Novel Bearingless Motor Topology With Diamagnetic Salient-Pole Rotor

This article proposes a novel bearingless motor topology with diamagnetic salient-pole rotor. The material of the rotor is pyrolytic graphite (PG) so that five degrees of freedom of the rotor are passively stabilized above a permanent magnet array. The stator consists of two components: a Halbach permanent magnet array and an axial-flux stator core with twelve teeth holding the eight-pole three-phase winding. Passive levitation forces are generated between the permanent magnet unit and the PG rotor. Rotating torque is generated between the stator core and the PG rotor. In this paper, the principle of the five-axis passively stabilized bearingless motor with the PG rotor is outlined. In experiments, passive axial forces and an acceleration process are measured. In the test, open-loop speed control is used. The proof-of-concept successfully achieves stable passive levitation, and allows acceleration up to 200 r/min.