Owing to the multi-degree-of-freedom characteristics and inherent ault-tolerant capacity, six-phase motors have been widely adopted in high-power applications, such as electric vehicle propulsion and aerospace systems. This paper presents the fault-tolerant control strategy of symmetrical six-phase permanent magnet synchronous motor (SSPMSM)under an isolated neutral point topology and proposes a fault diagnosis scheme based on joint diagnosis of multiple variables. First, two mathematical models of SSPMSM and their relationship are established. Subsequently, the current vectors in the torque subspace and harmonic subspace of the two winding sets under fault conditions are analyzed, and the cause of postfault torque ripple is explained as resulting from controller conflict. In addition, a multivariate fault diagnosis scheme based on voltage threshold in the x-y subspace and current trajectory characteristics in the α-β subspace is proposed to enhance the diagnostic accuracy. Finally, the feasibility and stability of the proposed control and diagnosis methods are verified by experiments.

Fault-tolerant control  /  Symmetrical six-phase permanent magnet synchronous motor (SSPMSM)  /  Isolated neutral point  /  Controller conflict  /  Multivariate fault diagnosis