Research On Vibration Suppression Of Control System Of Active Magnetic Bearing

Vibration is a common problem in rotating machine,which can cause noise,failure of key components and other shortcomings.Active Magnetic Bearing(AMB)levitates the rotor by magnetic force without contact.AMB has been applied in high-speed motor,flywheel energy storage,compressor and other situations because of advantages such as no friction,no collision,no lubrication.Taking advantages of AMB can solve the problem of vibration.This paper proposes several methods to suppress the vibration in displacement and current in AMB system,which benefits spreading application of AMB in industrial occasions.The specific research contents are as follows:Firstly,establishing model of the magnetic force AMB and linearize it at origin of displacement.Analysis and modeling of each component in AMB control system have been done.Single-axis model and multi-axis model of AMB control system are established.Transfer functions of displacement and current with unbalance excitation are obtained.Then,for vibration in current,this paper proposes vibration suppressing method based on generalized integrator(GI),it does not have to calculate trigonometric and with simpler structure.This paper also proposes vibration suppressing method based on phase shift generalized integrator(PSGI)to solve the unstable problem in low rotating frequency.For vibration in displacement,this paper proposes a vibration suppressing method without angular sensors.Generalized integrator-frequency locked loop is applied to obtain rotating frequency by current,and PSGI is applied to generating compensating signal.Comparing with traditional methods,this method can suppress vibration without angular sensors.Effectiveness of proposed method is verified by simulations and experiments.Active disturbance rejection controller(ADRC)is designed for the AMB system.Comparing with PID controller applied in AMB system,principle for designing parameters of ADRC is simpler and clearer and ADRC relies less on the model of control target.The traditional extend state observer(ESO)cannot observe the AC disturbance effectively,in order to suppress the vibration in displacement,generalized integrator extend state observer(GI-ESO)is applied to ADRC.Simulations and experiments are carried out to verify effectiveness of designed controller.For observation of unbalance excitation in AMB system.This paper proposes an observing and compensating strategy based on GI-ESO.After the unbalance excitation is observed effectively,compensating current is calculated and injected to the control loop to suppress vibration.Simulations are carried out.Combining the above series of methods can effectively improve the vibration problem of the magnetic bearing system.