Demagnetization Fault Diagnosis Based on Coupled Multi-Physics Characteristics of Aviation Permanent Magnet Synchronous Motor

Aviation permanent magnet synchronous motors (PMSMs) are particularly susceptible to demagnetization faults due to the thermal sensitivity of permanent magnet materials, compounded by high-altitude conditions where reduced air density significantly limits cooling. In addition, the pursuit of high power density and compact structure in aviation design intensifies local thermal stress, while stringent reliability requirements mean even minor degradation can threaten operational safety. This paper investigates the operating characteristics of aviation PMSMs under demagnetization faults and proposes an effective diagnostic approach. A coupled electromagnetic–thermal finite element model is established to evaluate rated and no-load performance and calculate losses under rated conditions, and its validity for the motor body is confirmed using the RT-LAB semi-physical simulation platform. Subsequently, altitude-dependent ambient air parameters are incorporated to analyze the thermal–magnetic field distribution, highlighting the influence of high-altitude operation. Based on the thermal results, a fault dataset is constructed by selecting typical local demagnetization cases and classifying global faults into levels according to temperature criteria, with features extracted in both time and frequency domains. Finally, an intelligent diagnostic method integrating a deep belief network (DBN) and an extreme learning machine (ELM) is developed. Comparative results demonstrate superior accuracy and robustness over conventional methods, advancing demagnetization fault diagnosis for aviation PMSMs.