Sensorless Control for Bearingless Permanent Magnet Vernier Motor with Special Windings Based on Decoupling Sliding-Mode Observer

Bearingless motors have attracted much attention due to its advantages of high reliability and efficiency. Among them, bearingless permanent magnet vernier motor (BPMVM) with special dual-purpose no-voltage (DPNV) winding, which can use the same winding to generate torque and suspension force simultaneously, has the advantages of high integration compared with traditional bearingless motor with double winding. Its high control performance depends on the rotor position information, but the installation of the position sensor reduces the reliability and increases the cost. Based on the special structure of DPNV winding, a rotor position estimation method based on decoupling sliding mode observer (DSMO) is proposed in this paper. The topology of BPMVM is introduced firstly, and the mathematical model of DPNV winding is analyzed. Next, after decoupling the suspension current and the torque current, DSMO is applied to estimate the rotor position. The back-EMF of the motor is successfully observed, and the position and speed of the rotor can be further estimated. Finally, the sensorless control with the proposed DSMO is carried out on a 1.1 kW BPMVM prototype to testify its stability, dynamic, and anti-disturbance.