Vibration Suppression of a Slotless Self-Bearing Permanent-Magnet Motor for Optical Applications

Magnetic bearings, particularly of slotless type, are ideally suited for optical applications by enabling operation in vacuum at high speeds with high lifetime, avoiding particle generation and allowing active control, and therefore suppression of bearing stator force and rotor displacements. In this paper, different approaches for vibration suppression are compared and experimentally verified with a dual hetero-/homopolar slotless self-bearing motor. A feed forward has advantages compared to a notch-filter approach as it allows rotor vibration suppression and lowering the stator vibration suppression activation speed into the rigid-rotor critical speed range. Finally, the rotational speed fluctuations, important for optical applications, are investigated.