Characteristics of Sideband Current and Noise Induced by Periodic Modulation Techniques in PMSMs

This study investigates the sideband currents generated by periodic-switching-frequency pulse width modulation (PSFPWM) strategies and their impact on the highfrequency sideband noise of permanent magnet synchronous motors (PMSMs). The harmonics of these sideband currents are analytically derived for PSFPWM strategies. Then, the influence of PSFPWM on the sideband force and acoustic noise in PMSMs with various pole/slot combinations is deduced. The features of sideband current and noise under these strategies are revealed and validated by experiment results. Selection criteria for the switching frequency variation rate and frequency extension width of PSFPWM are also discussed. The results indicate that PSFPWM introduces additional frequency components into the spectrum, thereby dispersing the concentrated energy. With appropriate parameter selection, PSFPWM strategies can effectively suppress the high-frequency sideband current and noise across the full speed range.