Vibration Suppression of A Middle-Point Current-Injection Type Bearingless Motor at 50000r/min

With the developments of power electronics technology and increments of rotational speed of motors, a critical speed is one of the problems. Vibration of rotational shaft has been reported to be suppressed by magnetic force of bearingless motors. In general bearingless motors, motor windings and suspension windings are separately enclosed in the stator slot. For only vibration suppression at a critical speed, however, suspension windings are not used except the critical speed. In this paper, vibration suppression of a rotor shaft by a middle-point current-injection type bearingless motor at 50000 r/min is presented. This motor can generate the torque and the magnetic force by only one set of three-phase windings. The test results of the vibration suppression are presented.