Fault-Tolerant Control for the Asymmetric Six-Phase Permanent Magnet Synchronous Motor With Open-Phase Faults

This article proposes a fault-tolerant control strategy suitable for the asymmetric six-phase permanent magnet synchronous motor (AS-PMSM) to improve its fault-tolerant performance and capability. The performance of the AS-PMSM with different types of the open-phase fault (OPF) is analyzed, and the best and worst fault-tolerant modes are pointed out. In order to make the motor have optimal fault-tolerant performance and reduce control complexity, a new transformation matrix is proposed based on the principle of constant magnetomotive force. The proposed transformation matrix and control method make the dimension of the AS-PMSM reduce to two. Good current tracking effect is achieved by using traditional proportional integral (PI) controllers, and there is no need to change the current reference and reconfigure the current controller. A topology structure and a definition and usage of the “pseudo-fault” leg are proposed for the worst fault-tolerant mode to improve the performance of the AS-PMSM significantly in this mode. Moreover, the redundancy of the topology can be fully exploited by using the “pseudo-fault” leg, enabling the AS-PMSM to operate in all types of three OPFs. Furthermore, the conversion criterion between different fault-tolerant modes is also proposed, so that the AS-PMSM can operate in multiple OPF modes with satisfied performance. The test platform is built to verify the proposed theoretical method.