Direct Control of Bearingless Permanent Magnet Slice Motor Based on Stator Flux Observer

The theory and method of direct torque control are applied to the torque and suspension force control of the bearingless permanent magnet slice motor (BPMSM) in this paper. Meanwhile, aiming at the defects of low precision and result lag of flux linkage observation, a novel stator flux observer combining the phase-locked loop (PLL) and prediction control module is introduced. Firstly, the operating principle of the BPMSM is analyzed, and the mathematical models are set up. Secondly, the PLL flux linkage observer is designed, then the prediction control models and direct control algorithm are given. Thirdly, the direct control system of the BPMSM is constructed by Matlab/Simulink. Finally, the feasibility and correctness of the flux linkage observer and control algorithm are verified through simulation and experiment. The research results show that the disturbance recovery time is shortened by 35 ms and the vibration amplitude and regulation time of the rotor are significantly reduced by around 39% and 40%, respectively.