Analysis and Optimization on Structural Parameters of a Fault-Tolerant Permanent Magnet Steering Motor for Electric Vehicles

In order to solve the problems of power fault shutdown and system runaway after electrical failure, improving the reliability and safety of electric power steering (EPS) system, this paper proposes a novel fault-tolerant permanent magnet steering motor (FTPMSM) with unequal tooth structure, high voltage (HV) and low voltage (LV) windings. The HV winding is controlled by the HV system for the normal operation of electric vehicle (EV). When the HV system fails, switch the working state of the motor, and the LV winding maintains the operation of the system, ensuring the EPS system can still operate within the fault time. Through unequal tooth structure, the area of armature teeth and slots are increased, and the proportion of fault-tolerant teeth is reduced to improve the slot full rate and utilization rate of the FTPMSM. Further, the influence of structure parameters is studied, the entropy method is used to establish an evaluation model of the motor, and the optimal structural parameters of the motor are obtained. The results show that the torque ripple and THD of EMF are reduced. Finally, according to the simulation results, the FTPMSM prototype is made, and its torque and EMF are tested to verify the correctness of the theoretical analysis.