Rotor design for 2 Pole Bearingless Interior Permanent Magnet Slice motor

This paper presents a novel rotor design and its performance evaluation for a two pole interior permanent magnet (IPM) bearingless motor. A previous base case design was targeted at achieving specified torque along with a balance of force along the d and q axis to control the levitation. However, this design has a significant cogging torque which affects the motor as well as bearing operation. This paper presents a refined rotor design to reduce the cogging torque while maintaining force and torque capabilities. While operational, motor currents can apply force to the rotor even under slightly off centered condition. As an effort to improve the operation of the base motor, an algorithm is used and evaluated to decouple these forces from motor currents. Some of the design iterations performed using finite element simulations are shown and the performance of the final modified design is discussed and compared with the base design using experimental and simulation results. The performance of the decoupling algorithm is also tested on experimental setup and the results are discussed.