Reduction of torque and flux ripples in direct torque controlled five-phase induction motor drive based on instantaneous voltage control technique

Abstract

This paper elaborates the use of instantaneous voltage control method for control of torque in a five phase induction motor drive. In this method, instantaneous time modulating signals are generated, without the feedback of position of rotor, which enhances its easier implementation. These modulating signals being compared with triangular waves gives the required switching states input to the inverter gate triggering circuit, based on the speed, flux and torque errors. Triplet component is added to the fundamental sinusoidal signal and the resultant signal is used as a modulating signal, because of the advantage of getting more effective switching states. This method is achieved by generation of inverter switching states by modulation of the errors in flux, speed and also real time speed control based on the instantaneous error values. A comparison is made with conventional Direct Torque Control (DTC) method and satisfactory results are observed.