Reduction effect of suspension input power using rotor eccentricity in a bearingless motor

Bearingless motors (BelMs) have two kinds of stator windings composed of motor windings and suspension windings in the same stator. Not only torque but also electromagnetic suspension force can be simultaneously generated in the same stator. Therefore, rotor shaft suspension can be realized without mechanical contacts and lubricant. In addition to advantages of magnetic bearings, the BelMs are expected to have advantageous features such as small size, low cost and high critical speed. This paper introduces reduction effect of suspension input power using rotor eccentricity actively in the BelMs. It is verified experimentally that the rotor eccentricity is effective in reducing the suspension input power.