Reduction of Torque and Flux Ripple in the DTC Drive

ABSTRACT This paper presents a new controller for the direct torque control (DTC) of induction motor, which is considering one of the most advanced drive for the control of induction motor. DTC provides a simple structure and gives effective way of controlling the torque and flux in transient and steady state condition. This drive provides an independent control of torque and flux just like in D.C motor without the necessary of speed feedback. In the method, the induction motor torque and flux are to be estimated from the stator terminal voltages and currents, this estimation does not depend on any motor parameters except the stator resistance. The main drawbacks of the DTC are variable switching frequency because of presence of hysteresis controllers in the closed loop and high torque and flux ripple. In this report present a new controller for the classical DTC where the normal hysteresis controllers are replaced with a new controllers where approximately constant switching frequency is obtained and it has also obtained the reduced torque and flux ripple