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

Carrier frequency current harmonic peaks induced by pulsewidth modulation (PWM) in motion control systems will cause high-frequency torque ripple, efficiency decrease, and electromagnetic interference problems. It is proved in this article that carrier-frequency harmonic current components in dual three-phase permanent magnet synchronous motor (DTP-PMSM) systems exhibit a different distribution and are more severe compared to the three-phase ones due to the existence of the low-impedance harmonic subspace, thereby limiting the further application of DTP-PMSMs. To address this issue, this article proposes an advanced carrier phase-shift modulation strategy. First, by introducing aπ/2 phase shift between two PWM modules, the dominating first carrier frequency harmonic current components inz1–z2subspace are halved. The high-frequency torque ripple, located at second carrier frequency, is also suppressed. Periodic frequency modulation is utilized in the proposed strategy to further suppress the high-frequency harmonic current components in bothα–βandz1–z2subspaces. 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 space vector pulsewidth modulation (SVPWM) and random SVPWM, the proposed strategy has a better harmonic suppression effect without inducing distortion.