Disturbance Force Self-Sensing and Suppression Method for AMB-Rotor System Based on Disturbance Observer

This paper explores a disturbance force self-sensing and suppression method for active magnetic bearings (AMBs) system. Since the displacement of the AMB-rotor is affected by both the output of the controller and the disturbance force, the mathematical expression of the external disturbance force is deduced based on the inverse model of the controlled plant of the AMB-rotor system. The rotor displacement and output of the controller are both the input of the disturbance self-sensing system. A third-order low-pass filter is added to the self-sensing system so as to avoid the self-sensing system being unstable due to model uncertainty of the controlled plant. Then an adaptive notch filter added to the self-sensing system is used to eliminate the synchronous frequency component in the estimated disturbance. Finally, experiment results validate the proposed self-sensing method can effectively sense the external disturbance force within the range of about 67 Hz, and the AMB-rotor system can well suppress the disturbance force with the sensed value.