Analysis of Demagnetization Faults in Surface-Mounted Permanent Magnet Synchronous with Inter-turns and Phase-to-Ground Short-Circuits

Demagnetization faults are troublesome in permanent magnet synchronous motors since they may greatly reduce their performance and efficiency. Additionally, the temperature of the magnets deeply influences the remanent flux density. Hence, the temperature may have a demagnetization effect on the magnets. This work studies the behavior of a surface-mounted permanent magnet synchronous motor running under inter-turn and phase-to-ground short-circuits faults. Concretely, the temperature increase of such faults and a potential reversible or irreversible demagnetization of the rotor magnets are analyzed. The analysis is based on 2D FEM simulations which includes rotor magnet skew. The simulations conducted in this work clearly show that inter-turn faults do not lead to irreversible demagnetization. However, in case of a phase-to-ground short-circuit an irreversible demagnetization may take place instantaneously.