Electromagnetic Characteristic Analysis of a Negative-Salient Hybrid Permanent Magnet Motor for Electric Vehicles

Negative-salient permanent magnet motors (NSPMMs) have a potential application in the field of electric vehicles (EVs) due to their wide constant-power speed range and high efficiency. However, the researches of NSPMMs used for EVs and the relationships between the design parameters of the motor and drive performances of the EV are still absent. First, the operating characteristics of permanent magnet drive motors are investigated. Second, the relationships between the distribution of the driving cycles of the EV and the design parameters of the motor are summarized. Then, a negative-salient hybrid permanent magnet motor with excellent performances in the full-speed range and remedies for its negative impact are proposed. The electromagnetic performances of the proposed topology are compared with the conventional motor by finite element method and the performance evaluation of the electrical driving system is carried out. Finally, a prototype is manufactured and tested. The simulation and experimental results show that the proposed motor exhibits favorable characteristics such as low torque ripple, wide constant-power speed range, high efficiency in a wide speed range and low rare-earth consumption. The results verify the feasibility of the proposed topology applied to EVs.