Local demagnetization fault detection in PMASynRM based on finite element modeling and characterisation
Authors: Jérémy Creux, Najla Haje Obeid, Thierry Boileau, Farid Meibody-Tabar
Extended abstract:
Good overall performances and efficiency of Permanent Magnet Synchronous Machines (PMSMs) are highly impacted by irreversible demagnetization faults. This paper proposes to analyze the electromagnetic behavior of a faulty Permanent Magnet Assisted Synchronous Reluctance Motor (PMASynRM) with neodymium-iron-boron (NdFeB) rare-earth magnets, to identify frequency fault signatures and develop an efficient fault indicator. Finite Element Analysis (FEA) is used to determine high current flux-weakening critical demagnetization areas in the rotor, to model local demagnetization defects and to evaluate precisely post-demagnetization characteristics of the baseline machine. The study focuses on flux and back-emf time and frequency analysis for their high potential to identify low severity fault signatures. The results mainly show that magnetic flux density distribution is impacted, and flux lines are disturbed and reduced in the demagnetization area. Also, the 3-phase back-emf is distorted with a third-order harmonic amplitude increase, while ninth and eleventh-order harmonics amplitude are significantly trended downwards. Finally, the Zero-Sequence Back-Emf Component (ZSBEC) frequency spectrum is significantly impacted, especially harmonics multiple of 3. Therefore, we suggest using this frequency pattern to develop a fault detection index which allows quantifying, with high sensitivity, the severity of local demagnetization faults in PMASynRMs.
