The Mechanism for Suppressing High-Frequency Vibration of Multiphase Surface Permanent Magnet Motors via PWM Carrier Phase Shifting

Switching-frequency vibration caused by pulsewidth modulation (PWM) is a critical shortcoming of permanent magnet synchronous motor (PMSM) drives in certain applications. This article reveals the mechanism for suppressing high-frequency vibration of multiphase surface permanent magnet (SPM) motors via PWM carrier phase shifting (CPS). The article first introduces a 12-phase SPM drive with three different modes of CPS. Then, it presents an analytical method to calculate high-frequency current harmonics as well as flux and force distributions along stator boundaries. By analyzing the calculated current harmonics and flux distributions under different CPS modes and parameters, the article discovers that CPS greatly alters the spatial distribution of high-frequency stator electromagnetic forces and, thus, significantly changes their zero-order components, which are the major contributors to high-frequency motor vibrations. Finally, the optimal CPS mode and parameter are determined analytically and are validated by experimental results.