Fault-Tolerant Control Method to Reduce Torque Ripple for Symmetrical Winding Multi-Phase Brushless DC Motor Under Open-Circuit Faults

For a symmetrical winding multi-phase brushless DC motor (BLDCM), this paper proposes a fault-tolerant control method to reduce torque ripple after an open-circuit fault occurs in the system. When a power switch device or phase winding experiences an open-circuit fault, the proposed method adjusts the conduction pattern of the windings in certain sectors, altering the magnitude and direction of the magnetomotive force (MMF) and thereby reducing torque ripple. This method is simple and easy to implement. It neither requires phase shifting of the healthy phases nor necessitates changes to all healthy phases. Finally, the effectiveness of the proposed method is verified through experiments on a 2kW nine-phase BLDCM experimental platform.

I. Introduction

Brushless DC motors (BLDCMs) have advantages such as high-power density and simple control, making them widely used in various industrial products. Due to the additional degrees of freedom, multi-phase BLDCMs offer more flexible driving options. Compared to traditional three-phase BLDCM systems, they are more reliable. Therefore, multi-phase motor drives are used in large-capacity electric propulsion systems, such as those in submarines and large ships, to ensure stable operation even under fault conditions [1]–[2].