Carrier Electromagnetic Vibration of DC Voltage Fluctuation in Permanent-Magnet Synchronous Motor with Distributed Winding

In this paper, we evaluate the noise and vibration in a permanent-magnet synchronous motor (PMSM) with distributed winding driven by voltage source pulse width modulation (PWM) inverters. Although the PMSM is a widely used device in a variety of fields, it tends to generate electromagnetic noise due to the PWM inverters. We describe the frequency of the electromagnetic vibration of DC voltage fluctuation. We investigated the PWM voltage harmonics and the modulation degree of DC voltage fluctuation through a theoretical analysis of the high-frequency voltage spectrum and found that a modulation degree near 0.56 was the maximum point of the doubled component of the carrier frequency 2f
_c
. Compared with the DC voltage fluctuation at this point, the dominant component of the PWM voltage harmonics was near frequency f
_c
at a lower voltage and near frequency 2f
_c
at a higher voltage. We also verified these tendencies of the carrier electromagnetic vibration of DC voltage fluctuation in an experiment.