Proposal of a Bearingless Consequent-Pole Motor Using Combined Winding with Functions of Three-Phase Radial Suspension and Single-Phase Motor Driven by Zero-Sequence Current

Conventional two-degree-of freedom (DOF) actively controlled bearingless motor has two kinds of three-phase radial suspension and three-phase motor windings and needs 2 three-phase inverters for the radial suspension and motor. To simplify the system, this paper proposes a two-DOF actively controlled bearingless consequent-pole permanent magnet (CPM) motor with combined winding, which integrates three-phase radial suspension and single-phase motor functions. The single-phase motor is driven by a zero-sequence current, which is superimposed onto three-phase suspension current in three-phase four-wire system. Therefore, the proposed system is operated with only one three-phase inverter for the radial suspension and motor. The FEA results indicate that the proposed bearingless CPM motor has superior suspension performance, compared to the bearingless surface permanent magnet (SPM).