Evaluation and comparison of sideband harmonics and acoustic responses with continuous and discontinuous PWM strategies in permanent magnet synchronous motor for electric vehicles

Abstract

High-frequency vibro-acoustics, introduced by voltage source inverter (VSI) and control strategies, are the critical features affecting the noise, vibration and harshness (NVH) performances of electric vehicles (EVs). In this paper, a comprehensive evaluation and comparison into sideband current harmonics and high-frequency vibro-acoustic responses has been studied with different control strategies in the study case of permanent magnet synchronous motor (PMSM). At first, the principles and implementation of continuous and discontinuous pulse-width modulations (PWM) techniques are explored. Then, the features of the sideband current harmonic and radial electromagnetic forces are deduced with analytical derivations, in which the frequency characteristics are also presented. Furthermore, all PWM schemes have been improved by a standard periodic dithering modulation with square signal-based to reduce the sideband harmonics. The experimental results show that the sideband current harmonics and vibro-acoustics are generally clustered around the carrier frequency and have a particular orders and spectral distributions. The overall level of the obtained DPWM schemes present a slight deterioration compared to the SVPWM ones. With the periodisation of the carrier frequency, the sideband components show a significant suppression, which is above 15 dBA reduced in the acoustic noise responses.