Separation of broken magnet and static eccentricity failures in PMSM

This paper deals with the separation of broken magnet failures from static eccentricity (SE) fault using phase current information in permanent magnet synchronous motors (PMSMs). Broken magnet and SE faults exhibit very similar fault patterns in back-emf and flux spectrums. Therefore, these two faults should be discerned from each other for accurate diagnosis. In this paper, phase current waveforms are exhaustively analyzed at different speed and torque profiles to discriminate broken magnet from SE in PMSMs. In order to specify the behavior of sideband harmonics, 2-D Time Stepping Finite Element Method (TSFEM) is used. Simulation and experimental results show that some distinctive harmonics such as 0.25th, 0.5th and 0.75th can define the fault type in PMSMs