Abstract：The self-sensing active magnetic bearing (SAMB), which doesn’t need independent displacement sensors anymore, owns the benefits of low cost, high integration level and compact structure than the conventional AMB. The key of this technique is to accurately estimate the rotor position from measurable physical variables like coil voltage and current of the MB actuators. Eddy current, as an important nonlinear factor of magnetic bearing, will affect the accuracy and linearity of self-sensing rotor position estimation and even the implementability of self-sensing magnetic bearing. In this paper, we firstly investigate the advantages of using laminated core rather than solid core for the SAMB, through the sensitivity between magnetic bearing inductance and air gap variation under eddy current. Then a single-turn virtual coil model is utilized to analyze the effect of eddy current on the properties of switching ripple currents in laminated core magnetic bearing, so that a self-sensing rotor position estimation method based on switching ripple currents modulation is proposed, with the eddy current considered. Finally, the proposed self-sensing rotor position estimation method is validated on a rigid rotor-four DOF radial SAMB platform.
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2018, Vol. 33 
