Fault-Tolerant Control and Fault Diagnosis of Symmetrical Six-Phase Permanent Magnet Synchronous Motor Drives without Controller Reconfiguration

Owing to the multi-degree-of-freedom characteristics and inherent fault-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 post-fault torque ripple is explained as resulting from controller conflict. In addition, a multivariate fault diagnosis scheme based on voltage threshold in thex-ysubspace and current trajectory characteristics in theα-βsubspace is proposed to enhance the diagnostic accuracy. Finally, the feasibility and stability of the proposed control and diagnosis methods are verified by experiments.