Improvement of Sensing Characteristics of Self-Sensing Active Magnetic Bearings

Abstract

A winding-current interference model of self-sensing active magnetic bearings (AMBs) and an improvement technique of position-sensing characteristics are proposed. In the self-sensing AMB systems, the electromagnets work not only as actuators suspending the rotor but also as position sensors. The self-sensing position signal, however, includes errors because of nonlinearity of the magnetic circuits. In the proposed model, the current is directly transmitted to the self-sensing position signal. This transmission means degradation of the self-sensing characteristics. This winding-current interference to the self-sensing signal is reduced by the proposed compensation method. The characteristics of the proposed self-sensing method agree well with a reference sensor signal up to over 1kHz.