Comparative Study of Vernier and Interior PM Machines for Automotive Application

Due to high torque at low speed, vernier machines are proposed for many direct-drive applications such as robotic arms, industrial applications and electric vehicles. In this paper, a vernier permanent magnet (PM) machine with 9-48 stator- rotor pole combination is designed for electric vehicle application and compared with the 2010 Toyota Prius IPM machine including the electromagnetic performances, the torque/power speed characteristics, as well as the efficiency map under full load operation. It shows that the vernier PM machine is superior at low speeds in terms of electromagnetic performance and efficiency. However, it has relatively low operating speed range and lower power factor, and therefore is not desirable for automotive application.