Comparison Study of Electromagnetic Performance of Bearingless Flux-Switching Permanent-Magnet Motors

To solve the thermal problem in a traditional rotor permanent-magnet (PM) bearingless motor having magnets in the rotor, in this paper, two topology structures of bearingless flux-switching permanent-magnet (BFSPM) motors were proposed, namely, a 12-stator-slot/10-rotor-pole BFSPM motor and a 12-stator-slot/14-rotor-pole BFSPM motor, in which the PMs, suspending windings, and armature windings are in the stator, whereas the rotor is only made of iron. The electromagnetic characteristics are compared based on two-dimensional finite-element analysis, including magnetic saturation, torque, suspension force, coupling, and loss. The calculation results show that the 12/10-pole motor can offer better decoupling, higher suspension force, and smaller loss at high rotation speed. In addition, although the 12/14-pole motor exhibits better torque performance, the motor loss is higher at high speed. The results lay a theoretical foundation for further study of the novel-type bearingless motor.