Diagnosis of Open-Phase Faults for a Five-Phase PMSM Fed by Closed-Loop Controlled Drives Using a Pendulous Oscillation Phenomenon

This paper introduces an on-line open-phase fault diagnostic approach for five-phase permanent-magnet synchronous machines (PMSMs) fed by closed-loop vector-controlled drives. Based on the concept of magnetic field pendulous oscillation (MFPO) phenomenon, typical operating characteristics under various faulty conditions are investigated for the PMSM drive system, including single-phase open fault, two-adjacent phase open fault, and two-nonadjacent phase open fault, respectively. Moreover, to reduce the implementation cost of the developed diagnostic method, a phase-locked loop (PLL) technique is adopted to overcome the fault masking difficulties associated with the compensation action of the closed-loop drives. In addition, original theoretical derivation of the proposed fault diagnostic technique is presented. This approach can effectively detect and identify various types of open-phase faults, as well as help localize the faulty phase.