Investigation on Torque Characteristic and PM Operation Point of Flux-Intensifying PM Motor Considering Low-Speed Operation

In this article, a new type of flux-intensifying permanent magnet (FI-PM) motor is designed, analyzed, and optimized. It focuses on the low-speed operation condition of electric vehicles (EVs). The key characteristic of this motor is the feature of the reverse saliency, so that it not only utilizes the positive reluctance under the positive d -axis current but also improves the PM operation point under maximum torque per ampere (MTPA) control strategy. The relationships among the key parameters, reverse saliency, and torque performance are analyzed and investigated. The response surface method is used to optimize the motor performances. Then, for a better presentation of the investigated motor, the motor performances are evaluated and compared with the traditional interior permanent magnet motor (IPM) in torque characteristic and irreversible demagnetization ability. Finally, for the experimental validation, the prototyped motor is manufactured and tested.