Development of hybrid type self-bearing slice motor for small and high speed rotary machines

A new type of self-bearing motor is proposed for the application of small and high speed rotary machines. The motor consists of two functions that use a stator in common; one part is a general permanent magnet motor and the other is the so-called hybrid active magnetic bearing. An outer rotor is actively controlled only in two radial directions while the other three motions are passively stable owing to the short-span structure. The main advantages of this hybrid-type self-bearing motor are the simple control mechanism and the low power consumption. First, the principle and theoretical background of this motor is introduced. Then, the minimum pole number of six is derived which guarantees the control independency of rotation and levitation. Finally, the outer rotor type disc motor is designed and fabricated. Experimental results show the feasibility of the proposed self-bearing motor.