Study And Design On Control System Of Magnetic Bearing Based On Auto-Disturbance Rejection Control Theory

Linear Auto-Disturbance Rejection Controller(LADRC)can real-time estimate the disturbance composed of inaccurate system model,parameter perturbation and external disturbances,and it can compensate the disturbance,improves interference resistance of the system.magnetic bearing system is often subject to uncertain disturbances include outside interference,system parameter perturbation,external interference.The paper study the control system of magnetic bearing based on LADRC.First of all,the Linear Auto-Disturbance Rejection Controller based on the mathematical model of magnetic bearing system was designed in the paper.Then,the simulation study the anti-interference of LADRC under the step,sinusoidal and square wave interference.Simulation results showed that systems with linear auto-disturbance rejection controller had a better anti-interference.Finally,the paper designed a digital controller of magnetic bearing based on TMS320F28335 DSP,and wrote the program of the Linear Auto-Disturbance Rejection Control algorithm.A series of tests were carried out on the magnetic suspension bearing experiment platform with the controller designed in this paper,and compared with magnetic bearing system of PID control.Experimental results show that compared with magnetic suspension bearing system of the PID control,when imposing the same pulse interference,sinusoidal interference,Square wave interference,the displacement of the disturbed degrees of freedom of the radial was reduced by 28.6% and 25.8 % and 26% respectively;When the rotor was rotating at a speed of 24000 r/min and 27000r/min,the displacement of the fourth degrees of rotor was reduced by 15% and 13.7% respectively.In order to further research the advantages of LADRC,the paper done the test in the system that a rotor is supported by three magnetic bearing,when the speed of the rotor was 9600r/min,compared with the PID,the displacement of the second and the fourth degree of rotor with the LADRC was reduced by 21.4% and 20.7% respectively.The LADRC was based on inaccurate model of the system that a rotor was supported by three magnetic bearing.These results show that compared with the PID,in the face of system modeling inaccuracies,parameter perturbation and external interference,the LADRC can make the magnetic bearing system have a better anti-interference ability.