Research On Digital Controller Of Magnetic Bearing System Of High Speed Magnetic Suspension Motor

The high speed magnetic motor is composed of a high speed motor and three degrees of freedom hybrid magnetic bearings at both ends,which can work at high speed.Magnetic bearing realizes frictionless suspension support for rotor,which not only reduces the friction loss of motor but also prolongs the service life of motor.The 3-DOF hybrid magnetic bearing is adopted to reduce the volume of the motor body and further reduce the power consumption compared with the traditional active magnetic bearing.Aiming at the problem of stable suspension and fault tolerance of rotor position by hybrid magnetic bearing,the corresponding control algorithm and fault tolerance control algorithm are studied in this paper.Firstly,the structure and composition of the 3-DOF hybrid magnetic bearing system are introduced.Based on the analysis of the magnetic flux circuit of the magnetic bearing system,the precise magnetic circuit mathematical model and linearized mathematical model of the system are deduced based on the equivalent magnetic circuit theory.By comparing the magnetic flux simulation results with the mathematical model calculation results,the accuracy of the mathematical model of each degree of freedom deduced is verified,and the nonlinear working range of the system is determined,which provided the theoretical basis and research basis for the control method of the hybrid magnetic bearing system.Secondly,aiming at the stable suspension control of the magnetic bearing on the rotor position,an incomplete differential PID control algorithm was designed,and the 5-DOF stable suspension support and anti-interference characteristics of the magnetic bearing system on the rotor are verified by Simulink simulation and experiments.Considering the open-loop nonlinear and uncertain characteristics of hybrid magnetic bearing,a back-stepping control method based on state observer is deduced and designed.Simulation results show that the magnetic bearing system has better support characteristics,position tracking characteristics and anti-interference characteristics when adopting this control method.Then,in view of the magnetic suspension bearing system after displacement sensor failure can lead to the system of rotor position is out of control problems,put forward a method of asymmetric position installing displacement sensor and displacement sensor based on geometric space position matrix relationship between the output signal is deduced,for displacement sensor fault diagnosis and fault-tolerant control provides a theoretical basis.Finally,the response speed and reliability of the system under the proposed control strategy are verified by experiments.Finally,the hardware control circuit and working principle of the 3-DOF hybrid magnetic bearing system are introduced in detail,and the reliability of each hardware subsystem is verified by experiments.The composition of control program and the function of subroutine processing algorithm based on DSP28335 digital processor are introduced.