Research On Control Strategy Of Active Magnetic Bearing Based On Sliding Mode Control

Active magnetic bearing(AMB)uses electromagnet to generate electromagnetic force,which makes the rotor suspend stably.Because there is no mechanical contact between rotor and stator,compared with traditional bearings,AMB has the advantages of lower power consumption,longer life and higher control accuracy.It is widely used in mechanical manufacturing,aerospace,military industry and many other fields.The core of AMB is the controller,which can ensure the rotor suspend stably.The performance of the controller has a great influence on the dynamic performance of the AMB,thus it is important to ensure the stability of the control system for the magnetic bearing system.In order to optimize the control method of magnetic bearing,the controller of AMB is designed based on sliding mode control theory and modern control theories.First,this paper introduces the research situation of AMB at home and abroad,and summarizes the control methods for AMB.Then the force of active magnetic bearing system is analyzed,the mathematical model of one-axis AMB is established and linearized.On this basis,the mathematical model of five-axis active magnetic bearing system is established.Then,based on the theory of sliding mode control and fixed-time control,this paper designs a fixed-time sliding mode controller for AMB,and carries out the simulation experiments.The simulation results show that the controller can make the system reach the equilibrium state in a short time,which proves the effectiveness of the controller.However,there is an inherent problem of chattering in sliding mode control.In order to solve this problem,a fixed-time fuzzy sliding mode controller is designed based on fuzzy control theory.The switching gain of the controller is adjusted adaptively by fuzzy control to weaken the system chattering.The simulation results show that the controller has a good effect on weakening the system chattering.Finally,the terminal sliding mode control theory is used to improve the slow convergence speed of linear sliding mode control.In this paper,terminal sliding mode control theory is used to improve the traditional sliding mode control.A five-axis active magnetic bearing system synchronous controller is designed under nonsingular fast terminal sliding mode control,which can make the magnetic bearing system reach stability synchronously.The simulation results show that the controller is effective for the control of magnetic bearing system.This paper has 37 figures,3 tables,and 90 references.