Research On Electronic Control System Of High Stability Magnetic Suspension Bearing

Through the research and accumulation of magnetic phenomena in nature for a long time,people can make use of the magnetic field by controlling it accurately and the magnetic bearing is one of the typical representative.Compared with the traditional mechanical bearings,the magnetic bearing which supports a rotor without contact has no loss,no need of lubrication and other advantages in applications,so the magnetic bearing has a great potential in industrial application.As the core of magnetic bearing,the electronic control system has always been the focus and difficulty.This paper mainly studies the electronic control system of the active magnetic bearing system,including the displacement detection and control system.Firstly,according to the characteristics of the magnetic bearing,the requirements of displacement detection are analyzed and the eddy current displacement sensor is chosen,then a kind of differential displacement detecting circuit is desigened according to the principle of electric eddy current displacement sensor in this paper,after that experiment and theoretical analysis on the main indexes of detection circuit has been done of which results show that the detection circuit can satisfy the requirements of the sensitivity,stability and dynamic characteristics.Secondly,this paper analysises and designs the control system including PID control circuit and voltage type power amplifier circuit.The effects of DC bus voltage and switching frequency of power amplifier circuiton the performance of the whole system are studied.Then the model of the control system is designed and through the experiment and the analysis of the closed-loop transfer function of the system,the method of PID parameter tuning is presented to stabilize the rotor.This paper studies the influence of the selection of PID parameters on the support characteristics of the magnetic bearing by using Matlab.At last,the experiments prove that the stability and anti-interference ability of AMB can obtain satisfactory results.