Multiple Open-Switch Fault Diagnosis for Five-Phase Permanent Magnet Machine Utilizing Currents in Stationary Reference Frame

Apart from the passive fault-tolerant control strategies, any active fault-tolerant strategy requires a timely fault diagnosis signal to trigger the control reconfiguration under asymmetric condition. This article proposes a fault diagnosis method where the inherent relationship between fundamental and third harmonic stationary reference currents is established by declaring two new groups of current-based variables. Then two distinct fault characteristics of current performance in the transient conversion from healthy to faulty operation are derived. Based on the fault characteristics, a fast, robust and easy-implemented diagnosis algorithm is proposed based on currents in stationary reference frame to address the multiple open-switch fault diagnosis in five-phase permanent magnet machines. In order to verify the effectiveness of the proposed algorithm, a series of experiments have been conducted and the results indicate the strong robustness even under load variation and the valid diagnosis to each type of faults are performed. Moreover, the proposed method possesses favorable generality and can be extended to other multiphase machines.