In the power transmission system, the semiconductor device in the inverter is one of the main fault points. When the open-or short-circuit fault occurs in the semiconductor device, the motor can be turned into the operation with open-phase fault. To take into account the non-ideal factors existing in the calculation, this study establishes a systemlevel calculation model including the permanent magnet synchronous motor (PMSM), inverter, and different control strategies, which is used to analyse the operating performance of the PMSM with or without fault-tolerant control under single-phase opencircuit fault. In addition, based on the finite element method, the current fault characteristic and the change of the internal magnetic field distribution before and after the fault are studied, and the temperature rise of the PMSM with and without fault-tolerant control is compared. The aim of this study is to compare the operating performance of the threephase PMSM under two common fault conditions, and quantitatively give the variation range of magnetic flux density and temperature rise. The theoretical analysis in this study is verified by building a systematic experiment platform. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Abstract-The partial demagnetization of surface-mounted permanent magnets of PMSM in the three phase symmetrical short circuit of different temperature is analyzed by the finite element method. Then, rules of the back EMF and flux change in different extent of demagnetization are summarized. Finally, the operation behaviors and secondary demagnetization of the demagnetized PMSM are analyzed. Conclusion, which can judge and prevent demagnetization fault, is presented.