Dampening of Axial Vibrations in a bearingless Flux-Switching Slice Motor by Field Current Regulation

Disturbance or resonance effects can cause axial vibrations in bearingless slice motors. Typically, these vibrations are only very poorly dampened, as the passive restoring force due the permanent magnets is proportional to the axial deflection (rather than to the axial speed). In this paper, a strategy to actively reduce axial vibrations is presented. In addition to reluctance forces for passive stabilisation, axial damping force is generated by modulating the permanent magnetic air-gap field. To model the rotor’s behaviour the equation of motion is set up and analysed. It is shown, that applying field current, which is proportional to the axial velocity, leads to an improved dampening behaviour. Several static and dynamic measurements are conducted to proove the function of the proposed vibration dampening strategy with a bearingless flux-switching slice motor. Finally, also the case without gravitational force is considered, which leads to a different operational behaviour.