Progress report about coupled finite element calculations for squirrel cage induction motors including various control strategies of power converters

Abstract

The continually rising technical requirements of modern industrial drive applications often demand an improved, efficient and almost reliable design process. In particular, a very accurate prediction of undesired current and torque harmonic magnitudes as well as the accuracy of the rotor shaft's true running during load within converter fed induction motors become nowadays of crucial interest. So, the complex nonlinear interaction of the converter and the squirrel cage induction motor have to be considered and analyzed with adequate numerical methods. The proposed complete system approach takes thereby implicit account of a very detailed converter circuit representation with discrete electronic devices and an extensive 3D squirrel cage induction motor modeling by the finite element method. Various control strategies of the power converter – π-mode or manifold pulse width modulation methods – have been established in the past and are successfully used until now. The generated respective arbitrary time-dependent output voltage waveforms of the power converter are almost directly processed within the non-linear finite element analysis of the motor in the time-domain. Such numerical analysis methods deliver novel and deep insight into an almost very sensitive and complex speed-variable drive system.