Rotational characteristics of a bearingless motor with passive magnetic bearings

A bearingless motor is a motor that combines a motor function with a magnetic bearing function. A prototype machine is an outer rotor bearingless motor, which is actively controlled in two perpendicular radial movements. The other three degrees of freedom, i.e., axial and conical movements, are supported by passive magnetic bearings (PMBs). In this paper, the results of rotation tests in a bearingless motor with and without PMBs are presented. The experimental results of the rotational characteristics are presented. The measured results of static torque are reported. The measurement results are compared to the calculated ones using three-dimensional finite element method (3D-FEM). It is presented that a bearingless motor is stably rotated thank1s to PMBs.