameters, dimension parameters, the lay-out of piezoelectric stack and stack connections are considered and analyzed.

ABSTRACT. These instructions provide you with the basic guidelines for preparing the one page digests for International Conference on Electrical Machines and Systems 2016, which will be held in Chiba, Japan, November 13 – November 16. Accepted digests will be included in the conference record. The conference record will be produced by photo-offset reproduction of the material prepared by the authors. Please carefully follow these instructions to ensure legibility and uniformity of digests in the conference record. I.Usage of this Template Application of Permanent Magnet Synchronous Motor (PMSM) has been increasingly popular in Electric Vehicle (EV) area since cost-effective magnetic materials were recently discovered. This paper mainly presents numerical calculation and experimental measurement of core loss of PMSM at various frequency among 50Hz, 100Hz, 200Hz and 400Hz. In the first section, a novel design strategy of PMSM will be described. The motor designed by authors is mounted on the vehicle and has 12 poles and 48 slots. The stator winding is equipped with field coils wound around each tooth. This configuration allows obtaining high torques at high speeds (14000 rpm), reduces motor size, increases high efficiency, improves high slot fill factor and lows cogging torque. The iron cores of silicon steel have been used with increasing frequency in all parts of EV motors. The second section gives a numerical algorithm for iron core loss. At first, the hysteric and eddy current loss of single electrical steel will be calculated, followed by measurement at different frequency among 20Hz up to 2500Hz. Then, the dynamic hysteresis loop and high-frequency harmonic losses will be accurately calculated with power loss and dimension of single sheet, which plays a key role in the total loss calculation, especially at high flux densities and high frequencies. The final section shows the experimental results of (1) power losses of single sheet of non-grain oriented electrical steel, and (2) high-frequency iron core losses at 50Hz, 100Hz, 200Hz and 400Hz, which verify numerical algorithm. It is clarified that the numerical model and experimental iron core losses in each experiment are showed to be in good agreement. The numerical model for iron core losses and experimental results for single electrical steel sheet are especially useful to estimate power losses of electric machines running at higher frequency of 1000Hz~2000Hz.

ABSTRACT. This paper proposes a safe turn-off strategy which could isolate the electric machine and the Inverter in case of an over-voltage fault in the DC link. The existing strategies like Freewheeling and Active short circuit of the machine either gives an over-voltage in the DC link capacitance or over-current in the phases of the machine. This strategy can prevent both these effects and is discussed in detail in the paper.

ABSTRACT. Abstract —In view of the appearance of parallel stator winding open circuit fault in large capacity permanent magnet wind turbines, the negative sequent current is caused in stator windings, which may endanger the stability of the wind turbine. With the 2-D transient electromagnetic field, the negative sequence current with the rated condition and fault condition is calculated. Further more, the change rule of the negative sequence current with degree and position is studied, which provides a theoretical basis for fault diagnosis of stator windings of permanent magnet wind turbines.

ABSTRACT. A Linear Rotary Permanent Magnet Generator (LRPMG) is proposed for Wind-Wave Combined Power Generation System (WWCPGS). The rotary unit and linear unit of the LRPMG can be used to generate electricity by wind energy and wave energy, respectively. Compared with rotary generator by single wind power and linear generator by single wave power, the LRPMG can improve the utilization rate of the material and the power density of the system. The main characteristics, including flux distribution，three-phase back electromotive force (EMF)，terminal voltage，air-gap flux density and external characteristic of the LRPMG are analyzed by the finite-element method (FEM).

ABSTRACT. Steady-state characteristics of self-excited synchronous generators with damper windings used for current-source type wind farm composed of series-connected wind generators are studied. A simulation model of the generators with damper windings is first derived based on dq transformation for salient-pole type machines. Experimental investigations were carried out to confirm the validity of the simulation model. The instantaneous voltage and current waveforms of the wind turbine generators are simulated with typical values of salient-pole synchronous generator constants, and the effects of the damper windings on the operating range of the wind generator are discussed. It is shown that the operating range for the generator with damper windings is extended in comparison to the case without damper windings.

ABSTRACT. Characteristics of PMSGs used for current-source type wind farm composed of series-connected wind generators are studied. A series of experiments was carried out with an experimental set composed of series-connected thyristor rectifiers with PMSGs as wind turbine generators and current-source thyristor inverter. A simulation model based on trapezoidal waveforms of armature electro-motive force for PMSG is used to discuss the characteristics of the machines, and the validity of the model is shown. Also, the basic characteristics of the current-source type wind farm including series-connected PMSGs are investigated.

ABSTRACT. In order to improve the power quality of wind power generation system, a direct power control (DPC) strategy of open-winding brushless doubly-fed generator (BDFG) system based on dual converters is presented in this paper. The control method is divided into two parts: the grid side converter control and the machine side converter control. In terms of the grid side converter, a model predictive-based SVPWM direct power control is used. This method combines the power predictive control theory with the space vector modulation technology instead of hysteresis comparator and switching table. Switching frequency is fixed and harmonic content is reduced, at the same time the grid side converter achieves basically constant DC bus voltage. In the machine side converter, the open winding structure of the BDFG is used and the accuracy of active and reactive powers is improved. The simulation of the proposed control strategy is carried out through Matlab/Simulink software and the simulation results prove the correctness and feasibility of the DPC strategy for the open-winding BDFG system on the grid and machine sides.

ABSTRACT. The purpose of this paper is to sum up concerns when designing a gate driver for SiC MOSFETs, and provide two examples. Both of them can detect over current of the power device. One use a gate driver IC and adapt it to meet the requirement of SiC MOSFETs, which is simple and convenient. For better performance in terms of switching frequency and reliability, the other one adopt magnetic transformers to provide the gate signals and the power for the secondary side respectively. The gate driver can work on any duty ratio and meet fast dynamic duty ratio command. A second order R-C network is designed to detect over current of the power device. Experimental comparison shows the latter performs better on propagation delay and coupling capacitance. At last short circuit experiment is conducted and both can survive the experiment.

ABSTRACT. Abstract —In this paper, PSFB (Phase Shift Full-Bridge) converter with synchronous rectifier is implemented using GaN HEMT. The difficulties and solving method are described for applying GaN HEMT. A 500W prototype is built to evaluate GaN HEMT based system and efficiency is improved 2% compared to conventional system with Si MOSFET.

ABSTRACT. This paper presents an electro-thermal based junction temperature (Tj) estimation method of insulated gate bipolar transistor (IGBT) power module. Firstly, the internal structure of IGBT and its transient characteristics are researched, through which the factors affecting the power loss as well as its basic influence rule are analyze and the multivariable loss calculation model is obtained. And then with the coupling of the loss and Foster model, the maximum Tj is obtained. The method is validated against the simulation of both IPOSIM and finite element method, and the comparison of the results shows the differences were less than 4% which illustrates the accuracy of the estimation model. Finally, the correlation of the module’s thermal performance with its internal structure is explored in ANSYS for optimization design. This model contributes to the reliability verification and more reasonable thermal design of IGBT module.

ABSTRACT. Abstract — This paper proposes a self-tuning model predictive direct power control (MPDPC) strategy for grid-connected power converters. At each sampling instant, a fuzzy logic controller is used to determine online the best weighting factor values for a given operating point. These values are then used to solve the multi-objective optimal control problem associated to the MPDPC. The optimal input (power switch state) that minimizes the multi-objective cost function is chosen. The proposed method is studied through a case study and verified numerically. A comparative study will be conducted in the full paper to demonstrate the effective performance of this approach.

ABSTRACT. The reliability of the rotor-side converter of doubly fed induction generator (DFIG) can be significantly reduced due to the large junction temperature fluctuation of the insulated gate bipolar transistor (IGBT) module, especially when the wind turbine generator system (WTGS) is running at synchronous speed. A depression strategy on junction temperature fluctuation is proposed based on DFIG rotor speed control. In this paper, an equivalent IGBT module thermal network model is derived from the IGBT module physical structure firstly. Then, based on the traditional maximum power point tracking (MPPT) control strategy of WTGS, an improved MPPT control strategy with the power-speed outer control loop is proposed. Moreover, an electrical-thermal model of wind power converter is presented based on PLECS platform, and the simulation results of the junction temperature and power loss of IGBT module per-formed in Matlab/Simulink is obtained by comparison of the simulation results coming from the improved and traditional control strategies. The results indicate that the improved MPPT control strategy effectively depresses the IGBT junc-tion temperature fluctuation.

ABSTRACT. In this paper, a control strategy of series-connected DC-DC boost converter for HVDC-connected photovoltaic unit is proposed, and the structure of the converter module is designed. The switching strategy of the module is designed for the wide output voltage range of the converter, and the steady-state constraint condition of the switch is given. Finally, the transient process of the switching process is simulated and the implementation of the switching strategy is verified.

ABSTRACT. In this paper, the engineering design method of phase-shifting reactor(PSR) is proposed according to the active power balance principle. The magnetic-thermal coupled method is adopted in the simulation of 6-phase rectifier system with PSR. The current waves in input-side and output-side, magnetic flux and temperature distribution reveal that the PSR designed in this paper meets the requirements of phase-shifting angle and the load.

ABSTRACT. This digest studies the transient and sustained ferroresonance phenomenon in wind farms connected to a power distribution system. Ferroresonance can be critical for wind turbines during switching or fault conditions. This results in effects such as harmonics, voltage dips and overvoltage in the system. The ferroresonance current is able to damage the machine and the rotor side converter, and as a consequence, the system must be protected. In general, engineers can often work around nonlinearities using a simplified linear approximation to calculate or predict performance within the “normal” range of operation. This is not possible in the case of ferroresonance since linearized calculations will not predict it.

ABSTRACT. This paper investigates the dynamic characteristics of a coaxial magnetic gear (CMG) system by using the analytical model of the CMG, which provides a quick and accurate method to predict the performance of the CMG. The dynamic characteristics under different conditions such as start-up and the abrupt change of load are studied. Moreover, the threshold overload torque which may cause loss of synchronism for the CMG is also estimated by simulation. The threshold overload torque is relative to the changing rate of load and is much lower than the static pull-out torque.

ABSTRACT. For high speed permanent magnet machine, it is necessary to meet the requirements including electromagnetic properties, mechanical properties and temperature, so it is a multi-physics field iterative design process. Based on the electromagnetic field, the temperature field, the stress field and the rotor dynamics, a 360kW, 7000r/min high speed permanent magnet machine is analyzed. Through the multi-physics field analysis, the design scheme meeting electromagnetic properties, mechanical properties and temperature rise is obtained.

ABSTRACT. Diagnosis of the patient with suspected stroke to determine the type of pathology is still widely applied, especially in Indonesia due to constraints in the implementation of the Gold Standard Procedure. The selection process to get the best features was performed by identifying similarity to the features of each class. Fuzzy Entropy generated entropy value of degree of membership of each feature. The result of the implementation of feature selection was able to select 13 of the best features for the accuracy of 96%. Therefore, the process was more effective than the one having to check 32 features.

ABSTRACT. A novel axial flux permanent magnet eddy-current coupling (PMECC) employing a new magnetic field adjustment (MFA) method is proposed in this paper. The structural feature and operation principle of the novel PMECC are illustrated. The magnetic equivalent circuit (MEC) model is built in this paper to analyze its electromagnetic characteristics efficiently. For improving the torque capability, the structure parameters effects on the air-gap magnetic field and output torque are investigated by FEM. The results derived from the finite element method (FEM) verifies the speed-adjustable capability of the proposed coupling equipped with the new MFA method.

ABSTRACT. Permanent-magnet (PM) direct-drive radial- axial flow turbine generator is widely used in the field of low-grade waste heat (below 200 °) Organic Rankine Cycle (ORC) power generation. However, special mechanical balance devices are needed to suppress the axial force produced by radial-axial turbine under the high-speed operation, resulting in not only the complex structure of the generator, but also higher cost and loss. Aiming at solving the above mentioned problems, a conical-rotor PM generator is proposed in this paper. The mathematical model of the generator is established to calculate the axial magnetic force. The effects of the air gap and cone angle of the conical-rotor PM generator on the axial force are analyzed theoretically. Moreover, a parametric design is conducted to optimize the axial force produced by the conical-rotor PM generator, which may balance with the axial force caused by the turbine. A simulation on the 3D FEM model is performed to validate the correctness of the analysis.

ABSTRACT. Compared to permanent magnet motors using rare-earth metals, a wound field synchronous motors tends to generate more heat due to increased windings, so it is required to consider cooling measures in design. In this study, a 3D computational fluid dynamics simulation and experimental verification of an 80kW Wound Field Synchronous Motor was performed to investigate the cooling performance of dual cooling passages. In order to evaluate the cooling effect of related design factors, a coolant temperature and coolant mass flow rate was considered in the analysis.

ABSTRACT. To investigate the influence of sectionalized stators on shaft voltage in integer slot permanent magnetic synchronous machine (PMSM), an aid of magnet circuit and analytical method is proposed to deduce the shaft voltage, whilst segment and pole number combinations are further discussed. Finite element method (FEM) is used to verify the accuracy of above qualitative analysis. The influence of various rotation velocity, different width of joint and multiple pole-arc coefficient on shaft voltage are also analyzed. The conclusion can help PMSM designer to avoid and weaken shaft voltage.

ABSTRACT. In this paper, a new structure of dual-channel coarse-exact coupling co-magnetic reluctance resolver is put forward on the basis of the magnetic analysis of multi-pole reluctance resolver. Both the magnetic field finite element method (FEM) and the analytic method are used to calculate the result of the self- inductance and the mutual inductance. The calculation accuracy of the inductance parameter is very important to design one high-precision reluctance resolver. At last, the experiment has been done to prove the correctness of the simulation result.

ABSTRACT. An electric machine with permanent magnets on both its rotor and stator is proposed and studied. The key idea is to using the bi-directional flux modulation effect to realize a structure with more rotor poles and less stator poles. Compared with the conventional machines with single-sided permanent magnet excitation, the proposed machine has more flexible pole-slot design when the pole number is large and it has a good potential to achieve better utilization of the ferrite material, which makes it suitable for high-torque low-speed applications. In this paper, the structure and working principle of the proposed machine are introduced. Its performance is studied in comparison with a conventional permanent magnet machine using finite element method.

ABSTRACT. In order to improve the output performance, multi-stator structure is applied to traveling wave type ultrasonic motor (TWUM). In this paper, taking into account the multi-stator traveling wave type ultrasonic motor (MSUM) with diameter of 60mm, authors apply the elastic contact principle to deduce the MSUM’s simulation model. By reason of the machining errors and installation errors, the stators and rotors can’t agree uniformly. So the errors of different stators and rotors are added this simulation model. According to the actual motors’ structure parameters, the operational characteristics are presented. In this paper, given the varied applied torque, and applied axial force, the MSUM’s operation performance is obtained. The measurement is also executed. The simulation results agree with the test results. And it shows this simulation model is valid. This model makes it possible to predict most of the behavior and performance characteristics of MSUM as a function of the external loading parameters. And the conclusion can also guide the design and assembly of MSUM.

ABSTRACT. This paper proposes a novel variable reluctance hybrid magnet memory machine (VR-HMMM), which is geometrically characterized by doubly salient structure having homopolar hybrid magnets alternatively mounted on the stator poles. The magnetizing coils are wound on the PM excitation teeth to vary the magnetization states of low coercive force(LCF) magnets, and hence the air-gap flux can be flexibly adjusted. The proposed design can offer the advantages of simple stator/rotor structures, easy thermal management and energy-efficient online flux adjustment. The machine structure and operating principle are briefly introduced, respectively. The basic electromagnetic characteristics of the proposed VRHMMMs having different rotor pole numbers are investigated to validate the feasibility of the proposed design.

ABSTRACT. A high-capacity doubly-fed start-up PMSM for low-speed high-torque driving system is designed. The machine with 33rpm, 180 poles and 2000kW has a new rotor structure and auxiliary windings to realize the doubly-fed start-up. This paper studies the mechanism of magnetic field modulation of high-capacity PMSM start-up process, puts forward the DC auxiliary exciting windings in the lower region of the rotor slots which will form the MMF contrary to the permanent magnetic field to weakening permanent magnet braking torque, and improving the motor start-up ability fundamentally without the large frequency convertor. Effects of the key permanent magnet braking torque, electromagnetic torque, starting ability on doubly-fed magnetic field modulation have been analyzed. The 2D transient finite element analysis method is used for the motor characters’ computation. All researches show that the innovative motor is potential to apply in high-capacity low-speed high-torque driving system.

ABSTRACT. A novel two-speed line-start permanent magnet motor (TSLSPMM) is proposed to replace the traditional pole-changing two-speed induction motor for energy saving. The proposed TSLSPMM, featured with pole-changing stator winding and a squirrel cage rotor with fixed permanent magnet poles, starts by a winding connection with higher pole number, and runs as an induction motor for a period of time, and after the pole-changing, the speed of the motor is increased to run in synchronous mode for long time operation. The higher efficiency of the synchronous mode can contribute to energy saving. In this paper, the topology and design characteristics of the motor are introduced in detail. Besides, the performances of the proposed motor under different operation modes are investigated through finite element simulation.

ABSTRACT. In order to increase the output power density and maintainability of the conventional driving system in electric vehicle, the research on magnetic gears is being carried out variously all over the world. In this paper, the design technique of the magnetic-geared permanent magnet synchronous motor(MG-PMSM) is first studied for the application of the MG-PMSM structurally integrated with magnetic gear and PMSM to the electric vehicle driving system. In addition, a small-scale MG-PMSM model is designed and analyzed using an electromagnetic FEM tool.

ABSTRACT. Abstract — An outer-rotor permanent magnet synchronous machine (OR-PMSM) with amorphous stator core(OR-PMSMASC) is proposed in this paper, which exhibits higher efficiency than conventional PM machine. Based on the electromagnetic characteristics of the amorphous alloy material, the general design of the proposed machine is studied, including the structure parameters and the stator-slot/rotor-pole combinations. The combination principle of permanent magnets and winding turns for OR-PMSMASC is investigated. Based on the 2-D finite element analysis (FEA), the electromagnetic performances of the proposed machine are investigated and compared with an OR-PMSM with silicon steel stator core(OR-PMSMSSSC). A prototype of the OR-PMSMAMC is manufactured and tested to validate the FEA results.

ABSTRACT. We have proposed a claw pole type half-wave rectified variable field flux motor (CP-HVFM) with special self- excitation method. The claw pole rotor needs the 3D magnetic path core. This paper reports an analysis method with experimental BH and loss data of the iron powder core for FEM. And it shows a designed analysis model and characteristics such as torque, efficiency and loss calculation results.

ABSTRACT. In this work we investigated the thermo-electromagnetic properties of coated superconductor magnets as the secondary of a synchronous linear motor based on a two-stage segregated model approach using a unidirectional coupling from motor model to coated superconductor magnets model. Two types of the working conditions for a motor, locked-mover and starting situation, were analyzed and we found that, the ac losses and temperature increase more quickly after traveling magnetic field stimulates the coated conductor magnets for both the conditions above, which is crucial to the design of the cooling system for a motor, and the temperature distribution in coated conductor magnets depends on the moving direction of traveling magnetic field.

ABSTRACT. The purpose of this paper is to investigate the flux leakage effects in the transverse-flux magnetic gear (MG), in which two typical flux leakage phenomena are identified and analyzed, namely, end leakage and fringing leakage. By using the JMAG 12.1 software, the three-dimensional finite element analysis (3D-FEA) modeling surrounded by some blocks with setting as different material properties are built to comparatively analyze the flux leakage effects. Based on the established 3D-FEA models, the influence of main dimension parameters on the stall torque in the analyzed transverse-flux MG with taking the flux leakage effects into account compared with that without flux leakage effects are studied. And the torque-angle characteristics comparison is also conducted. The results show that there is a significant reduction for the torque capability due to the flux leakage effects in the analyzed transverse-flux MG.

ABSTRACT. The permanent magnet eddy current loss of permanent magnet will result in the increase of permanent magnet temperature and the change of magnetic properties, and the efficiency and performance of the motor will be reduced. In this paper, the permanent magnet eddy current loss of the generator is analyzed by finite element method, and the curves of permanent magnet eddy current loss under different generator parameters are given. The results show that the optimization of generator parameters can effectively reduce eddy current losses. The theoretical basis for the optimal design of the generator is provided.

ABSTRACT. The high-speed rotor supported by active magnetic bearings (AMBs) has been applied to air blower and gas compressor progressively for their advantages of high power density, low loss and small volume. In order to improve the modal of the multi-ring configuration rotor, the temperature gradient method was proposed. This method can reduce the axial gap width to increase the rotor stiffness and to further increase the rotor modal. Firstly, the influence to the first order bending frequency of the rotor caused by the axial gap was detailed analyzed. Secondly, the realization method based on an actual high-speed maglev rotor was designed and analyzed. Finally, the axial gap width comparison experiment was carried out by two rotors and the first order bending frequencies were comprised by the sweeping frequency method respectively. The experiments validated the feasibility and validity of the proposed method.

ABSTRACT. Magnetic geared linear motor (MGML) realizes a high thrust force and downsizing. This paper proposes a new design of MGLM. In addition, two designs of magnetization direction, axial direction and radial direction, are compared. In this paper, MGLM with different magnetization direction is analyzed. From the analysis result, suitable magnetization direction is discussed.

ABSTRACT. In order to fix the problems for high speed EMU that non-uniform temperature rise exist in axial and circumferential directions while running asynchronous traction motor. We establish three dimensional solid models to analyze electromagnetic filed and fluid solid coupling of motor. And we make the comparison between numerical results of finite elements and experimental results. Based on that, we adjust circumferential distribution form and structure of axial vent of stator and rotor to research the relationship between the changes of key components inside the motor and temperature rise. We find a ventilation structure scheme of relative balance between axial and circumferential temperature of motor and provide a reference strategy of temperature rise design of motor with forced ventilation.

ABSTRACT. Direct-type lead exit for UHV transformer was designed. Electrical field calculation and analysis of the lead exit were performed with finite element method, and then the insulation structure was optimized. The stress distribution and displacement of the lead exit under vibration condition were calculated. The reliability of the lead exit was verified by electrical test and vibration test.

ABSTRACT. This paper focuses on investigating the influence of design parameters on characteristics of external rotor permanent magnet synchronous machine (PMSM). Under the constraint of torque density, the effect of pole number and teeth height ratio on copper and iron losses, motor efficiency and winding temperature rise are studied. Finally, to meet the need of a new micro-EV C11CB by Beijing Automotive Industry Corporation (BAIC), two optimal PMSMs are built the simulation models, one is optimized for maximum motor efficiency, and the other is designed for minimum winding temperature rise. The characteristics of two optimal PMSMs are analyzed by the finite element analysis (FEA), and compared with analytical results.

ABSTRACT. Magneto-Rheological Elastomers (MREs) materials are used in a variety of devices as smart material. However the application of this material is limited to damper or vibration absorber because of lacking understanding of its magnetic properties, such as magnetic hysteresis and magnetostrictive properties. This paper systematically presents our recent study on measurement, modeling and simulation on magnetostrictive properties of MREs materials. The measurement was completed by using a 2d magnetic field excitation equipment with an MRE sample container. A large-scale atomic/molecular massive parallel simulator (LAMMPS), which combined Stoner-Wohlfarth hysteresis model, was employed for simulation of the magnetostrictive and magnetic hysteresis properties of MRE material. The results will be useful for modeling of magnetostrictive properties of MRE materials.

ABSTRACT. This paper presents works about the measurement and simulation of hysteresis characteristics on soft magnetic composite material. By using the three dimensions magnetic properties tester developed in University of Technology Sydney, the magnetic properties of a kind of soft magnetic composite material under alternating field and rotational field have been measured. Meanwhile, based on the magnetization mechanisms, a hysteresis model is introduced to simulate the hysteresis characteristics of soft magnetic composite material

ABSTRACT. Ironless axial-flux machines present an attractive machine design avoiding core losses. The design challenge with these machines is to find a suitable winding arrangement that does not generate additional losses in return. In a novel approach of using a ceramic plate winding carrier, this paper discusses the design considerations for a four-pole, high speed axial-flux machine winding. The work compares winding properties with respect to manufacturing suitability and presents an implementation. Furthermore, the paper proposes additional improvements for the winding design.

ABSTRACT. Based on the structure characteristics of the amorphous alloy transformer with runway shape winding, the paper proposed the leakage-stress-acoustic coupled calculation model to calculate the electromagnetic force-vibration displacement-noise of the load winding. It also researched the vibration characteristics of the amorphous alloy transformer with runway shape winding and analyzed the influence factors of winding vibration noise. The validity of the model is verified by building test system and comparing with the calculated results.

ABSTRACT. In order to control and reduce the electromagnetic vibration of motors, the stresses in motor cores, which are the inherent reason of vibration, should be computed accurately. Electromagnetic stresses in motor cores are mainly generated from magnetostrictive effect of silicon steel and Maxwell electromagnetic force between the stator and the rotor. So far, stress analysis on motor cores was based on one-way coupled numerical method, which did not consider the influence of stress on magnetic properties of the core material. Thus, multi-group magnetostriction and magnetization characteristics curves of non-oriented silicon steel sheet under different tensile and compressive stresses are measured firstly to support the computation. Then an electromagneto-mechanical two-way coupled numerical model for motors considering magnetostrictive effect and electromagnetic force effect is proposed and stress distribution of motor cores is calculated. From the computed results, it can be seen that electromagnetic stress and magnetostrictive stress show different contributions to motor vibration at different locations, which provides a theory basis for further analysis of vibration and noise reduction.

ABSTRACT. For ferrites cores in high frequency transformer, the real excitations waveforms are often non-sinusoidal. Thus, it is of great significance to study the magnetic properties of soft ferrites cores under non-sinusoidal excitations. In this paper, the high frequency magnetic properties of soft ferrites cores are measured by exerting several typical non-sinusoidal excitations in high frequency transformer such as SPWM wave, rectangular wave with adjustable duty ratio and symmetric wave with dead time, which are the real excitation waveforms of high frequency transformer cores. The core loss of soft ferrites cores under different excitations and frequencies are calculated and compared. This study can offer a reference for the design and optimization of high frequency transformer.

ABSTRACT. The efficiency of motor can be increased by optimizing stator, rotor slot design and using more materials, but there is limit within the narrow space of motor frame. Because of limited dimension, high quality material can be adapted, such as copper bar instead of aluminum bar, or low core loss Si-steel. However, adapting low core loss electrical steel does not always mean reduction of core loss. Because of non-linearity of B-H and B-Loss data, applying high grade material could unintentionally increase losses. It is important to consider magnetic flux density and harmonics core loss when applying low core loss electrical steel. In this paper, losses of motor are analyzed with respect to the various electrical steel. Using the finite element analysis (FEA), core loss and stray load loss are calculated with B-H, B-Loss data of electrical steel. Also, test results of 440V, 4pole, 15/30kW induction motor are also provided.

ABSTRACT. Core losses of nanocrystalline alloy high frequency transformer (HFT) are calculated by adopting the finite element method with magnetic hysteresis effects considered. A normal Preisach model is used to represent the magnetic hysteresis during the numerical simulation. A dynamic circuit model of laminated magnetic cores for high frequency operation is used to calculate the core losses. Results are compared between finite element method (FEM) and magnetic circuit method to prove the accuracy of finite element method, and it also provides a more accuracy way to compute the core loss of magnetic cores.

ABSTRACT. In this paper, conventional MG rotor, which has surface mounted permanent magnet magnetic gear (SPMMG), and consequent-pole permanent magnet magnetic gear (CPMMG), which has high torque density, is proposed. For analysis, output characteristics of SPMMG and CPMMG are analyzed considering torque density according to magnet usage and MG volume, as well as core loss and irreversible demagnetization. In addition, various pole pieces are adopted to analyze output characteristics. Analysis on SPMMG and CPMMG is verified by 2D and 3D finite element analysis(FEA).

ABSTRACT. This paper proposes a new axial flux permanent magnet (AFPM) motor, whose stator is composed of laminated steel and Soft Magnetic Composite (SMC) material. AFPM motor is a preferred solution compared to radial flux (RF) machines for electric vehicles and industrial equipment because of its high torque density and slim disk-shaped size [1]. However, the manufacturing cost of conventional AFPM is greater than RFPM due to its fundamental structure. The hybrid construction of the stator core presented in this paper reduces the manufacturing complexity and fabrication cost of AFPM. In this paper, a novel AFPM motor with hybrid stator core is proposed and designed for electric bicycles. The characteristics of the developed motor are analyzed using the 3D Finite Element Analysis (FEA) to verify the advantages of the proposed AFPM motor. Finally, a prototype of the new AFPM motor is manufactured and tested in the laboratory. Recently, Axial Flux (AF) machines have been a focus of researchers due to its inherent ability of high torque density and small disk-shaped size. However, despite the enormous advances in fabrication techniques, it is still a challenge to manufacture the AFPM motor with high torque density and a reduced cost simultaneously compared to RFPM [2]. AF machines can be constructed with strip wound laminations however the teeth alignment becomes less reliable during the process. Therefore, many researchers have studied to develop the AFPM using a different type of material i.e. SMC instead of laminated steel. SMC is characterized in the literature as having lower performance and higher material cost compared to steel laminations [3]. However, it can make the machine parts as a single component reducing the fabrication complexity. In this paper, we proposed a novel AFPM motor having a hybrid stator core consisting of SMC and steel laminations for electric bicycles. The hybrid structure of the proposed AFPM tends to reduce the fabrication complexity and cost while maintaining a good overall performance.

ABSTRACT. In this paper, we design a controller using H infinity control theory and examine its frequency fluctuation suppressing performance in a small-scale system composed of real machines. The introduction of distributed power sources such as photovoltaic power generation and other sources of natural energy into smart power grids has been increasing in recent years. However, given that the amount of power generated by these distributed power sources depends on dynamic environmental factors, it is difficult to supply stable electric power. For this reason, in frequency fluctuations may occur in small-scale power systems in which a large amount of distributed power sources are introduced, leading to system performance degradation or even device failures.

ABSTRACT. This paper presents the analysis and experimental verification of applying Selective Harmonic Elimination (SHE) technique for cascaded half-bridge multilevel inverters. This technique is used to eliminate the low order harmonics and minimize the total harmonic distortion. The adopted inverter is fed from PV modules throughout a dc-to-dc converter to regulate the inverter input voltage. Genetic algorithm is used to calculate the suitable switching angles that guarantee elimination of a specified number of harmonics and minimize the total harmonic distortion when using a proper objective function. A laboratory system is built based on a data acquisition controller. Experimental results for a single phase 7-level inverter show a satisfactory successful application of the system when feeding motor load and 11-levels for static loads.

ABSTRACT. Recently, multilevel inverters have become more attractive for researchers due to low total harmonic distortion (THD) in the output voltage and low electromagnetic interference (EMI). This paper proposes a three-phase cascaded H-bridge quasi switched boost inverter (TCH_qSBI). As a result, cost, weight and size are reduced. Furthermore, the dc-link voltage of each module is controlled by individual shoot-through duty cycle to get the same values. Therefore, the proposed inverter solves the imbalance problem of dc-link voltage in traditional inverter. This paper shows a control strategy for the proposed inverter and the simulation results are to verify the operating principle of the three -phase cascaded H-bridge quasi switched boost inverter.

ABSTRACT. A double-Galfenol-rods magnetostrictive transducer is designed and manufactured. This device can simultaneously generate output displacement in axial and radial direction. The output characteristics of the transducer can be analyzed by structural dynamic model. It is found that the radial resonance frequency is 1000 Hz when the two driving coils of the transducer are connected to opposite current, and the output vibrating peak values in radial and axial directions are 52 μm and 7.5 μm, respectively. The output characteristics were studied by experiments. Comparisons between the experimental and calculated results show the validity and practicability of the model. Moreover, the research can effectively investigate the effects of the bias magnetic field, excited magnetic field, and frequency on the output amplitude.

ABSTRACT. In order to increase the weighted efficiency of the photovoltaic micro-inverter, this paper proposes a flexible topology DC/DC converter as the former stage in the micro-inverter. The flexible converter includes two operation modes, which are improved dual-switches forward mode and full-bridge mode, respectively. The analysis is verified by the experimental results from a 300W prototype.

ABSTRACT. The development of industries around the world has led to the use of large amounts of electricity in industry and homes. However, due to the large volume of ESS parts, the distribution of ESS is slowly proceeding. Therefore, this paper try to make the transformer and the reactor which are important part of ESS into one body in order to minimize the volume compared with the conventional one.

ABSTRACT. Output voltage of renewable energy resources, such as fuel and solar cells, varies widely with load and environmental condition, so a DC-DC converter should be suitable for wide input-voltage range application and be with low input ripple current. An integrated boost three-phase half-bridge converter is proposed. The boost and three-phase half-bridge converters are integrated to reduce number of switches. As input inductor exists, the input ripple current is low. The output filter frequency is three times of the switching frequency, so the output filter can be reduced. Operating principle is illustrated. Simulation results verify the theoretical analysis of the converter.

ABSTRACT. Abstract —Compared with the traditional L filter, LCL filter is more suitable for the three-phase grid-connected inverter in high power occasion, with its lower cost and better high-order harmonic attenuation. However, the LCL filter is a three order system without damping, which is easy to produce resonance. In order to suppress the resonance, passive damping is proven as a robust stabilizing technique for LCL-filtered voltage source converters. This paper proposes a novel passive damping LCL filters with a coupled reactor which can obtain the similar filtering performance with reduced power loss and improved efficiency robustness. In this paper, comparison and analysis of this passive damper with LCL-filtered VSCs are illustrated. The passive method is verified through simulation studies carried out on a three-phase grid–connected voltage source converter. For verification, experimental testing has been performed with the results obtained matching the theoretical expectations closely.

ABSTRACT. Realization of Vector Control (VC) for Doubly Fed Induction Generator (BDFIG) system requires the exact synchronous rotating d-q transformations. However, such a d-q transformation is complicated since a BDFIG contains two stator windings and one rotor winding. In this paper, a d-q transformation with self-correction is proposed to eliminate the detection of the rotor position and the stator displacement angle. The voltage regulation is realized in the d axis via a dual-loop control; while the self-correction is realized in the q axis via the other dual-loop control. With the self-correction, the exact d and q components can be obtained and the high performance VC can be ensured. Simulation and experimental results are carried out to verify the control strategy.

ABSTRACT. Single-stage buck-boost gird-connected inverter is widely used in distributed generation systems because of low cost and high efficiency. However, shoot-through problem exists, so reliability of the system is reduced. In addition, output voltage of renewable energy resources varies widely with load and environmental condition, so voltage stress of switches is high in wide input-voltage range application. An improved single-stage buck-boost gird-connected inverter is proposed. It can operate at buck and boost modes, so it is suitable for wide input-voltage range application. Operating principle is illustrated. Simulation results verify the theoretical analysis of the inverter.

ABSTRACT. This paper discusses the power gain (PG) and loss under partial shading conditions (PSC) by series voltage compensation. Partial shading in a PV system creates multiple maximum power points (MPP) which causes mismatch losses. To overcome the partial shading effect, series voltage compensation methods have been suggested. Theses methods can remove the multiple MPPs as the result for mismatch loss compensation. However, these methods require additional power to compensate the mismatch loss; but they do not consider the gain or loss between the input power required for compensation and the increased output power obtained after compensation. This paper analyzes the PG resulting from series voltage compensation under PSC and the condition for maximizing the PG, and verifies that PG exists.

ABSTRACT. To solve the issues of the open-loop control accuracy in a proton exchange membrane (PEM) fuel cell power conditioning system (PCS) with active clamp push-pull DC/DC converter for input current ripple reduction, a novel closed-loop digital-controlled method is proposed. The proposed PEM fuel cell PCS consists of a high-efficiency high-step-up current-fed resonant push-pull DC/DC converter and a half-bridge inverter. A fully digital-controlled strategy in the active-clamped circuit is employed to reduce the voltage spike and low frequency current ripple (LFCR) on the power switches for improving the lifespan of PEM fuel cell and raising the system reliability. By using the closed-loop current ripple reduction control, the LFCR is further reduced. A 300 W prototype is implemented and tested. Experimental results show that the minimum efficiency at full load is about 94.8% and the ripple current is less than 1.2% of the rated input current.

ABSTRACT. Solar energy generation requires efficient monitor-ing and management in moving towards technologies for net-zero energy buildings. This paper presents a dependable control system based on the Internet of Things (IoT) to control and manage the energy flow of renewable energy collected by solar panels within a micro grid. Data for optimal control include not only measurements from local sensors but also meteorological information retrieved in real-time from online sources. For system fault tolerance across the whole distributed control system featuring multiple controllers, dependable controllers are developed to control and optimize tracking performance of PV photovoltaic arrays to maximally capture solar radiation and maintain system resilience and reliability in real time despite failures of one or more redundant controllers due to a problem from communication, hardware or cybersecurity. Preliminary experimental results have been obtained to evaluate the validity of the proposed approach.

ABSTRACT. Dual-stator brushless doubly-fed generator (DSBDFG) make full use of the inner cavity space, it has the advantages of brushless doubly-fed motor (BDFM) and solve the problem that power density of BDFM is low. Based on the design principle of brushless doubly - fed generator, this paper designs the main parameter of a 50KW DSBDFG for Wind Turbine. The electromechanical energy conversion of the DSBDFG is based on the modulation effect of the rotor. So this paper analysis and simulat of the both inside and outside rotor under different condition.

ABSTRACT. This paper proposes a dual-stator HTS reluctance-rotor brushless doubly-fed wind generator, which owns two stators and one salient reluctance rotor sandwiched between two stators. Two sets of windings with different pole-pairs locate on the two stators, separately, named as control winding and power winding. The modulation of reluctance rotor makes two sets of windings couple with each other. The material of control winding is HTS, while that of power winding is common copper. The topology and operating principle of the proposed generator are described, and the basic performances are analyzed by the 2d-FEM.

ABSTRACT. The electrostatic precipitator (ESP) system depends heavily on the three-phase IGBT intelligent inverter high voltage (HV) power supply. To improve the dynamic responses of ESPs during the event of flashovers and back corona, a magnificent nonlinear-controll technology called hysteretic current-mode control (HCMC) concept is proposed based on the working characteristics of ESPs. This method adapts the parameters to the load conditions of ESPs dynamically and accurately. It can also greatly improve the vibrant behavior of HV power supply with a fast variation of input voltage or load current according to different working conditions. PSIM simulation results and the physical application waveforms of JiNan Steel Group demonstrate that the valid values of current and voltage can be increased by this fast automatic adjustment control and the average corona power can also be increased to improve the ESP efficiency significantly.

ABSTRACT. Many islands in China are far from the mainland and electricity is difficult to cover or the cost is high, due to this issue, the wind energy, wave energy and solar energy can be used to meet the demand of island power supply. However, the energy density of these renewable energy sources is low and the stability is poor, which may cause power supply instability. To deal with this issue, a multi-energy hybrid power system based on wave and wind energy is introduced to improve power supply stability and power quality. Based on wave energy and wind energy, a multi-energy hybrid power system is established in this paper, and the whole system model and the control strategy of wind generator and direct-drive wave generator and the grid-side inverter control strategy are analyzed and deduced. The PSCAD simulation model of the whole system is built, and the simulation analysis is carried out. The results show that the wind energy and wave energy can be used to generate electricity, the output power is stable and power tracking is achieved.

ABSTRACT. This research newly introduces an equivalent electrical-circuit model (ECM)-based state-of-charge (SOC) monitoring of a lithium-iron phosphate battery (LiFePO4) at various temperatures. Particularly, because of inevitable hysteresis phenomena, the revised ECM including two open-circuit voltages (OCVs) with discharging/charging condition is considered and well applied to the dual extended Kalman filter (DEKF). In order to know the temperature-dependent SOC performance in the DEKF, this research selected some temperatures with a range of 0-50°C. This research has been extensively verified by experimental results of a LiFePO4 cell with a rated capacity of 14Ah.

ABSTRACT. There are many software can be carried out simulation of photovoltaic (PV) system such as PSIM and Matlab. Those software have their own advantages in the simulation of PV system. This paper proposed a joint-simulation of a stand-alone PV system based on PSIM and Matlab to achieve the maximum power point tracking (MPPT) of PV cells and the stability of PV system. In this paper, the main circuit is built in PSIM and the control circuit is built in Matlab. The results of simulation show that the method can make PSIM and Matlab give full play to their advantages in power conversion and control algorithm.

ABSTRACT. Large-capacity energy storage generator with short-term rapid conversion of mechanical energy into electrical energy characteristic, is often used as a pulse power supply for short-term and high-power load occasions. The rotate speed will rapidly decline, when large-capacity energy storage generator releases large energy to a DC load, and the power of the load will approximately linearly increase in a short time. In order to maintain voltage stability of the DC side, the excitation control system needs to have the characteristic of fast and strong excitation. For the sake of improving the response speed of the excitation control system, the principle of feed-forward control is introduced based on voltage and current double closed-loop control. This paper shows derivation method of feed-forward control equation by space-time phasor diagram of synchronous generator, and feed-forward control parameters solution method is given. The experimental results verify the effectiveness of the excitation control strategy.

ABSTRACT. This paper proposes an improved predictive torque control based on stator flux vector. By investigating the relationship among torque, the reference of stator flux magnitude and the phase angle of the stator flux, the reference vector of stator flux is designed. The desired deadbeat voltage vector is calculated based on the time delay compensation, which relieves the big calculation effort of conventional deadbeat direct torque and flux control. The two voltage vectors that adjacent to the reference of stator voltage vector are the candidate voltage vectors for next control period. A cost function consisting of tracking error of stator flux vector is then designed and the optimal voltage vector and its duration are determined simultaneously. Experiment tests were carried out and the results validate the effectiveness of the proposed method.

ABSTRACT. The overall efficiency of a marine electrical power system is reliant on its condition monitoring algorithm. A competitive system has quick fault detection functionalities and maintenance enabled. This paper examines existing method to develop an online approach for superior detection of eccentricity fault in surface-mounted permanent magnet synchronous motors, in a marine propulsion setting. Detection of eccentricity fault is best detected by monitoring the vibration, air-gap flux density and induced emf. With the introduction of search coils, the methodology’s aim is to obtain the induced emf voltage in the air-gap . Search coil were found to decisively segregate fault symptoms appearing from other asymmetric interruptions such as load imbalance and input unbalanced voltage. Vibration in the motor was monitored by placing sensors on the stator yoke to detect vibration during various levels of eccentricity fault. In this research, eccentricity fault was simulated in 2D finite element analysis (FEA) platform using Ansys Maxwell and Ansys Mechanical. The simulated results shown in the paper shows a robust online based fault diagnosis method applicable for marine propulsion motors.

ABSTRACT. This paper presents an improved model predictive torque control (MPTC) for permanent magnet synchronous motor (PMSM) drives. The proposed MPTC is different from the conventional MPTC in applying two voltage vectors in every control period. The duty ratio is firstly calculated using a simple but effective method with the consideration of the one-step delay. The cost function is then modified by incorporating the duty ratio, and thus to calculate the optimal voltage vector applied in every sampling period. Test results show that the proposed control strategy contributes to lower torque and flux ripples compared to the existing MPTC.

ABSTRACT. Considering that the magnetic performance of the ferrite magnet is relatively weak, an interior ferrite Permanent magnet synchronous motors (PMSM) with reliable flux-focusing structure is presented in this paper.An optimal maximum torque per ampere (MTPA) control strategy is proposed, which fits the variation of core saturation and winding inductances.In order to simplify the computation complexity and to obtain a good performance over the full load range, an optimal three-segmented control strategy is proposed.Analysis results show that the optimized motor and the control strategies can perform well under various loads.

ABSTRACT. with the increasing capacity of grid connected wind farms, the influence of wind power to stable operation of an electric power system is becoming more and more important. In order to analyze the power and voltage characteristics of all-dc offshore wind farm, a multimachine representation dynamic equivalent method based on the fuzzy clustering algorithm is proposed.First,indicators whichcan characterize the power and voltage performance of a permanent magnet synchronous generator (PMSG) are researched.Second, a fuzzy C-means (FCM) clustering algorithm is first applied tothe modeling of all-dc offshore wind farm.PMSGs are divided into groups byanalyzing the indicator data with FCM. Finally, PMSGs of thesame group are equivalent as one PMSG to realize the dynamicequivalent modeling of wind farm with PMSG. Simulation resultsdemonstrated that the established dynamic equivalent model canreflect the power and voltage dynamic response characteristics of all-dc offshore wind farm with PMSG effectively.

ABSTRACT. The unpredictability and variability of the wind makes the Pitch Control System (PCS) of the wind turbine always operates under the changing conditions, which may cause large dynamic response deviation. A novel control scheme based on that the feed-forward control with differential feedback compensation is proposed in this paper to overcome the aforementioned problems. The feedback differential compensation could significantly decrease the overshoot of the servo system but with the loss of response speed. The overshoot of the position and speed of the Permanent Magnet Synchronous Motor (PMSM) could be effectively reduced by introducing the control of feed-forward differential and adaptive regulation based on the position error, it can ensure the premise that feedback differential is effective to reduce the overshoot, and offset its speed inhibition. Furthermore, a better position tracking performance could be achieved as well. Extensive test have validated the effectiveness of the proposed control method.

ABSTRACT. Abstract — In this essay, the relationship between the load and the performance of uncontrolled discharge process of the flywheel system had been studied. On the basis of the above study, the influence of the load and the control circuit on the constant voltage discharge performance of system was analyzed. The results could provide a reference for the design of high performance flywheel energy storage system.

ABSTRACT. This paper investigates the flux density and radial force spatial harmonics in large salient pole synchronous hydrogenerators. Vibration due to magnetic forces are mainly caused by low order harmonics in the airgap flux density distribution. The influence of winding layout and airgap length on the lowest order radial force component are analysed. Airgap flux density and radial force density distributions of three different generators are computed using finite element calculations. The flux density components that contributes to the lowest order force component, and the source for these harmonic components, are investigated. It is found that reducing the airgap length leads to a less than proportional increase in the lowest order radial force component. A rearrangement of the winding layout is found to be an effective method for reducing the lowest order radial force component.

ABSTRACT. The evaporative cooling system for wind power generator inclines at an angle of 3～5 degrees. Due to the special structure, it forms a liquid-gas two-phase self-circulation. Two-phase flow self-circulating system is a typical nonlinear dynamic system. So it is important to study the nonlinear characteristics. In this paper, the nonlinear characteristics were studied through theoretical analysis and experiment, according to the design parameters of 2MW evaporative inner cooling wind power generator.

ABSTRACT. This paper proposes an output power smoothing control strategy for the wind farm without any other energy storage devices (ESS), which is based on the allocation and control of the wind turbines (WT). The wind turbines in the wind farm are divided into control wind turbines (CWT) and power wind turbines (PWT) separately while playing different roles. The simulation model of the wind farm based on the proposed control strategies is built and the efficiency of the proposed strategy is verified by the simulation results.

ABSTRACT. As a kind of green energy, the wave energy exhibits high energy density, abundant global reserves, extensive application and high predictability, which is paid more and more attention. This paper proposes a PM-assisted reluctance synchronous linear generator (PMRSLG) for wave energy generation. It is optimized for obtaining not only high thrust, high efficiency and low cost but also high thrust ripple and low power factor. To weaken the longitudinal end effect and reduce thrust ripple, the effective solutions of adding assistant teeth and skewed slot are put forward. Finally, the performance of PMRSLG is investigated.

ABSTRACT. Modern developments in advanced material technology has produced new magnetic materials such as Nanocrystalline metals. These materials are of interest in many applications dealing with high frequencies, such as in high-speed machines. However, such metals are typically found to have low mechanical strength and are found to be brittle. In order to manufacture magnetic devices with such new materials, it has to be reinforced with a mechanically strong structure. One option is to incorporate core materials such as Si-steel or ferrite sandwiched together with the brittle material resulting in a multi-magnetic material laminated core (MMLC). In this research, BH characteristics of the MMLCs are analyzed. The equivalent mathematic modeling is presented. The final paper will also present the loss characterization under different frequencies for MMLCs.

ABSTRACT. The amplitude of magnetic permeability and electromagnetic losses are the basis of application of Fe-Ga alloy. Different magnetic hysteresis curves of Fe-Ga alloy are measured using AMH-1M-S dynamic testing system under different conditions, which are the same saturated magnetic field and the same maximum saturation flux density under different frequencies. The complex magnetic permeability, medium energy storage and magnetic losses are analyzed. Electromagnetic loss increases and energy storage of material reduces with increasing of frequency. Hysteresis loss increases linearly with increasing of frequency, the eddy current loss increases dramatically, and the residual loss increases rapidly. The experimental results of this paper can provide guidance for the design of high frequency Fe-Ga ultrasonic transducers.

ABSTRACT. In this paper, a novel stator structure with axially tapered stator tooth tip is proposed to mitigate cogging torque and reduce the machine back EMF harmonics. Furthermore, the stator tooth tips are specifically designed to provide balanced axial electromagnetic force. In order to realize continuous variation of stator tooth tip widths, the soft magnetic composite (SMC) material is used for the stator core. It is theoretically demonstrated that the cogging torque of the new structure can be reduced greatly compared with the conventional stator structure. Finally, the theoretical analysis results are confirmed by the finite-element analysis (FEA) results. A prototype has been designed and under manufactured.

ABSTRACT. Magnetic properties of ferromagnetic materials at high frequency are important features which should be measured accurately. A novel 2-D magnetic properties tester for ferromagnetic material specimen has been designed and constructed. The 2-D magnetization structure is combined by four multilayer excitation windings, and each winding is divided into three sections to extend the frequency range. The H coil is wound and covers the B coil, which is embedded evenly in the epoxy resin. Accurate simulation and comparison was made to verify the new structure is more suitable for measurement. Moreover, magnetic flux path and magnetic field distribution are obtained by finite element simulation.

ABSTRACT. Standard measurement method and equipment for soft magnetic materials can’t measure the magnetic parameters in deep saturation. Using the measurement equipment for hard magnetic materials, which has strong excitation ability, the parameters in deep saturation can be measured, whereas the measurement error is very large. Based on the analysis of the error sources, this paper proposes an approach to improve the measurement accuracy. The error is caused mainly by the non-uniformity of field inside and outside the test sample, which makes it difficult to deduce the internal values of B and H from outside measurement signals accurately. The approach presented is forming a matrix of relatively accurate internal-external relation by using numerical simulation technique first, then based on the matrix the iterative optimization method is used to determine the internal B and H from the external measured values. The approach manages to obtain accurate values of B and H at the same point inside the sample, which can reflect the material property, from the external measurement results, so that accurate hysteresis loop can be provided.

ABSTRACT. There has been a revived and growing role for electrical machines and drives across a wide range of applications. Such applications include, hybrid/electrical traction applications, aerospace applications, and renewable energy. All these applications present different set of requirements and challenges. The common trend is that there is a need for higher-performance electrical machines in terms of higher power/torque density, and higher efficiency while keeping cost under control. There has been a lot of work done around coming up with novel machine topologies, optimizing more conventional topologies as well as improved thermal management schemes. Like many other areas of engineering/research, advanced materials can play a key role in opening up the design space for electrical machines leading to a step improvement in their performance. This paper will present a comprehensive overview of some of the key advanced materials that are either recently developed or under development and their potential impact on electrical machines.

ABSTRACT. Conventional LC filters cannot compensate effectively harmonics due to non-linear loads in a grid-connected photovoltaic (PV) system. This work presents a three-phase voltage-fed shunt active power filter to mitigate the harmonics in which the filter control system focuses on generating reference source current for compensating harmonic effects from non-linear loads. The use of such filters for a grid-connected PV system will be introduced in the study.

ABSTRACT. In this paper, a novel supply voltage harmonic mitigation method using a simple DVR without harmonic detection is proposed. In contrast to the conventional DVRs control methods, the proposed method realizes two independent control objectives at fundamental and harmonic frequencies without couplings, with the adoption of the proposed voltage controller with two independent inputs focusing on different frequency regions. The fundamental voltage control is adopted to compensate voltage sags. The harmonic control loop compensates the load side harmonic voltage simultaneously without any harmonic extraction. Verification results are provided to validate the correctness of the proposed system.

ABSTRACT. This paper presents a voltage balancing method for a symmetrical hybrid nine-level inverter with reduced voltage sensors. A capacitor voltage estimation method is proposed based on phase-shifted PWM by only measuring the total DC-link voltage and the multilevel phase voltage. Simulation and experimental results are presented to demonstrate this method.

ABSTRACT. In this paper, zero-voltage-transition(ZVT) interleaved bi-directional low voltage DC-DC converter(IB-LDC) for a mild-hybrid electric vehicle is proposed. And, the steady state analysis and operation principles of IB-LDC are introduced by mathematical analysis. To decrease loss by high current of auxiliary inductor, switching frequency modulation is employed depending on output current. Finally, a 600W laboratory prototype is implemented to verify proposed converter.

ABSTRACT. This paper proposes an current PR+repeat control with voltage notch filter for H6 topology based PV inverter subject to grid voltage harmonics. The mathematical model of the H6 inverter control system is established, and the current harmonics is analyzed. A compound harmonics suppression method based on PR+repeat current controller and DC voltage notch filter is designed. The controller parameters are tuned by the root-locus analysis method. The experiment is studied with a 10 kW H6 topology based PV inverter platform, which shows good current harmonics suppression performance of the designed method.

ABSTRACT. In order to increase the output voltage levels and reduce the isolated DC sources, a symmetrical hybrid nine-level inverter for high speed motor drive applications is presented in this paper. Each phase of this inverter is composed of a five-level DC/DC converter cell and an H-bridge cell. The DC/DC converter is operated at high frequency with low voltage devices and the H-bridge is operated at fundamental frequency with high voltage devices. Phase-shifted PWM is used to control this inverter. However, the line voltages include intervals that switch between nonadjacent voltage levels, deteriorates the harmonic performance. This paper proposes an improved PSPWM technique for the symmetrical hybrid nine-level inverter to improve the quality of the line-to-line voltages. Simulation and experimental results are presented to demonstrate the feasibility of this topology and control method.

ABSTRACT. A DC bus voltage ripple suppression method based on super-capacitor (SC) was proposed under unbalanced load. Firstly, the influence of unbalanced load on DC microgrid was analyzed. And then, depending on the mathematical model of the SC compensation device, current control strategy of the SC was designed using the sliding mode control (SMC) to precisely track the pulsating current. Furthermore, parameters design of the SC compensation device was given considering the most serious condition of unbalanced load. Finally, simulations were carried out to verify the effectiveness of the proposed control strategy.

ABSTRACT. Multi-area economic emission dispatch (MEED) problem provides an optimal schedule for active power of generators and interchange active power between different areas by considering the operational limitations such as balance between generation and consumption, tie line limitation, generators output constraint, and transmission losses. In this paper, a hybrid method based on shuffled frog leaping algorithm (SFLA) and particle swarm optimization (PSO) has been presented to achieve better solution to the underlying problem. Furthermore, the stochastic nature of energy consumption has been modeled as uncertainty source by scenario reduction technique, to achieve the results which are closer to the real condition.

ABSTRACT. In a DC microgrid, the loads are interfaced through power electronic converters. These loads behave as constant power loads (CPLs) when tightly regulated. CPLs have negative incremental impedance which may cause instability. Consequently, the stability analysis is very important to ensure the whole system stable, especially in island mode. This paper investigates the large signal stability of the DC microgrid, considering the effects of the CPLs and the storage system. Based on mixed potential theory, the large signal stability criteria are derived, and quantitatively describe the relationship between system parameters and the stability. The proposed criteria are simple and straightforward. The power of the storage system and the negative incremental impedance of the CPLs are both taken into account to ensure stability. The proposed region of asymptotic stability around the stable equilibrium point is large enough, and validates the effectiveness of the given stability criteria. The simulation and experimental results also indicates the criteria could guarantee the whole system stable during large disturbances.

ABSTRACT. Abstract--In order to meets the selectivity and the speed of requirement DC protections, this paper proposes a new DC protection scheme for DC substation systems. This scheme is developed based on the single-ended natural variation characteristics of DC current and its first and second derivatives under fault transients. It extracts the transient characteristic difference between the internal fault and external fault to realize the fault identification. The proposed scheme can identify internal fault or external fault quickly without communication to satisfy the speed, reliability and selectivity requirements of the protection. Testing on PSCAD/EMTDC was carried out to verify the feasibility and superiority of the proposed scheme.

ABSTRACT. In Constant speed constant frequency (CSCF) AC power supply system, generator output constant frequency and constant voltage AC power by connecting engine with constant speed transmission device (CSD). However, CSCF has many disadvantages, such as complex structure, heavy weight, high cost and low energy conversion efficiency. By eliminating CSD in CSCF and taking output voltage and output frequency as feedback quantities, this paper proposes a dual excitation control method to achieve the same effect as CSCF power source. From the perspective of engineering applications, this improved method can greatly reduce the weight of aviation power generation system. It has a simple structure and can cut down the cost of power system operation and maintenance. Simulation results show that the method of dual excitation control presented in this paper is effective, and it also provides a new idea for the improvement in aviation power generation system.

ABSTRACT. The purpose of this paper is to determine the optimal location, size and controller parameters of Static Var Compensator (SVC) to simultaneously improve static and dynamic objectives in a power system. Four goals are considered in this paper including transient stability, voltage profile, SVC investment cost and power loss reduction. Along with the SVC allocation for improving the system transient stability, an additional controller is used and adjusted to improve the SVC performance. Also, an estimated annual load profile including three load levels is utilized to accurately find the optimal location and capacity of SVC. By considering three load levels, the cost of power losses in power system is decreased significantly. The combination of the active power loss cost and SVC investment cost is considered as a single objective to obtain an accurate and practical solution, while the improvement of transient stability and voltage profile of the system are considered as two separate objectives. The problem is therefore formulated as a multi-objective optimization problem, and Multi Objective Particle Swarm Optimization (MOPSO) algorithm is utilized to find the best solutions. The suggested technique is verified on a 10-generator 39-busbar New England test system. The results of the nonlinear simulation indicate that the optimal sizing, location and controller parameters setting of SVC can improve significantly both static and dynamic performance of the system.

ABSTRACT. Abstract —This paper presents thermal analysis of a water-cooled dual-stator axial-flux permanent magnet (AFPM) machine with focus on the sandwiched rotor which features combined rectangle-shaped magnets. Firstly, 3-D electromagnetic finite element analysis (FEA) is used to calculate the eddy current losses of the PMs and rotor support parts. Secondly, lumped-parameter and FE thermal models are established to calculate the temperature of the machine. The results of the two methods show good agreement. Additionally, a detailed thermal analysis of the rotor is carried out. It shows that the non-uniform heat transfer coefficient on the rotor surface and the shaft heat transfer have a significant influence on the location of the rotor hot spot. Finally, a 90-kW AFPM prototype is implemented to verify the proposed thermal models of the AFPM machine.

ABSTRACT. Insulation failure between the electrical sheets of electrical machines or transformers might occur due to the burrs formed during the cutting process. Together with welding seams or screws used to hold the stack together, the burrs provide a conducting path for eddy currents. In this paper, equivalent conductivities of the EI core with and without interlaminar contacts are determined using 3D finite element computations and measurements. The core loss of the EI core is measured, and the eddy current loss is segregated from the measurements. Based on the acquired eddy current loss, the equivalent conductivities are determined using an iterative approach. In the case of interlaminar fault at one limb, eddy current loss coefficient increased by 2% and in the case of interlaminar fault at two limbs, eddy current loss coefficient increased by 2.7% compared to the healthy case.

ABSTRACT. Due to the space size of the vehicle itself and vehicle energy capacity constraints, hybrid electric vehicles (HEV) usually use high power density and high efficiency permanent magnet synchronous motor (PMSM) as the integrated starter/generator (ISG) motor of drive system, but the temperature rise caused by the losses in the process of running will lead to some problems. It is necessary to obtain the temperature distribution accurately of the motor. In this paper, a nine nodal point thermal resistance network is established by choosing the key parts of the motor according to the motor structure. The mathematical model is established. Finally, the transient characteristics of the temperature field are obtained. By comparing to the thermal analysis of the motor performed by finite element simulation, the reliability of the results is verified, results show that thermal resistance network method have great advantages on thermal analysis of motors.

ABSTRACT. A two-dimensional (2-D) field-circuit coupled finite element model of induction motor (IM) is built. The equivalent circuit of three-phase squirrel cage rotor is modeled. Based on time-stepping finite elements analysis (T-S FEA), core losses in the stator and rotor of a no-load IM under sinusoidal and Sinusoidal Pulse Width Modulation (SPWM) excitations are studied. The rotating flux density distributions with time variation at different locations of the core are obtained. The areas where high-order harmonics mainly concentrated are simulated and the core losses in terms of the Bertotti's three-term separation model are calculated. All presented computations and models are verified through experiments.

ABSTRACT. In this paper, a contact loss simulator for a rigid catenary system was designed and the characteristic of arc is analyzed. Especially, occurrence of arc due to the excitation frequency is analyzed because the excitation frequency is generated by impact between current collector of the railroad vehicle and R-bar. This study will help to acceleration of railway vehicle in real systems.

ABSTRACT. The eddy current loss should be optimized to be as less as possible for the stability of permanent magnet in high speed permanent magnet synchronous motor (HSPMSM) rotor and ensure the high efficiency and low temperature of the motor. This paper analyzes the eddy current distribution in rotor by circuit-field coupled calculation method, which is appropriate for instantaneous condition and the actual control mode for HSPMSM. Then calculate the eddy current loss (ECL) and the thermal distribution via Separation of variables method for solving maxwell's equations with analytical model of ECL constructed. The experimental separation of ECL of HSPMSM whose power and rated speed is 100kw 30000r/min, based on drag system, is improved to get more precisely separation result without torque meter, and get other loss components incidentally.

ABSTRACT. Recently a novel electric hammer driven by tubular permanent magnet linear synchronous motor (TPMLPSM) has arouse great interest among researchers in the field of deep drilling for its distinctive advantages compared with hydraulic and pneumatic hammers. The working temperature in deep down-hole is relatively high, so the research of the influence of high temperature in deep hole on the electromagnetic thrust of the linear motor is very important. In this paper, a numerical electromagnetic calculation model of the thrust of the hammer was established to analyze the influence as a result of the loss of permanent magnet, coil resistance variation and coil volume expansion due to the temperature variation from 20°C to 300°C. The calculated results showed the increase of the copper loss reduced the thrust by 31%, loss of permanent magnets reduced the thrust by 18%, from 20°C to 300°C. And the effect of the air-gap variation by thermal expansion can be neglected.

ABSTRACT. The PWM modulation technology based on third harmonic injection(THI) can improve the voltage utilization ratio of 15% but without affecting the harmonic content of output voltage. Comparing the traditional SPWM modulation, THIPWM inverter can drive three-phase induction motor more efficiently. In this paper, taking the THIPWM inverter supply of three-phase induction motor as the object, calculation and analysis of the influence on iron losses fed by different carrier wave ratio and modulation index, via harmonic analysis method and time stepping finite element analysis (FEA).The impact on iron losses of both SPWM modulation parameters and THIPWM modulation parameters are also discussed.

ABSTRACT. Thermal irreversible demagnetization of rotor is a problem of permanent magnet synchronous machines (PMSMs) specially when there are large harmonic components in magnetic field. Permanent magnet segmentation and electrically conductive alloy sleeve are always used to reduce permanent magnet (PM) eddy current. Two novel methods to optimize magnetic circuit of PMSM to reduce the PM eddy current loss is presented in this paper.

ABSTRACT. Abstract--For the motorized spindle applications, the interior permanent magnet (IPM) machines is preferred to be chosen than surface mounted permanent magnet (SPM) machines, since it has better magnet protection ability, easier magnet installation, and less magnet loss. However, IPM machines usually has higher stator core loss, higher torque ripple, etc. Especially, when the machine is working under over loading condition. In this paper, some different structures of rotor design are analyzed on flux density, core loss, magnet loss, torque ripple and so on. Furthermore, the optimizations of those structures have been done to obtain better design which is suitable for motorized spindle application. As a result, compared to the traditional V-type IPM machine, through suitable rotor design and optimization, the stator core loss could be reduced about 20%, and torque ripple could be reduced from 30% to less than 10% without the slot skewing or some others methods.

ABSTRACT. A new and improved technique is presented for the measurement of iron loss in motor stators. The most accurate existing technique rotates dummy-test rotors, one for each field strength of interest, inside the stators to be tested and measures the reaction torque on the stators. The new technique uses a wound ‘rotor’ component that does not rotate mechanically but does rotate electrically. Therefore the speed and magnitude of the rotating flux can be controlled electrically without the inherent difficulties of rotating mechanically at high speed and without building different dummy-test rotors for each field strength test.

ABSTRACT. A method to reduce loss of permanent magnet synchronous machines (PMSMs) in dynamic state by the decoupling control strategy is proposed in this paper. Additional loss is produced when the speed of the PMSM drive system is changed if the common id=0 control strategy is used. The new decoupling control strategy could reduce the additional loss comparing with the traditional method by holding the value of id near zero. The simulation results validate the effectiveness of the proposed decoupling strategy.

ABSTRACT. For evaluate the thermal behavior of a permanent magnet motor under different types of losses and various loss distributions, a simplified thermal circuit is proposed. The result shows that, the model presented in the companion paper is suitable to use in machine design with certain accuracy.

ABSTRACT. The stability of magnetic bearings will seriously affect the overall operation of the motor. Magnetic bearing temperature is closely related to the performance of magnetic bearing (MB) system. Therefore, loss calculation and thermal estimation are very important in the design of MB system. A MB system including a pure radial magnetic bearing (RMB) and a combined radial and axial magnetic bearing (CRAMB) was designed for a high-speed permanent magnet motor. An approach of loss and temperature field calculation considering electromagnetic and temperature coupling was proposed. Two electrical machines supported by this MB system, whose power is 30kW and related speed is 3600rpm have been developed for experiment. The experimental results verify the validity and accuracy of this method.

ABSTRACT. This paper presents a three-dimensional (3D) electromagnetic-fluid-thermal coupling approach to compute the hot-spot temperature-rise of winding area for large power transformer. An ODFS-400 MVA / 500 kV single-phase auto- transformer is used as the prototype model being studied and the 3D fine computation model of the winding area is established. To validate the correctness and applicability of the proposed method, the numerical results obtained from the proposed method are compared with those of experimental ones.

ABSTRACT. Linear oscillating motor can produce linear reciprocating movement directly. Due to its special topology and motion type, segmented laminations are generally used as the stator core with coils wound inside. Though it contributes to eddy current elimination and air-forced cooling, the magnetic field suffers from severe saturation in the stator and affects the thrust output severely. In other words, magnetic field and thermal distribution should be both taken into considerations for thrust optimization. In this paper, a hybrid thrust predicted model based on magnetic and thermal circuit is proposed to analyze the coupling effects on thrust. In addition, comparisons are conducted to demonstrate the influence of segment number, lamination structure and eddy current effect on output performance. FEM simulation are used to validate the model which in turns offers a practical solution to segmented lamination stator design.

ABSTRACT. In the inner evaporative cooling turbo-generator, the cooling medium flows in the hollow conductor of stater and the cooling system depends on the sensible heat and latent heat of cooling medium to achieve the cooling goal of generator. Due to each cooling medium has unique thermal properties, the flow characteristics of different cooling medium in the hollow conductors is disaffinity. In this paper, two kinds of cooling medium were chosen as the study objects. Through simulating, the flow resistances of different cooling medium in the hollow conductors under different working conditions were compared. The exit dryness and the lengths of two-phase section in the hollow conductors were also discussed and the reason of the discrepancies were analyzed. The flow resistance simulation results of flow resistances were compared with the experimental data and the accuracy of simulating prediction is satisfactory.

ABSTRACT. In this paper, a set of remote monitoring system is designed for the experimental platform of million kilowatt-class stator bars and bus bar whole evaporative cooling cycle model. The system data acquisition is based on the PXI architecture, the monitoring platform is based on LabVIEW, and the system has real-time signal acquisition, analysis and storage of pressure, temperature, flow and other signals. The system Uses TCP / IP communication protocol to achieve the remote transmission of data. Eventually it forms a set of portable power station using remote monitoring system of evaporative cooling.

ABSTRACT. In this paper, based on the special requirements and rigor conditions of the power air cooling island motor for fan, a 115kW 67.9RPM 380V low-speed high-torque directdriven PMSM with fractional-slot winding for fan used on power air cooling island was designed to state design feature and difficulties. For the air cooling island vertical motor for fan, due to space and weight restricted, cooling difficulties,larger axial force, electromagnetic calculation and cooling structure design, as well as the design of the bearing is the focus and difficulty. A new stator cooling structure design is studied by fluid and temperature field, and some measures on how to reduce stator temperature rise and enhance the capability of bearing and shafting are also propose. Finally, the prototype machine was developed and tested to validate the feasibility and correctness of design and analysis.

ABSTRACT. Skew angle used to minimize cogging torque is generally determined to cancel the fundamental and sub-harmonics of the fundamental components. In a mass production environment, manufacturing variation always cause low order cogging components like slot and/or pole orders on top of fundamental and sub-harmonics of fundamental. To cancel this low frequency cogging components effectively a higher skew angle would be necessary at the penalty of lower motor torque. But, there could be a compromise in selecting the skew angle that can moderately reduce these low orders along with a substantial reduction of fundamental and it’s sub-orders to achieve an optimum reduction of overall cogging torque. This study investigated mainly to find an optimum skew angle for a given motor topology and for a skew scheme selected by the manufacturer to attain such objectives. It also identified through experiments and simulation the sensitivity of motor torque with skew angle and various skew schemes like step skew, continuous skew, axial overhang, etc. for six-different motor topologies.

ABSTRACT. Taken permanent magnet synchronous motor with similar number of slots and poles as an object, in order to solve electromagnetic vibration problem, the restrain effect on electromagnetic vibration and its harmonies by auxiliary slot is researched in this paper. This paper analyzes the reasons of radial electromagnetic force wave by the analytical method. The influence of different numbers of auxiliary slots in a single stator tooth on the radial electromagnetic force wave and harmonic content is calculated and analyzed by the finite element software. The result shows increasing auxiliary slots can reduce radial electromagnetic force wave and its harmonic content amplitude. But also need to take into account the cogging torque performance and choose the appropriate auxiliary slot.

ABSTRACT. This paper addresses trade-off with starting capability to maximize efficiency of a small single-phase line-start permanent magnet motor. In general, as the number of main winding turns is larger, the induced voltage and efficiency are larger. However, the start-up and synchronization capability is conversely lower. In this paper, the rotor with the excellent start-up and synchronization capability has been used. The effects of the number of main winding turns on the efficiency and starting capability are clear experimentally by using two single-phase line-start permanent magnet motors with different one.

ABSTRACT. A saturation map for the non-uniform magnetic saturation of a V-shaped interior permanent magnet rotor is formulated in this paper. This saturation map is used in conjunction with the magnetic equivalent circuit theory to propose an analytical method for accurate computation of the airgap permanent magnet flux density for interior permanent magnet rotors. Unlike the conventional methods, the proposed technique accounts for the rotor non-uniform local saturations and relative permeability variations. The proposed permanent magnet flux density model is further used or analytical calculation of the back-EMF in interior permanent magnet machines. The proposed methodology is compared against the conventional analytical techniques and validated through experimental results on a prototype interior permanent magnet machine.

ABSTRACT. Flux reversal permanent magnet (FRPM) machine, with magnets mounted on or inserted into the stator, is favorable for the direct drive applications. In this paper, a novel FRPM machine with Halbach array magnets in stator slot opening is proposed. While the magnets are moved to the slot opening, effective airgap length is reduced and slot area is enlarged. The analysis results indicates that the torque density of proposed machine is 2.3 times that of the conventional FRPM machine with the same magnet usage. And for the same torque specification, the power factor of proposed machine is 0.79, while that of the conventional one is 0.58.

ABSTRACT. A bipole magnet configuration comprising two cylindrical magnets with opposite magnetisation directions is rotated to high speed to create electric fields of high gradient in adjacent tissue, in order to activate nerves within the tissue. Calculations are presented for the electric field generated in a rectangular volume of conducting fluid, and for the electric potential established inside nerves within the fluid (or tissue).

ABSTRACT. Aimimg at the problem of multi-degree-of-freedom bionic drive, a new type of hybrid driven permanent magnet multi-DOF motot with liquid suspension mode is presented. In this paper, the structure and working principle of the motor are introduced. The analytical method and the finite element method are used to analyze the air gap magnetic field. The results provide theoretical and data support for further optimization and experiment of the motor.

ABSTRACT. Stirling power generating system, which has the advantages of multiple energies applicable and high efficiency, is promising for aerospace applications. As the main part of Stirling power generating system, single-phase oscillating permanent-magnet linear machine (PMLM) is investigated in this paper. Firstly, the electromagnetic performances, such as no-load back electromotive force (EMF) and thrust, are analyzed by finite element method. The influences of main parameters, including PM width, inner and outer diameter of mover iron core and tooth width, on performance are further investigated to obtain the optimal scheme. The proposed scheme can reach the power density of 0.177kW/kg. To ensure safe operation, the thermal field distribution law of the single-phase oscillating PMLM is investigated.

ABSTRACT. This paper presents an Equivalent Remanence Method (ERM) to obtain the analytical expression of the magnetic field distribution in the air-gap of single-stator single-rotor (1S1R) AFPM machines with SE under no load condition. And the slot effect in 1S1R AFPM machine with SE is studied by ERM. In addition, by applying ERM, the magnetic field distribution in other types of AFPM machines with SE is investigated. The accuracy of the analytical method is verified by FEM.

ABSTRACT. Permanent magnet vernier machines are receiving more and more attentions in low-speed high-torque applications due to their inherent features such as compact structure, high torque density, low torque ripple, etc. This paper compares several linear topologies of permanent magnet vernier machines, all of which have double-sided secondary and toroidal-winding configuration. By using finite element analysis, the no-load and load performances for three proposed linear vernier machines are compared. Additionally, the influence of the main parameters, such as PM thickness, pole-arc coefficient and slot opening ratio, on the thrust force and force ripple are analyzed.

ABSTRACT. In spoke-type ferrite interior permanent magnet machines, flux focusing factor is of essential importance for high performance. Hence, higher number of poles is preferred to boost the air-gap flux density. On the other hand, multi-layer magnet configuration is commonly employed to increase the rotor saliency. Thus, novel two-layer spoke-type structure can harness considerable reluctance torque and enhance the torque density. Besides, the rotor saliency is heavily influenced by the number of poles in such machine. In this paper, the design of two-layer spoke-type ferrite interior permanent magnet synchronous machines are investigated with particular emphasis on the influences of number of poles. The machine performances are compared in terms of torque composition and capability, electromagnetic losses and efficiency. Finally, a prototype machine with such novel two-layer structure is built and tested to validate the advantageous performances.

ABSTRACT. ISOP (Input Series Output Parallel) modular DAB (Dual Active Bridge) converter based topologies have been mostly considered for solid-state transformer (SST) based power substation design, involving multilevel converters at the high voltage side [1]. As DAB converter is one of the core components of this topology, an important question to address is thus the freewheeling currents of DAB which increases the overall losses and reduce the effective duty cycle, in addition to the design optimization issue of the medium frequency transformer [2]. Here, we show the design of 100 kVA SST based power substation which utilizes an isolated bi-directional dc-dc converter in ISOP modular configuration to mitigate these issues. In addition to the alternative approach in the dc-dc section, our work sheds light on the design of a 20-kHz transformer which serves as a key component for SST.

ABSTRACT. This paper presents predictive control for single phase multi-module UPS inverters with output LC filter modeling. In the previously proposed current predictive control, it has finite dynamic response of transient time by voltage PI control. To complement this problem, double model predictive control is proposed to substitute voltage PI control with output LC filter modeling. Multi-module UPS inverters proposed to X electrical load increase has some problems such as SOC difference between battery modules and circulating current. Therefore, control strategies is necessary with battery balancing algorithm in order to decrease SOC difference and circulating current. The proposed method is verified by simulation.

ABSTRACT. In this paper, an advanced droop control using a multinomial model for operating the parallel-connected uninterruptible power supply (UPS) inverters is proposed. To control the parallel inverters without any physical communications, the control method using a P/Q droops is conventionally used. The conventional method droops voltage and frequency using the monomial model. In conventional droop control, the tradeoff between dynamic response and steady-stare error restricts the gradient of droop function. The proposed multinomial droop model has advantage of steady-state error by minimizing the tradeoff which is mentioned. The simulation results with MATLAB and PSIM are provided.

ABSTRACT. This paper proposes a topology of magnetically coupled residential micro-grid consisting of a multi-port dc-dc converter and a single-phase bidirectional grid-connected inverter. In this topology the output energies of a PV array and fuel cell stack are integrated to supply the residential load. A battery is used as energy storage device to store the surplus energy of the system and release it when there is a demand. The micro-grid structure includes a three port phase shift converter for integrating renewable sources, a bidirectional buck-boost converter for charging and discharging the battery and an interleaved boost converter for controlling the PV output voltage and maximum power point tracking. Using interleaved topology has reduced both high frequency current ripple and low frequency voltage ripple propagated from dc bus and inverter and improved the MPPT performance. The proposed micro-grid is able to operate in multiple grid-connected and islanded operation modes. A detailed study of the dc-dc converters including their steady state operation, small signal modelling and control techniques are provided. A prototype of the system is developed and experimental tests are conducted.

ABSTRACT. Conventional grid-interconnected inverters for variable-speed wind turbines cannot provide the effects of inertia moment and synchronizing power. This paper proposes an application of model following controlled (MFC) PWM inverter to grid-connected variable-speed wind generators, which is based on the parallel-connected two-generator model. The wind generator system controlled by the proposed grid connected MFC PWM inverter can behave as a virtual synchronous generator.

ABSTRACT. This paper proposed a method to eliminate the DC component in the measured three-phase grid voltage as the input signals of phase-locked loop (PLL). This DC component causes a low-frequency oscillation of grid frequency. The DC component elimination can be achieved by replacing the integrator in the second-order generalized integrator (SOGI) with a differentiator, named as second-order generalized differentiator (SOGD). The good performance of proposed SOGD is validated with experimental results with 32-bit DSP by using unbalanced three-phase signals with DC component.

ABSTRACT. In this paper, a new control strategy for seamless mode transfer of grid-connected single-phase inverter is proposed. Generally, power flow between DC side and AC side is controlled by current reference of grid-connected inverter in d-q synchronous rotating frame. Therefore, it is general to reverse the current reference if the direction of power flow is changed. However, it causes a rapid change in current and aggravate the power quality of AC side. Therefore, this paper proposes an enhanced control strategy for seamless transfer in synchronous rotating frame. Theoretical Analysis and Simulation result demonstrate validity of the proposed control strategy

ABSTRACT. In this paper, a new control method of single phase PLL (Phase Locked Loop) which can be useful in electric railway PWM converter system is presented. The similarities and differences of the conventional APF (All Pass Filter) PLL control method and the newly proposed mMAF (modified Moving Average Filter) PLL method are compared and examined. The feasibility of mMAF method was investigated through the computer simulation. Finally, the proposed method was applied to the auxiliary power supply system for the 8200 series electric locomotives.

ABSTRACT. A large number of distributed generations (DGs) connected to the distribution network have a significant impact on the stability of the power system due to their low inertia. Meanwhile the DGs are generally linked to the end of the distribution network, where power quality problems are very common. This paper applies virtual synchronous generator (VSG) technology to three-phase four-leg inverter. And a compensation of harmonics strategy is utilized to reduce the harmonic pollution caused by unbalanced and nonlinear load. This paper analyzes the dynamic response characteristics and parameter selection of the active power-frequency and reactive power-voltage control. The inner current control loop is used so that the inverter output current could track the reference value accurately. The simulation results prove the validity and correctness of the control strategy.

ABSTRACT. For precision machining of a complex shaped object, Non-uniform rational B-spline (NURBS) interpolator is often preferred over conventional linear and circular interpolator. However, the use of NURBS interpolators has been limited due to heavy required computational load and feed rate fluctuation. It is desired to suppress feed rate fluctuation as it would degrade the quality of the machined objects. In this study, a computationally efficient feed rate fluctuation compensation algorithm is proposed. The proposed algorithm predicts and compensates feed rate fluctuation in real-time, and its performance is evaluated through simulations.

ABSTRACT. With the increase of the electrical machines capacity and voltage level, the main insulation of the stator coil becomes thicker. Heat dissipation and voltage endurance becomes a contradiction. The traditional cooling, such as air-cooling and water-cooling, will not well meet design needs. New cooling methods with both advantages of good cooling effect and good insulation are in keen needed in industry. The spray evaporative cooling system should have the advantage of higher heat transfer efficiency, less power consumption and minimum weight. The paper aims to study how key spray parameters affect the heat transfer in the large electrical machines.The experimental result is the key reference for the motor cooling system optimization design.

ABSTRACT. The Power density of ECRIS magnet coil is larger than 3000kW/m3, and evaporative cooling technology is an ideal method to achieve the cooling requirement. The two phase flow of evaporative cooling system affects the cooling efficiency of coil. This paper introduces the self-driven evaporative cooling system of magnet, and analyses the pie structure of magnet coil and two phase flow channel in the coils. To coordinate contradiction between structural strength of coils and flow resistance, the CFD model of flow channel is built and the computational model of two phase flow is used to simulate the fluid field. The experiment model of coils is built to verify the calculation. The comparisons between simulation and experiment results show that the simulation method can satisfied the application of project.

ABSTRACT. The vibration of reactors not only produces noise pollution, but also affects the safe operation of reactors, so it is very important to design lower vibration reactors. In previous research, the measures to reduce vibration and noise of reactors are mainly concentrated on vibration isolation and noise shielding. But they are not fundamental solutions to solve the vibration noise problem. This paper uses the principle of mutual offset between the giant magnetostrictive force produced by giant magnetostrictive materials and the original vibration force of reactors to reduce the vibration of reactors. But the inductance can be changed when the giant magnetostrictive materials are inserted into the gaps, which will change the operation situation of reactors. This paper optimizes the size and position of the giant magnetostrictive material by particle swarm optimism (PSO) algorithm, which selects the size and position of the giant magnetostrictive material as design variables, the stress of the observation points with bigger vibration displacement as the optimization objective and maintaining inductance constant as constraint. The designed lower vibration reactor is validated by simulation.

ABSTRACT. Air Cooled Motor used for Mini Vehicle has high power density, internal cooling conditions are poor, the thermal design and temperature control of the motor put forward high requirements. In this paper, the relation between electromagnetic load and motor loss is deduced, the equivalent thermal network model of air cooling motor is constructed, and the law of temperature rise distribution is calculated. The optimal design scheme of air cooling motor cooling system is put forward, and the temperature rise of each part of motor under different electromagnetic loads is calculated. The power density of the motor is improved significantly after optimization by the simulation results.

ABSTRACT. This paper proposes an analysis of multi-factor fabrications of magnetic membranes. In order to acquire some knowledge about the influence of fabrication factors, an analysis is performed using a Design of Experiment (DoE) methodology. The latter is applied on the mechanical model (Yeoh model), which describes the deformation of the magnetic membranes; specifically, the influence of the fabrication factors on the constants of the Yeoh model.

ABSTRACT. In order to design devices using coil or conductive media, an analysis of precise eddy current distributions is necessary. However, the distribution of eddy current inside a conducting media is somewhat complicated. In this paper, the eddy current distributions by finite element analysis inside a conductive media is analyzed. Based on the eddy current distributions, several skin depths are compared and discussed. Then, effective skin depth is proposed to analyze eddy current suitable for conductive media. The result could be applied to the accurate design of coils or electrical devices in conductive media.

ABSTRACT. In this paper, a fluid-thermal coupled finite element model is established to calculate the temperature field of dry type air core reactor, the inner structure of reactor is built both considering the calculation accuracy and computation time. According to simulation results, the detailed temperature distribution regularity are given both with and without the rain cover, and it can be achieved that the highest temperature of inner encapsulations are different after adding rain cover, and higher compared to the situation of without the rain cover. At the same time, the reasons are given by analyzing the fluid field around reactor, which is of guiding significance to the design of reactor.

ABSTRACT. In this paper, the temperature characteristics by change the width of teeth and yoke in the stat or parameters were analyzed. temperature characteristic analysis was performed for each width change of the stator teeth and yoke, and the effects of the width of stator teeth and yoke on the temperature characteristics were analyzed

ABSTRACT. In a processing line of thin steel plates, occurrence of scratches on the steel plate-surfaces by mechanical contact becomes a fatal problem. In order to resolve such a problem, our laboratory already proposed the noncontact conveyance system of thin steel plates by means of magnetic levitation techniques. However, there still remain other problems that the sideslip-sensors essential for the guidance control are very expensive and become obstacles in conveyance of steel plates. Thus in this paper, we will propose a guidance control methodology that doesn't require any actuators and any sideslip sensors in a processing line for thin steel plates levitated. In addition, we will conduct these interesting levitation and conveyance experiments for thin steel plates, actually without using any guidance actuators and any sideslip sensors, and we will report these successful results.

ABSTRACT. Abstract—A novel rotating magnetic properties testing structure in high frequency is designed. It can be used to study the magnetic properties of the core magnetic materials in high frequency transformers. Meanwhile, the stress effects are considered in the testing method. The excitation structure using nanocrystalline materials is designed simulated. By using the finite element analysis (FEA), the structure size and magnetic circuit are optimized. Compared with the copper wire windings, the copper foil excitation windings are designed and modeled by FEA. According to the simulation results, the influence of the magnetic core assembly error and the material characteristics of the excitation windings on the measurement results is analyzed and discussed.

ABSTRACT. This paper focus on the measurement of magnetic properties of soft magnetic composite(SMC) materials at high frequencies and high flux densities. Since SMC materials are very promising in the design of high frequency and high power density motor, the losses at a very high frequency are needed to measured and calculated accurately. In this study, the hysteresis loops and magnetic losses of an SMC material Somaloy ® 700 were measured and discussed up to 8 kHz.

ABSTRACT. Silicon steel is one of the key magnetic materials in Electrical Vehicle(EV) traction motor. In terms of high power density and high torque density for the next generation EV traction motors, conventional Non Grain-Oriented (NGO) silicon steel is difficult to satisfy these requirements because of limited saturation flux density and magnetic permeability. This paper mainly presents that a novel anisotropic Grain-Oriented (GO) silicon steel is used in traction motors after deeply analysing magnetic saturation, power loss, thermal conductivity and mechanical property of a traction motor with high-frequency and high-torque running status. It applies a combination design between NGO and GO steel in order to avoid the low magnetic permeability in the transverse direction. The noise and magnetostriction of the traction motor can be reduced by applying a self-stick punching technique between GO steel sheets in a stator. The research on numerical modeling has been done. The new prototype is being fabricated and it can be produced in mass production in next few years.

I.New Design of Combination of NGO and GO steel The measured B-H curve states the difference between NGO and GO silicon steel in the direction of magnetization, which can be shown in Fig. 1-1 and Fig. 1-2. B35P115, B30P105 are GO silicon steel grades. B50AY-3 is a NGO silicon steel grade. 35, 30 and 50 are the thickness of silicon steel. 115 are the iron loss 1.15W/kg at 50Hz.

According to the relationship of flux density, iron loss and offset angle of the rolling direction for GO and NGO steel, we should use the magnetic property of GO steel in the range of 0o and 30o of the rolling direction to design a stator. The new design can be shown in the Fig. 1-3. The new design shows the power loss of the stator remarkably decrease by using GO steel. Moreover, the saturation flux density and magnetic permeability will rise.

II.Results Fig.2-1 and Fig.2-2 shows the modeling thermodynamics and torque-speed performance of the prototype using NGO and GO new designing compared with only NGO steel.

ABSTRACT. This paper considers the minimizing of eddy current losses of PM motor through the proper choice of the magnet material, rotor magnet design and the comparison analysis between with and without rotor segmentation. Both 3D analysis and the experiment are used to validate the effect.

ABSTRACT. Post-assembly magnetization can greatly simplify the manufacturing process and improve the performance of PM motors, especially for high speed PM rotor with metallic retaining sleeve. The retaining sleeve has to be heated up during the shrink-fit process and the high temperature will cause irreversible demagnetization of the pre-magnetized magnet. We had developed a post-assembly magnetization fixture and successfully magnetized the rotor of a 100 kW high speed Sm2Co17 permanent motor. In order to optimize the magnetizing pulse width and the energy of power supply, we investigated the required magnetizing pulse width of the permanent material, and the influence of eddy current in the metallic sleeve on the magnetizing field. In this paper, we will give the experimental and FEA simulation results. A design criterion of the magnetizing pulse width of high speed PM rotor with metallic sleeve is obtained.

ABSTRACT. A wide part of the proposed paper is devoted to designing soft magnets using a stereolithography 3D printer. A state of the art on soft magnetic materials is carried out together with an overview of the existing printing technologies to obtain complex, not machinable and solid magnet. All steps to implement such magnet using this method are detail. A cushion made of 30% of mass ratio of magnetic powder included into commercial resin is printed. In order to justify the interest of this process-flow, the material is characterized (mechanically and magnetically). A discussion about results explains limitation and advantages of this process.

ABSTRACT. With the increasing rotated speed of the magnetic electrical machine with active magnetic bearings (AMBs), improving the dynamic response and the resolution of the displacement sensor turn into a key problem. In this paper, a novel self-differential eddy current displacement sensor (ECDS) based on the Hartley principle for high-speed electrical machine was proposed. First, the integrated structure of the ECDS probe and the novel design scheme were presented. Then a method of phase advance network to improve the dynamic characteristic of the sensor was described in detail. Finally, the detailed procedure was given to suppress the sensor-to-sensor crosstalk noise to improve the resolution of the sensor. Experimental results showed that the ECDS with high dynamic response and resolution is valid in the application to high-speed maglev rotating machinery in industry.

ABSTRACT. This paper investigates the influence of stator slot/pole number combinations on the rotor bar current waveform and electromagnetic performance of a squirrel-cage induction machines (IMs) designed with a slot number per pole per phase of two. 36-slot/6-pole (36S6P), 48S8P, and 60S10P IMs, all having 52 rotor slots, have been designed by using the same winding layout, stator outer diameter, stack length, stator current, and rated speed as the Toyota Prius 2010 interior permanent magnet machine (IPM). The waveforms of flux density in different parts of stator and rotor, and the leakage flux in the slots are considered and their influences are investigated. It has been revealed that even if the winding layout is the same, the stator slot/pole number combination has a considerable effect on the distortion level of the bar current and the electromagnetic performance, including torque, torque ripple, power factor, and efficiency.

ABSTRACT. There has been a growing need for high power density electrical machines for a wide range of applications. These include hybrid/electric traction applications, aerospace applications and Oil and Gas applications. There has been a lot of work done to accomplish significantly higher power density electrical machines especially for aerospace applications. Several machine topologies as well as thermal management schemes have been proposed. Even though there has been a few publications that provided an overview of high-speed and high-specific power electrical machines [1-3], the goal of this paper is to provide a more comprehensive review of high-power density electrical machines with special focus on machines that have been built and tested and are considered the leading candidates defining the state-of-the art. Another key objective of this paper is to highlight the key “system-level” tradeoffs involved in pushing electrical machines to higher power densities. Focusing solely on the machine power density most probably can lead to a sub-optimal solution at the system-level.

ABSTRACT. The effect of number of rotor slots on the stator and rotor current waveforms, slot and tooth flux densities and performance characteristics, such as torque, torque ripple, losses, electromagnetic force, power factor, and efficiency, are numerically studied in case of a 3-phase, 8-pole squirrel-cage induction machine (IM). The IMs have been designed by using the same winding layout, stator outer diameter, stack length, stator current, and rated speed as the Toyota Prius 2010 IPM machine. The designed IMs have 48 stator slots and the number of rotor slots is varied from 30 to 76. The harmonic content of each curve including the force and flux density curves were studied in detail. It has been revealed that the rotor slot number has a significant effect on the distortion level of the rotor bar current and performance characteristics. It has also been shown that there is an optimal rotor slot number at which the maximum available power factor, torque, efficiency and minimum torque ripple are achieved.

ABSTRACT. In this paper, different iron loss models are experimentally evaluated. A lamination ring specimen test is carried out firstly to evaluate the prediction accuracies of iron loss models for alternating flux density. Furthermore, different methods to consider the influence of rotational flux density are presented. In order to further validate iron models, an electrical machine iron loss test is carried out in this paper. The comparison of prediction and measured results shows that the iron loss model having variable coefficients has better prediction accuracy. Furthermore, it is more accurate to consider the rotation flux density as two alternating flux density on the major-minor axes.

ABSTRACT. This paper presents the filter setting for expand the operation range of IPMSMs in overmodulation region of inverter. To operate IPMSMs in the overmodulation region, it is necessary to deal with harmonics components. In this paper BSF is utilized to suppress the harmonic components, and its setting method is mentioned. The operation range in the overmodulation region is expanded appropriately by setting the filter focusing on resonant frequency of the system.

ABSTRACT. This paper presents three configurations of flux-barrier in a V-type interior permanent magnet synchronous machine to reduce the cogging torque and on-load torque ripple. As concluded with the frozen permeability (FP) analysis, these methods have little impact on machine’s reluctance torque and mutual torque, hence, are rather effective, and are simple to implement, too.

ABSTRACT. This paper presents an improved analytical model for estimating the high-frequency current ripple of interior permanent magnet (IPM) synchronous machines due to PWM switching. The proposed model accounts for the impact of slotting effects, magnetic saturation, and cross-coupling between the d- and q-axes. The model is subsequently used to investigate several factors that influence the PWM-induced current ripple. These include the PWM switching frequency, fundamental frequency (i.e., machine speed), dc-bus voltage, current control angle (i.e., γ angle), and the excitation current amplitude (i.e., saturation level). Experiments have been conducted to verify the analytical prediction results. These results show that the analytical model can predict the PWM-induced current ripple waveshape very well for many operating conditions and accurately estimate its rms value over a fundamental period.

ABSTRACT. This paper conducts a comparative study on the predicted operating characteristics of a series of optimally designed concentrated-winding, V-shaped magnet Interior Permanent Magnet Synchronous Motors (IPMSMs). A local optimizer (nonlinear Simplex) and a global optimizer (Genetic Algorithm (GA)) are separately used to determine the dimensions of each optimized machine based on three distinctive Objective Functions (OFs) to (i) minimize the weight, (ii) minimize the electromagnetic losses, and (iii) minimize the losses and weight in a multi-objective solution. In order to conduct the experimental analysis and verify the predictions, a prototype of the optimized machine is fabricated.

ABSTRACT. Restarting with speed for PMSM is critical to Rail Train application. And the switching frequencies must be restricted to several hundred hertz to minimize the switching losses. In order to output more torque with limited DC supply voltage, square wave should be used in the condition of high speeds. Hybrid synchronized PWM control schemes are often used to satisfy these restrictions. The restart and control schemes contain a variety of PWM patterns which is applicable to the whole speed range. And a simple but very effective method is proposed to determine the PWM patterns that should be used when restart is enabled. The motor speed feedback as a flag is employed in this method. An improved current controller for IPMSM is proposed to solve the zero speed start problem.

ABSTRACT. A sliding-mode model reference adaptive (MRA) observer-based model predictive current control (MPCC) strategy is developed for permanent magnet synchronous motor (PMSM) drive systems with DC-link voltage sensorless. Generally a DC voltage sensor is indispensable for voltage source inverter (VSI)-based PMSM drives to implement MPCC. In response to DC-link voltage sensor fault, by combination of MRA and sliding-mode techniques, a novel sliding-mode MRA observer for estimating DC-link voltage is proposed to perform MPCC. Moreover, in view of the variation of system parameters and external disturbance, a new nonlinear exponential function-based sliding-mode (NEFSM) speed regulator is synthesized to enhance the system robustness. In order to reduce the drive current ripple and improve speed & torque control performance, MPCC strategy is employed. The resultant NEFSM-based MPCC PMSM drive system with sliding-mode MRA Observer has excellent dynamical performance. In comparison with PI-based MPCC PMSM drive systems with sliding-mode MRA observer, the proposed NEFSM-based one possesses better dynamical response and stronger robustness as well as smaller THD index of three-phase stator currents in the presence of variation of load torque. Numerical simulation validates the feasibility and effectiveness of the proposed scheme.

ABSTRACT. Conventional model predictive control (MPC) presents high steady state ripples due to the application of only one voltage vector during one control period. Furthermore, the enumeration-based evaluation of the cost function poses high computational burden. Recently two-vector-based MPC has been proposed to improve the steady state performance, but it still requires many calculations to obtain the two optimal vectors and their duration. This paper proposes an efficient two-vector-based MPC for induction motor (IM) drives, which achieves the same performance as prior method but greatly reduces the control complexity and computational burden. The inherent relationship between the proposed method and deadbeat control based on space vector modulation (SVM) is also revealed in this paper, which has not been reported before. The effectiveness of the proposed method is confirmed by the presented simulation and experimental results from a 2.2 kW IM drive platform.

ABSTRACT. The life cycle cost (LCC) has being actively researched due to the increase of maintenance cost. The maintenance cost is increasing because of the aging of railway vehicles and the rising in the price in order to the low compatibility of newly developed parts and existing parts. In the case of Korea, Level of the LCC research is a beginning step but various maintenance related standards have been established such as IEC 60300-3-3 and IEC 62278. And various research activities have being conducted based on this standard in overseas. There are some power conversion systems in 8200 electric locomotive. It supplies power to electric motor. So It was related to the safety and reliability. There are many parts of main conversion system. Among that, The GTO (Gate Turn-Off thyristor) is important device in Korean 8200 electric locomotive because GTOs which are switches of converter and inverter in main conversion power system frequently break. Also the price of GTOs are very high. So maintenance cost of GTOs has increasing. In this paper, LCC analysis was conducted for GTOs of the main conversion system in 8200 electric locomotive. In order to LCC analysis, cost of breakdown maintenance and operating was applied.

ABSTRACT. Several position sensorless control methods of IPMSMs(Interior Permanent Magnet Synchronous Motors) using the observers have been proposed. In case of the full-order observers, these designs are difficult, because the order of the error equations of the observers becomes four. In this paper, for the position sensorless control of IPMSMs, a design method of the full-order observer based on the extended electromotive force (EEMF) is studied. The experimental result shows that this design method of full-order observer is very useful.

ABSTRACT. This paper discusses the main circuit topology and control method of a three-phase asynchronous motor current source controller(CSC). In the circuit, the three phase AC power supply is taken as the input part of CSC, which is rectified into three phase controlled rectifier. In DC circuit, the DC bus inductor is used to store energy and filters harmonic so that the circuit is shown as the current source character. The DC bus current used Space Vector PWM(SVPWM) method is converted to three phase AC current. SVPWM driving pulses of the three value logic eventually are obtained through the zero state distinction and two-three value logic transformation. Meanwhile, MATLAB/Simulink tools are used to finish the simulation on the control system, and the simulation results are consistent with the experimental results.

ABSTRACT. Synchronous reluctance motors (SynRMs) have attracted studies, because SynRMs have no magnets in the rotors. Position sensorless control at low speeds of SynRMs is now desired, and several methods have been proposed. In this paper, by using the high-frequency current control system, a new position sensorless control method of SynRMs at low speeds by superimposing high-frequency current whose amplitude is small constant value has been proposed. The experiments show that the proposed method is very useful even if the very low speeds region.

ABSTRACT. With the development of technology, The power density of permanent magnet synchronous motor application in aerospace is increasing rapidly. The integration of the machine with the power electronic converter and control system has many advantages such as high power density, high reliability and small size, etc. However the cooling design of it is challenging [1]. In this paper, the optimal design of the heat dissipation structure of a 2 kW Integrated Motor Drives adopted in aviation pump is studied by Tauchi method. First, a three-dimensional finite element simulation model is established, based on fluid mechanics and heat transfer theory. Second, the parameter sensitivity analysis of the size of the radiator fin, the size of the drive plate shell, the thermal insulation material of the electric power device on the temperature rise of system is carried out .Then, according to the results of the sensitivity analysis of the parameters, the Tauchi method is used to optimize the design. At last, the temperature field simulation and experiment are carried out to verify the rationality of the optimization design.

ABSTRACT. This paper presents the design and construction of a single-arm crane in a reduced form, as a model to understand the working and control principle of a crane motor being useful for instructive purposes. The crane model uses an arm length of 70 cm, representing a reduction scale of 1:100 of its actual size. The assigned maximum load was 2.5 kg, considering the availability of mechanical structure materials. A separately excited direct-current motor has been chosen based on the requirements of load-torque characteristics and considering its ease of control handling and its availability in the market. The designed miniature crane uses 3 motors of 20.844W, 11.256W, and 10.81W to manoeuver the crane, i.e. to drive the boom, to tow the rope, and to rotate the crane respectively. The motors were driven using MOSFETs as the power converter. The triggering control has been facilitated using a microcontroller. The experiment results indicated that the miniature of a single-arm crane was able to move the given load as desired in accordance with the previously established specifications.

ABSTRACT. Mechanical characteristics analysis of defective transformer windings under short-circuit fault is conducted by coupled electromechanical finite-element method, considering the influence of nonlinear elastic-plastic property of copper wires and spacers. The differences of dynamic response between defective winding and normal winding under short-circuit condition are compared and analyzed. The change characteristics of maximum stress and displacement of defective windings with the change of eccentricity of windings, the numbers of axial insulation strips keeping no effective support and the numbers of loss spacers between disks respectively are obtained. The results can provide reference for the design and maintenance of transformers.

ABSTRACT. This paper presents a developed copper-iron alloy which made as the rotor sleeve in a high speed permanent magnetic machine (HSPMG), whist investigating its benefits in improve machine thermal performance. The features of the new alloy is experimental tested against the performance, which includes the conductivity, the permeability, and thermal conductivity, and the variation of loss distribution inside machine with sleeve conductivity and permeability are studied. A fluid-thermal coupled analysis model is proposed, by using which the fluid velocity and temperature distribution are obtained via numerical analyzing. The variations of machine operating temperature with new material are evaluated.

ABSTRACT. This paper proposes the study of the thermal management system of an energy storage system centered on lithium-ion capacitor (LIC). The investigated system is a LIC module made of 12 cells. A proposed passive thermal strategy has been designed in a 3D model using COMSOL Multiphysics. The strategy consists of integrating phase-change materials (PCMs) in the LIC module. Initial results showed that the module temperature is above the optimal operating temperature after a simulation of 3500s. Therefore, a optimal thermal solution comprising a liquid cooling method and PCMs needs to be investigated

ABSTRACT. In this paper, a method of deep learning is built to reduce the needed time on performance analyze and optimization of permanent magnet synchronous motor (PMSM). The analysis of the electromagnetic speed, torque and efficiency of PMSM is carried on with Finite Element Method (FEM), which is 8 pole-pairs, 48 stator slots and 195mm of stator external diameter. FEM model of PMSM is established, and the finite element analysis is carried out to obtain the structural parameters which have great influence on the maximum efficiency of permanent magnet synchronous motor. Then, the training samples of deep learning about efficiency are generated by FEM. We build a multiple regression model with 3 hidden layers, two inputs, and one output, which is trained and optimized by using the deep learning neural network algorithm. The accuracy of the model is verified by the comparison of the finite element calculation and the multiple regression prediction model fitting results.

ABSTRACT. This paper presents a new 2-D cylindrical permanent-magnet array for a linear and rotary permanent magnet actuator (LRPMA), in which the angle between the magnetization directions of any two adjacent magnets is 45º. By the given magnetization distributions and boundary conditions in the cylindrical coordinate system, the magnetic field distributions of the actuator with the new 2-D array are analytically analyzed using the magnetic scalar potential and the modified BESSEL functions. The analytical optimization of the magnetic flux density distribution is made by analyzing the harmonics of the flux density. Analytical linear electromagnetic force and rotary electromagnetic torque, respectively, are derived. A three-dimensional finite element (FE) model and a protype are also established and manufactured to validate the correctness of the analytical results.

ABSTRACT. This paper investigates an induction machine using a novel concept of a converter-fed rotor. The stator is directly connected to the grid while the rotor is fed by a converter with a floating capacitor over the dc-link. This paper explores the possibility to improve the power factor and efficiency of a squirrel-cage 12-pole 17.5 kW induction machine by redesigning the cage rotor to a wound rotor to enable connection of the rotor windings to the converter. Performances of the designed wound rotor induction machines (WRIM) show good potential for power factor and efficiency improvement. Particularly, an optimum efficiency improvement of 6.8%, compared with the original squirrel-cage induction machine (SCIM), has been achieved.

ABSTRACT. The external rotor surface permanent magnet (SPM) machine is attractively used for in-wheel traction application. In view of energy consumption, the efficiency of SPM over a driving cycle is more important than that at a single working point. This paper focuses on optimizing the external rotor SPM machine considering a target driving cycle.

ABSTRACT. This paper proposes a multi-step optimization method that performs the shape optimization, the topology optimization, and the step-by-step post-processing for the optimal design of electric machines. Because of the multi-dimensional representation of the solutions and the geographic crossover, the genetic algorithm is used in this method. The usefulness of the proposed method is verified by applying it to the rotor design of the interior permanent magnet synchronous machine.

ABSTRACT. The multi-objective optimization of Interior Permanent Magnet Synchronous Motor (IPMSM) used for Electrical Vehicles (EVs) is widely concerned by many researchers. However, it not only suffers from its lower optimization efficiency, but also is difficult to achieve the global optimal solution. Therefore, an effective multi-objective optimization design scheme is presented and it innovatively integrates Taguchi method, sequential subspace optimization method (SSOM) with differential Evolution (DE) algorithm by using VB script. And then, through finite element analysis (FEA), a 50 KW IPMSM is researched for validating its technical advantages and satisfactory optimization benefits.

ABSTRACT. This paper proposes a novel optimization algorithm inspired by the principle of plasma in nature. The algorithm mimics the motions of plasma state ions for global optimization. The proposed algorithm is validated with test functions by investigating the number of function calls and average values of the objective function, and a permanent magnet motor (PMSM) is then designed to verify optimal design performance capabilities.

ABSTRACT. the low-efficiency traditional motor design usually needs a long period, so Cloud Computing is introduced into the traditional finite element method and BP neural network to solve above-mentioned problem. In this paper, utilizing Cloud Computing approximately curtailed 4 times hour, the back EMF and air-gap magnetic density of 16kW permanent magnet synchronous motor (PMSM) is used as calculation case. The Cloud Computing can achieve mixed computing between windows and Linux, with running MATLAB on windows and running COMSOL on Linux in the form of non-GUI. BP network training needs hundreds of group samples. Though a group data of FEM calculation does not need a long time, hundreds of group data will cost plenty of time. High performance cloud computing is utilized for shortening samples achieved time, the synchronous parallel computation is executed on the cloud elastic cluster, which can obtain the multi calculation samples of PMSM in the meantime. Then achieved data regard as BP network input and output samples, which is used for training and learning. The results show that motor optimization combine cloud computing with BP algorithm has feasibility and high-efficiency.

ABSTRACT. Nowadays electric tools have been widely used in many fields, such as woodworking, home decoration and mechanical maintenance. Permanent magnet (PM) machine have many merits such as high efficiency, high torque density, and high structural reliability. Due to these advantages, PM machine is suitable for electric tools. Firstly, this paper compares three rotor topology including surface mounted PM (SPM) machine, tangential interior PM (TPM) machine and V-shape interior PM (VPM) machine with material consumption, torque density and mechanical stability. Then, selecting VPM machine as optimized object, the rotor parameters, including magnet length, magnet thickness, rotor shape, i.e. All optimizations is present by finite element analysis (FEA) and validated by experiments.

ABSTRACT. Based data interpolation and design optimization algorithm for an Interior PM Synchronous Machine. Data interpolation using Neural Network (NN) is suitable for estimating the performance of an electric machine, because NN is good approximate function for representing nonlinearity data. To utilizing NN as approximate function, training process is required. After training, optimal design of an electric machine can be found by applying search algorithm such as Particle Swarm Optimization, Mesh Adaptive Direct Search etc. This procedure does not demand any additional numerical analysis of electric machine based on finite element method, so that optimal design is searched in such short computation time.

ABSTRACT. In this paper, different electromagnet structures are compared for improving the general type of the electromagnet on the market. The different electromagnet structures are compared with the same size. In the research process, the circuit model of the original electromagnet is given and the parameters such as resistance and inductance of the circuit model are calculated. Under the condition that the working area is kept constant, the working area of the internal plunger is changed to the working area of the outer wall. The magnetic flux density decreases from inside to outside. Then, wire resistance will be reduced. IW and the length of the air gap remain unchanged. It will compare the force and coil resistance by calculation. Window area and winding diameter are the key points of the proposal. Finally, ANSOFT Maxwell3D is used to simulate the static characteristics of the electromagnet, and the results are compared by ANSOFT Maxwell.

ABSTRACT. This paper presents a magnetic circuit model considering the leakage and coupling effects to analyze a 3 degrees of freedom magnetic bearing (3-DOF MB). The results illustrate that the stiffnesses of radial force are significantly influenced by the axial control current. An auxiliary coil can effectively reduce the coupling effect and adjustment of the PM length can slightly reduce the coupling effect.

ABSTRACT. In the course of treatment and diagnosis of transcranial magnetic stimulation (TMS), the target and nontarget are stimulated simultaneously, which produces undesirable side effects. To reduce the risk of such side effects, it is essential to test the stimulation before the real treatment. This paper presents the structure of a magnetic field measurement system for TMS pre-testing. The 3D magnetic field measurement structure can use a 3D magnetic sensor to measure the value of electromagnetic field in some specific points of the brain model to reduce the risk that could be caused by directly measuring in human brain and effectively avoid the side effects of TMS.

ABSTRACT. a linear actuator suitable for sun tracking applications, heliostats, was investigated. First, a linear actuator segment was modelled using the Finite Element Method and then a prototype was constructed. The simulated magnetic force were found to be in good agreement with experiment. Next, a complete periodic structure of the proposed three phase linear actuator was analyzed. The analysis shows that the linear actuator is able to produce an 850 N/m force-linear-density and a step size of 1.81 mm

ABSTRACT. A novel method of post-assembly magnetization is proposed in this paper. The magnetizing windings are directly wound on the outer surface of the permanent magnet (PM), and then assembled on the rotor of the motor. The PM poles can be magnetized and demagnetized after assembly by the integrated magnetizing windings. Once the PM poles experienced demagnetization fault, the magnetizing windings can magnetize the PM poles again without disassemble of the motor. In this paper, we selected a 32-pole 20kW surface-mounted PM motor as the prototype, designed the integrated magnetizing windings, and carried out the magnetizing test. The FEA simulation and experimental results will be presented.

ABSTRACT. This paper proposes an interior permanent-magnet synchronous motor with a novel tangential-magnetic rotor for use in variable-frequency refrigerant compressors. The structural design of a rotor with a salient pole effect and tangentially magnetized magnets is proposed so as to reduce cogging torque, improve torque ripple, and reduce the usage amount of magnets. Based on magnetic circuit analysis, the proposed rotor structure not only can reduce total harmonic distortion of clear air-gap flux so as to reduce cogging torque and improve cogging torque, but also can reduce the usage amount of magnets. Furthermore, this paper employed the design of experiment (DOE) method to optimize the geometric structure of the rotor. Based on the findings, the proposed method has proven to reduce cogging torque, torque ripple, and production costs of a motor, thus making the proposed motor suitable for use in variable-frequency refrigerant compressors.

ABSTRACT. A novel adjustable magnetic liquid damper is designed in this paper which dissipates the vibration energy by viscous flow of magnetic liquid with movement of inertia mass. Firstly, the influence of uniform magnetic field and gradient magnetic field on the magnetic field force and viscous force of the magnetic liquid is analyzed. The magneto-mechanical coupling model of the magnetic liquid damper is established. Secondly, based on the magneto-viscous characteristic of the magnetic liquid, the effect of the magnetic field on the damping is studied. The dependence of damping force on magnetic field and the size of inertial mass is analyzed. Finally, the parameters of the damper are optimized by genetic algorithm, and the optimal combination is obtained. This damper can finely adjust the damping parameters, and has good damping effect on the vibration of low frequency and small damping.

ABSTRACT. We have previously proposed an integrated radial-axial flux rotor permanent magnet synchronous motor for EV traction motor, and confirmed that the motor had almost the same performance as a IPMSM, which uses sintered NdFeB magnet, based on a computer simulation. Our next target is general industrial-use motors, whose design policy is different from EV traction motors with a requisite forced cooling system. This paper describes a comparative study based on computer simulation using FEA and the experimental results in a compared motor, which is the comparison between our IRAF-PMSM and an IPMSM for general industrial-use.

ABSTRACT. Abstract — This paper presents a novel double-fed flux-modulation (DF-FM) machine which offers an effective electric solution for electric vehicle (EV) propulsion. This design can realize adjusted speed and torque transmission without planetary gearbox and brush system in EVs. Main advantages of this design involve high torque density, wide speed range operation and low friction loss. The steady and transient performance of this newly proposed DF-FM machine is analyzed using finite element method (FEM).

ABSTRACT. The permanent magnet synchronous motor (PMSM) direct torque control (DTC) system does not control the current directly. It is necessary to restrict the stable operation region from own point of PMSM DTC system. This paper analyzes the stable operation region of PMSM DTC theoretically from the point of torque angle limit, flux linkage limit and monotonicity. Detailed simulation and experiment results will be showed in full paper.

ABSTRACT. This paper proposes a sensorless field-oriented control strategy for SPMSM. Firstly, a rotor flux estimation method is introduced. Secondly, the basic principle of PLL and PI parameters tuning method derivation are demonstrated. Finally, simulations and experiments verify the correctness and validity of the proposed method.

ABSTRACT. In 2016, the licensee found that load sequence logics for the emergency diesel generator (EDG) of some Nuclear Power Plants (NPPs) in Korea were errors that can operate two component cooling water pumps (CCWP) in a train. The rated power of the EDG is designed with consideration for one CCWP. An increase of the load due to operation of two CCWPs can exceed the rated power of the EDG and cause a serious transient state. To improve this problem, the licensee modified to the logic of load sequence which operates one CCWP per a train. We evaluated the integrity for the modification of load sequence logic through the review of the software verification and validation (V&V) documents and the result of the field test.

ABSTRACT. Recently, the electromagnetic pump (EM pump)has been widely used for cooling the high thermal power system such as the nuclear reactors, because it has many advantages of lower pressure loss, absence of moving components, and allowance of continuous fluid flow compared with conventional mechanical pump. In this paper, DC EM pump was designed and analyzed using finite element method, and the performances of the pump such as flow rate, velocity, pressure and the pumping power were predicted.

ABSTRACT. In recent years, the direct drive, high torque density type permanent magnet synchronous motor (PMSM) is widely used in the field of marine driving. The influence of the vibration and noise of PMSM on the comfort of the crew and water environment has been widely attention. Based on the analysis of the generation principle of the electromagnetic exciting force (EEF), the influence of the motor parameters such as the non-uniform air gap, the pole arc coefficient and the stator slot width on EEF is studied. In order to reduce the vibration and noise of marine driving PMSM, this paper presents a method to optimize the design of this kind of motor.

ABSTRACT. This work presents the modelling and simulation of the dual stator-winding induction machine (DSIM) with squirrel-cage rotor. The transient and dynamic performances of the machine under two cases of input conditions have been analysed and presented both at no load and when a constant load torque is applied. The modelling and simulation has been carried out in complex vector form using MATLAB-Simulink. A step-wise procedure clearly set forth for the complex vector Simulink implementation forms the balance of this work, which can be a good teaching aid. The approach presented in this work can easily be applied to other types and configurations of electric machines and drives

ABSTRACT. The integrated starter generator (ISG) is one of the key components of hybrid vehicles. However, with the significant difference in power range between the two operation modes of the starter and generator, it is difficult for the generator to exhibit excellent behaviors in both modes. To solve this problem, a dual air-gap permanent magnet ISG is investigated in this paper. Torque characteristics and output power capability are verified by an analytical solution, simulation and experiment results.

ABSTRACT. In this paper, a new approach applied in linear synchronous motor (LSM) drive system is proposed based on different proportion of converters’ current in double-end supply for traction-system. The theoretical model of LSM of double-end supply is established and the control strategy consists of an outer PI speed closed-loop, an inner current closed-loop and a circulating current loop. In order to distribute the current reasonably, the proportion of the two ends of the current supply can be chosen to be different. Simulation results verify the feasibility of the control method in double-end supply traction-system.

ABSTRACT. Principle of rotating magnetic field is very difficult to understand because the field is in high speed and invisible. In this paper a novel dynamic demonstrating device for rotating magnetic field is designed. With the help of synchro transmitter and phase demodulating technologies, a rotating handle is adopted as speed input to drive the magnetic field rotating at only several revolutions per second, which enables the operators to observe the magnetic field directly and clearly. The device is a good assistant for teaching of some Electrical Engineering courses, such as Electric Machinery and Motors and their Drives.

ABSTRACT. Inrush current caused by residual flux is the main reason that makes transformers fail to be re-energized. The concept of calculating transformer residual flux by the integration of the port-voltage after de-energization was proposed previously. In this paper, the principle of the concept is analyzed using phasor method. The concrete implementation is put forward, including two methods of determining the time limit of the integration. To verify the integration method, the transformer voltage waveforms are simulated under different hysteresis loops of core by the software Simulink. The method can provide more accurate results of residual flux after de-energization, improving the accuracy of the method of residual flux calculation.

ABSTRACT. The ferrite permanent-magnet-assisted synchronous reluctance motors (F-PMa-SynRMs) have been introduced as a motor with low-cost and high power density, which will be widely used as a servo motor. In this paper, a 1.5kW low-cost F-PMa-SynRMs is introduced, and various key points in the electromagnetic design of the motor are studied and the performance are analyzed.

ABSTRACT. Stabilization of a Cascaded AC/DC System Based on Small Signal Analysis

ABSTRACT. For high power rectifiers, owing to the limit on switching loss, operating at low switching frequency is necessary. In this paper, an effective approach is proposed to restrain grid harmonic current and DC-link pulsating voltage, which is discrete-time domain of complex vector current regulator combined with synchronized PWM modulation strategies. Methods to keep synchronization is also illustrated in detail. The results of simulation and experiment verifies the validity, effectiveness of the proposed strategies.

ABSTRACT. The technique of the electric lightings has been more and more grown. In the energy consumption, the power consumption in the lightings is very important part. Among them, a short arc lamp is widely utilized as illumination sources for the digital and film projection, stage lighting, UV sterilization, search lights and medical illumination, etc. This paper presents a phase shift full bridge(PSFB) converter with the zero-voltage-switching range expansion. In addition, the proposed converter provides both good efficiency and low switching device noise. The experimental and simulation results from the prototype are provided to verify feasibility

ABSTRACT. In this paper, a virtual platform for the performance of the LLC resonant converter for magnetron in microwave oven is introduced. According the operation characteristic of magnetron, its equivalent circuit is derived firstly, and then, based on the principle of LLC resonant converter, its detailed switching model is built. Several techniques are applied to calculate the parameters of circuit in the converter. By running the model in MATLAB/Simulink, not only the system state but also the performance such as the curve of the efficiency vs. output power can be obtained. The model can be acted as a virtual platform for studying and designing new converters. At the end, an existing LLC converter with the rating power of 1200 W for microwave oven is studied. Analysis results show that the developed model can work very well.

ABSTRACT. According to the requirement of the powerfactor and the dynamic performance of the asynchronous machine tool field, an asynchronous motor inverter with active power factor correction is proposed. The proposed inverter is a 3kW asynchronous motor drive control platform. At first, the proposed single phase converter with APFC is realized by using the MATLAB/SIMULINK. Then, the boost APFC is designed based on the UC3854. Finally, in rated load conditions, experimental results about the power factor and the dynamic performance highlight the effectiveness of the APFC module.

ABSTRACT. The fast command tracking provided by the dual-loop fast finite-settling-step (FSS) control for a DC-to-DC converter has been shown to have more energy saving capability than using the conventional PID controller. FSS control is developed based on the accurate nonlinear converter modeling. Thus, circuit parameter mismatch can affect the performance of FSS control so that the loss minimization capability degrades. By modifying the inductor flux observer structure to be the reference model, a model reference adaptive system (MRAS) is developed in this paper to provide the real-time estimation of series inductance and output capacitance. The estimated parameters are updated into the dual-loop FSS control system in every switching period. The paper develops the theory and evaluates the loss minimization consistency achieved in simulation and experiments on an automotive traction drive DC-to-DC converter.

ABSTRACT. A nonlinear proportional resonant (PR) control strategy is presented for single-phase cascaded H-bridge rectifier in this paper. By using state feedback linearization (SFL) technique and linear quadratic riccati method, the proportional control loop is constructed and tuned. To achieve zero phase’ tracking of sinusoidal grid current, a resonant transfer block is added, which form a PR control frame. The new PR controller features of global stability and simpler and clear parameter tuning process. Experimental results show the proposed control strategy guarantees fast regulation and stability of sinusoidal grid current and dc voltage, meanwhile achieves unity power factor

ABSTRACT. This paper presents a space vector pulse width modulation and proportional resonant control scheme for single-phase three-level rectifier for electric railway traction applications. The proposed SVPWM modulation has been tailored to the single-phase rectifier without an additional PLL. Moreover, vectors and vectors sequence have been carefully designed to achieve neutral point voltage balance. Based on the analysis of transfer function of rectifier system , the defect of classical PI control scheme has been discussed. And then, PR control is deployed in the current inner-loop to eliminate steady-state error and enhance the control effects. A series of simulations and experimental tests demonstrate the effectiveness of SVPWM+PR control.

ABSTRACT. This paper discusses the commutation of dead-time in dual bridge series resonant DC/DC converter (DBSRC). The shifted phase in DBSRC is usually small, and voltage polarity reversal (VPR) occurs in dead-time, which may bring EMI and affect efficiency. This paper proposes a compensation method to eliminate the VPR. Simulation and experiment results verify the effectiveness of the proposed compensation.

ABSTRACT. A novel semiconductor switch test circuit for power converter optimization is proposed in this digest. Simplified circuit configuration and basic operational principle are introduced. Detailed operational principle, circuit analysis, design consideration, and experimental results will be included in the full paper.

ABSTRACT. In the grid-connected modular multilevel converter (MMC), grid faults not only cause the current to be higher than the rated current, but also bring the unbalanced issues to the inner unbalanced currents and arm voltages. In this paper, a multi-variable coordinated control method which is employed in the d-q coordinate is presented. First, a parameter is introduced in the calculation of the grid currents references. Afterwards, the relationships between the system operating parameters and the parameter are derived. Furthermore, the influences of parameter on the safe operation areas are analyzed in details. In addition, the P-Q diagrams of the MMC are deduced in terms of the safe operating areas under unbalanced conditions, and an adaptive multi-variable coordinated control is proposed. Finally, the simulating results from MATLAB/Simulink are presented to verify the theoretical analysis.

ABSTRACT. When the variable speed wind turbines with virtual inertia are connected to the grid, the transient stability control of the interconnected system will be more flexible. Firstly, the linearized state equation of equivalent two-machine system with wind power was derived, and respective influences of terminal unit inertial changes on the transient stability of power system were analyzed. Secondly, a power angle transient stability control strategy based on inertia regulation was proposed, which can improve the system transient stability by coordinating the inertia of two sub-regions. Finally, this paper established a simulation model of the two regional power grids with high wind power penetration. The simulation results verified the correctness of the analysis results and the effectiveness of the proposed control strategy.

ABSTRACT. Non-intrusive load identification is one of the important development directions of the future power load monitoring, the recognition algorithm is its core part, due to the discrete optimization algorithm of chickens has lower recognition accuracy when multiple appliances simultaneously open, so a new method was proposed, which is based on the discrete optimization algorithm of chickens. As we can see from the discrete expression of hen, foraging hens should around rooster in later iteration, and hen’s speed is approximately zero. Considering hen’s velocity which is consist of 0, greater than 0 and less than 0, A new iteration formula of hen was got when sigmoid function was improved to get a higher accuracy. Finally, the simulation experiments based on the REDD database is performed by MATLAB, the simulation results show that the improved discrete optimization algorithm of chickens for load identification has high stability and accuracy, and it is more suitable to make a load identification of non-intrusive.

ABSTRACT. Nowadays, many studies on LVDC (Low Voltage Direct Current) distribution system are underway as the future solution for reliable power system network. This new concept in power distribution is expected to improve power system efficiency, reliability, and uninterrupted power supply capability when it is implemented. This paper is based on Bipolar LVDC distribution system and it focuses on analysis of voltage variation according to the load variability in the above-mentioned system, in most of the previous researches upon this system the voltage imbalance issue has been showcased, so this paper proposes the solution for that drawback; that is, balancer and its position in the network. The simulation results for this system were obtained by using PSCAD/EMTDC software.

ABSTRACT. The short-time high capacity reactive power output and quick dynamic response performance are two key performances of new large synchronous condenser. In this paper, the effect of load condition on transient response capability of synchronous condenser by finite element analysis (FEA) model. A 300/-150Mvar prototype synchronous condenser is provided for modeling analysis at a group of different steady state operating conditions. Then the suddenly three-phase short circuit is carried out to compare the inrush current in different load condition.

ABSTRACT. In this paper, RDFT(Recursive Discrete Fourier Transform) FLL(Frequency Locked Loop) based on DSCPLL(Delayed Signal Cancellation Phase Locked Loop) is proposed for coping with frequency variation. This method shows significant performance for detection of fundamental positive sequence component voltage when the grid voltage is polluted by grid harmonics and frequency variation. The frequency tracking technique of DSC-PLL is tracking the drift in the phase by the RDFT and TEO(Teager Energy Operator) concept. The performance of the proposed RDFT based DSC PLL method is also compared with the traditional DSC-PLL. These compensation algorithms can correct for discrepancies of changing the frequency within maximum 28ms and improve traditional DSC-PLL

ABSTRACT. This paper proposes a new method to control frequency fluctuations of power system with large scale wind farm (WF) installed by using High Voltage Direct Current (HVDC) interconnection and battery systems. The proposed system is designed to decrease the frequency fluctuations. Simulation analysis is performed on a multi-machine power system model composed of synchronous generators (SGs), squirrel cage induction generator (SCIG) based WF, HVDC interconnection line, and battery by using PSCAD/EMTDC software. The simulation results show that the proposed control strategy is very effective to decrease the frequency fluctuations of the power system.

ABSTRACT. The phase-locked loop based a synchronous reference frame (dqPLL) is usually employed in grid-connected power generation systems (PGSs). However, the voltage amplitude drop of stand-alone PGSs is often greater than that of the grid-connected PGSs when loads are added drastically, which makes the response of dqPLL deteriorated. This paper presents an improved dqPLL (IdqPLL) for stand-alone PGSs. The simulation results verify the dynamic performance of the IdqPLL.

ABSTRACT. This paper analyzes the influence of Doubly Fed Induction Generator (DFIG) ,connected to a weak network ,on the stable operation of DFIG itself and weak network when stator winding inter-turn short circuit (SWITSC) occurs.The fluctuation of electromagnetic torque in DFIG and voltage at the point of common coupling (PCC) in weak network will be obtained by analysing the simulation results and the mathematical model of DFIG. Then the power system stabilizer (PSS) and the static synchronous compensator(STATCOM) are used to reduce the fluctuation of the electromagnetic torque and the voltage at PCC. A series of simulation results verify the correctness of the measures adopted in this paper.