A Comparison of Permanent-Magnet Vernier Motor and Interior Permanent-Magnet Motor for Hybrid Electric Vehicles

In this paper, a new U-shape permanent-magnet vernier (U-PMV) motor with improved flux modulation effect is proposed for hybrid electric vehicles (HEVs). The key is to place the iron core sandwiched by U-shape PMs between the rotor poles. Due to its improved flux modulation effect, the proposed U-PMV motor can provide higher torque and PM utilization than the conventional counterpart. In addition, the influences of slot pitches on both conventional and proposed PMV motors are investigated. The results show that 2-slot-pitch winding can facilitate PMV motors to achieve higher output torque/power, efficiency, and PM utilization under the condition of high power factor. To further evaluate the performances and potential of PMV motors for HEVs, both the conventional and proposed PMV motors are optimized and compared with the Prius interior permanent-magnet (IPM) motor under fair conditions. The results show that PMV motors offer higher torque density, power density, and lower torque ripples compared to Prius IPM motor. However, more PM consumption and higher cost of PMV motors are the disadvantages of PMV motors for automotive applications where cost constraints are sensitive.