Suppression of Rotor Eccentric Effect in Sensorless Bearingless Permanent Magnet Vernier Motor Drives

Bearingless permanent magnet vernier motors (BPMVM), due to the characteristics of high torque density, no friction and high efficiency, have great potential for application in high-precision fields such as Hydrogen fuel cells and wind power generation. This article presents a suppression strategy for rotor eccentricity effect in sensorless control of BPMVM. In this paper, firstly, the effect of rotor eccentricity on BPMVM is discussed, which results in DC offset and harmonics of back electromotive force (EMF), and thus impact on the accuracy of sensorless control based on sliding mode observer (SMO). Secondly, a second order generalized integrator with DC offset rejection capability (SOGI-DCRC) based observer is proposed to compensate for the abnormalities in the back-EMFs caused by rotor eccentricity to achieve accurate sensorless operation. Lastly, the good steady and transient performance of the proposed method has been confirmed by experimental results.