Unbalance Vibration Compensation For Active Magnetic Bearing Rotor System Aboard Satellite

Recent years have witnessed the rapid development of magnetic bearings due to their advantages of no friction,no mechanical contact,and no lubrication.The residual imbalance of the rotor,arousing forces and moments,is one of the main causes of the vibration of the rotating machine.As a result of the controllable electromagnetic force,the magnetic bearings can achieve active vibration suppression.This paper researches unbalance vibration compensation for rigid magnetically suspended rotors and the main results are as follows:First,the dynamics of an unbalanced rotor is studied.The static and dynamic unbalance of the rotor are regarded as the intrinsic property rather than the external disturbance.On the basis of rigid-body assumption,complete dynamics of the rigid unbalanced rotor is established.By comparing with the traditional dynamic model,the simplifying conditions are given and the correctness and versatility of the built dynamics are proved.On this basis,the multi-body satellite quasi-coordinate Lagrange equations are deduced,and the dynamics of the whole satellite is given.Combined with distributed PD control,the effects of rotor imbalance on rotor’s and satellite’s motion are analyzed from both theoretical and mathematical simulation aspects.Then,the problem of unbalance compensation of rigid rotor with fixed base is researched.Based on the built dynamics of the rotor,a controller is designed using a backstepping method,and adaptive control is adopted to deal with the uncertainty of dynamic and static unbalance.The unbalance vibration compensation is realized without any knowledge of the rotor imbalance.Mathematical simulations demonstrate the effectiveness of the controller under the cases of constant speed,uniform acceleration and sinusoidal rotation.Finally,unbalance compensation for an unbalanced rotor abroad an earth-oriented satellite platform is studied.Considering the conditions such as platform’s motion,unknown rotor imbalance and external disturbance,based on finite-time control theory,a finite-time-convergence rotor imbalance compensation controller is designed.Mathematical simulation shows that the controller can achieve rapid convergence of the rotor states and realize unbalance vibration compensation under the conditions of external disturbance and platform’s motion.