Topic: 1. Electric Motors

For the integration of variable frequency drives in existing plants the 
mechanical characteristics regarding the dynamic behavior of the system need 
to be analyzed and assessed to ensure reliable operation with low vibration lev-
els. Structural as well as rotor dynamics assessments ensure the successful me-
chanical integration of the electric drive system. As an exemplary application 
the replacement of steam and gas turbines by variable frequency drives is used 
to demonstrate the adaptation to existing foundation conditions and the related 
challenges regarding the flexible characteristic of these foundations. 

The rotor dynamics assessment requires an advanced approach regarding the 
representation of the support structure. The usual representation of the rotor 
support in rotor dynamics models by linear flexibilities is not sufficient if the 
support, particularly the foundation or the adapter frame, shows dynamic be-
havior. A frequency dependent representation of the support needs to be estab-
lished in the rotor dynamics model. Thereby the compliance with separation 
margins or vibration limits can be evaluated and adjustments of the system de-
sign can be developed and assessed. 

Facing the high variance of customer plants and the application-specific needs, 
a customized solution needs to be handled during the design process. The effi-
ciency of the engineering phase of a project can be significantly improved by 
automizing time-consuming simulation tasks. That includes a parametric finite 
element model generation of the motor and the subsequent simulation and eval-
uation process. The automized simulation approach reduces processing time for 
design optimization loops.