ABSTRACT. A tubular flux-switching permanent-magnet linear machine (PMLM) is proposed and designed for freepiston energy converter. The machine performances such as force, power density and machine efficiency are improved by optimizing the structure parameters. Further, the sources of detent force and its reducing methods are discussed. Finally, with high ambient operating temperature considered, thermal field distribution of the proposed machine is evaluated by 3D FEA, which ensures safe operation of the machine.

ABSTRACT. Most torque ripple reduction strategies for rotating motor are not suitable for long stator linear synchronous motor (LSLSM). In this paper, the electromagnetic force ripple reduction method for LSLSM based on the structure that the pole pitch of the mover is different from the pole pitch of the stator is analyzed. Both mathematical derivation and 2-D finite element method (FEM) are adopted for the ripple analysis. Simulation results of the electromagnetic force with different pole pitch are given in the paper. The results show that the proposed method is effective for reduction of electromagnetic force ripple in LSLSM.

ABSTRACT. This paper presents an approach to completely eliminate common-mode voltage (CMV) of an AC motor fed by a three-level neutral point clamped (NPC) inverter. CMV is produced at the star point of an AC machine fed from the inverter. Its parasitic coupling with the motor frame has a negative effect on the motor itself and other equipment, particularly in underground environment. The proposed approach to eliminate CMV, in combination with capacitor voltage balancing, is based on simplified model predictive control (MPC). Simulation results implemented in MATLAB-Simulink environment confirm that the proposed MPC algorithm successfully removes CMV, which makes it a promising control technique in industrial applications.

ABSTRACT. Mechanical gearboxes are widely used to improve system torque density. Although it is very common to employ mechanical gearboxes, they also have limitations including backlash, vibration, high maintenance requirements and noise. To overcome these problems, magnetic gearboxes have been considered for decades. Magnetic gearboxes have many advantages include contactless torque transmission, maintenance free operation and inherent overload protection. Early attempts at magnetic gearboxes were limited by low torque density [1]. The topology introduced in [2] demonstrated high torque density compared with other magnetic gearboxes and some mechanical counterparts. The gearbox consists of three circumferential parts; outer magnetic pole-pieces, ferromagnetic poles and an inner high-speed rotor. Torque production in the magnetic gearbox relies on the modulation of the flux linking the high speed and low speed rotors by the ferromagnetic pole pieces. The purpose of this paper is to introduce a new high-speed rotor configuration for a coaxial magnetic gearbox. The proposed gearbox optimizes the magnet volume and employs cage rotor bars integrated into the high-speed rotor as shown in Fig. 1. The resulting proposed gearbox aims to offer the same performance with reduced magnet volume, and give better torque production in overload conditions. The objectives of the paper are to analyse the modulated flux as a function of the magnet-span on the high-speed rotor and to observe the torque contribution of the cage rotor bars in overload conditions. The results are then compared with a conventional magnetic gearbox.

ABSTRACT. The utilization of asynchronous induction machines applied in railway traction drives is much higher than those used with industrial drives. Since this applies to both electromagnetic and thermal parameters, a multi-physics optimization with respect to electromagnetic and thermal behaviour will be introduced into the industrial design process. The discussed optimization approach consists of a sequential coupling of electromagnetic, thermal and fluid dynamics analyses. Its application is shown with a sample design task in order to fulfil the specific requirements of such machines.

ABSTRACT. Interior permanent magnet synchronous motor (IPMSM) has stronger reluctance torque and mechanical strength and better dynamic performance, being highly suitable for high-speed operation. Practically, the performance of IPMSM is dramatically influenced by various rotor structures. This paper studies a fractional-slot IPMSM and it is analyzed that how those parameters, such as the number of permanent magnet segments, the width of magnetic bridge and the thickness of flux barrier, etc., impact on the motor characteristics, namely, no-load back electromotive force (BEMF), dq-axis inductance, cogging torque and speed regulation range, and so on.

ABSTRACT. This paper presents a control strategy of integrated switched reluctance motor(SRM) base on split-winding. A novel SRM converter topology which integrated driving and battery charger are proposed in EV application. The boost inductance is limited by the phase winding of the motor, so the performance of the integrated battery charger is cut down. In the proposed integrated motor drive, a novel converter topology and split-winding method are used to reduce the inductance and resistor of boost inductance and obtain high performance. The split-winding design of SRM is analyzed in magnetic field by finite element method. The symmetrical magnetic field of phase A and B is easy to product the zero torque in battery charger mode. The operational modes of two functions are introduced in detail. The control strategy of proposed drive is suggested to more stable working. Some simulation and experimental results are done to verify the performance of proposed converters.

ABSTRACT. This paper presents a voltage control scheme for a high efficiency generator including a PM exciter through frequency detection. The proposed generator generates a constant exciter output voltage in the exciter according to the engine speed. The generator output voltage is generated by controlling the field current by the exciter output voltage. The generator output voltage changes according to the field current and the rotation frequency. The field current is controlled by the rotational frequency to suppress overshoot and improve dynamic performance when steady state is reached.

ABSTRACT. Nonlinear loads are one of the main factors which affect the output voltage quality of a stand-alone system. This paper proposes a novel control strategy with 5th and 7th harmonic elimination in the power winding voltage for a dual-stator brushless doubly fed induction generator (DSBDFIG), which feeds a three-phase rectifier load. The scheme of the control strategy was deduced and detailed in the paper. Simulation results validate the effectiveness of the proposed control method.

ABSTRACT. Rated power of a specific motor is highly dependent on cooling capacity for its own protection system. This paper addresses an effect of counter rotating vortices generated inside a weather-protected housing mounted over a IP23W motor, deteriorating thermal-flow characteristics. Generative process of the vortices was initially investigated with computational fluid dynamics and passive control device was added up to attenuate the rotational flow structures causing a sharp pressure drop. After the flow-control, both hydraulic resistance of the housing and temperature rise of the winding were significantly decreased according to CFD and test, respectively.

ABSTRACT. Aiming at the problems of the poor speed identification performance of a bearingless induction motor (BIM) speed sensorless vector control system based on traditional model reference adaptive system (MRAS), a novel speed identification method based on sliding mode variable structur-model reference adaptive system (SMVS-MARS) is proposed. Simulation and experiment results showed that the stable sensorless suspension operation of BIM can be achieved. The rotor speed can be more precisely observed and the dynamic performance significantly improved using the proposed method.

ABSTRACT. This paper presents a sensor-less control method for a stand-alone ship shaft generation system based on brushless doubly-fed machine (BDFM) with a novel wound rotor structure. A speed estimation based on the Model Reference Adaptive is introduced into the control winding field-oriented control method. The control block diagram is set up including the adjustable model and reference model and relevant simulation and experiment are carried out. All studies show that the control method is verified and applicable in stand-alone generation system.

ABSTRACT. Conventional sensorless controls for induction motors require two PID regulators and precise gain turning. This paper presents a sensorless control for induction motors using an extended Kalman filter (EKF) and linear quadratic tracking (LQT). The proposed method requires only a single controller, and no gain tuning of PID regulators.

ABSTRACT. A novel extended state observer (ESO)-based vector control (VC) strategy is developed for permanent magnet synchronous motor (PMSM) drive systems with only one phase current sensor. Generally, to achieve high precision control, two phase current sensors are indispensable for successful operation of the feedback control. In response to a phase current sensor fault, by use of technique of ESO, a novel observer for estimating both the remaining two phase currents and time-varying stator resistance is put forward. To improve the performance and decrease system chatting, a nonlinear exponential function is used to replace the switch function in conventional ESO. The resultant ESO-based VC strategy for PMSM drive system with single phase current sensor has excellent control performance. Numerical simulation validates the feasibility and effectiveness of the proposed scheme.

ABSTRACT. Ballscrew drive system has high mechanical efficiency and is able to get high gear ratio easily. But it also has non liner friction elements like rolling friction and viscous friction, so it makes ballscrew control accuracy worse. For that reason, it is proposed that inserting disturbance observer into control system and compensating disturbance torque. Generally, rotary encoder is used for position sensor in ballscrew control, but its resolution affects accuracy of drive control and disturbance observer. In this paper, we propose a speed control system using AC servo motor ball screw drive system, compare driving characteristics in low speed range when using low resolution encoder and high resolution encoder as position sensor. Also we examine effects for driving characteristics by using and compensating disturbance observer. These verifications were carried out by simulation and actual machine.

ABSTRACT. The conventional stand-alone brushless doubly-fed generator (BDFG) control strategies need the feedback from the rotor position or speed sensors, which will reduce system reliability, increase the cost, increase the generator axial volume. In this paper, a sensorless direct voltage control (DVC) strategy is presented for the stand-alone BDFG. The satisfactory dynamic performance is verified by experimental results under variable rotor speed and load. Besides, the proposed control strategy is robust due to no generator parameters being required.

ABSTRACT. In this paper, a novel DC-link voltage variation method using a high-efficiency dc-dc converter for the three-phase-inverter of IPMSM(Interior Permanent Magnet Synchronous Motor) is proposed. The proper variation method of DC-link voltage is needed to reduce the torque ripple of IPMSM and, switching loss of the inverter. Also, to meet the high-efficiency requirement of the DC-DC converter with the proposed method and, regenerative operation requirements of the motor-driver, a novel DC-DC converter is proposed. Simulation results are given to verify the reliability of the proposed DC-link variation method and DC-DC converter.

ABSTRACT. A high gain single stage Buck-Boost inverter (SSBBI) is proposed in this paper. The proposed topology has low component count. The tapped inductor is applied to attain high gain feature. One-cycle control (OCC) is adopted to control the SSBBI and attain superior source ripple rejection. The paper presents the operation principle of the proposed topology, and the derivation of the OCC control law. The proposed topology and the control scheme are verified by simulation.

ABSTRACT. This paper proposes a novel integrated nine-switch converter for the dual stator Doubly Salient Electro-magnet Motor (DSEM) for compact driving system. The dual stator windings are connected to the dual output ports of the converter, and the operation principle and normal commutation method are analyzed, then the optimized control strategy of multi-modes injection and direct current control is proposed for the elimination of the current peak in the non-conducting phase in order to decouple the dual stator windings with the nine-switch converter. The experimental results demonstrate the feasibility and effectiveness of the proposed driving system.

ABSTRACT. There is variety of converter topologies applicable for switched reluctance machines. The simplicity, reliability and suitability are inevitable factors to consider for converter selection for the motor. The selection of switching schemes is also of worth important for either converter used. This paper presents the calculation method of switching losses in asymmetrical H-bridge converter for the motor. The data of energy loss is experimentally obtained and then included in the simulation model of the machine to predict the converter loss. The experimental based input data suits the trend of energy loss for range of current.

ABSTRACT. Following publication considers synchronous reluctance machine with increased number of phases. The main goal of this research is to investigate the alternative solutions to the existing and well-known 3-phase electrical machines. In particular, a 5-phase reluctance machine with concentrated stator winding is briefly mentioned and a 42-phase electrical motor equipped with stator solid bars is shown. Electrical machine with stator cage and solid conductors (cage bars) seems to be a valuable alternative to the motors with conventional stator windings (coils) and stranded conductors. The combination of a multiphase cage winding in the stator and a reluctance rotor for synchronous operation was not considered before and is observed in this work. Based on the finite element analysis, the main performance characteristics such as the saliency ratio, the torque ripple, the power losses, the efficiency and the power factor, as well as the power-speed characteristics have been examined.

ABSTRACT. The follow-up control system has the feature of input signal random changing. On the basis of motor driving technology, the system can follow the change of the input signal. Permanent Magnet Synchronous Motor (PMSM) has small output torque ripple feature. And it has broad application prospect in the follow-up control system. The vector control of PMSM has coupling feature, reducing the speed dynamic control performance. Aiming at improving the follow-up control system performance, one speed control decoupling method is proposed in the view of the engineering application. The quadrature-axis voltage control instruction is given by the direct-axis and quadrature-axis current. The simulation result verifies the effectiveness of the proposed method.

ABSTRACT. The superconducting cable has shown the advantages in large power transmission with higher efficiency and lower loss. In particular, the application to DC electric system is now attracting increasing attention. However, after introduction of superconducting cables, the increased fault current may be a threat to the safety and stability. To cope with this issue, the resistive SFCL offers one of the most ideal solutions due to its operating principle and limiting performance. This paper discusses the influence of three main design parameters of resistive type SFCL with a model DC system using superconducting cables, and proposes the design method and criterion. Then, the electromagnetic and thermal design of the SFCL is discussed for two model systems: low voltage HTS DC distribution system and high voltage HTS DC transmission system. Furthermore, it is shown that how the differences in system characteristics influence the design of SFCL.

ABSTRACT. A novel electromagnetic clutch system is proposed to resolve the mechanical and electromagnetic impacts in the in-wheel motor drive electric vehicles. The dynamic analysis of the system is presented for researching the engagement process. Based on the dynamic analysis, the relationship between the action forces during the engagement is studied and the range of the clutch’s angular deflection is given for the design optimization of the clutch.

ABSTRACT. A novel electromagnetic linear actuator for a tactile display is proposed. The features of actuators for this use may be evaluated by output force, stroke, compactness, and so on. The proposed new actuator has better performance in terms of above features compared with other actuators. Moreover, it does not need a position sensor to detect the mover position.

ABSTRACT. Sub-span Oscillation is a low frequency and long lasting-time fluid-solid coupling phenomenon, which usually causes serious damage, especially in the ultra-high voltage (UHV) overhead power transmission lines with multi-bundle conductors. Although some simplified sub-span oscillation theories have been proposed, the oscillation behavior of transmission lines, which strongly depends on the working currents, is still unclear. Here, the meticulous finite element method (FEM) for calculating the electromagnetic force between sub-conductors, a method for sub-span oscillation of considering the electromagnetic force is achieved. Furthermore, the effect of current intensity on sub-span oscillation behaviors, including dynamic responses, oscillation orbits, frequencies, vibration modes and amplitudes, of typical quad bundle conductor transmission lines are investigated. The results show that the electromagnetic force has obvious effect on oscillation behavior, especially on long span line. Thus, it is necessary to consider the electromagnetic force during oscillation.

ABSTRACT. The goaf of the transmission line possesses a great threat to the surface power facilities, and the effective detection of the goaf can greatly reduce the probability of accident. The complex electromagnetic environment under the transmission line makes traditional detection method not work well. An electromagnetic detection emission system is designed by using spread spectrum code technique and correlation algorithm, which can improve the anti-jamming capability and detection efficiency.

ABSTRACT. In this paper, an 18-slot/26-pole fractional slot permanent magnet surface-mounted machine (FSPMSM) with 2 slot-pitches is firstly proposed. The torque production of this machine is based on both the principle of fractional slot machine and magnetic gearing effect. The performance of the 18-slot/26-pole FSPMSM is analyzed and compared with an 18-slot/10-pole FSPMSM. The results show that the 18-slot/26-pole FSPMSM has larger torque, torque density, smaller torque ripple, smaller iron losses and higher efficiency than its 10-pole counterpart, and other feasible slot/pole combinations based on the same working principle will be provided.

ABSTRACT. This paper presents a transverse flux linear motor (TFLM) with the superconductor-aluminum hybrid as the secondary and E-shaped ferromagnetic yokes wrapped the conductor windings as the primary to generate the transverse flux, the hybrid secondary is made of aluminum plate and close-ended coated superconductor coils, with the latter placed over the former to realize the stable levitation, guidance and self-propulsion. In this paper, a multi-degree of freedom 3-D finite-element dynamic model of the proposed superconducting TFLM was established, in which the actual geometry of the motor and the nonlinear behavior of superconductor were represented. We investigated the motion characteristics and response characteristics for disturbance and also studied the influence of aluminum plate on performance. The achieved results clearly display that, the self-stability and self-propulsion could be integrated by the proposed superconducting TFLM, which provides a novel alternative to the scientific community of maglev transit.

ABSTRACT. This paper investigates a three-phase 12/8 poles bearingless doubly salient permanent magnet machine (BDSPMM) with suspending windings, armature windings and PMs on the stator. Based on the topology and operating principle, the influence of PM magnetization length on the performance of the BDSPMM is analyzed and a mathematical model of radial suspending force is deduced from the magnetic circuit. The 2D finite element analysis (FEA) is carried out to verify the mathematical model. A prototype BDSPMM has been built. The simulation and experiment results show that the correctness of the motor design method and mathematical model, which laid a theoretical foundation for the high performance control strategy of BDSPMM.

ABSTRACT. This paper introduces a submerged LNG (liquefied natural gas) pump cryogenic permanent magnet synchronous motor (PMSM). A 22kW/6000rpm prototype is designed for low temperature operation at 68K. The influence of temperature on magnetic and electric parameters of materials is analyzed, and a coupled simulation model of electromagnetic-fluid-thermal-stress field is established. On this basis, the motor characteristics such as the loss, back EMF and torque are obtained. The accuracy of the simulation model is verified by the prototype test at 68K liquid nitrogen. Simulation and test results show that the performance of the cryogenic PMSM is better than that of the traditional motor.

ABSTRACT. This paper suggests asymmetric stator teeth design to reduce torque ripple and back EMF Total Harmonic Distortion(THD) for Interior Permanent Magnet Synchronous Machine(IPMSM). IPMSM which has 8 poles, 12 slots is analyzed in this study. From changing design parameter in stator structure, 8 comparison models are analyzed. Analysis of proposed method is carried out using Finite Element Method(FEM). Suggested method has advantage to reduce torque ripple and back EMF THD without average torque decrease. Comparison between reference model and comparison models applying proposed method proceeds to verify advantage of this method.

ABSTRACT. In this paper, an Interior permanent magnet (IPM) synchronous machine design is proposed having the advantages of higher machine torque characteristics by minimizing the flux leakage through the ribs of a bar-type IPM machine. An IPM base model is taken and two models are proposed. The specific merit of the proposed IPM model is to consider the d-axis pole area and the tangential length of rotor ribs. Finite element analysis is performed for performance analysis of proposed models. The no-load flux linkage wave shows improved shape, which results in increase value of back-EMF. Additionally, reluctance torque is also increased. The increased in back-EMF and reluctance torque contributed in the overall improvement in the output average torque. In addition, the torque ripple of the machine is also reduced.

ABSTRACT. Along with the higher requirement of aircraft’s generation system proposed, Integrated Starter Generator system appeared on the stage of history which can work as an electric motor and a generator at the same time. This paper talks about a Permanent Magnet Machine (PMM) which is applied as Integrated Starter Generator (ISG) used into the unmanned aerial vehicle (UAV). Permanent Magnet Machine has superiority in high-efficiency compared with other motors such as Squirrel-cage Asynchronous Motor. Moreover it has advantages of excellent starting performance as a starter and higher quality when it works in the state of power generation. This paper analyses the motor’s starting torque, no-load back-electromotive force (BEMF), torque-speed curve and power-speed curve by using the finite element software Maxwell to establish a model of Permanent Magnet Machine.

ABSTRACT. In This paper, an improved adaptive genetic algorithm is presented for the design optimization on Permanent magnet synchronous motor(PMSM), which can availably reduce the iterative time and simplify the magnetic circuit calculation during optimization designing. To obtain higher computation speed, C++ language is applied to develop both the basic electromagnetic calculation program and optimization algorithm based on the Microsoft Visual studio 2010 development tools. According to the developed program, the optimal solution of motor designing can be quickly and accurately gotten, thus shortening the development cycle and improving the optimization design efficiency. In addition, the finite element analysis (FEA)is used in the motor design scheme before and after the optimization with static and transient ways, and the optimization design validity is confirmed through the simulated results.

ABSTRACT. This paper studies the characteristics and design concept of low-speed high-torque direct-driven PMSM with fractional-slot concentrated winding used in coal mine belt conveyor system. The fractional slot concentrated winding PMSM with high efficiency, high power density and simple windings type is used widely, and more attention is paid to the influence of cogging torque with different slots and poles, but less attention is paid to the effect of the different between different stator conductor turns loss on open-slots motor and rotor magnet loss caused by harmonic field. In this paper, taking a 500kW 60RPM 1140V low speed permanent magnet direct-driven motor as an example, it presents that the different between different stator conductor turns loss of multi-polar few slot motor and the rotor magnet loss by the EFA simulation and temperature field calculation, which are not uniform and easily overlooked, will be leaded to serious temperature rise problems.A new rotor topology structure design and some measures on how to reduce stator copper loss and rotor eddy current loss are propose. The prototype machine was developed and tested to validate the feasibility and correctness of design and analysis.

ABSTRACT. Due to the changed parameters of double sided linear induction motor (DSLIM), the field oriented control (FOC) is not suitable in control and it will result in thrust fluctuation. The thrust control in the DSLIM is a better solution to suppress the thrust fluctuation. This paper establishes the dynamic model of DSLIMs according to the change principle of parameters and uses the model predictive thrust control (MPTC) to restrain the thrust fluctuation. For comparison, the direct torque control (DTC) results are also presented. The control results show the MPTC has a better control performance in parallel connected DSLIM systems.

ABSTRACT. This paper presents an experimental set up to measure the deformation in an iron sheet under the influence of electromagnetic field, and the results of Finite Element Analysis used for segregating the magnetic forces and magnetostriction induced mechanical deformation. The magnetic forces are calculated using Virtual Work principle and the magnetostriction is modeled by means of an energy-based model. The 3D computations are performed in an open source finite element software Elmer. The experimental results and numerical simulations were analyzed and the deformation due to magnetic forces and magnetostriction were identified.

ABSTRACT. This paper proposes an end-effect equivalent 2D model to analyze back-EMF of high speed permanent magnet synchronous motor(PMSM) in order to consider a leakage flux in the end region of stator and air-gap. Since 2D FEA does not provide a precise analyzing result of back-EMF calculation due to the long airgap, an equivalent back-EMF simulation method is proposed. The proposed model of back-EMF analysis can be applied to the high speed SPMSM using a can, and the method is verified by results of 3D FEA and experiment.

ABSTRACT. The canned solid-rotor induction motors are widely used in petroleum, chemical, and pharmaceutical fields. This paper deals with analytical method of performance calculation for canned solid-Rotor induction motors with squirrel-cage and the results are validated by finite element analysis.

ABSTRACT. Single-phase capacitor induction motors are the most common low cost solutions for household appliance. An alternative high efficiency motor is the novel three-winding series-connected single-phase motor. This paper proposes the simulation and analysis of the fractional order model of the novel motor with no load and light load. A transfer function with a fractional derivative order has been selected to represent the admittance of the capacitors by the help of a non-integer integrator. Numerical simulations and experimental results show the performance of the modal approach for modeling.

ABSTRACT. For the vacuum arc, the parameters of the interelectrode plasma have influences on the electrode process in turn. It is important to obtain the parameters and characteristics of the plasma by simulating the plasma among the electrodes. In the paper, the MHD model of vacuum arc is deduced and the boundary conditions are determined by combining the characteristics of vacuum arc under different interrupting cases, considering the influence of kinetic energy of ion and electron, average charge of ions on the vacuum arc based on the analysis the existing vacuum arc models. The basic characteristics of vacuum arc MHD model under low current interrupting condition are obtained finally.

ABSTRACT. A method for the time-step analysis of single-phase induction motors is proposed. The unknown variables in the differential equations are the currents flowing through the rotor bars. They are coupled with the distributed magnetic flux densities in the air gap instead of the inductance matrix while applying Kirchhoff’s and Faraday’s induction laws. Two patterns for magnetic flux densities are necessary. One is given by an ideal stator winding distribution, whereas the other is produced by currents flowing through a rotor bar with unit magnitude and is calculated using the finite element method (FEM). The formulated set of equations is solved for a simple three-phase and single-phase example model and the resultant speed torque curve is shown in this paper.

ABSTRACT. Non-destructive testing (NDT) has preoccupied a growing number of scientists in recent years. In the field of NDT, the eddy current testing is widely used in industry occasions. It is important to enhance the accuracy and efficiency of the eddy current testing system. In this paper, a planar coil with multi-frequency stimulations was applied to an eddy current testing system. The distribution of magnetic flux density of the coil was studied. It is showed that the coil with multi-frequency could check the cracks simultaneously in different depths of the specimen and enhanced the performance of the eddy current testing system significantly.

ABSTRACT. In this paper, a novel 2-D Halbach magnet array for magnetically levitated synchronous planar motor is investigated. The magnetic flux density distribution of the novel 2-D Halbach array is solved analytically and validated by the finite element method. Compared with the well-known Halbach magnet array, the proposed magnet array has lower higher harmonic components and higher z-component of the magnetic flux density, which will reduce the force ripples of the magnetically levitated synchronous planar motor.

ABSTRACT. This paper presents an evaluation of transient electromagnetic phenomena inside lightning protection systems (LPS) model of truss bridge resulting from direct lightning strikes. The simulation model is base on the coupled transmission line network in the frequency domain combined with the Fourier transform technique, which is employed to evaluate the electromagnetic transient surge current distribution in LPS. The transient magnetic fields are calculated based on difference method. After comparing with the standard "IEC62305-4", it can be seen that the calculation is accurate and the method is simple The paper provides a new idea for the optimization design of truss bridge LPS.

ABSTRACT. The modal analysis has an important place in analyzing the vibration and noise of the motors. The model of the stator by the 3D finite element software which are based on the interior permanent magnet (IPM) machine are analyzed. First, it is significant to find out the rules of the different parameters of the stator on the natural frequencies by considering the geometric structure of the stator core and the stator rind. Meanwhile, the influence of the stator coils has been reported. Finally, the results of the stator core considering the stator rind and the simplified stator rind are compared. The research work provides theoretical data support for estimating the vibration and acoustic noise.

ABSTRACT. This paper focuses on the rapid regression modeling research for the design optimization of Permanent magnet synchronous linear motors (PMSLM) which are applied in the linear motion machines. Based on the Finite Element Analysis (FEA), the initial PMSLM model is built and the modeling data of optimization are obtained. Then, the machine learning regression algorithm named K-Nearest Neighbor Algorithm (KNNA) is introduced to mapping the nonlinear relations of structure parameters and performances, and establishes the rapid calculation model for the next optimization. Finally, the superiority and reliability of this method is confirmed by the FEA experiments

ABSTRACT. This paper describes the causes of cogging torque in Permanent Magnet synchronous Motor. Establishes a motor model by ANSOFT software, uses Finite Element Method to quantitative analysis and comparative peak cogging torque and torque with notches at different locations, and different number of auxiliary slot. The conclusion is that notch reasonable can reduce the cogging torque of permanent magnet motor effective.

ABSTRACT. The numerical prediction of the main state of the equipment is the first step in the prognostic and health management (PHM) study. Temperature is one of the most important health indicators of segment – powered linear motor. A NARX (Nonlinear Autoregressive with exogenous input) Neural Network model is trained to predict the temperature of the segment-powered linear motor. Based on the single - value prediction, the optimal prediction model is introduced. Based on the working condition information, the joint prediction model is designed and trained for the temperature prediction. The model is applied on the multi - stage test data obtained on different dates and the prediction result is compared and analyzed.

ABSTRACT. An external rotor transverse flux motor has been proposed in our previous research, which has the advantages of low manufacturing cost and high torque density. In this paper, a novel transverse flux is introduced based on the foregoing motor’s structure. At first, the detail motor structures and working principle are introduced. Then, the three-dimensional model of proposed motor is analyzed by finite element software. At last, the comparison of electromagnetic characteristic is done, the results show that the novel motor can provide 89.6% torque density of foregoing one by using 74.7% permanent magnet.

ABSTRACT. This paper is concerned with the strength analysis of salient rotor for stator permanent magnet electrical machines (SPMEMs) with the influence of rotational speed and rotor temperature. First, the rotor stress conditions were simplified as a plane stress problem. Then the analytical solution for rotor strength was proposed based on displacement method and stress potential method in polar coordinate. Finally, the effectiveness of the analytical solution was validated by the finite element method. It is shown that the analytical solution proposed can accurately predict the stress distribution of the salient rotor in SPMEMs.

ABSTRACT. A hybrid high temperature superconducting (HTS) linear synchronous propulsion system composed of a HTS linear synchronous motor (HTSLSM) in the middle and HTS magnetic suspension sub-systems on both sides has been proposed for a high-speed maglev. Four carriages have been made up for the proposed maglev, and each carriage consists of four HTSLSM modules, which weight 10 tons. The maglev has been designed to reach a speed of 1000 km/h. The finite element analysis has been used for the theoretical verification and character analysis. The obtained results show that the HTS linear propulsion system satisfies the principal requirements for the maglev.

ABSTRACT. In this paper, a large wind farm is divided into two sub wind farms, represented by two aggregated doubly fed induction generators (DFIGs) at different locations. Impedance model of two sub wind farms are established and Nyquist criterion is applied to analyze the effect of DFIGs at different locations on sub-synchronous resonance (SSR) when different influencing factors vary. The results show that the DFIGs near the point of common coupling (PCC) have greater impact on SSR than the DFIGs far from PCC as one of the influencing factors varies. Time domain simulation is performed in PSCAD/EMTDC to verify the correction of the conclusion. The method this paper proposes doesn't need complex calculation and can judge the impact of different factors on SSR intuitively.

ABSTRACT. In this paper, we are investigating two different approaches to reduce the torque ripple in PM-assisted SynRel machines. First, we will demonstrate the effectiveness of closing slots in such topology. Then, we will show that it is possible to drastically reduce the torque ripple using particle swarm optimization algorithm. The latter approach particularly makes sense for industrial fast-prototyping needs.

ABSTRACT. Highly dynamic DC-machines, used in low power applications, often contain ironless or so called bell shaped wind-ings. Because there is no massive iron core to support the windings, one of the limiting factors for the torque of the machine is the force on the single wires of the copper weave. Therefore, the knowledge of the force distribution on the single wires could be a helpful design criterion. In order to examine the distribution of forces inside bell shaped windings, in this work the coil wires are subdivided into discrete wire elements within this work. For each of these elements the Lorentz-force and the torque caused by a permanent magnet excitation are calculated. To calculate the currents through the elements a time variant electrical network is presented, which is also capable to consider non-ideal commutation effects. The model itself consists of two single blocks, which will be explained below.

ABSTRACT. This paper analyzes high-speed performance characteristics of fractional-slot concentrated-wound (FSCW) interior permanent magnet (IPM) machines during a multi-objective design optimization for achieving a high saliency ratio and a high efficiency. Tradeoffs between the high-speed performance characteristics and the saliency ratio and efficiency of an FSCW IPM machine in its design optimization are comprehensively discussed. It is shown that a predefined characteristic current significantly affects the maximum achievable saliency ratio and efficiency for FSCW IPM machines during a multi-objective design optimization process. A large-scale design optimization is performed leading to a family of optimal machine designs. The high-speed performance characteristics of these optimal designs are investigated, leading to proposing a criterion for the tradeoff between the high saliency ratio and efficiency and the high-speed performance characteristic. The results reported here provide a deeper insight into the optimal design of FSCW IPM machines with a high saliency ratio and a high efficiency.

ABSTRACT. This paper proposes a novel modular linear primary permanent-magnet vernier (LPPMV) machine. It possesses a simple secondary side, suitable for long stroke applications such as urban rail transit. Owing to its appropriate primary structure and the halbach PM arrays, the proposed LPPMV machine offers higher force density, higher back-EMF and lower harmonic compared than the existing one. Its performance is predicted for verification by using finite-element method.

ABSTRACT. This paper proposes an improved model predictive torque control (MPTC) method for an open-end winding permanent magnet synchronous motor (OEW-PMSM) with reduced computation time. First, a basic predictive torque control algorithm is derived, which is based on the discrete system model and cost function. Then, a direct torque control (DTC) based switching table is developed to reduce the computation time. In addition, a weighting factor elimination method is adopted to avoid the tuning work, which is based on the equivalent reference vector of the reactive torque. Also, the optimal switching state selection strategy based on the principle of least switching losses is introduced. Simulation results are offered to verify the proposed method.

ABSTRACT. In this paper, two modified and simplified space vector pulse width modulation (SVPWM) methods are presented. The relationship of them is comprehensively studied. A variable factor k0 is introduced into the unified voltage modulation method. Due to factor k0, the time duration of application of two zero state vectors is made changeable from 0 to 100% over the sampling period for their combined application, which makes the strategy is flexible and universal. Additionally, by introducing factor k0 into the unified voltage modulation, it can prove that the two simplified SVPWM schemes are exactly identical. Owing to the variable factor, the two simplified SVPWM methods can be employed to balance the neutral-point potential in the neutral-point-clamped three-level inverter. Experimental results are shown the validity.

ABSTRACT. A single-phase two-stage inverter generally uses an intermediate capacitor to buffer the power imbalance between DC input and AC output. However, the resultant low-frequency voltage ripple on this intermediate capacitor may produce low-frequency current ripple at the source side, especially when the front-end dc/dc converter operates in continuous conduction mode (CCM). Some common solutions to reducing this ripple are feedforward control and power decoupling circuits. Alternatively, this paper analyzes a two-stage inverter where the front-end is a basic dc/dc converter operating in discontinuous conduction mode (DCM). In general dc/dc converters operating in DCM have inherent natural capability to reduce this low-frequency input current ripple, without needing a sophisticated control or complex circuitry as compared with its CCM operation. Analysis with simulation verification is reported to demonstrate such capability

ABSTRACT. This paper presents a random space vector pulse width modulation (SVPWM) strategy for a three-phase voltage source inverter based on Field Programmable Gate Array (FPGA). It is more flexible and faster to realize randomization algorithm in FPGA than digital signal processor (DSP). What’s more, it is easily extensible for multiphase driving systems with FPGA. Models in Simulink and an experiment platform with FPGA have been built up. Results of experiments have proved the correctness of the proposed strategy and the effectiveness and feasibility of implementation using FPGA.

ABSTRACT. In order to suppress harmonics and optimize power grid quality for the indirect matrix converter (IMC), harmonic characteristics of the input current in IMC are analyzed. The classic dual space vector modulation (SVM) method is adopted for IMC. Generally, only the rough results of harmonic analysis can be achieved by using the conventional mathematical model based on the transfer function. In this paper, the pulse barycentre theory, in which the pulse width，distribution position and amplitude are all considered, is introduced to obtain the accurate harmonic components and their magnitudes. Furthermore, the principle of the zero voltage vector pulse proportional symmetrical distribution has been found to attenuate input current harmonics. Simulation and experimental results show that the input current harmonics coincide with the theoretical results and demonstrate the validity of the theoretical analysis ultimately.

ABSTRACT. This paper deals with the stability evaluation of the direct matrix converter considering the effects of input voltage measurement and input filter designing. The performance of the converter is investigated in both generator and motor mode using a voltage oriented control (VOC) method. The essence of some existing methods for improving the stability of the matrix converter is discussed and compared. In order to analyze and compare the methods, the behavior of the system has been tested by simulation in PSIM software.

ABSTRACT. This paper is concerned with the process of current commutation and overvoltage protection in matrix converters. The mechanisms involved in the commutation process and clamp circuit are described and simulation waveforms are presented. A four-step semi-soft commutation strategy is described that this technique relies on knowledge of the output current direction and the ability to control the direction of current within the switches. Also a clamp circuit is demonstrated by simulation as an overvoltage protection for matrix converter. Simulation results are presented using a simulation model of the three-phase direct matrix converter in MATLAB/Simulink.

ABSTRACT. This paper presents a simplified DQ current controller for single-phase grid-connected inverters in synchronous reference frames. The proposed controller cancels the orthogonal signal generator (OSG) block, and is equivalent to proportional resonant (PR) controller in stationary frame. Thus, LCL filters can be implemented to improve grid current quality. A novel decoupling technique for the axes cross-coupling is also implemented to improve the performance of current control. Simulation and experimental results show that the proposed controller have excellent performance.

ABSTRACT. This paper, based on the three dimension (3D) coordinates, presents the cause of the zero-sequence voltage in the open winding asynchronous motor system which is driven by double inverters with single power supply. The large vectors which have zero-sequence voltage are selected to realize PWM. For eliminating the zero-sequence voltage, the space zero vectors are inserted in every control period. This modulation algorithm is easy to be realized by digital controller. The validity of the proposed method has been verified by MATLAB simulation.

ABSTRACT. We proposed slim type DC to DC converter modules based on wireless power transmission technology, and 500W class prototype was produced with applying the technology on Switching power supply converter designing. The wireless power transmission technology is actively studied in these days to increase isolated voltage of transformer. The power transmitting transformer was fixed on ceramic centered multi-layer PCB to increase efficiency and to lower height of the prototype. Also, winding wire of the transformer was designed with PCB patterns to minimize the height. And wireless power transmission technology is important for the output compensation circuit, so we applied for Bluetooth technology. The Specification of the prototype was 400V of input voltage; 1 Mhz of switching frequency; 90% of maximum power transmission efficiency full-load respectively. Even though wireless power transmission structured transformer was used, the power transmission efficiency was relatively high.

ABSTRACT. In order to convert more vortex induced vibration energy into electricity, a piezoelectric energy harvesting system using a modified circular cylinder is studied to evaluate its performance in water. The circular cylinder is often used to induce the Karman vortex street. To produce stronger and more regular vortices, a circular cylinder with a slit and concave rear surface is adopted in this paper. For the cylinder and the modified cylinder, the vorticity magnitudes are computed and compared. Then, the system performances with two kinds of bluff bodies are simulated and compared with physical fields fully coupled. The related experiment is conducted to verify the simulation result. Both of them prove the effectiveness of this modified energy harvesting system in improving the energy harvested and output.

ABSTRACT. Today, a lot of accumulator trains are introduced for saving the global environments. In the East Japan railway, a new battery powered railway vehicle called ACCUM on the non-electrified Oga line has been operated on March 4. ACCUM is provided AC-20kV energy from Oga substation. This substation has to possess earth fault protection system not to effect railway peripheral facilities and customers. However, it is necessary to considerate a special protection circuit because the substation has a short feeding circuit. Therefore this paper shows the earth fault protection system provided on Oga line.

ABSTRACT. Conceptual design and performance evaluation of a DC-type dynamic voltage restorer (DVR) system are presented for mitigation of DC voltage quality disturbances in various sensitive-load situations such as in electric vehicle charging stations and data centers. A 3-mH/225-A superconducting magnetic energy storage (SMES) coil is structurally designed and optimized to cooperate with conventional battery energy storage (BES) device for developing a new hybrid energy storage (HES) system in the DC-type DVR. Various simulation cases with regard to combined voltage sag and swell disturbances are carried out. The simulations and comparisons among the SMES-based, BES-based and HES-based DVR schemes have demonstrated that the HES-based DVR scheme integrates the merits of fast response speed and high power density from the SMES-based scheme and the merits of low capital cost and high energy density from the BES-based scheme.

ABSTRACT. In this paper, starting with the flywheel energy storage system discharge controller, the field coupling model based on flywheel energy storage constant voltage discharge can be established by using the field coupling method. The change of the electromagnetic field in the motor during the whole discharge process is studied. Then, the change law of the air gap flux density of the motor is given, which can provide reference for the design of flywheel energy storage motor and controller.

ABSTRACT. This paper proposes a new control method for enhancement of transient stability of synchronous generators in power system with variable speed wind generators (VSWG). Kinetic energy stored in a rotor of VSWG is actively used for the transient stability enhancement, which is controlled based on responses of the kinetic energy of each synchronous generator in the power system. The effectiveness of the proposed method has been verified by the transient stability analysis performed for IEEE 9-bus system model, which is composed of conventional synchronous generators, photovoltaic (PV) systems and VSWG.

ABSTRACT. Demagnetization is one of the noticeable problems of almost every permanent magnet linear generator (PMLG) for oceanic wave energy conversion (OWEC). To prevent the degradation of electrical power generation capability, a PMLG with a new feature of variable air gap length is proposed in this paper. The voltage, current, power, magnetic flux density, and force components of the PMLG are analyzed and discussed. The finite element analysis is performed by using the software package ANSYS/ANSOFT to analyze the PMLG with the proposed method. The simulation results show that the new method can effectively prevent the demagnetization problem of PMLG.

ABSTRACT. In this paper a novel E-core Linear Variable Reluctance Vernier Hybrid Permanent Magnet (LVR-VHPM) machine with inherent magnetic gearing is proposed for use in the long stroke application of a wave energy converter. The proposed topology is a combination of a doubly salient flux reversal machine, a consequent pole machine and a surface mounted Halbach array Permanent Magnet (PM) machine. The stator teeth interact with horizontally and vertically magnetized PM and ferromagnetic poles in such a way as to maximize the flux density in the machine by minimizing flux leakage. The translator is segmented to ensure the most effective use of material for minimum mass. A performance comparison study between the novel LVR-VHPM machine, a baseline linear Vernier Hybrid Permanent Magnet (VHPM) machine, a linear Halbach VHPM machine and a linear Consequent pole VHPM machine is used to show that the best result is achieved by the combined topology. All four designs consist of the same double sided E-core stators, segmented translators and an equal magnet mass.

ABSTRACT. This paper investigated into a comparative study of modified swarm intelligence based algorithms for solving multi-objective optimal power flow incorporating wind power and load uncertainties to improve its efficiency and optimize power system generation. The proposed method has been tested under a number of modified IEEE test systems. The results show that solving the multi-objective optimal power flow with the proposed algorithm are more effective than other swarm intelligence methods in the literature.

ABSTRACT. This paper investigates a novel hybrid axial- and radial-magnetic circuit permanent magnet synchronous machine with flux weakening capability. The presented machine consists of a solid rotor and two stators, i.e. radial stator and axial stator. The PMs are radially buried in the solid rotor so that the flux flows into both radial and axial stator. This paper describes the principle of the presented machine and designs a prototype machine. First, influence of some key structural parameters on flux control capability of this machine is investigation by using equivalent magnetic circuits. Then a 3-D FEM model is established for magnetic analysis. The results indicate that the presented machine exhibits higher power density and good capability for flux weakening thus can be a good candidate for PMSM with large scale of running speed.

ABSTRACT. In this paper, a novel 5-phase double-sided C-core modular linear permanent-magnet synchronous machine (MLPMSM) used for the linear steering engine is researched. Firstly, the structure of the MLPMSM is depicted. Then the thrust produced by one module and the total thrust force of the machine are deduced and analyzed. In the ideal condition, all the harmonics in the thrust force can be eliminated except the 5qth (q= 1, 2, 3, 4……) order harmonic, when 5 modules are arranged equidistantly. To suppress 5th order harmonic in thrust force, the opening of module’s slot (Bs) is optimized. In addition, the first harmonic thrust ripple caused by the different flux distributions in end modules is researched and reduced by a proper current in the windings, located at the edge. The thrust ripple is greatly reduced by the adopted methods.

ABSTRACT. Linear induction motor (LIM) drive suffers heavily from low efficiency due to its large air-gap length, the end-effects, and the partial load working conditions. Therefore, an optimization method is proposed in this paper to improve the LIM drive operating efficiency from both design and control levels. First, the genetic algorithm (GA) is applied to design optimization of LIM to attain higher efficiency and power factor. Second, a novel loss model for LIM drive is proposed to analyze both LIM loss and inverter loss. Third, efficiency optimization control (EOC) scheme based on the loss model is put forward to improve the LIM drive working efficiency. Simulations and experimental results validate the effectiveness of the proposed method in efficiency improvement of LIM drive under various operation conditions.

ABSTRACT. Linear flux switching motor with segmented secondary (LFSMSS) is characterized by two kinds of windings, i.e. the DC field windings and AC armature windings, which are distributed alternately on the mover. LFSMSS is vulnerable to large force ripple. This paper investigates the influence of two design techniques (dummy slot and auxiliary tooth) on the force ripple of LFSMSS. In addition, the simulation results of average force, force ripple and back electromotive force (back-EMF) are analyzed by 2D finite element analysis.

ABSTRACT. This paper presents the comparative study and optimal design of a transverse flux linear machine with different PM configurations, viz. surface-mounted and consequent-pole, in which the consequent-pole version is firstly proposed. Firstly, the effect of variation of the main design parameters on both topologies are studied. Then, the multi-objective optimization method based on genetic algorithm combined with response surface methodology (RSM) is adopted to realize the optimal design of these two topologies and Pareto front solutions will be obtained. Finally, the characteristics of these two topologies are analyzed and compared, with particular regard to the advantages and disadvantages of the consequent pole topology.

ABSTRACT. The effect of slots poles combination on inductance, torque and magnet eddy current loss was investigated on the motor with bonded NdFeB Halbach cylinder outer rotor. The calculation was done using FEA 2D and 3D models. Motor with Halbach have better performance with higher number of slots and poles combination. The magnet loss using 3D calculation is much lower than 2D.

ABSTRACT. In this paper, a novel comprehensive design, including inverter and motor topology, and PWM scheme, is proposed to reduce iron losses for high speed induction motors. In the proposed method, two inverters are connected with a twin-coil motor. Two counteracting PWM schemes are applied in the two inverters, feeding the same fundamental currents into the twin coils, meanwhile switching in opposite phase so as to cancel the field variation at the switching frequency by the coupling of the twin coils. In such a way, it is found that the copper loss increases unexpectedly. Therefore, two improvements are further proposed, which can improve the overall motor efficiency. All the methods are investigated with coupled electrical circuit and finite element analysis (FEA) software.

ABSTRACT. Abstract —Stator core of high speed high power permanent magnet machines can be segmented in the axial direction, so that air flow can be forced through the gap between the core segments in order to enhance the cooling condition. Extra end effect thus exists, which will be studied in this paper. First, a 3D FEA model of the stator segments with end windings is built to reveal the relationship between the segmentation gap length and the stator iron loss and the magnet eddy current loss. Then, considering the negative impact of the end effect, the stator core segmentation is optimized, thus the machine losses such as the eddy current loss in the magnets are reduced. The analysis and optimal design have been applied in a 39krpm 110kW PM synchronous motor.

ABSTRACT. This paper investigates the effect of AC losses on the steady-state temperature rise distribution in concentrated windings of permanent magnet machines with parallel strands by combined electromagnetic and thermal FEA analyses. The copper losses are decomposed into DC loss, strand-level AC loss and bundle-level AC loss. It shows that the AC losses can significantly increase the winding temperature and influence the temperature distribution in the slot. The bundle-level loss becomes dominant at high speed but has a small influence on the location of the hot spot in the slot, while the strand-level loss could pull the hot spot to the slot opening. A 12-slot 10-pole FSCW permanent magnet machine was prototyped and measured to validate the effect of AC losses on the winding temperature rise. The obtained results could be helpful for designers to build a detailed lumped-parameter thermal model of the winding or for the manufactures where to insert a thermal sensor to capture the real hot spot in the slot.

ABSTRACT. The magnetic properties of soft magnetic composite is actively studied under 1-D and 2-D magnetic flux excitations in order to estimate the total core loss produced by the material during the magnetization. To keep lowering the loss, SOMALOY 700 material is considered in this paper. 2-D magnetic measurement flux has been conducted by controlling to be in ellipse shape by using LabVIEW software and the core loss calculation has been computed by MathCAD software. The performance of this material under different frequency is compared.

ABSTRACT. When designing a very-high-speed (VHS) machine, it is crucial to evaluate the windage losses accurately, because they are an important part of the total losses. It is therefore important to validate a reliable model, further used for the design and optimization of the motor. In this paper, an empirical windage loss model has been compared to measurements on a motor running up to 155 krpm in a pressure chamber. Indeed,in order to simulate the behavior of a motor running at higher speed, the air pressure surrounding the motor has been elevated up to 9 bars. The error encountered was 16 % at most compared to measurements.

ABSTRACT. Abstract— In recent years, the magnetic field modulation motor (MFMM) is attracting more and more attentions due to its compact structure and contactless torque transmission function, etc. However, its multi design parameters and ouput ports make the optimization design for the MFMM necessary and difficult. In this paper, an automatic multi-objective optimization of the MFMM based on the advanced differential evolution (DE) and finite-element analysis (FEA) is presented. The method was presented and used in order to improve the efficiency of optimization. A MFMM is studied as an example, the result demonstrates the method presented in this paper gives out a very excellent design with 6.65% increasement in the torque of modulating loop and 3.56% increasement in the torque of rotor compere with the motor design optimized by manual operation and only use 6 hours which is several tens of times faster than manual operation.

ABSTRACT. The single-phase line-start synchronous reluctance motor (LSSynRM) is suitable for household appliances, but an optimized design of rotor, crucially influences the performance of motor, is hard to obtain. This paper optimizes the rotor design of LSSynRM to make a higher saliency ratio with the trade-off between saliency ratio and synchronizing ability. The mechanical-field-circuit coupled Finite element (FE) simulation is employed. The simulation turns out the improvement of motor torque by the presented optimization.

ABSTRACT. This work presents an application-oriented optimization method for different kinds of permanent magnet (PM) motors used in hybrid electric vehicles (HEVs). A robust technique called design for six-sigma (DFSS) is included in the proposed method to deal with the manufacturing variations. To decrease the huge computation cost caused by finite element analysis (FEA) and Monte Carlo analysis required by DFSS, multi-level optimization method is presented to improve the optimization efficiency. By investigating a design example on flux-switching PM machines, it is found that the obtained optimal motor can have the best performance in terms of topology and structure parameters. More importantly, the manufacturing quality of the motor was increased greatly while the computation cost of FEA was decreased significantly.

ABSTRACT. High speed induction motors are necessary to meet the requirements including electromagnetic properties, temperature rise and mechanical properties. Its design is a comprehensive multi-physics field iterative process. In this paper, a 10MW, 10000r/min high-speed solid rotor induction motor is designed based on the calculations of electromagnetic field, fluid field and temperature field, rotor strength and rotor dynamics. Based on the multi-physics field analysis, some important parameters are optimized and final design scheme meeting electromagnetic properties, temperature rise, rotor strength and critical speed is obtained. The results provide the references for the successful development of large power high-speed solid rotor induction motors.

ABSTRACT. This paper proposes a new design concept for bidirectional wireless power transfer system using dual active bridge topology. This paper suggests that the coil system could be designed as a weakly coupled transformer having high leakage inductance, and therefore is applicable to dual active bridge topology to increase bidirectional inductive power transfer for optimal results. The new design enables three benefits: elimination of resonant capacitor and external inductor, more compact coil structure, and soft-switching operation, leading to significant improvement in cost saving and efficiency. The proposed design allows future electric bicycles to use existing batteries to support an electrical system silently at high frequency and good efficiency. This paper presents analytical design of the system using finite element analysis and circuit simulation.

ABSTRACT. Abstract — In this paper, a multi-channel temperature transmitter is designed, aiming at temperature measurement of rotors, which can also be extended to other parameter measurements of rotating objets. The device receives power with contactless power transfer technology. And the measured temperature data is transferred through wireless data communication. The problem of electromagnetic interference between wireless data transmission and contactless power transfer is solved. The temperature transmitter uses high precision PT100 sensors to achieve temperature measuring accuracy, and converts temperature signals to standard 4-20mA current output.

ABSTRACT. For inductive wireless power transfer (WPT) systems, the air-gap flux density between the transmitter (TX) and the receiver (RX) coil generally reduces as operating frequency increases. According to Lee et al, MHz operating frequency is ideal for making the system safe to humans and animals [1-4]. Conventional Litz-wires are not efficient at MHz frequency because of the irregularities in the fabrication process and parasitic capacitances between the adjacent strands. A surface spiral winding (SSW) was proposed to reduce the skin and proximity effect losses at MHz [4]. SSW design methodologies were explored with respect to copper loss and dielectric loss. A seven-turn SSW with twist factor of 1 to maintain low copper loss, and penetrated spacing dielectric substrate geometry using minimum wallthickness to support the structure was built to validate proposed design methodology [4]. It is the spatial voltage stress between adjacent turns that causes the dielectric losses. Since the highest stress is between the first turn and the end turn, the main dielectric losses are located between the first turn and the end turn. In addition, the gap between the first turn and the end turn is the first region that voltage breakdown would happen when transferring high power. In this paper, new surface spiral coil designs are proposed to equalize dynamic voltage stress between adjacent turns, and improve efficiency as well as power scalability.

ABSTRACT. The model of mismatched transceiver coils in wireless power transfer system is proposed in this paper. System transmission efficiency and transferred power are analyzed against coupling coefficient. The mismatched charging scenario and ways to achieve optimal charging are investigated based on theoretical analysis and validated by experiment results.

ABSTRACT. Modular multilevel converters (MMC) have shown a great potential in the area of medium-voltage drives, for it can produce excellent output waveform with low average switching frequencies. A key issue of MMC is that it requires a complex voltage balancing method to balance the capacitor voltage of each submodule (SM). In this paper, a medium-voltage motor drive based on diode-clamped modular multilevel converter (DCM2C) is proposed. This topology is prominent in reducing voltage balancing control complexity by using a balancing branch between each SM to clamp the capacitor voltage.

ABSTRACT. Based on a simplified engineering model for PV array, the influence on the output characteristics of PV array is analyzed when Rs, Rsh and α, β, γ change. According to the measured data of a PV power station, the shuffled frog leaping algorithm (SFLA) is adopted to identify the parameters of the simplified model. The results show that a good agreement is achieved between the identified and measured curve. Then, the particle swarm optimization(PSO) algorithm is adopted to identify the same parameters as comparison with SFLA which further verifies the superiority of SFLA.

ABSTRACT. The proposed paper presents an economic optimization case study for a medium-scale hybrid PV-battery system. PV energy yield and battery operation models based on hourly satellite insolation and daily temperature data form the basis of an underlying objective function aiming to maximize the net present value of potential energy cost savings. Forecasted system prices and energy tariffs over a nine-year period are considered enabling the opportune year to invest and the characteristics of the corresponding optimal system to be determined.

ABSTRACT. Parameter identification of the PV cell is of great significance to establish an exact model of grid connected PV power generation system. In this paper, the conventional four-parameter model of the PV cell is transformed to the Recursive of Least Square (RLS) form, and the Recursive of Least Square with Forgetting Factor (FFRLS) method is used to identify parameters of the model. The output of the simulation model with the identified parameters is consistent with the measured data, which further proves the validity of the proposed method.

ABSTRACT. The accuracy of PV array model is very important for grid connected operation and scheduling of large scale PV system. Based on the measured data of a PV power station, the hybrid artificial fish swarm and frog leaping algorithm is adopted to identify the unknown parameters in the mechanism model of PV array. The identification results of hybrid algorithm and the results of individual identification of artificial fish swarm algorithm (AFSA) and shuffled frog leaping algorithm(SFLA) are compared and analyzed which proves that the hybrid algorithm has the superiority and effectiveness of the two algorithms.

ABSTRACT. Modeling and coordinated control of a large-scale concentrating photovoltaic integration system with VSC-MVDC (Voltage Source Converter-Medium Voltage Direct Current) technology has been investigated in this paper. The average controlled-source model of PV integration system is established firstly. Then a novel control strategy without fast communication is proposed to improve reliability of the coordinated control system. An extra voltage loop is added to basic control block, which is able to assure stable operation of the PV system in various conditions. Finally, the proposed control strategy is verified with simulation results.

ABSTRACT. LSPV is generally located in remote area and has a trend towards scale-up and clustering in recent years. However, electric grid in remote area is so weak that many AC-related issues arise and turn to limit LSPV integration. Considering that peak solar hours in a year is not so long relatively, an efficient and economical way for bulk electricity transmission of LSPV is also required. In this paper, DSDCS-CPAS of LSPV is proposed to avoid AC-related issues in principle of DC system. Efficiency, cost and reliability of four CPASs are analyzed and compared. DSDCS has advantages of high efficiency and potential of low cost, which is required by LSPV.

ABSTRACT. The flux weakening control is significant for the interior permanent magnet synchronous motor to obtain a wide constant power range which is required in the electric vehicle application. A representative flux weakening method is to design an outer voltage loop using the voltage reference and the voltage limit. If the characteristic current of the motor is less than the current limit, the deep flux weakening can be achieved by applying the Maximum Torque per Voltage (MTPV) control. The proposed scheme in this paper can achieve smooth transitions among the constant toque region with the Maximum Torque per Ampere (MTPA) method, the flux weakening region with the voltage reference regulated method and the deep flux weakening region with the MTPV method. Besides, the six-step overmodulation strategy is adopted to improve the DC voltage utilization for the whole speed range. The performance of the drive system is confirmed by experiments.

ABSTRACT. The efficiency analysis of Runge-Kutta family methods for solving ordinary differential equations (ODEs) in order to simulate typical transient processes in AC machines is performed in the paper considering the expedient choice of the set of variables in the state-space vector. The detailed analysis of the generalized AC machine ODEs is performed based on the estimation of their higher order derivatives and the numerical solution error using constant and variable step solvers. The AC machine is described by Park’s two-axis model which is extended with the effect of rotor current displacement and elastic coupling with the load in the mechanical system.

ABSTRACT. In order to reduce the torque ripples generated during the synthesis of voltage vector, this paper proposes predictive sequence control (PSC). In PSC, different switching sequences for every voltage vector are included in the control set, and the switching sequence which has minimum torque ripples can be selected by corresponding predictive algorithm. Therefore, excellent torque performance can be achieved.

ABSTRACT. This paper proposes a novel technique to online estimate the inductances of PMSM based on the measurement of the three phase current derivatives corresponding to one active voltage vector and one zero voltage vector during standard PWM cycles. The direct and quadrature inductance of PMSM are calculated during normal operation of the drive system. The influence of frequency, magnetic saturation and cross saturation is also considered by the proposed estimation method. The full system simulation and experiment were implemented to verify the robustness of the proposed method

ABSTRACT. As a significant part of electrical load, air conditioners draw attentions for their sometimes-unfriendly load characteristics, especially their dynamic responses during grid voltage disturbances. In this paper, a novel under-voltage control strategy for variable-speed air conditioners is introduced, which can keep air conditioners load characteristic as constant impedance when unexpected voltage disturbances occur. The dynamic response of each type of air conditioners is analyzed under different voltage sags and interruptions situations. At last, the validity and effectiveness of the proposed strategy are verified by the simulation results.

ABSTRACT. This paper reveals a kind of adjustable reactor. Firstly, it introduces the basic principle of the reactor. The reactor is based on a transformer with air gap. The current signal of primary side is detected and then directly injected into the secondary side. In this paper, the phase difference(caused by time delay) between the detected current signal of primary winding and the injected current signal of secondary winding is taken into consideration. The effect of phase shift on the equivalent impedance of the reactor is analyzed. And its effect on system stability is also analyzed. The validity of the theory is proved by the simulation results.

ABSTRACT. A novel nonsingular terminal sliding mode control strategy is proposed. Firstly, the sliding mode surface is designed as a combination of linear sliding mode and nonsingular terminal sliding mode to solve the singularity of terminal sliding mode and improve convergence performance of the linear sliding mode. Then, the differential sliding-mode hyper plane is produced according to the speed error and position error of BIM. Current signal and radial force is extracted by the combination of the sliding-mode hyper plane, the electromagnetic torque and the equation of motion. Finally, the faster convergence speed of system state variables can be obtained during the whole process and make system chattering-free moving.

ABSTRACT. In order to reduce the low-order torque ripple of the permanent magnet synchronous motor, methods of suppressing the torque ripple by suppressing harmonics are become the main way. Among them, through the control system to inject additional harmonics to suppress the low harmonics method is getting more and more attention.But , due to the large amount of calculation, making the result of calculation is difficult to follow the motor rotation in real time, this is a serious obstacle to the development.Therefore, in order to reduce the computational complexity, in this paper,a computational surrogate model is established to replace the harmonic calculation module. Through the harmonic injection model, the data and mathematical relations are obtained to establish the surrogate model. So a new harmonic suppression system is built with the surrogate model .Through the simulation, the effect of harmonic suppression of the surrogate model is analyzed and compared with the harmonic injection module.

ABSTRACT. This paper makes a detailed research about uncontrollable phenomenon and digital control delay for a high-speed permanent magnet synchronous motor(PMSM) drive. System stability and the influence of digital control delay are serious problems which have been concerned in the past few years. Traditional work about this point cares only about the stability margin of dynamic mathematical model. However, in this paper, it is pointed out from the analysis results that the drive system may be out of control even though the system has enough stability margin. It is induced by abnormal saturation of PI current regulator in d-axis, and this phenomenon may be deteriorated by digital control delay. This paper makes detailed analysis about this uncontrollable phenomenon and deduces an essential stability operating condition which is relative to motor parameters and digital control delay. To solve this problems, a compensation unit is required. In this paper, a simple compensation matrix is added to the control scheme of high-speed PMSM. At last, simulation results verify the correctness of the analysis results and compensation effectiveness in this paper.

ABSTRACT. In this paper, a mixed analytical model is introduced for quick and accurate optimization of axial flux permanent magnet(AFPM) machines. Nowadays the precise universal calculation people used commonly in modeling is finite-element (FE) analysis. However, sometimes this method can be very time-consuming. So we choose a hybrid analytical model based on sub-domain calculation and particle swarm optimization to solve the problem. In the comparison of magnetic field distribution, cogging torque, back electromotive force and other parameters with FE model, we can conclude that sub-domain analytical model agree with FE analysis in results well. And particle swarm optimization (PSO) is an efficient and fast method to optimize machine. The result also shows that this mixed model is quick and accurate.

ABSTRACT. Abstract —A tubular transverse-flux flux-reversal permanent magnet linear machine(TTFFRPMLM) for long stroke applications is designed and analyzed in this paper, which not only has the advantage of low cost because of the existing FRM by combining both PMs and armature coils in short primary, but also can address the problem of complicated structure of the existing TFM by using rotating machine technology. This paper analyses the machine topology and proves the correctness of motor design.

ABSTRACT. Five-phase tubular linear PM (TLPM) motors have high thrust force density, zero net radial force and volumetrically efficient. Conventional direct thrust control (DTC) improves the dynamic performance of TLPM motor, but exhibits significant ripple in thrust force and flux. To solve the problem, a new DTC strategy based on third-harmonic current suppression is proposed. The effect of inverter voltage vectors in the fundamental and third subspaces on the flux and the thrust force is analyzed. Then the voltage vectors in third subspace are used to restrain the third-harmonic currents. Simulated results are presented to verify the effectiveness of the proposed control strategy.

ABSTRACT. This paper proposes analysis and investigation on the behavior and performance of single phase, 0.40 kW, 220 V, 4.80 A, 4 poles grid connected induction generators system. Analysis and investigation on grid connected induction generators based on equivalent circuit under transient and steady state conditions. The obtained results can be guidelines for the design of suitable induction generators and system for efficient wind energy applications.

ABSTRACT. In this paper, an optimal switching table for PMSM DTC system using zero voltage vector is proposed. Zero voltage vector decreases stator flux and torque very slowly, so it can be used to suppress torque ripple when the system is at steady-state. And when the system is at dynamic-state, non-zero voltage is used to get quicker response. As both 111 and 000 can be used to generate zero voltage vector, switching state selection strategy in order to minimize switching times is given when zero voltage vector is used. Thus, an optimal switching table using zero voltage vector is proposed. Simulation results show that PMSM DTC system can work properly under control of the proposed switching table. The time of system stator flux response using optimal switching table is reduced by 73% and the time of system torque response is reduced by 82% compared with switching table only using zero voltage vector to decrease stator flux and torque. The torque ripple of the system is reduced by nearly 51% and switching times are reduced by 41% compared with conventional switching table.

ABSTRACT. This paper presents a new speed control system for a flux-modulated permanent-magnet (FMPM) in-wheel motor. It is based on deadbeat-direct torque and flux control (DB-DTFC) to reduce the torque ripple and improve the steady performance compared with conventional SVPWM-DTC system. DB-DTFC calculates the control input of next control period so that a new stator current observer is proposed to predict the stator current in next control period. Simulation is built up to verify the accuracy of the current observer and to validate the system performance. Then, experiments of the observer and the DB-DTFC system is implemented based on a 2-kW prototype motor. The results demonstrate the advantages of the DB-DTFC system.

ABSTRACT. In virtual flux droop method, power sharing is achieved by adjusting flux amplitude and angle which has some advantages of simplicity of control and lower voltage and frequency deviation. In this paper, a switch module of power calculation was firstly designed to balance system dynamic response and power fluctuation in flux droop controller. Then an improved direct flux controller was proposed to reduce the flux pulsation by tighter flux linkage control. At last, simulation results prove that the improved virtual flux droop method has better dynamic and static performance.

ABSTRACT. The phenomenological model, examined in this paper, uses mechanically supported magnetic dipoles, which are ar-ranged to a collective on a regular Cartesian grid. In a former work, the authors showed, that the model is capable to re-enact the basic dynamics of a measured hysteresis after a parameter optimization process. One of the main issues of the parameter optimization process is the mechanical differential equation, which is used to rotate the dipoles. In some cases, it causes an apparently unstable and random trem-bling of the dipoles. Therefore, the resulting hysteresis curves seem to be covered by a strong distortion. However, while comparing different measured curves to different hysteresis curves that contain trembling dipoles, it turned out, that there is still information in the dynamic behaviour of the dipole collective. Therefore, the apparently unstable trem-bling behaviour and different approaches to filter the includ-ed information are examined here.

ABSTRACT. This paper presents a communication system with double level network used in motor-driven spindle spinning frame. It uses a double level network detection system. The first level contains several microcontrollers, and every single chip is directly connected to several motor-driven spindle detection devices. The second level has only one microcontroller, which is connected with the microcontrollers on the first level. Each level adopts polling method to complete the detect communication. The two levels transmit motor speed, current value and the working state of the spindle through a special communicating protocol. By using this network, the period time for polling 1200 motor-driven spindles can be controlled below one second.

ABSTRACT. The cogging torque of variable flux reluctance machines (VFRMs) is usually large, which will result in undesired vibrations and acoustic noises. This paper introduces several methods to reduce the cogging torque of VFRMs including asymmetrical rotor teeth, circumferential rotor teeth pairing, rotor teeth shaping and rotor dummy slots. First, the cogging torque of VFRMs are analytically calculated, giving instructions how to effectively reduce the cogging torque. Then, the principles of each method are analyzed, and the effects of these methods on average torque and pulsating torque are compared and analyzed. Finally, the electromagnetic performances at various load conditions of each method are compared and analyzed, which can help to choose the most effective cogging torque reduction technique in the VFRM design.

ABSTRACT. This paper presents a novel 6/8 pole changing line-start permanent magnet synchronous motor (LSPMSM) which can decrease braking torque and pulsating torque fundamentally and improve starting capability effectively. The impedance parameters of 6-pole winding and 8-pole winding are calculated in use of two-dimensional (2D) finite element analysis (FEA). MATLAB/Simulink simulation model is then built. Then the influences of switching speed and phase difference between induced electromotive force of 8-pole winding (E8) and applied voltage on inrush current and synchronization when switching are analyzed, and the results show that the inrush current is related to the phase difference and the synchronization is related to both phase difference and switching speed.

ABSTRACT. Torque ripple can’t be considered in the torque calculation using the d, q-axis equivalent circuit,because the time-dependent component is removed. When d, q-axis transformation was performed, it was founded that some parameters has some characteristics. These characteristics were considered for representing torque ripple.

ABSTRACT. Direct-drive in-wheel motors have become an extremely attractive option for electric vehicles. Two kinds of motors are devised, Permanent Magnet Synchronous Motor (PMSM) and Permanent-Magnet Flux-Modulated Motor (PMFM), respectively. Keeping the same back EMF, current density and copper loss, torque density, flux-weakening performance, loss and efficiency of the motors are analyzed and compared in this paper. The results indicate that compared to PMSM, PMFM has higher torque density, lower material cost and wider speed range, but with the penalty of lower efficiency, higher iron loss.

ABSTRACT. Knowledge of the magnetic properties of electrical steel is very important to build highly efficient electrical machines. Many approaches, which are either of mathematical, physical or phenomenological kind, were developed in the past in order to predict the phenomenon of hysteresis in case of unmeasured conditions. In this paper, a phenomenological 3D hysteresis model using magnetic dipoles, which are mechanically supported on a 3-dimensional grid, is investigated. The different interactions between these dipoles are based on the equations of micromagnetism. Instead of minimizing the free energy in the system by mathematical optimization methods, each elementary dipole is able to rotate into an individual energetically favourable positon due to its mechanical mounting. Hereinafter, a collective that is ring-shaped, according to the ring specimen test for hysteresis measurements of electrical steel sheets, is observed. In the following, a mathematical description of the included field contributions and parameters is given. Secondly, the influence of the parameters on the shape of a hysteresis, simulated with the presented model is discussed. To show the performance as well as the limitations of the presented phenomenological model, the measured hysteresis curve of a ring specimen of a real steel sheet is recreated by a 3D-dipole collective and the deviations are discussed.

ABSTRACT. Sequential multiobjective optimization method is presented in this work to deal with the multiobjective design and optimization problems of engineering electromagnetic devices. Firstly, the initial sample set can be generated by using the sequential optimization method (SOM). SOM can greatly reduce the sample size by integrating the advantages of optimization algorithms and approximate models. Secondly, the optimal Pareto solutions of the multiobjective design problems can be obtained by updating the samples and approximate models sequentially. Thereafter, we calculate the root mean square error (RMSE) for each objective to determine whether it has achieved the default value. Finally, to illustrate the performance of the new method, a classic mathematic test function and a design example of permanent magnet synchronous machine are investigated. It can be found that the proposed method combined the advantages of effectiveness of sequential optimization strategy and lower computation cost of approximate models. The obtained solutions are satisfactory while the computation cost of finite element analysis needed by the new method is less than 1/5 compare with that of direct optimization algorithm.

ABSTRACT. This paper proposes a single-phase five-level buck-boost inverter with a combination of Z-source network and T-type inverter. The proposed inverter has advantages as reducing a number of switches and shoot-through immunity. In this paper, operating principle and analyses circuit are presented. Simulation and experimental results are shown to verify the validity of the proposed inverter and control strategy.

ABSTRACT. To obtain a clear digital implementation structure with excellent dynamic performance for dual-active-bridge converter (DAB), this paper proposes a finite-state-machine (FSM) model of boundary control. It is based on a generalized way to analyze the natural switching surface (NSS) of DAB with explanation of its physical meaning. NSS illustrates the effect of charging and discharging of main energy storage elements. Its geometrical features help reveal the optimal transient process between different steady states. During load transient, the FSM model uses NSS to select switching state of the converter. Under this mechanism, both amount and direction of transmission power can be changed swiftly by only a few asymmetrical switching actions, while voltage overshoot and settling time can almost be eliminated. The proposed FSM model is a unified description of common boundary control, which makes its digital implementation more systematic and flexible. Simulation results have verified its feasibility.

ABSTRACT. In order to solve the parameter sensitivity problem of model prediction control, this paper presents a strong parameters robustness model predictive current control method, which combine a sliding mode observer (SMO) with model predictive current control (MPCC). This method can simultaneously observe the current of the next control period and the disturbance caused by parameter errors. The observed disturbance and current are substituted into the system model to improve the control performance. The simulation results show that the proposed control method can effectively reduce the parameter sensitivity and eliminate the influence of model parameter variation.

ABSTRACT. The traditional methods of the neutral point potential (NPP) control for three level converters can’t be suitable for SHEPWM. A suppression method of the low frequency NPP fluctuation is raised based on 3-order harmonic in this paper. By analyzing the relationship between 3-order harmonic and the NPP, an optimal 3-order harmonic is derived. Using the optimal 3-order harmonic to calculate the switching angles for SHEPWM, the low frequency NPP fluctuation is suppressed obviously.

ABSTRACT. In this paper, two dual random space vector pulse-width modulation (RSVPWM) methods, Random Switching Period-Random Zero Vector Timing SVPWM (RSP-RZVT-SVPWM) and Variable Daley-Random Zero Vector Timing SVPWM (VD-RZVT-SVPWM), are proposed to apply in five-phase inverters. The proposed RSVPWM methods can decrease the amplitudes of high harmonics and spread harmonics concentrated around switching frequency and its integer times to a wider frequency band, which will alleviate acoustic noise and restrain electromagnetic interference (EMI) of the system effectively. In this paper, a series of simulation results are provided to verify the effectiveness of the two dual RSVPWM methods for five-phase inverter.

ABSTRACT. This paper presents a control technique for ultra-high switching frequency rectifiers based on virtual-flux direct power control (VF-DPC). The proposed VF-DPC using voltage sensors in AC side exhibits several advantages as compared to the conventional VF-DPC schemes, e.g. lower total harmonic distortion (THD) of input currents and less ripple at the output DC voltage. The effect of switching frequency and inductor size on a rectifier using the proposed method is also investigated in this study.

ABSTRACT. This paper presents a seven-level multilevel inverter designed utilizing switched-capacitor technique. This topology employs two asymmetric DC voltage sources as input and generates a multilevel staircase output. The structure includes a front-end switched-capacitor based DC-DC converter cascaded by a back-end H-bridge inverter. The front-end SC DC-DC converter feeds three DC voltage levels to the H-bridge inverter which produces the corresponding bipolar levels. The inverter naturally solves the problem of capacitor voltage balancing as the capacitor is charged to a constant value twice every cycle. This topology also eliminates the need for series connection of individual voltage sources which require voltage balancing algorithms.

ABSTRACT. a neutral point voltage feedback control strategy based on double modulation waves carrier-based PWM for three level converters is proposed in this paper. Using this strategy, neutral point voltage can be adjusted at will，output AC current can be guaranteed no distortion caused by imbalanced neutral point voltage, and the neutral point fluctuation can be eliminated completely. The strategy is suitable to enhance conventional neutral point balancing control or applications where need to control up and down DC link voltage separately. The control limits of neutral point current when using proposed strategy is given. Simulations and experiments are made to verify the correctness of the theory.

ABSTRACT. A silicon carbide (SiC) vertical field effect transistor (VJFET) with ultra-low feedback capacitance Crss has been developed, which is called as screen grid VJFET (SG-VJFET). The SG-VJFET is a very promising power device because of the superior static characteristics such as normally off, low on-resistance, and high breakdown voltage, furthermore, issueless in terms of gate oxide reliability and long-term threshold voltage stability. The screen grid inserted between the gate and drain electrodes reduced the feedback capacitance Crss and improved the turn-off switching speed remarkably. On the other hand, the turn-on switching speed is considerably slower than the turn-off switching speed due to the influence of the forward pn diode parasitic between the gate and source of the switch. This drawback is inherited from normally-off SiC-JFETs with a similar device structure between the gate and the source. In recent years, several gate drive circuits have been reported to overcome this drawback for the normally-off SiC-VJFET, but there are limitations such as the need for complex logic circuits, switching frequency and possible duty cycle, additional cooling, and complexity of selecting electronic components. In this paper, we propose a novel gate drive circuit that can fully exploit the performance of the SG-VJFET. The proposed circuit consists of two standard gate driver ICs, a capacitor, and diodes, which can achieve fast turn-on switching without excessive power loss and can use with any duty cycle and high frequency.

ABSTRACT. A modified over-modulation (OVM) scheme with phase disposed carriers to improve switching performance of cascaded H-bridge multilevel converter is depicted in this article. With the regular OVM techniques, pulse dropping region has higher conduction loss, greater signal distortion and voltage gain. In the proposed OVM method, the switching and conduction loss scenario is improved with lower harmonic distortion. Also, the voltage gain can be increased up to limited range. Four types of reference signals, such as pure sinusoidal signal, sinusoidal 60◦ bus clamped signal, third harmonic injected signal and third harmonic injected 60◦ bus clamped signal are used to investigate the overall performance with the proposed OVM method. The OVM technique is applied to a 3.0 kV, 120 kW, 5-level cascaded H-bridge converter and simulated in MATLAB/Simulink environment. The results demonstrate reduced output harmonic distortion, increased voltage gain, lower switching and conduction loss as well as improved efficiency on the whole.

ABSTRACT. High-voltage disconnectors are the largest and most important primary device in the transformer substation. During the closing of the disconnector, there are many problems, such as not in place, over the place, the contact is loose and so on. Through the analysis of the vibration signal in different closing state, the characteristic parameter can be extracted, and then the closing state can be distinguished. And the modal dynamics of the high voltage disconnector is studied by means of numerical analysis.

ABSTRACT. This paper proposed a single-phase to three-phase converter with APF in house-service power supply of traction substation. The single phase part of converter is controlled as the rectifier, with implement of the active power filter (APF). The three phase part of converter is used as an inverter. The experiment of the step-down prototype verified the control strategy of the converter

ABSTRACT. Due to the slowdown in the growth of the electric power industry and intense competition among companies, utilities are feeling the need to cut maintenance costs and maximize profits. Therefore, the efficient replacement cycle of the power transformer, which is an important part of the power system, has been studied. In this paper, life cycle cost method was used to analyze the cost of the transformer during its entire lifetime. Then changes of the EUAC curve according to the variables were analyzed.

ABSTRACT. In order to improve the efficiency of high voltage power supply for electron beam welder, the characteristics of LCC series parallel resonant converter with capacitive filtering are studied in this paper, and the circuit model of LCC resonant in discontinuous current mode(DCM) is established. The working mode of the converter is analyzed by mathematical time domain analysis method, and the mathematical formula of the converter is derived. In addition, this paper discusses the characteristics of the voltage gain in DCM, and the influences of the series parallel capacitance ratio and the voltage gain on the converter efficiency. Finally, the simulation and experimental results are given to verify the correctness of the theory.

ABSTRACT. This paper investigates the dual active bridge based modular DC solid state transformer, intended for interface between medium/high voltage DC distribution grid and the low voltage DC micro grid. In order to achieve input voltage sharing among sub-modules and meanwhile guarantee stability and fast regulation of output voltage under bidirectional power operation, a combined decoupling control strategy is proposed. Through small signal analysis and transfer function derivation, the decoupling conditions between the control loops are identified, and the loop gains are well-tuned. Experiment is provided for verification purposes.

ABSTRACT. At present, voltage regulation of no load distribution transformer is not flexible and failure rate of mechanical on-load tap-changers is high. To solve these problems, a scheme of automatic on-load voltage regulation system designed via thyristor for distribution transformer was proposed. The system improved the existing topology of on-load voltage regulation system via power electronic device and added the overvoltage protection circuit of thyristor. The prototype of automatic voltage regulation system has been tested completely. The results show that, compared with the voltage regulation system via mechanical switch, transition waveforms of voltage regulation system via thyristor are of better quality and transition time is shorter.

ABSTRACT. Transformer short-circuit force insufficient has been a hot research issue. There is some residual stress on the conductor section when winds the wounding, which produces adversely affect on winding short-circuit strength. This paper deduces the calculation model of the circular winding considering the residual stress. Taking the test transformer as an example, winding internal radiation short-circuit strength is simulated and researched. By comparing with the test, verifies the accuracy of the numerical model.

ABSTRACT. In order to reduce the ripple of DC-link and capacitor, this paper present a way to select reasonable capacitance for rectifier (full-wave controlled) and inverter. At the same time, a braking unit is developed to prevent the overvoltage of DC bus. Finally, the MATLAB simulation and the test results of the actual braking unit validate the correct of the selection of the capacitance and the validity of the braking unit.

ABSTRACT. In recent years, Hardware-In-the-Loop (HIL) simulation such as RT-LAB, RTDS are widely used in power electronic system study. In order to keep the simulation accuracy, the main concern of researchers normally focuses on the minimum simulation step size of the simulator, while neglects the role of input-to-output delay of the simulator. Concentrating on the study of hysteresis current control of grid connected converter, this paper investigates the importance of the simulator delay. With theoretical analysis, simulation and experiments, it is found out that the delay of the simulator seriously affects the control performance: it can apparently increase the hysteresis current band, reduce the switching frequency, increase the current THD (Total Harmonic Distortion) and therefore deteriorate the control. With the input-out-delay, even if the simulation step is kept small, the simulation results are neither accurate nor trustable. Upgrading the simulator hardware to reduce the delay might be feasible in future but definitely very costly. While upgrading hardware is not a final solution, as an alternative software solution, this paper proposes a novel time expansion method. The experimental results prove that the proposed time expansion method can effectively cope with simulator delay in the HIL study of hysteresis current control, making it possible to achieve satisfactory performance with an ordinary simulator.

ABSTRACT. This paper presents a mid-voltage experimental voltage generator used for the testing mainly of distribution power equipment, high-power drives and renewable power generation. It utilizes thyristor-controlled zigzag transformer as its primary circuit. Based on the analysis of the operation mechanism, the voltage equations are derived and control strategy is proposed. This power electronic zigzag transformer is capable of providing various experimental voltage conditions, including voltage swell, voltage sag and phase angle change. It has more rapid and accurate response than impedance-type voltage regulators and has lower cost and less footprint than back-to-back voltage source converter. Simulation model is developed with PSCAD software and simulation results validates the proposed schemes.

ABSTRACT. With the access of large-scale new energy sources, the distributed characteristics of microgrid are becoming more and more obvious, the traditional centralized control method relies on communication, which reduces the reliability of the system. According to controllability theory of nonlinear coordinated control with multi-agent, this paper proposes a coordinative optimization method based on the model predictive control (MPC) to achieve the coordination control of energy allocation. Between the micro sources with the incremental cost of consistency algorithm for leader-follower, using an interactive algorithm to achieve the exact optimal solution to the optimization problem based on MPC, each micro source as an intelligent agent through the interaction between the adjacent micro sources, while achieving coordinated optimization control in microgrid to meet the incremental cost. The obtained results show that multi-agent systems (MAS) using MPC for coordinative optimization control of microgrid can effectively manage the micro source, to fully explore the key role of individual intelligence in group cooperative behavior. The effectiveness of distributed consistency algorithm & MPC algorithm are verified by examples.

ABSTRACT. The performance of reactive power sharing in an islanded microgrid is significantly affected by feeder impedance, mismatch parameters and unbalanced local load. To reduce the negative impact of mismatched link impedance on reactive power sharing, the adaptive virtual impedance strategy for voltage compensation is proposed with paralleled inverters in an islanded mode. The on-line adaptive control of virtual impedance can be realized based on conditions of link impedance and load power, and the reactive power sharing performance is improved greatly. The feasibility of the proposed strategy is validated by simulation results.

ABSTRACT. Abstract--In this paper, a new self-adaptive droop control strategy based on Micro-grid Energy Storage System is presented. Through the tracking control of delayed power, the reference droop coefficient in the control strategy is adjusted and corrected, thus changing the P-F and Q-V droop characteristic curves. This control strategy allows the energy storage system to track the power balance of the grid-side in real time and whereby the system can stabilize the voltage and frequency when the load changes, which can leave out the communication devices installed on the energy storage system and the micro-grid central controller. In addition, the feasibility of the control strategy is verified by Matlab / Simulink simulation platform.

ABSTRACT. In this paper, the power flow management algorithms for a power generation system is presented. An Energy Control Unit (ECU) was used to monitor and optimize the power flow from the microturbine-generation to the battery and the load, to improve not only the dynamic performance but also the safety and reliability of the power generation system Finally, an energy management algorithm and its behavior are presented, and results are concluded.

ABSTRACT. The trend of using the front-end converters in Electric Vehicles, PV Inverters and Home appliances for grid support especially reactive power support is gaining popularity. For concurrent operation of primary and secondary functions, it is necessary to have instant knowledge of the power processed by the converter for proper regulation and preventing overload of converter. This paper presents a fast and simple technique to measure the active and reactive power component of single phase inverter/PWM rectifier used for reactive support. The proposed method can detect the active and reactive current component within 1/8th of fundamental period.

ABSTRACT. Particle Swarm Optimization (PSO) has been widely used in the reactive power optimization of distribution networks, and the basic PSO algorithm takes too long time to solve the reactive power optimization problem of low voltage distribution network with multiple constraints. To solve this problem, a scheme of reactive power optimization for low-voltage distribution network using improved particle swarm optimization has been proposed. Improved particle swarm optimization algorithm dynamically classifies the particles according to constraints that voltage of each node is qualified, the reactive power compensation capacity of each node does not exceed the preset value and the total reactive power of the system is compensated rationally by roulette. Finally, the optimal solution of the voltage and reactive power optimization problem satisfying the above constraints can be obtained. The voltage and reactive power optimization scheme proposed in this paper combines the decentralized parallel capacitor with the voltage regulation of the distribution transformer. Compared with the centralized reactive power compensation method, the node voltage deviation of the scheme proposed is smaller and the grid loss is lower. Compared with the basic particle swarm optimization algorithm, the dynamic multi-population particle algorithm applied in this paper greatly improves the running speed and optimizes the calculation results.

ABSTRACT. In recent years, environmental problems are becoming serious and renewable energy systems, especially wind power generation, have attracted much attention and been introduced into power systems. However, wind power generator output is intermittent, resulting frequency fluctuations in the connected power system. A doubly fed induction generator (DFIG) based diesel generation system is proposed in this paper to suppress the frequency fluctuations of the small power system with the squirrel cage induction generator (SCIG) based wind turbines installed. Simulation analyses have been performed using PSCAD/EMTDC software. The simulation results show that DIFG based diesel generation system is very effective to suppress the frequency fluctuations of the power system compared to conventional synchronous generator (SG) based diesel generation system.

ABSTRACT. This paper investigates the control strategy of direct torque control using harmonic voltage control for fivephase induction generator (IG) system. For IG generating system, the direct torque control strategy has the advantages of easy implementation, high bus voltage utilization, improve the flux density, and good performances with load. The simulation results support the effectiveness of the control strategy.

ABSTRACT. This paper investigates virtual inertia control (VIC) of a dc microgrid using voltage droop control as the power-sharing strategy. An adaptive virtual inertia control (AVIC) strategy based on an improved variable droop coefficient is proposed. By swinging the droop curve during power fluctuations, the dc voltage change rate is reduced and the system inertia is increased with AVIC. The droop controlled converter’s capability on VIC is fully used by AVIC, which has a good adaptive ability to various operating states. Matlab/Simulink simulations are carried out and results reveal that the transient response is improved and the quality of the dc bus voltage is enhanced under AVIC.

ABSTRACT. Islanded DC microgrid is equipped with energy storage unit to coordinate power balance between new energy power generation and load. Battery becomes one of the optimum choices for energy storage unit with many advantages. To avoid battery deep charging and discharging and prolong its service life, a multi-source coordinated control strategy including primary decentralized control and secondary centralized control for islanded DC microgrid is proposed based on battery’s state of charge (SOC). Primary decentralized control is used to realize autonomous coordinated operation of micro-sources. The droop curve of primary control is adjusted by secondary centralized control which is used to eliminate the stable voltage deviation produced by primary control when the SOC is close to the upper limit. Finally, experimental hardware-in-the-loop simulation (HILS) system of wind-battery based islanded DC microgird is constructed and effectiveness of the proposed multi-source coordinated control strategy is verified by experimental results.

ABSTRACT. A new topology for a robust HFAC enabled bi-directional AC-AC converter is presented in this paper. HFAC PDSs are gaining traction in critical applications within outer space, aerospace and ground transportation systems as well as in renewable energy systems due to their advantages of being with light dead weight, high power density, smaller capacitors and low arc flash risk etc.

Due to prominent adverse factors such as skin effect and higher impedance, the grid parameters (frequency, voltage etc.) selected for HFAC PDSs vary depending on the application. Many of the appliances available today cannot be cross matched and used in PDSs with other parameters than 50/60Hz, therefore the use of power converters as interfacing devices has been proposed. Currently, there are only a few types of HFAC converters available in the market; out of which a majority uses resonant filters for sine wave generation whereas the remainder generates non-sinusoidal waveforms requiring complex controllers for voltage and frequency regulation along the PDS.

The proposed two-stage symmetrical topology converter provides the operational flexibility within a band of voltages and frequencies. The 1^st stage H-bridge is PWM switched to boost the DC link voltage, whereas the 2^nd stage H-bridge is SPWM switched followed by a low pass filter to generate sine wave output. The two separate PWM controllers used are implemented on a single microcontroller board and swapped for bi-directional operation. Thus, the new converter supports mass production leading to availability in abundance at low cost and PDS efficiency improvement by capturing regenerative power.

ABSTRACT. Improvements in characteristics of magnetic material and switching device have provided the feasibility of replacing the electrical buses with high frequency magnetic links in micro-grids. This effectively reduces the number of voltage conversion stages, size and cost of the renewable energy system. An accurate evaluation of copper loss of the windings considering both current waveforms and parasitic effects is required to design the magnetic link optimally. This paper studies the accurate copper loss analysis of a three-winding high-frequency magnetic link for residential micro-grid applications. The loss analysis is carried out on a harmonic basis taking into account variations of amplitude, duty ratio and phase shift of the non-sinusoidal wave-forms. The high frequency parasitic including skin and proximity effects are taken into account. The maximum and minimum copper loss of the magnetic link and their dependency on the phase shift angle and duty ratio of the waveforms are studied. The theoretical analysis is validated through experimental test on the prototype.

ABSTRACT. In most cases, the grid faults are asymmetrical in nature, while they have less impact on permanent magnet synchronous generator (PMSG) wind turbines, it is of the great practical significance to study the asymmetrical fault ride-through (FRT) capability of PMSG wind turbines. A three-phase four-leg inverter topology for small-sized PMSG wind turbines is proposed in this paper to address the asymmetrical FRT issue. Mathematical models for the grid-side converter and the wind turbine under asymmetrical fault conditions are established using symmetrical components method and rotational coordinate transformation. A PID and repetitive controllers based hybrid control strategy is proposed for the three-phase four-leg inverter. The system is simulated under asymmetrical fault conditions. Simulation results show that, in the case of asymmetrical fault, the three-phase four-leg grid-connected inverter can restrain the negative-sequence current effectively with excellent dynamic characteristics.

ABSTRACT. Abstract — The hybrid AC/DC microgrid structure is considered to be the future trend of power systems, due to the vital necessity of connecting more renewable energy sources and storage elements to supply modern AC and DC loads. This paper proposes a power sharing and control strategy for hybrid AC/DC microgrids using the droop control technique. A new structure of the hybrid microgrid is suggested by connecting different AC, and DC sub-grids by an interlinking converter. This can be symbolized by a bi-directional converter that acts as a rectifier when power flows from the AC sub-grid to the DC subgrid. And operates as an inverter when power flows from the DC subgrid to the AC one. The proposed structure and power management strategy also allow power flows between DC sides of the system through the AC subgrid as a common bus. Five scenarios of transferring power from one sub-grid to another are studied using. MATLAB/Simulink. The results indicate a high level of the system’s felexibility in managing th power flow.

ABSTRACT. Microgrid (MG) consists of distributed generation (DG) units which supply MG loads via the power network. Droop-based control system has been proposed for power sharing implementation among DG units in MG. As the control system at the primary level, droop controller plays a major role in secure operation of MGs in terms of stability concern. In this work, a suitable small signal model is developed to model droop controllers’ interaction through the transmission network. The proposed model reveals unstable regions which have not been discovered by the conventional parallel-based small signal models.

ABSTRACT. In this paper, the multi-port power electronic transformer (PET) is applied as an interface of energy interaction for power grid and hybrid AC-DC microgrid, and through the reasonable configuration of power supply, load and energy storage system (ESS) at each port, the bidirectional power flow is realized between ports and the grid. This paper analyzes two kinds of operation modes -- grid-connected and islanded, and the corresponding control strategies are also designed to ensure the stable operation of microgrid when distributed generation (DG) power fluctuates in microgrid. The simulation verifies the correctness and validity of the proposed topology and control strategies.

ABSTRACT. this paper proposed a novel fault model based on spare core technology, and a fault-aware low power-dissipation dynamic task mapping algorithm FLDMA is designed based on NoC system fault, power dissipation and system performance. Also, this paper presented the minimum mapping area selection method, designed the first-node optimization strategy, in the process of dynamic task mapping, a real-time aware NoC system state is proposed, the number and specific location of the spare cores are set according to the state of the fault node, the mapping scheme of the task migration is implemented in real time. Finally,a NoC simulation platform was created to evaluate the proposed task mapping algorithm.

ABSTRACT. Owing to Insulated Tubular Bus-bar has a significant advantage in the way of mechanical strength, current-carrying capacity, insulating performance and so on. Currently, it widely applies to electric power, petrochemical engineering etc. However, the device operation stability is low, frequent failures and bad influence, due to lacking of correlative standard and management. Most of these failures occurred as a result of field installation technique are lacking, even these faults cannot be effectively detected by normal testing measure. Because of above issues, this paper is aimed at field installation and handover test of insulated tubular bus-bar. By means of depth analysis all segments of the field installation, find out the possible faults during the installation. The test strategies aiming at the above faults were formulated. At last, experiment and analysis were done and conclusion was made in the paper. The research can make foundation for promoting the device’s operation stability.

ABSTRACT. Online bearing fault detection is an important method for monitoring the health status of bearings in critical machines. This work proposes a classification algorithm towards online bearing fault detection. The objective is to detect and classify the bearing faults in early stages. The proposed method is validated using experimental data. It was found in the study that the proposed method can be applied for an online early fault detection and classification system.

ABSTRACT. In view of the appearance of asymmetrical operation condition in the air-cooled turbo-generator, the negative sequent current is caused in stator windings, which may endanger the stability of the turbo-generator. With the 2-D and 3-D direct coupled transient electromagnetic field, the end region electromagnetic field distribution with the rated condition and single-phase earth fault condition is studied. Furthermore, the attenuation law of magnetic field under asymmetrical operation condition is discovered. The calculated result is finally compared with the measured value; the analysis indicates that the error is within the permitted range of engineering application.

ABSTRACT. Based on the continuous transition model, the development stage of the sheath during the dielectric recovery of the post-arc is simulated and analyzed. Then the influences of the major variables, including arc energy, contact erosion rate, and longitudinal magnetic field between the contact, on post-arc dielectric recovery are analyzed. The results show that the sheath grows exponentially with time, and higher arc energy and contact erosion rate result in larger initial ion density, longer ion decay time and slower sheath development. A stronger fore-arc longitudinal magnetic field reduces the initial ion density and promotes sheath growth.

ABSTRACT. With the R&D of high voltage direct current (HVDC) transmission, HVDC circuit breaker as the protection equipment has been widely applied in the power system. In this paper, the HVDC vacuum circuit breaker (VCB) based on active artificial zero mode is analyzed, and the genetic algorithm is used to optimize the parameters of DC VCB. Moreover, an optimization design method of converting parameters for HVDC VCB is presented and applied to the optimization of converter parameters for DC VCB. The simulation results show that the proposed method can improve the interrupting performance of the DC VCB.

ABSTRACT. Abstract -This paper presents a robust distributed secondary control for voltage control of an islanded microgrid with droop-controlled and inverter-based distributed generators (DGs). A consensus-based distributed control approach is proposed to restore the islanded microgrid’s voltage and frequency to the reference values for all DGs within a very short time. An autonomous micogrid test system consisting of 4 DGs is built in MATLAB to test the proposed design method, and the results show the effectiveness of the proposed control strategy.

ABSTRACT. This paper presents a new method for energy management in distribution networks in the presence of energy storage, photovoltaic (PV) systems and diesel generators. Achieving optimal charge and discharge pattern for batteries and optimal diesel generator output with minimal operation cost is the main goal of the problem. The innovation of this paper is considering network effect on underlying method with considering power loss, voltage and current limitation. The performance of proposed method is evaluated on a 33-bus IEEE standard test system

ABSTRACT. Energy Router(ER), one key technology of Energy Internet (EI), is raising more attention in current years，especially in distribution network. However, little work has been done for simplified models of ER, which will greatly improve the joint simulation efficiency of ER and distribution network. This paper proposed a simplified model based on a 10kV/40MVA multi-port Energy Router utilized in 10kV distribution network. The determination method of model parameters is also given for general purpose. The simulation results verify the feasibility of the proposed topology.

ABSTRACT. In DC microgrid, the majority of the loads are connected to the grid via power electronic converters. These loads act as constant power loads (CPLs) when tightly regulated. If the voltage changes, the CPLs behave negative incremental impedance characteristic, and could cause system instability. To guarantee the system stability and simultaneously maintain the CPLs good performances, this paper utilizes the active stabilization control strategy for the battery converter paralleled with CPLs. Based on the mixed potential theory, the large signal models of the storage system and the CPLs are established. The control strategy considers the negative incremental impedance of the CPLs in the outer control loop, and consequently, the converter with the proposed strategy could actively compensate the CPLs during large disturbances. The stability constraint is very simple and easy to be implemented. The simulation and experimental results validate the effectiveness of the active stabilization control strategy.

ABSTRACT. This paper proposes a distributed control strategy based on multi-agent systems to solve the economic dispatch problem. Two consensus algorithms are compared for economic dispatch problems of microgrid. With the incremental cost of each micro source as consistent variables, through mutual communication between adjacent micro sources, every micro source meets equal incremental costs and the system realizes the optimal economic objective. Simulation verifies the validity of the distributed algorithm in IEEE14.

ABSTRACT. Recently, distributed generations (DGs) have been widely used in distribution networks. Using DGs in grid-connected mode leads to increase of the fault current level. This increase can affect the existing equipment especially circuit breakers (CBs) and operation of overcurrent relays. Current limiting reactor (CLR) is proposed to reduce the effect of micro-grids (MGs) on the existing protection scheme during the fault conditions by many researchers. However, there are some factors for interrupting the current by CBs which do not only depend on the fault current magnitude. Transient recovery voltage (TRV) and rate of rise recovery voltage (RRRV) can also affect the operation of CBs. This paper presents the equivalent analysis of the TRV and RRRV across a CB connected with CLR. The transient stability is studied through simulation of a practical network, which shows the impact of using CLR on the burden of CBs. In addition, some possible solutions are studied in this paper.

ABSTRACT. Offering strategy of a price-maker demand response aggregator (DRA) in a two-settlement market is presented in this paper. The aggregator minimizes its cost by offering energy and price bids in the day-ahead market and energy bids in the balancing market. On the other hand, DRA optimally manages the aggregated demands of a large number of electric vehicles and properly distributes them through the time. The problem is formulated as a stochastic mixed-integer nonlinear optimization problem. The risk of the problem is managed by conditional value-at-risk measure and finally, the proposed approach is numerically evaluated through a detailed case study.

ABSTRACT. The combination of residential photovoltaic (PV) panels and battery energy storage system (BESS) is a promising solution in a building's microgrid. This paper presents an optimal energy management system (EMS) to minimize the electricity bill of residential buildings. The objective is to achieve peak shaving and electrical energy cost minimization for the owner, making use of a dynamic energy pricing model. Due to variability of PV generation and limitations of BESS, the optimization method should account for the utilisation of PV power generation and the conversion losses of power electronics converters. To deal with nonlinearities involved, a particle swarm optimization (PSO) algorithm has been developed for minimization of the cost function. Simulation results show that the PSO-based EMS can achieve, as compared to standard schedule for a 24 hour period, a significant saving of daily electricity cost, which prompts for a suitable on-line control strategy.

ABSTRACT. This paper presents a collaborative control strategy based on virtual synchronous generator (VSG) for DFIG’s rotor side converter and grid side converter under unbalanced grid voltage. The control strategy of VSG makes DFIG system have a strong self-regulation ability for frequency and voltage of the network. In the proposed control strategy, the rotor side converter is controlled to achieve the smooth electromagnetic torque, while the grid side converter is controlled to compensate the output power of DFIG system to satisfy the operation requirement of VSG. Finally, the simulation and experimental results verify the proposed control method.

ABSTRACT. To solve the low power density disadvantage of direct-drive wave energy converter, caused by low direct-drive speed. A novel linear tubular field modulated permanent magnet generator is proposed, which can effectively improve the performance of this kind of generators. The operation of the proposed generator is analyzed. The generator performance is evaluated using finite element method. The results show that the proposed generator has advantages of larger air-gap effective area, higher power density, more steady output power and voltage, low cogging fore and harmonic component, which is well suit for wave energy conversion.

ABSTRACT. In the direct-drive wave energy conversion(DDWEC)system, the rotor of the linear generator oscillates along the vertical direction, as a result, the active power of the DDWEC and the DC voltage obtained by PWM rectification fluctuate greatly. To deal with this issue, a new biological intelligent controller which is based on the modulation principle of testosterone release is introduced. The models of direct-drive wave energy conversion system based on biological intelligent controller and PID are built. The simulation results show that the new biological intelligent controller has faster response speed, smaller overshoot and better stability.

ABSTRACT. In this paper, a Halbach arc linear permanent magnet machine (ALPMM) for large telescope application is analyzed by finite element method (FEM). The ALPMM employs one rotor and three segmental stators in which the stator core and windings are characterized by “C” shape. A 3-D air-gap is formed between the C-shape stator and the rotor, which can significantly increase the torque density. The key electromagnetic parameters of the ALPMM are designed. A simplified 2-D model is proposed to investigate the electromagnetic performances of the ALPMM. Further, a modified 2-D model is developed for precise results of which are approximately the same with those of the 3-D model, when the axial length of the 2-D model is 85% of the total active winding length of the 3-D model.

ABSTRACT. The study proposes a system that can detect the concentration and turbidity of a sample using white LED and color sensor. Using this method, the concentration and turbidity of the sample can be detected without using expensive turbidimeter devices. It is determined that it will be possible not only to detect turbidity but also measure sediment, and it is expected to be applicable to many application fields.

ABSTRACT. To calculate the fatigue life of shield ring following steps untaken: First, obtain the dynamic characteristics by using image recognition method and the finite element method. Second, calculate fatigue life cycle on the basis of the time-domain analysis results of vortex-induced resonance. Third, estimate the fatigue life of shield ring considering the probability of wind speed. Finally, design a new kind of shield ring with a function of vibration energy consumption.

ABSTRACT. Clustering is a well-recognized data mining technique which enables determining underlying patterns in datasets. In electric system it has been traditionally utilized for different purposes like defining customer load profiles, tariff designs and improving load forecasting. Some surveys summarized different clustering techniques which were traditionally used for customer segmentation and load profiling. However, the recent changes in power system structure and introduction of new technologies necessitate the new investigation of applications and benefits of clustering methods for power systems. In this regard, this paper aims at reviewing the new methods and addressing the challenges of clustering techniques for residential customers.

ABSTRACT. In terms of power supplies and power conversion, power electronics based converters have their own advantages. Proper condition monitoring for power electronic converter has become necessary which is now in the incipient stage. This paper includes different kinds of failure modes associated with power electronics at the converter as well as device level and recent Condition Monitoring (CM) techniques to detect those faults at the earliest stage. Proper reliability improvement has to be performed on power electronic systems so that they could be more resistive to regarding different aspects such as safety, cost, and availability. Semiconducting power devices are considered to be the most sensitive part of power electronic systems and the main causes of stresses on these devices could be initiated due to the atmospheric conditions as well as short duration heavy loads, which should be considered during power electronic system design and normal operation as the consequences of these can’t be felt at the initial stage which demands conservative converter design

ABSTRACT. Electrical and mechanical faults in a three phase Induction machine is modelled and analysed, to identify potential fault signatures. Electrical, magnetic and torque signatures are analysed for various faults and their combinations, for potential fault signature identification. A multi-physics Finite Element tool is chosen for this analysis considering the possibilities to extend the study to thermal and structural analysis.

ABSTRACT. Model predictive current control (MPCC) is a powerful control strategy for the control of three-phase power converters, but it suffers from inaccurate parameters or parameter variations. To solve this problem, model-free PCC (MFPCC) has been proposed in the literature, which only needs the information of sensed current and eliminates the use of system model. However, when applying MFPCC to PWM rectifiers, it presents high power spikes at steady state. This paper proposes an improved MFPCC to eliminate the high power spikes. Both Simulation and experimental results are presented to validate the effectiveness of the proposed method.

ABSTRACT. In this paper, active clamp snubber method was proposed to reduce effectively the switching surge voltage of the conventional quasi resonant (QR) flyback converter. The usefulness and practicality of the proposed method in QR flyback converter were verified through steady state analysis and its experimental results. The performance of the proposed circuit was compared with the RCD snubber method. It was verified from the experimental results that the switch peak voltage of the proposed method was limited below 5% while the switch peak voltage of the RCD snubber was continuously increasing accordingly with the load current. Furthermore, this new active clamp snubber method could be applied to QR flyback and its power conversion efficiency was superior to the RCD snubber one.

ABSTRACT. This paper introduces a generalized Space Vector Pulse Width Modulation(SVPWM) technique for an N-phase current source inverter (where N is an odd number). Generally for N-phase CSI there are N^2 possible switching states. Each state generates an output current space vector. The resulted space vectors are N(N-1)active-vectors with (N-1)/2 levels and N zero-vectors. These vectors are mapped in (N-1)/2 subspace planes. Each plane is divided into 2N sectors with (N-1)active and N zero vectors. The first plane is called the fundamental plane or αβ, while the others are called auxiliary planes which are labeled by x_1 y_1,x_2 y_2⋯ etc. Two different SVPWM schemes are presented in this paper. The first scheme represents an extension of the three-phase case and it uses the largest vectors to maximize the current gain. On the other hand, the second scheme utilizes all active-vectors to minimize the switching transitions. Generalized equations to determine the dwelling times in both SVPWM schemes for an N-phase CSI are proposed based on the ampere-second balance concept. In order to check the validity of the generalized technique, a case study for five-phase CSI feeding an inductive-load is presented. A sample of simulation results is obtained to confirm the presented technique effectiveness.

ABSTRACT. Induction heating can convert electrical energy to thermal energy with high conversion efficiency. Currently, a parallel resonant circuit method is widely used for forging applications in which the thyristor current source converter and inverter drives it. However, the conventional induction heating power supplies have low efficiency and power factor at input side, and require additional starting circuitry. Therefore, this paper investigates the induction heating power supply topologies for forging applications which have high power factor, high-efficiency, and large-power, and compares their characteristics and performance.

ABSTRACT. A single-phase inverter with buck-boost converter is proposed for single-phase utility connected applications such as photovoltaic (PV) system. The proposed inverter consists of buck-boost converter and a H-bridge unfolder circuit. The proposed inverter features high compatibility with next generation semiconductors because the uses of a high voltage H-bridge clamp circuit at grid frequency switching. The proposed inverter requires only 1 controllable switch to obtain a 100 Hz pulsating DC-link voltage. In conventional PV inverters shown in Fig. 1, two-stage power conversions are required. The proposed inverter shown in Fig. 2 requires one-stage power conversion. Thus, the power conversion efficiency can be increased. The experimental results, the control strategy and the numerical parameter design method are discussed in the final paper.

ABSTRACT. Energy balanced control method for converters with natural trajectory tracking is presented in this paper, and is visualized to show converters’ energy conversion inside converters. This paper specially designs and analyzes a single-phase full-bridge inverter based on energy balance with natural trajectory tracking. Natural trajectory tracking introduces a better dynamic response than the conventional PI control with the same circuit. A design method based on energy balance is proposed for the inverter with the natural trajectory tracking as well. It helps to optimize the inverter's both steady and dynamic performance. Theoretical analysis and simulation results confirm the conclusions.

ABSTRACT. This paper studies a head-up display that displays virtual images of horizontal multichannel windows in order to protect drivers from potential dangers and possible accidents, which occur due to eye recognition response time for object distance in fast moving vehicles, as well as to provide a wide range of information. A head-up display with a combiner lens structure that can simultaneously project multiple virtual images without antireflective coating material applied to the windshield has been studied. This includes an optical ray tracing system, which displays a virtual image of more than 8 inches in size at a distance of more than 3 m from the human eye. In addition, asymmetric and aspheric optical folding mirrors and a concave mirror system are applied to enlarge the virtual image. In order to create simultaneous multichannel virtual image displays, two liquid crystal display (LCD) panels, an optical projection system utilizing a combiner lens, a back light unit, and a control circuit are configured together. Two virtual images are created at a position more than 3 m away from the human eye. Throughout this study, the brightness uniformity of the two displays exhibited high performances of 83.4% and 82.2%, considering the structural characteristics of the LCD panels.

ABSTRACT. This paper studies how the lifetime of power electronic devices are affected by the operation condition and design configuration in power networks of aerial vehicle platforms. With the increased interest for vehicle electrification, it is necessary to study the reliability and lifetime performance of power electronic interfaces in highly electrified vehicular platforms. In particular, this study focuses on the effect of various operation conditions and different system configurations to the interface reliability. In order to achieve practical results, the analysis considered a realistic flight profile and life time models of power electronic devices

ABSTRACT. Chip resistors are widely used in switching mode power supply (SMPS). The output voltage sampling circuit of PFC is usually composed of several series-connected chip resistors. When fully-immersed evaporative cooling is applied to SMPS, a rise of PFC output voltage occurs after a period of operation, which is caused by resistance increase of the chip resistor applied to voltage sampling circuit. This paper investigates the reasons and influence factors of the resistance increase by experiment. Three voltage sampling circuits made up of six different kinds of chip resistors, powered by different voltage levels are designed and operate in evaporative coolant for a period of time. The experimental results are analyzed to reveal the external influence factors of resistance change. The energy spectrum analysis is conducted to analyze the causes of the problem from the perspective of chemistry. At last, the solution methods are discussed.

ABSTRACT. The evaporative cooling technology has high cooling efficiency and high reliability and it is a promising cooling method which can be applied to switching mode power supply (SMPS). Thermal simulation is an effective way to analyze the performance of the cooling system, and can provide guidance for the optimization of SMPS. In this paper, thermal simulation models of fully-immersed evaporative cooling SMPS and forced air cooling SMPS are established and the simulation results of the two models are compared to demonstrate the advantages of the fully-immersed evaporative cooling technology. The simulated temperature distribution of fully-immersed evaporative cooling SMPS is consistent with the experimental data， thus the accuracy of the thermal simulation model is verified.

ABSTRACT. In this paper, we propose a fault diagnosis scheme for power transformer using confidence weight based fusion method. The final diagnosis is performed by multiplying the result of diagnosis in the four diagnostic methods (IEC, Duval, Rogers, and Doernenburg) by the confidence weight. To show its effectiveness, the proposed fault diagnostic system has been intensively tested with the dissolved gases acquired from various power transformers.

ABSTRACT. The HVDC measurements are attracting interest for future energy grid and electrical transportation, requiring energy storage, energy conversion, load regulation and power monitoring technology. DC high voltage and high current measurement are usually ensured by precision calibration of voltage divider ratio and current shunt resistance. In order to extend the voltage and current range, step-up method had been developed and applied up to 100 kV and 1 kA. As the range extension up to high level of voltage or current, the step up method is applied multiple times, and the uncertainty sources are propagating with correlations. In this presentation, the step up results up to 200 kV and 4 kA is reported with the uncertainty propagation calculations. The calculated uncertainty is in the level of 10-5 for 200 kV and 10-4 for 4 kA.

ABSTRACT. Cable conductor temperature is the key condition to determine whether current in operation reaches to cable’s ampacity. In order to optimize cable operation, it is important to calculate cable conductor temperature with high accuracy. A simple and quick method of calculating temperature field for double-circuit underground cables is introduced in this paper. The superpose principle is applied to establish a calculation model of conductor temperature, and the conductor temperature is divided into three parts: initial temperature decided by environment temperature, temperature rise caused by its loss, and conductor temperature rise generated by other cable heat sources. Theoretical calculating models are established by combinating analytical method and the finite element method, then the formula of conductor temperature is deduced. On this basis, double-circuit soil buried cables’ ampacity is calculated and optimized. Finally, the validity of conductor temperature field model and calculation formula proposed in this paper is verified by calculation examples.

ABSTRACT. When the fault is happening in the ring DC system, the fault process can be divided into the current discharge stage, the diode freewheeling stage and the steady-state phase under the AC power supply. This paper mainly studies the capacitor discharge stage. Firstly, the fault model for multi-terminal DC system is decomposed into n single-ended fault model. Secondly, write the state equation of the single-ended system and solve the expression of fault current and voltage. Thirdly, get the fault analysis expression of the multi-terminal system by the relationship expressions for each transient value between single-ended system and multi-terminal system. The simulation are carried out by MATLAB/Simulink to provide the basis for fault location and isolation.

ABSTRACT. Abstract —The high temperature superconducting (HTS) cable has a wide application prospect in the future power grid because of its low loss, large capacity and friendly environment. Since without AC loss, the HTS DC cable has a longer cooling distance, and is more suitable for large capacity and long distance transmission. In the near future, with large-scale application of renewable energy, HTS DC cable is a potentially effective way to solve the transmission problem. To more effectively utilize an HTS DC cable and its transmission system, the influence of HTS DC cable capacitance on harmonics in high voltage direct current (HVDC) transmission system will be studied in this paper.

ABSTRACT. Insulated tubular bus-bar, functioning as the current -carrier, is widely used in electric generator. Once the bus-bar malfunctions, the generator could not be working properly which would lead to serious economic loss. Therefore, a three dimensional simulation model of 35kV/4000A epoxy resin pouring type insulated tubular bus-bar was established based on the principle of finite element simulation to study the variation law of the electric field with bubble defect in insulation in this paper. The electric field distribution of insulated tubular bus with or without bubble defect in insulation was simulated, and influence of the bubble size and position on the electric field in the insulation structure was analyzed systematically. The simulation results showed that the existence of bubble defect could easily lead to the partial discharge, or even worse, the breakthrough of the insulation finally since the electric filed of the bubble surrounding was serious distortion. The result has important implications for promoting the operation reliability of the generator.

ABSTRACT. The core temperature of power cables is a key supervising factor which concerns the operation safety of transmission line. However, direct measurement influences insulation performance due to embedding instruments into the cable. In this paper a measurement method using temperature retrieval is proposed. The finite element models of the cable are established for excavating the implicit relationships between the surface temperature easily measured and the core temperature. In the calculation models, some thermal parameters cannot be acquired from the production specifications. Consequently, parameter identification is employed to identify these parameters. By the improved models, the relationship curve of the core temperature and surface temperature is obtained for inverse calculation. At last, a case study is conducted to demonstrate the efficiency.

ABSTRACT. A new Preisach type hysteresis model for the high temperature superconductor is used to consider the magnetic hysteresis inductance of the high temperature superconducting (HTS) cable in this paper. The nonlinear dynamic circuit model of the HTS cable is established. In the circuit model, the hysteresis inductance and hysteresis loss described by using the new Preisach type model are deduced. Applying the hysteresis circuit model, the currents flowing in different superconductor layers of the HTS cable are simulated, as well as the hysteresis loss of the superconducting cable. The simulation results are verified by comparison with the data recorded in literatures. Finally, the influences of hysteresis on superconducting cable are analyzed and discussed.

ABSTRACT. The electromagnetic arresting gear is a kind of close-loop controlled arresting gear, electromagnetic force of which could be adjusted precisely, and it is an important safeguard which arrests the aircraft veering off the runway and ensures the aircrafts safely landing. Arresting cable is an essential part of arresting gear, and its performance has a significant impact on arresting process. Arresting cable dynamics principle was studied. The impact of arresting cable with different materials on arresting gearing performance was analyzed. Research shows that compound cable, comparing with steel cable, can effectively reduce the negative arresting acceleration of plane, the tension of cables as well as the arresting electromagnetic torque output of the arresting gear, and compound cable enable the closed-loop control more smoothly, which is more helpful to arrest the plane safely.

ABSTRACT. A teaching example is built in Simulink, and then, based on the communication between Matlab and LabVIEW, a teaching virtual platform in LabVIEW is realized. This platform is about a wind power generation system and used mainly for the renewable energy sources course of the undergraduate students of electrical engineering major. Compared with Simulink simulation teaching, the virtual platform adopts the advantages of both MATLAB and LabVIEW. By using this platform, a whole process of wind power generation can be viewed easily, legibly and intuitively. The operation results verify that this teaching virtual platform is practical for the teaching of undergraduates.

ABSTRACT. Industry applications in fields of electrical engineering have a high demand for engineers with knowledge and experience in using digital signal processor(DSP).Many universities offer this type of training in DSP and motor control courses. However, in traditional teaching of motor control with DSP platform, it is difficult for the undergraduate students of electrical engineering to program the motor control algorithm. Two Simulink models of vector control and direct torque control motor systems are built then, based on the communication between Matlab and DSP, Simulink-DSP teaching examples is obtained. The teaching experience based on the Simulink-DSP teaching examples verify that it is helpful for motor control technology course.

ABSTRACT. Developed a FEM platform that can support high precision electric field computing and data analysis. Approaching regular trigle mesh algorithm is realized in this paper. Dynamic compressing storage structure, multi-thread parallel computing and quick access mechanism are adopted in solver, and FEM precise computing which use Hermite interpolation calculation method is realized, all of these measures contribute to deal with contradictions between mesh quality and computing efficiency.Calculated instances analysis show that the efficient of matrix solution raises 30%~40% than general method for this model, and calculation accuracy of this algorithm raises respectively 290% and 150% than Lagrange method and ANSYS solver.

ABSTRACT. “Electrical Machinery” is the electrical engineering professional basic subject featured with theory and abstract content, involving many disciplines, and closely linked with the engineering practice, which makes it hard in the teaching and learning process. Based on the “Electrical Machinery” course offered to the "Excellence Engineer" class for Electrical Engineering and Automation, the paper introduced the properties and characteristics of the “Electrical Machinery” course and discussed the teaching reform of "Electrical Machinery " course. The author included the selection of teaching content and organization, the development of teaching, selection and organization of experimental projects and curriculum appraisal way, etc.

ABSTRACT. A new approach for the computation of electric fields is described, based on the response surface methodology (RSM) and geometric feature charge simulation method (GFCSM). And the novel combination of RSM and GFCSM is applied to calculate the electric field of the high voltage SF6 arc quenching chamber in this paper. The electric field distribution with higher calculation precision has been achieved. The results of the comparison between the conventional and proposed techniques are presented. Moreover, the new approach proves to be more efficient, minimizing computation of the electric field with multi dielectric medium.

ABSTRACT. With the rapid increase of the substation grade, the noise caused by the vibration of the transformer is becoming more and more serious. The vibration of ultra-high voltage (UHV) transformer is generated by the iron core and winding under the action of the electromagnetic force. In this paper, the sound intensity and vibration of 1000kV UHV Transformer are measured and the frequency characteristic is analyzed in detail. The vibration acceleration distribution on the oil tank surface is researched. The results can provide data support for transformer noise source identification and noise suppression.

ABSTRACT. With the enlargement of the scale of UHV transformers, more and more attentions have paid to the noise problem caused by the transformer. In this paper, the noise of 1000kV UHV transformer is measured and analyzed. The results show that the transformer noise has low frequency characteristics, and the frequency is mainly concentrated in 100Hz and its integer times. According to the noise characteristics of the transformer, the adaptive active noise reduction system is built and the experiment is carried out. The influence of the filter step size factor and the filter coefficient on the convergence and stability of the LMS adaptive filtering algorithm is simulated and analyzed.

ABSTRACT. In this paper, a three-dimensional model of cupshaped axial magnetic contact with core structure is established. And the finite element method is used to analyze the axial magnetic field(AMF) and lag time distribution of arc center plane at current peak / zero crossing for cup-shaped axial magnetic contact and the ring core with different slotted depth and slotted angle by COMSOL multi-physics coupling simulation software.

ABSTRACT. In this paper, the development of the performance measurement system for UPS product is introduced. The system consists of a testing demonstration main thread and some child threads including database operation, serial port communication etc. Several key techniques such as MFC based window design, MySQL database operation, communications assistant design of serial port are used. All these techniques introduced here will bring much merit for engineers to develop other similar measurement system.

ABSTRACT. In this paper, an auxiliary power unit (APU) for railroad car, which is applied a resonant DC/DC converter and a single-switch boost converter with SiC device, is proposed. The proposed circuit adopts SiC device in order to overcome disadvantages of IGBT. Compared to IGBT, since SiC has smaller switching loss, SiC can be operated at higher switching frequency. Therefore, the proposed APU with SiC can reduce the output ripple voltage. The proposed APU of 150 kW prototype is validated through a computer-based simulation.

ABSTRACT. The efficiency improvement of the energy router is one of the significant issues for applications in the future power networks. Power losses of switching devices play a key role about the efficiency and have close relationship with the device, topology and control of the energy router. Based on models of actual Si IGBT and SiC MOSFET, the power losses for the prototype of single sub-module in the medium voltage energy router are simulated and compared among several circuit combinations of device and topology. Finally, the experimental results in this prototype are presented.

ABSTRACT. This paper focuses on the mechanical design and static strength analysis of permanent magnet (PM) Halbach array configuration for ironless stator axial-flux PM machine. Finite element analysis of electromagnetic field is used to verify the severity of attractive force between twin rotors and the complexity of repulsive force among PM segments of Halbach array. These not only cause difficulty during assembly of PMs and rotors, but also influence integrity design of rotor for highspeed operation. In order to solve the problems above, two kinds of rotor with different installation methods of PMs are comparatively analyzed by finite element method. The strain and deformation of each part for two kinds of rotor are confirmed to locate the reason for the fracture of PMs with the original rotor design. Based on FEA model, a new rotor design and optimization are undertaken to validate the mechanical construction.

ABSTRACT. Traditional circuit breakers are vulnerable to external factors, such as external wire size, ambient temperature and installation mode. The effect of external wire length on the protection ability of circuit breaker is studied by experiment. The research shows that protection ability of circuit breaker will decline with the external wire length increase. Intelligent circuit breaker can solve the above problem, and it can achieve full selective protection. A new heating element instead of bimetal is proposed in this paper. Current will be determined by temperature of heating element. MCB will act by measured current instead of temperature of bimetal. This method is fast and effective.

ABSTRACT. Alternating current contactors as low-voltage electrical products are largely used . The arc and the contact bounce generated in the opening and closing movement are the main factors which influencing its electrical life of the AC contactor. How to extend its electrical life of the AC contactor to improve the reliability is a problem we must solve.

ABSTRACT. Abstract--atomization parameters of liquid droplets in the spray cooling system-droplets velocity, droplets diameter, droplets distribution and others influence significantly on the heat exchange efficiency. This paper uses Phase Doppler Particle Analyser(PDPA) to make a precise measurement on atomization parameters on the spray cooling system used pressure atomizing spray nozzle. Then described the distribution of atomization parameters and summarized its regularity. Through the fitting on large quantities of data obtained in test, it’s practicable to get the correlation formula between atomization parameters and pressure. Quantitative links between flow and atomization parameters will have an important reference to quantitative design of spray cooling system.

ABSTRACT. Spray cooling is a new type of high heat flux heat transfer cooling technology. In the process, cooling medium is sprayed into certain microscale droplets through the nozzles and injected to the stator core and winding. The spray characteristics will affect directly the heat transfer coefficient. So in the paper a test rig using a nozzle was constructed to explore the atomization characteristics of spray.Spray parameters (droplet diameter and particle velocity) were captured by using a phase Doppler Particle analyzer. The basic principle and the measure test of PDPA are described in detail. The experimental result is the key reference for the motor evaporative cooling system design.

ABSTRACT. A novel thermal network analysis method is introduced to investigate heat characteristic of high power density motor YJKK-500-4 in the paper. According to the special structure of motor and the related theories, and the influence of the motor cooler, radial ventilation channel, air gap and air flow in the rotor field spider to the motor temperature rise is fully considered, the thermal network model is established. And each node temperature of single motor is solved by energy balance equation. Then the exergy destruction rate in the Second Law of Thermodynamics is introduced to analyze the heat transfer characteristic of each motor component in the paper by the thermal network method. The exergy destruction rate analysis can be used to determine the heat transfer efficiency of the motor components, and can also provide a diagnostic tool for optimizing the cooling effect of the motor.

ABSTRACT. The switching frequency of high power traction driving system is very low. Aiming to improve the performance of speed sensor-less vector control in the case of low switching frequency (for example, it is low to 500 Hz), this paper introduces these technologies, such as multi-mode modulation strategy based on space vector pulse width modulation(SVPWM), design of the current regulator based on complex vector, and full-order stator flux observer. As a result, the motor can run over modulation, field current and torque current are effectively decoupled, and the flux and speed of motor are accurately estimated. Simulation and the recent project practices have proved this control system has a good operating performance.

ABSTRACT. Linear compressor is becoming more utilized in refrigeration for high efficiency, compared with the traditional rotary motor. Both stroke and frequency controls need to implement for steadiness and efficiency. In this paper, a strategy of resonant frequency tracking control based waveform fitting phase detection is presented to optimize the efficiency of the compressor. Compared with zero crossing phase detection, which is sensitive to signal interference and DC bias, waveform fitting phase detection is more accurate in detecting phase difference between displacement and current. Dual stroke and frequency control loop are implemented in experiment. Simulation and experimental results verify the effectiveness of the proposed algorithm.

ABSTRACT. This paper presents an electronically controlled continuously variable transmission (E-CVT) function for a power assisted system designed for use in a bike and implemented by a single planetary gear and an electric motor. The kinematic analysis of the planetary gear is investigated based on the block diagram representation. Moreover, the design of feedforward controlled speed ratio of the power assisted bike is coordinated with pedaling speed. The performance of the E-CVT power assisted system is evaluated experimentally in this study.

ABSTRACT. This paper proposes a novel sensorless speedup method for doubly salient electro-magnetic motor (DSEM). Based on the characteristic that phase self-inductance varies with rotor position, accurate and quick estimation of rotor sector is achieved through three-phase response currents with only one test injection pulse needed. Besides, no negative torque will be produced by the test pulse unless the rotor passes the commutation instants. To improve the speedup performance, the rules for selecting the width of test pulse and acceleration are analyzed as well. Experiments on a 12/8-pole DSEM validate the correctness and feasibility of the proposed method.

ABSTRACT. Using magnetic levitation techniques to a process line for thin steel plates is very profitable. We have succeeded in the stable magnetic levitation of a steel plate with various thicknesses by using an optimal compensator. This compensator consists of three feedback coefficients (k1, k2, k3) designed for each thickness. The sets of (k1, k2, k3) have a border of stability in the space of (x, y, z) corresponding to (k1, k2, k3) and its border depends on the thickness of steel plate. In this study, we try to levitate various steel plate with different thicknesses each other, by using the identical compensator. And based on various experiments, we will show that the stable levitation can be performed even if we adopt the identical compensator to steel plates with various thicknesses.

ABSTRACT. The traction and levitation force of the long stator linear synchronous motor (LSLSM) are key points to evaluate the performance of the Maglev train. However, it is not easy to be achieved due to the non-linear and dynamic coupling characteristics between thrust and levitation force. In this paper, the finite element analysis model of long stator linear synchronous motor is built for analyzing the thrust and levitation force. Experiments will be carried out on the prototype experimental platform.

ABSTRACT. This paper investigates the thermal performance of a three-phase 10kW flux-switching permanent magnet (FSPM) machine used as an integrated starter generator (ISG) for hybrid electric vehicles, temperature rise experiments are conducted under different operating conditions. Also, the thermal analysis of FSPM motor is simplified into one-dimensional steady heat conduction with two heat sources in cylindrical coordinates. An analytic formula for temperature distribution of motor is proposed which is verified by thermal finite element method (FEM) analysis. Finally, optimizations on the cooling system are conducted by analytic calculations and verified by computational fluid dynamics (CFD) predictions.

ABSTRACT. In this paper, a three-dimensional (3-D) generic magnetic equivalent circuit (MEC) using mesh-based formulation was developed for the electrical engineering applications. The particularity of this model consists in a discretization with hexahedral mesh elements, which can be chosen by the designer. For example, the 3-D generic MEC has been applied to a U-cored static electromagnetic device. In order to confirm the effectiveness of the proposed technique, the semi-analytic results have been compared with those obtained to 3-D finite-element analysis (FEA). The computation time is divided by 3 with an error less than 1 %.