High-Frequency Current Harmonic Analysis and Suppression in Dual Three-Phase PMSMs With Advanced Carrier Phase-Shift PWM

Abstract

Carrier frequency current harmonic peaks induced by Pulse Width Modulation (PWM) in motion control systems will cause high-frequency torque ripple, efficiency decrease and EMI problems. It is proved in this article that carrier-frequency harmonic current components in dual three-phase permanent magnet synchronous motor (DTP-PMSMs) systems exhibit a different distribution and are more severe compared to the threephase ones due to the existence of the low-impedance harmonic subspace, thereby limiting the further application of DTP-PMSMs. To address this issue, this paper proposes an advanced carrier phase shift modulation strategy. Firstly, by introducing a π/2 phase shift between two PWM modules, the dominating 1st carrier frequency harmonic current components in z1-z2 subspace are halved. The high-frequency torque ripple, located at 2nd carrier frequency, is also suppressed. Periodic Frequency Modulation (PFM) is utilized in the proposed strategy to further suppress the high-frequency harmonic current components in both α-β and z1-z2 subspaces. The effectiveness of the proposed strategy is demonstrated theoretically and verified by simulation and experiments. DC-link current can also benefit from the proposed strategy. Compared with conventional SVPWM and random SVPWM, the proposed strategy has a better harmonic suppression effect without inducing distortion.