Space-Vector Models for Torsional Vibration of Cage Induction Motors

Electromagnetic response of induction motors to torsional vibration is studied using space-vector and finite-element (FE) models. Comparison of the results shows that the skin effect in the rotor bars plays an important role, and the basic space-vector model has to be updated to a double-cage or triple-cage model. The results of the higher order models agree well with those of the FE analysis as long as motors with semiopen rotor slots are studied. In case of closed rotor slots, the saturation of the iron bridges on top of the bars causes problems in modeling accuracy.