Research On Control Algorithms Of Active Magnetic Bearing

Bearings are the core components of mechanical equipment.Compared with traditional mechanical bearings,active magnetic suspension bearings have broad application prospects in the industrial manufacturing field due to their high speed,high performance,high precision,low noise,zero friction and high reliability.However,since the magnetic suspension bearing system is a natural open-loop unstable model with nonlinear time-varying and strong coupling,it is difficult to control,and the control system is complex and costly,which has become the bottleneck of its industrialization popularization to a certain extent.In this paper,classical control strategy,state feedback control strategy andH_?robust control strategy are used to study the control algorithm of magnetic bearing and the corresponding controller is designed.The research work is summarized as follows:(1)The structure and working principle of the magnetic suspension bearing system are analyzed.Combined with the electromagnetic field theory,the linearization control model of the magnetic suspension bearing system is established by magnetic circuit analysis and mathematical processing.(2)Research on classical control strategy of magnetic suspension bearing system.Drawing an equivalent analogy of control model between magnetic bearing system and spring-damper system,the influence of the change of each control parameter on the control effect is analyzed,According to the requirements of the damping and stiffness of the magnetic bearing system,the closed-loop PD/PI controller is designed and the stability,rapidity and accuracy of the control are analyzed.(3)To solve the problem that the classical control based on analog circuit is mostly limited to small power,low precision,low speed and can not observe the control quantity in real time,a modern control strategy of magnetic bearing based on state feedback theory is adopted in this paper.The state space mathematical model of the magnetic suspension bearing system is established,and the simulation module is built to verify the stability performance of the magnetic suspension bearing system under static load and resonance interference.(4)Based on the state space model of magnetic bearing,a robust control method of magnetic bearings based onH_?theory is adopted to deal with the parameter uncertainties of magnetic bearing systems.The selection of sensitivity weighting function of the system is analyzed,and the augmented model of the magnetic bearing system is established.TheH_?robust controller of the magnetic bearing system is designed by the algorithm.The simulation results show that the robust controller can suppress external disturbances.H_?robust control strategy can improve the robustness of AMB system.(5)The control experiment of magnetic bearing is designed.A method of magnetic pole force control for magnetic bearing based on double bridge structure is proposed.The experimental results preliminarily demonstrate the feasibility of the method.