Proposal of 2-DOF Actively Controlled Consequent-Pole-Type Bearingless Single-Phase Motor Using Zero-Sequence Current

This paper presents a 2-DOF actively controlled consequent-pole-permanent magnet (CPM) type bearingless single-phase motor. In the proposed bearingless CPM motor with 6-poles/6-slots, the combined windings, which integrates functions of both the single-phase motor and radial suspension windings into one, is wound on the stator, and thereby the system can be driven by one three-phase four wire inverter. Furthermore, the CPM structure does not require a rotational angle for the suspension force regulation and consequently the proposed system is small size and low-cost. First, the constraint regarding the combined windings using zero-sequence motor current is theoretically derived and then based on the above constraint, a bearingless CPM single-phase motor is proposed. Finally, design of the proposed motor is conducted with 3D-finite element analysis.