Synchronous Force Elimination in the Magnetically Suspended Rotor System With an Adaptation to Parameter Variations in the Amplifier Model

For a magnetically suspended control moment gyro (MSCMG), the mass imbalance of the high-speed magnetically suspended rotor (MSR) will induce a synchronous force, which is the main disturbance for the attitude control of satellites. In this work, an elimination method with an adaption to parameter variations in an amplifier model is presented. First, the MSR system with a hybrid magnetic bearing is modeled. Next, a generalized notch filter is utilized to identify the synchronous displacement, according to which a feedforward controller is designed to generate synchronous current so that the electromagnetic force can counteract the permanent magnetic force precisely. To keep the feedforward controller unaffected by the power amplifiers whose parameters vary with the temperature, another notch filter is adopted to obtain the synchronous coil current, and then two types of adaptive controllers, which can tune the synchronous feedforward controller adaptively, are proposed and compared. Finally, simulations and experiments are carried out to demonstrate the validness of the adaptive control methods in an MSCMG test rig. The proposed control strategy does not need an accurate MSR model, and the methods of adaption to parameter variations in the amplifier model are suitable for various applications according to the elimination precision and computational effort.