Research on open-circuit fault diagnosis methods for parallel branches in open-end winding permanent magnet synchronous motors

Background Multi-branch parallel permanent magnet synchronous motors (PMSM) are prone to parallel branch open-circuit faults (PBOCF), which may result in winding overheating, insulation damage, and other reliability issues. Objective This study aims to propose an effective fault diagnosis method that can distinguish between open-circuited faults (OCF) and PBOCF in PMSMs, while maintaining robustness under varying operating conditions. Methods The winding function method is employed to analyze the inductance matrix differences between healthy and faulty states. Based on this analysis, mathematical models of PMSM under both conditions are established. Fault diagnosis is realized by comparing the zero-sequence current (ZSC) AC components before and after the fault, and the faulty phase is identified by analyzing the root mean square (RMS) values of the three-phase currents. Results Simulation results verify the effectiveness of the proposed method. The approach successfully distinguishes between OCF and PBOCF without the need for additional hardware. Conclusions The proposed method provides a reliable and robust solution for diagnosing PBOCF in PMSM, demonstrating strong resistance to variations in torque and speed.