New method to reduce torque ripple in DTC control system of three-phase induction motor

Aiming at the problem of high torque ripple at low speed in traditional direct torque control system, a method of replacing reverse-vector with zero vector is proposed on the basis of analyzing and verifing the relationship between voltage vectors and torque ripple. Additionally, it is adopted to optimize the hysteresis controller of torque and flux linkage, both of which are utilized to solve the problem on high torque ripple. The simulation results indicate that this proposal can decrease torque from 4 N·m to 1.5 N·m, optimizes system performance and extends the low-speed range.