Enhanced Rotor Position Estimation Method Considering Current Coupling Effect for Bearingless Permanent Magnet Vernier Motor

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 novoltage (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. Aimed at the special structure of DPNV winding, an enhanced rotor position estimation method considering current coupling effect is proposed in this paper. The topology of BPMVM is introduced firstly, and the mathematical model of DPNV winding is analyzed emphatically. Next, decoupling sliding mode observer (DSMO), which can decouple the torque current and suspension current, is applied to estimate the rotor position. The back-EMF of the motor is successfully observed, and the speed and position of the motor rotor can be further observed. Finally, the proposed DSMO is experimentally verified based on a 1.1 kW BPMVM experimental platform, and the stable operation under different conditions is realized, verifying the feasibility and effectiveness of the proposed method.