Disturbance Rejection for a Zero-bias Controlled Active Magnetic Bearing Based on Disturbance Observer and Notch Filter

This paper introduces a nonlinear disturbance observer plus general notch filter based zerobias control strategy to handle disturbance and reduce power consumption for the radial magnetic bearing in the magnetically suspended spindle. The zero-bias control is used to decrease the power consumption of magnetic bearings, as large power consumption causes temperature rise of system and temperature drift of sensor. The suspension of the rotor is affected by complicated disturbance including non-periodic and periodic disturbance. In order to reduce the deviation of rotor brought by external disturbance, the nonlinear disturbance observer is used. However, since the response lag to the disturbance, the nonlinear disturbance observer cannot suppress the periodic imbalance force well. Therefore, the general notch filter is introduced to reduce the periodic vibration. The effectiveness on the disturbance suppression and power reduction of the proposed method is verified by experiment results.