Abstract
Harmonic force and torque, which are caused by rotor imbalance and sensor runout, are the dominant disturbances in active magnetic bearing (AMB) systems. To eliminate the harmonic force and torque, a novel control method based on repetitive control and notch filters is proposed. Firstly, the dynamics of a four radial degrees of freedom AMB system is described, and the AMB model can be described in terms of the translational and rotational motions, respectively. Next, a closed-loop generalized notch filter is utilized to identify the synchronous displacement resulting from the rotor imbalance, and a feed-forward compensation of the synchronous force and torque related to the AMB displacement stiffness is formulated by using the identified synchronous displacement. Then, a plug-in repetitive controller is designed to track the synchronous feed-forward compensation adaptively and to suppress the harmonic vibrations due to the sensor runout. Finally, the proposed control method is verified by simulations and experiments. The control algorithm is insensitive to the parameter variations of the power amplifiers and can precisely suppress the harmonic force and torque. Its practicality stems from its low computational load.
Highlights
Control moment gyroscope (CMG) is one of the most important spacecraft attitude control actuators [1]
The CMG consists of a high-speed rotor mounted on a gimbal, which is fixed in the spacecraft platform [2]
To precisely eliminate harmonic force and torque, the synchronous force and torque caused by the active magnetic bearing (AMB) displacement stiffness and rotor imbalance has to be compensated accurately and adaptively unaffected by the parameter variations of the power amplifiers, and the harmonic force and torque caused by the sensor runout have to be effectively suppressed simultaneously
Summary
Control moment gyroscope (CMG) is one of the most important spacecraft attitude control actuators [1]. Setiawan proposed a simultaneous identification and compensation method of the synchronous sensor runout and the rotor imbalance based on adaptive controller and bearing stiffness variation [18]. To precisely eliminate harmonic force and torque, the synchronous force and torque caused by the AMB displacement stiffness and rotor imbalance has to be compensated accurately and adaptively unaffected by the parameter variations of the power amplifiers, and the harmonic force and torque caused by the sensor runout have to be effectively suppressed simultaneously. 3 of 16 repetitive the rotor imbalance controller,suppressed insensitive to the parameter ofwith thefeed-forward power amplifiers, is are designed to track the on-line. The parameter variations of the power amplifiers, is designed to force and torque by insensitive the sensor track the synchronous reference formulated by the identified rotor imbalance and to eliminate the harmonic torque of caused the sensor runout
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