Drive Direct Torque Control of Permanent Magnet Synchronous Motors Based on Discrete Space Vector Modulation

Abstract

To solve the problems of unsmooth stator flux linkage locus, large torque ripples and big power loss in conventional direct torque control system of permanent magnet synchronous motor, the discrete space vector modulation technique is analyzed, and a new direct torque control method (DSVM-DTC) is proposed in this paper. PI controller and DSVM modulator are used to instead hysteresis controller and switch table in conventional DTC system, which increased the equivalent voltage vectors and selected accurate zero vectors in different sectors. Therefore, the errors of flux and torque can be compensated accurately. Simulation results prove that DSVM-DTC effectively improved the steady-state performance of the system, declined the switching loss, reduced torque ripple, and flux linkage locus is more smooth under the premise of ensuring constant switching frequency.