Second-Time Fault-Tolerant Topology and Control Strategy for the Open-Winding PMSM System Based on Shared Bridge Arm

To further improve the fault-tolerant operation capacity of the open-winding permanent magnet synchronize motor system after second-time fault occurring, a novel fault-tolerant topology and a fault-tolerant control strategy for single phase open-circuit is proposed in this article. The fault-tolerant topology proposed in this article can operate stably in case of second-time fault that occurs after one-phase open-circuit fault by the way of sharing a bridge arm. Thus, the fault-tolerant ability of the driving system is further improved. In the terms of control strategy, the amplitude and the phase of the remaining two-phase current are redesigned to keep the system operating steadily according to the conventional expression of motor torque. Moreover, considering that the electromagnetic torque of the system will contain the third harmonic component when the three-phase current is unbalanced, the torque fluctuation will affect the stability of the system. A torque optimization strategy for suppressing the third harmonic component of the torque by injecting corresponding harmonics into the current is proposed. Finally, the experimental results validate the effectiveness of the proposed topology and strategy.