A Fault-Tolerant Control Strategy for FOC of Fivephase PMSM Based on Zero-Sequence Current Suppression

This paper proposes an SVPWM-based faulttolerant control strategy for five-phase open-winding permanent magnet synchronous motors (PMSM) under single-phase or twophase open-circuit faults. In this method, the stable rotating magnetic fields can be kept by using remaining healthy phases, which means that the high torque output can still be achieved under fault conditions. However, conventional DC bus openwinding systems face a critical limitation, that the circuit configurations of them inherently create low-impedance paths for zero-sequence currents. The structural flaw fundamentally restricts the system reliability under fault conditions. During the operation, the modulated common mode voltages produce large zero-sequence currents. These circulating currents could increase motor vibration, electromagnetic losses, and thermal stress, which may result in poor system reliability and safety. Therefore, an unequal zero-vector distribution method is proposed in this paper to solve these problems mentioned above. This technique can actively adjust the duration of zero vectors in the modulation process to counteract zero-sequence voltage distortions caused by dead-time effects in power switches. In the simulating results, the zero-sequence current can be eliminated and good torque characteristics can be maintained, which means that the reliability of the five-phase PMSM can be improved.