Interturn Short-Circuit Fault Diagnosis of Permanent Magnet Synchronous Motor Based on No-Load Back Electromotive Force Analysis

Inter-turn short circuit faults (ISCFs) in the stator winding are considered one of the most serious faults in permanent magnet synchronous machines (PMSMs). To address the need for timely and accurate ISCF diagnosis, the characteristics of the ISCF are studied, and corresponding fault diagnosis methods are proposed on this basis. Initially, an ISCF model that incorporates mutual inductance within the coil is developed, and its characteristics are thoroughly analyzed. A crucial mathematical relationship between fault severity and fault characterization is established, with a specific focus on how the variation of back electromotive force (EMF) correlates with the number of faulty coils. Based on the no-load back-EMF characteristics of ISCF, a novel method is proposed to obtain the no-load back-EMF during motor operation. Subsequently, ISCF diagnosis becomes feasible by analysing the no-load back-EMF. Through a combination of simulations and experiments, the effectiveness and reliability of the proposed principle and method are validated. Importantly, it is demonstrated that this diagnostic method remains robust and consistent, irrespective of the motor’s operating conditions.