Unipolar flux in bearingless two-pole machine

Bearingless two-pole machine is made of a standard two-pole induction motor by adding an additional four-pole stator winding. The rotor can be suspended by the magnetic force produced by the interaction of two- and four-pole magnetic fluxes. In two-pole machines, rotor eccentricity causes unipolar flux to appear in the air-gap. In this paper, it is shown that a constant unipolar flux can remain in the machine even without the eccentricity. This unipolar remanence flux is not affected by loading conditions or rotor position control by the four-pole actuator. The unipolar flux contributes to the magnetic forces and can be detected as additional rotor vibration. The unipolar flux is studied with unipolar actuators added to a test machine. It is shown that the unipolar actuators can remove the constant unipolar flux.