Torque Ripple Minimization in Direct Torque Control based IM Drive Part-I: Single-rate Control Strategy

Present work shows the merits of space vector modulation direct torque control (SVPWM DTC) over the conventional direct torque control (conventional DTC). SVPWM DTC technique is helpful in solving the basic issues of torque ripple and variable switching frequency present in the conventional DTC. Three PI controllers one each for speed, torque and flux feedback loops is used in SVPWM DTC based IM drive. The major issue related with SVPWM DTC based IM drive is the proper setting of the parameters in speed, torque and flux control loops. As they are inter-dependent in nature, their parameter setting is a tricky issue. No proven technique is available to address this issue and so it can be observed that because of the lack of proper parameter settings, the induction motor drive performance is affected in terms of higher torque ripple. In present work an attempt is made to address this problem using the frequency analysis technique. Simulation results for the SVPWM DTC based on this method and conventional DTC are compared. Hardware results validate the simulation result and hence proposed technique.