Diagnosis of Open-Phase Faults for a Five-Phase PMSM Fed by a Closed-Loop Vector-Controlled Drive Based on Magnetic Field Pendulous Oscillation Technique

An online diagnostic approach of open-phase faults for a five-phase permanent magnet synchronous motor (PMSM) fed by a closed-loop vector-controlled drive is presented in this article. This approach is accomplished based on the magnetic field pendulous oscillation (MFPO) phenomenon, in which a significant 'swing-like' pendulous oscillation in the magnetic field is observed in case of open-phase faults. According to an analysis of the signatures of MFPO patterns under faulty conditions, all possible open-phase faults are detected, including single-phase open faults, two-adjacent phase open faults, and two-nonadjacent phase open faults. Moreover, this approach is capable of localizing the faulted phase/phases by further extracting the phase angle features of MFPO angular position waveforms under faulty conditions. Meanwhile, in order to minimize the number of sensors to reduce the implementation cost of this diagnostic approach, a phase-locked loop technique is developed to overcome the fault masking difficulties associated with the compensation action of the closed-loop vector-controlled drive. As a result, this diagnostic approach only requires four current sensors and a speed sensor, which are typically already available in five-phase PMSM drive systems for control purposes. Finally, experimental results demonstrate the effectiveness of the presented approach.