Hysteresis Synchronous Optimal PWM with Continuous Switching Angles for PMSMs

Synchronous optimal pulse-width modulation (SOPWM) is an effective solution to reduce switching frequency without increasing the current distortion. This method is widely used along with stator flux tracking in traction applications of induction motors. However, stator flux tacking is not an ideal control technique for permanent magnet synchronous motors (PMSMs). This paper studies SOPWM with stator current tracking for PMSM traction applications. Stator current tracking with SOPWM suffers poor steady-state performance when the PMSM operates around discontinuity of the switching angles due to the voltage disturbance generated from current harmonics. This problem is usually solved by using continuous switching angles. However, this approach brings more overall current distortion due to sub-optimal switching angles. To address this issue, a novel hysteresis control-based SOPWM scheme with continuous switching angles is proposed. Preliminary simulation results indicate that the proposed method can offer low current distortion compared to conventional and continuous SOPWMs.