The Influence of Saturation on Induction Machine Drive Dynamics

A small signal model which employs two different magnetizing reactances to incorporate the effect of main flux saturation on induction machine dynamic response is presented. Three different types of experiments which confirm the improved accuracy of the saturated model are discussed, and the model is used to examine the effect of saturation on dynamic response in variable frequency applications. The results indicate that whereas saturation has a relatively small effect under normal operating conditions, it does have an important stabilizing effect when the damping is poor. It is also shown that neglecting saturation leads to significant errors in both pole and zero locations when the operating frequency is low.