Levitation Control of IPM Type Rotating Motor

A new type of synchronous type bearingless motor is introduced In previous work, PM type and induction type rotor has been used for bearingless motor. PM synchronous motor has a merit of independent control capability of rotation and levitation, but the levitation force is weak. Conversely the induction type motor produces a strong levitation force , but the efficiency is not good and the control of rotation and levitation would be coupled. This paper introduces an internal permanent magnet (IPM) type bearingless motor which has the merits of strong levitation force and relatively easy control capability. The merits of the proposed IPM motor are confirmed experimentally.