Lorentz Force Type Self-Bearing Motor

A new type of self-bearing motor is proposed. It is intended for a single rotor to have two functions of rotary motor and radial active magnetic bearings. Previously proposed PM type self-bearing motor uses reluctance force which requires relatively thin permanent magnet. Hence it has defects of low eÆciency and poor reliability. Nonlinearity of magnetic material causes undesirable coupling effect between the radial two directions. Demagnetization of the thin permanent magnet is serious problem for long term use. This paper introduces a new type of self-bearing motor which uses Lorentz force. The rotor has eight strong permanent magnets on the surface of it. The stator has six concentrated windings. Hence it has merits of good dynamic response, good linearity and high reliability. First, the fundamental principle is introduced how the motor produces rotating torque and radial levitation force. Then separate control capability is theoretically developed. Finally two sets of experimental setup are made which will confirm the principle of this motor. The results show high capability of the proposed motor-bearing functions.