ISMB16, the 16th International Symposium on Magnetic Bearings
We present a bearingless slice motor that levitates and rotates a magnet-free solid-steel reluctance rotor. The motor stator uses permanent-magnet arrays near the tips of the stator teeth to provide the rotor with a homopolar bias flux. The magnet arrays are in a Halbach configuration to improve the rotor passive stiffness. The reluctance rotor has two radial fins, at the top and bottom surfaces, through which the bias flux from the magnet arrays enters. The homopolar bias flux exits the rotor via four salient rotor teeth located between the rotor radial fins. The bias flux passively stabilizes the rotor in the axial translation and in the out-of-plane tilts. The two radial translations are actively stabilized via feedback control. The stator winding consists of two sets of three-phase windings. One set of windings generates two-pole magnetomotive force (MMF) for levitation control, and the other set of windings generates eight-pole MMF for rotation control. Finite element analyses are performed to compute the performance estimates, and a prototype system is built and tested for the take-off, levitation, and rotation capabilities.