A New Method for Compensating Current Interference of Self-Sensing Active Magnetic Bearings Using a Bias Source Current Waveform

Abstract

A new improvement technique for position sensing characteristics of self-sensing active magnetic bearings (AMBs) is proposed. In self-sensing AMBs, the electromagnets work not only as actuators for suspending a rotor but also as position sensors. However, the current that controls the suspending force influences the position sensing because of the nonlinear magnetic characteristics of the electromagnet. Conventional methods for compensation of the current interference complicate the AMB systems and adjusting their parameters becomes difficult. The method proposed in this paper uses bias source current measurement and demodulating timing adjustment. This simple method effectively achieves the compensation of the current interference and offer good position sensing characteristics.