Optimal Design and Performance Analysis for Interior Composite-Rotor Bearingless Permanent Magnet Synchronous Motors

The bearingless permanent magnet synchronous motor (BPMSM) is widely developed due to the advantages such as high speed, high power factor, high power density, and zero friction. In this paper, in order to provide more space for the placement of a permanent magnet (PM), a new type of BPMSM with interior composed magnetic structure is designed. The operation principles of the proposed BPMSM with the Maxwell force are introduced first. Then, by using of the finite element method (FEM), the pole-arc coefficient of BPMSM is optimized to reduce the cogging and increase the levitation force. In addition, the electromagnetic properties including magnetic field, levitation force, electromagnetic torque, loss, and cogging torque are simulated and analyzed. Finally, the static levitation experiment is carried out to verify the performance of levitation force. The research lays a foundation for further research about optimal design of the new type of BPMSM and also provides a mathematical model foundation for research of the control system.