Vibration Suppression for Bearingless Motor System with the Ampliative Band Repetitive Controller

Non-ideal factors are inevitable in the bearingless motor (BM) system, such as rotor mass unbalance and displacement sensor detection error, which will lead to the vibration of the system with the integer multiples of the rotational speed frequency. Firstly, the influence of non-ideal factors on rotor displacement is analyzed by establishing a rotor dynamics model. The repetitive controller can better filter out the signals whose frequencies are integer multiples of the rotating speed in the levitation system simultaneously to suppress the motor vibration. However, the traditional repetitive controller (RC) is highly sensitive to frequency fluctuations, and there is a disturbance positive gain when the motor changes speed. To solve the above problems, an ampliative band repetitive controller (ABRC) suitable for variable speed conditions is proposed in this paper, effectively supposing the active levitation force vibration caused by irrational factors. Besides, introducing real-time speed information into the internal model has greatly improved the stability of the levitation system when the BM speeds up or down. Finally, simulation results demonstrate the effectiveness of the proposed improved scheme.