Mismatched Disturbance Rejection Control for Voltage-Controlled Active Magnetic Bearing via State-Space Disturbance Observer

Abstract

A novel composite control method based on disturbance observer for the precision suspension of a voltage-controlled active magnetic bearing (AMB) system is presented in this study. The voltage-controlled AMB system always suffers from the mismatched disturbances, which act on the system via different channels from the control inputs. In this study, we reconstruct a new system, which is equivalent to the original voltage-controlled AMB dynamical system. The reconstructed system targets to divide the mismatched disturbances into the matched component and the mismatched component. The matched component is attenuated by the feedback robust controller, and the mismatched component is rejected on the basis of disturbance observer. Both simulations and experiments demonstrate the effectiveness in rejecting the mismatched disturbances on the voltage-controlled AMB system in a magnetically suspended control moment gyro. The proposed control method handles the mismatched disturbances from the state variable and preserves the nominal performance of the baseline robust controller to the best.