Torque Ripple Minimization in Direct Torque Control based IM Drive Part-II: Multirate Control Strategy

This paper presents the work in continuation with part-I. Present work deals with the basic issues associated with the direct torque control (DTC) of induction motor drive. The work is focused to reduce the electromagnetic torque ripple using the concept of multirate sampling. DTC based induction motor drive is simulated using space vector modulation incorporating the multirate sampling. It is also claimed that the electromagnetic torque ripple of the induction motor drive is smaller than that exists in conventional DTC or single rate SVPWM DTC based induction motor drive. For the same digital signal processor smaller sampling time can be selected in implementation of multirate SVPWM DTC based induction motor drive than implementing the conventional DTC and single rate SVPWM DTC based induction motor drive. Gain setting of flux and torque controller is again plays a vital role in the performance of induction motor drive. The values of Kpt, Kit Kpf and Kif which are proportional and integral gains of torque and flux PI controllers respectively are set using the technique discussed in part-I such that the voltage vectors selected using space vector modulation technique gives optimum performance in terms of magnitude of torque ripple in induction motor drive.