Eddy Current Loss Reduction and Thermal Analysis of Ultrahigh-Speed Bearingless Permanent Magnet Synchronous Motor

Due to the bright development prospect of the self-levitation technology in the field of high-speed motor and the importance of eddy current loss to permanent magnet motor, a 10kW, 100krpm ultrahigh-speed bearingless permanent magnet synchronous motor (UHSBPMSM) is designed in this paper and the eddy current loss are reduced with the using of auxiliary slots and multi-objective optimization method. Then the thermal analysis is carried out to reveal the effects of suspension windings and the optimization scheme on temperature rise of the designed UHSBPMSM.

I. Introduction

As the bearingless permanent magnet synchronous motor (BPMSM) has the merits of no mechanical contact, wear-free, energy-saving and high environment adaptability, it has great potential applications in the fields of high-speed, high precision and other special electric drive. The main research point of BPMSM at present is how to realize the stable suspension of rotor. With the continuous innovation of the multi-degree-of-freedom motor structure [1–2], the establishment of the different accurate mathematical models [3–4] and the rational use of control strategies [5–6], the ability of stable suspension of rotor has been continuously improved. And the change of the arrangement of suspension windings [7] and the optimization of the design parameters [8] could further reduce the fluctuation of the suspension force.