Magnetically Levitated Motor with Five Actively Controlled Degrees of Freedom

A magnetically levitated motor can realize non-contact support of a rotor using magnetic force. Therefore, it has many advantages over conventional mechanical bearings. In order to accomplish complete magnetic levitation of the rotor, it is necessary to control five degrees of freedom actively. However, this gives rise to major issues such as complicated control system and associated electronics, resulting in enlarged equipment size. The proposed magnetic levitated motor uses a radial self-bearing motor to control both radial translation motion and rotation, and an axial magnetic bearing to control both axial translation and tilt motion. Moreover, stators were installed on the inner side of the rotor, such that the flux path of the axial magnetic bearing and radial self-bearing motor are partially-shared. Therefore, the proposed magnetic levitated motor is small, while achieving five degrees of freedom active control. The prototype device was designed using FEM. According to this analysis, the device had sufficient magnetic force to control the rotor within a designed airgap of +/- 1.8 mm.