Optimal design of asymmetric rotor overhang lengths in an axial-flux dual-stator permanent magnet vernier machine

The permanent magnet vernier machine (PMVM) has been proposed as a suitable alternative for direct-drive applications due to its high torque feature at a low operated speed, where the usage of high-torque low-speed motor can effectively eliminate the additional cost and losses caused by gearbox. One effective design as a dual-stator PMVM with spoke-type PMs in rotor has been developed for both high torque density and improved power factor compared to the traditional PMVM [1]. As a competitive machine in the direct-drive system, the axial-flux topology is adopted for a larger torque density and two balanced stators with half slot pitch shifted can effectively eliminate the machine cogging torque and the axial directional force.