Rotor Design Study for Exterior Rotor Bearingless Permanent Magnet Machines

This paper focuses on the rotor design considerations for an exterior rotor bearingless permanent magnet machine (ERBM). With the goal to maximize torque while achieve sufficient bearing forces passively and actively, several feasible rotor topologies are derived and compared, and the parameter design of rotor magnetic-iron thickness ratio is investigated in detail. Finally, an optimal design is derived based on performance comparisons of bearing and torque, using the three-dimensional finite element method (3D-FEM).