Current control in overmodulation range for space vector modulation based vector controlled induction motor drives

Abstract

Overmodulation enhances the power utilization of the installed capacity of a voltage source inverter. A space vector strategy is used for constant switching frequency inverters. In order to achieve the overmodulation a modified reference signal with non-uniform angular velocity is generated using a preprocessor. Such a reference wave produces low frequency harmonics in currents. The presence of current harmonics restricts the bandwidth of the fundamental component current controller in the overmodulation range. On the other hand high bandwidth current controller is mandatory for vector control. A compensating current control is presented to allow for high bandwidth current control in synchronous coordinates.