Implementation and control of a electromagnetic actuator for miniature magnetically levitated rotating machines

In miniature magnetically levitated rotating machines, permanent magnet bearings are generally used for rotor levitation in the radial directions, while and electromagnetic actuators are used for stabilization in the axial direction. In this configuration rotor radial oscillations are inevitable because no controllable force is applicable in these directions. This paper presents the implementation and control scheme of a electro-magnetic actuator for these machines. The actuator can produce axial as well as radial forces on the rotor. The axial force is used for rotor axial direction control, and the radial force is used to assist the suppression of rotor resonance related oscillations. Theoretical analysis and experimental investigations of the actuator control are performed, and the results are provided in the paper.