Temperature Analysis for the Asymmetric Six-Phase Permanent Magnet Synchronous Motor in Healthy and Fault-Tolerant Modes

Abstract

The asymmetric six-phase permanent magnet synchronous motor (AS-PMSM) can switch to five- or three-phase operation in the case of winding and drive leg fault. This paper analyses the temperature distribution of the AS-PMSM with different fault-tolerant modes and provides theoretical support to improve the reliability of the machine and its drive system. A 22-pole 24-slot AS-PMSM with physical, magnetic, and thermal isolation is designed first. Then, the systematic analysis method, considering the inverter, the machine and the control algorithm, is proposed. The magnetic field and losses of the AS-PMSM are addressed in multiple modes, including the six-phase, the five-phase (minimum loss / maximum torque) and the three-phase operation. Furthermore, a three-dimensional model, bi-directionally coupling electromagnetic field and temperature, is established based on the theory of transient temperature field and fluid dynamics. The model reveals the temperature propagation law and the temperature variation of the AS-PMSM in four modes. The proposed theoretical analysis is finally proved effective by experiments.