Advanced Severity Monitoring of Interturn Short Circuit Faults in PMSMs

Abstract

This paper presents a new method to estimate the severity level of interturn short circuit (ITSC) fault in permanent magnet synchronous machines (PMSMs). Instead of evaluating the fault severity by the number of shorted turns, the proposed method directly estimates the short circuit current, which is the most critical variable in ITSC faults. In the proposed method, the short circuit current generates voltage fluctuation on back electromotive force (EMF), which can be obtained via a proportional-integral (PI) estimator in the two-axis stationary reference frame. Based on the number of shorted turns information, the magnitude of the short circuit current can be estimated through the voltage fluctuation. Since the short circuit current is the main cause of deterioration in the ITSC fault, the proposed method provides an effective and straightforward way to monitor the ITSC fault. More importantly, the findings in this paper are beneficial for the fault mitigation algorithms and postfault operations. In order to verify the findings, a three-phase equivalent circuit model supported by finite element analysis (FEA) is used in the simulation. In addition, various experiments are carried out on a faulty PMSM to validate the proposed method.