Modified direct torque control of matrix converter fed induction motor drive

Abstract

In this paper, a torque ripple minimization technique with constant switching frequency is proposed for direct torque control (DTC) of a matrix converter fed squirrel cage induction motor drive. Some drawbacks of conventional DTC are the generation of relatively large torque ripple in a low speed region and a variation of switching frequency according to the amplitudes of torque and flux hysteresis bands. In this proposed strategy, an optimal switching instant during one switching cycle is calculated for torque ripple minimization, which is derived from torque ripple based on an instantaneous torque. The proposed strategy improves the performance of the DTC-IM drive by combining a low torque ripple characteristic in the steady state and the conventional fast torque dynamic characteristic. Simulation results prove the feasibility of proposed strategy compared with conventional method.