A Novel Middle-Point-Current-Injection-Type Bearingless PM Synchronous Motor for Vibration Suppression

In this paper, a novel stator main winding structure of a middle-point-current-injection-type bearingless permanent-magnet synchronous motor is proposed. Unlike the conventional bearingless motor consisting of both main motor windings and radial force control windings in the same stator, this special motor has only motor stator windings and no radial force stator windings. Only middle-point terminals are needed in the motor stator windings to inject currents. The principle of operation and its special structures are briefly described. The effectiveness of the proposed bearingless motor is presented with respect to conventional bearingless motors. Test results of a laboratory prototype machine highlighting vibration suppression are also presented.