Rotor radial displacement sensorless control of bearingless permanent magnet synchronous motor based on MRAS and suspension force compensation.

Limitations exist on the displacement sensors employed in a bearingless permanent magnet synchronous motor (BPMSM). They lead to the increase in cost, size and complexity of the motor. Apart from that, the measurement errors are sensitive to the temperature and the electromagnetic noise. In order to resolve these problems, a novel rotor radial displacement sensorless control method of the BPMSM is proposed. In this paper, the operation principle and mathematical model of the BPMSM are introduced firstly. Secondly, the rotor radial displacement self-sensing method using the model reference adaptive system is designed. Thirdly, a direct control strategy of rotor eccentric displacement with suspension force compensation is proposed to promote the property of the displacement sensorless control system. Finally, a torque control subsystem based on the id=0 control scheme and a displacement control subsystem based on the proposed displacement self-sensing method and the suspension force control method are constructed. The related simulations and experiments are carried out. According to the research results, the rotor radial displacements of the BPMSM are effectively estimated and the stable suspension of the BPMSM rotor without displacement sensors is achieved.