Research on Direct Torque Control Based on RZVSVPWM of PMSM

Abstract

The traditional direct torque control (DTC) method for permanent magnet synchronous motor (PMSM) has the problems of unstable switching frequency, large torque ripple and high current harmonic distortion rate. To solve the above problems, this paper proposes direct torque control based on random zero vector space vector pulse width modulation (RZVSVPWM-DTC). Firstly, the mathematical model of PMSM is analyzed. It is found that the control current $i_{q}$ can directly control the torque. It is combined with the mathematical model of DTC, pointing out the shortcomings of the traditional DTC method. Secondly, the RZVSVPWM-DTC is analyzed to illustrate its advantages. Finally, the RZVSVPWM-DTC is used to replace the traditional DTC, and the torque and flux linkage are used as the control objects for simulation analysis. The simulation results show that the RZVSVPWM-DTC has a constant switching frequency, smaller torque ripple and lower line current distortion rate. The system has good dynamic and static performance, which verifies the feasibility and effectiveness of the method.