Speed Control of Bearingless Permanent Magnet Synchronous Motor Based on Flux Strengthening and Voltage Regulation

In order to reduce the speed fluctuation of bearingless permanent magnet synchronous motors (BPMSMs) and considering the effect of suspension force load on the suspension performance, a novel speed control method of the BPMSM based on flux strengthening and voltage regulation is presented in this paper. First, the structure of the BPMSM and the principle of suspension force generation are introduced. Second, based on the mathematical models of the BPMSM, the principles of the flux strengthening and voltage regulation control are analyzed. Besides, the effect of the flux strengthening control method on the suspension performance is illustrated. Third, the control system of the BPMSM is designed on the foundation of the proposed control method, and the cooperation strategy of the flux strengthening and voltage regulation control is proposed to improve the speed performance. Finally, the experimental results on the BPMSM prototype confirm that the proposed control strategy can reduce the speed fluctuation and improve the suspension performance of the BPMSM effectively.