Improvement of Stability of an Tilt-Controlling Axial Gap Self-bearing Motor with Single Stator

This paper discusses the stability of a tilt-controlling axial gap self-bearing motor with a single stator. The proposed motor consists of a stator and a disc rotor and is capable of controlling motor torque, axial displacement and tilt angles. By using passive stability in radial direction, it is possible to achieve non-contact levitation and rotation. In previous work, we have succeeded levitation and rotation with a two-pole rotor and a six-coil stator. However, there were problems with low stiffness and different tilt moment gains. To solve these problems, higher position of the center of gravity (COG) of the rotor and eight-coil stator are adopted. Axial force, motor torque, tilt moments and radial forces are theoretically analyzed, and the stability of radial motions are discussed. Results show that higher COG position increase the stability in radial motion. The experimental results show that the characteristics in tilt motions are almost the same, and the stable levitation and rotation are achieved.