Investigation of Dual-Stator Spoke-Type Vernier Machine for EV Application

This paper presents an investigative study on a dual-stator spoke-type vernier machine (DSSTVM) suitable for direct-drive electric vehicle (EV) propulsion systems. DSSTVM was a superior choice as a direct-drive motor because of its high torque density per volume, wide speed range operation, and high power factor, which are critical features for the direct-drive EV propulsion system. However, previous research on DSSTVMs was restricted to conventional 12 slots and 20 poles (12S20P) with distributed windings. Thus, the 12S22P combination, which has a higher gear ratio, was presented to enhance the torque performance. Different winding configurations were also considered to further improve the performance, as concentrated and distributed windings in vernier machines show different performances due to their different vernier effects and different end windings. A total of four models, 12S20P and 12S22P models with concentrated and distributed windings, were suggested and compared. The finite-element method analysis was performed to confirm the characteristics of each model. Consequently, the 12S22P model with a distributed winding was chosen for EV applications due to its good overall performance.