Sinusoidal periodic carrier frequency modulation in reducing electromagnetic noise of permanent magnet synchronous motor

This study introduces a simple method to reduce the electromagnetic noise of permanent magnet synchronous motor (PMSM) fed by pulse-width modulation (PWM) inverter. The analysed relationship between PMSM electromagnetic noise and current harmonic shows that PMSM electromagnetic noise concentrating on integral multiples of switching frequency is produced by the concentrative current harmonic. To spread the current harmonic spectrum, sinusoidal periodic carrier frequency modulation (PCFM) is presented and discussed theoretically. Simulations and experiments of PMSM fed by PWM inverter are conducted to verify the effectiveness of sinusoidal PCFM in reducing PMSM current harmonic and electromagnetic noise. The most efficient sinusoidal PCFM strategy in alleviating PMSM current harmonic and electromagnetic noise is put forward based on the comparison about reductions of PMSM current harmonic and electromagnetic noise by sinusoidal PCFM with different modulation frequency ratios.