Decoupling of Magnetic Circuits Between Combined Radial-Axial Magnetic Bearing and Permanent Magnet Bearingless Motor

This paper presents a structure of five degree-of-freedom (DOF) actively positioned bearingless motor with a combined radial-axial magnetic bearing (CRAMB). The magnetic bearing has a thrust permanent magnet (PM) that creates bias fluxes for both the radial and the axial magnetic bearings. In this paper, two structures of full models are compared in 3D-FEM analysis, and the proposed structure can reduce undesired magnetic coupling between the bearingless motor and the CRAMB. It is significantly effective to reduce fluctuations of the radial suspension force. Furthermore, detailed losses of the bearingless motor and the CRAMB are calculated.