Predictive stator flux control with overmodulation and dynamic torque control at constant switching frequency in AC drives

Abstract

In this paper the authors propose a simple inverter switching strategy that achieves dynamic torque and dead-beat control of stator flux. Depending upon the error in torque, the torque controller creates a dynamic slip that defines a new flux reference. Error in flux is used to directly obtain the inverter switching states. The procedure to obtain the inverter duty cycle using the error in flux has been elaborated for operation in the normal and in the overmodulation range. The advantages of this scheme lie in achieving a constant switching frequency operation and being able to apply the maximum voltage vector for fast torque dynamics.