PMASynRM Local Demagnetization Fault Behavior Study Under Targeted Harmonic Excitation.

Permanent Magnet Assisted Synchronous Reluctance Motors (PMASynRM) are high energy density topologies, widely used in the automotive industry. However, their very good performances and efficiencies can be severely impaired by irreversible demagnetization faults on their rare-earth magnets. The aim of this work is to achieve the earliest possible fault detection, with a very low demagnetization rate, to prevent power density losses. For this purpose, we used demagnetization frequency signatures of a baseline traction PMASynRM and based our diagnosis on high-order harmonic component behavior. Due to the low magnitude of these frequency features it may be difficult to identify the fault with a reliable and robust approach, therefore, a harmonic excitation scheme has been proposed to exacerbate local low severity demagnetization fault signatures. Finite Element (FE) modeling and analysis have been used to develop and to validate the method principles. Thus, different local demagnetization faults have been simulated in order to optimize and to evaluate the sensitivity of this high-frequency injection technique. Flux frequency spectrums were then used to develop a harmonic component-based fault indicator. Numerical results show that the proposed harmonic excitation strategy amplifies fault features while taking them out of the noise. Therefore, the fault indicator becomes more reliable, with a more robust and sensitive detection.