Research On The Supercritical Characteristics Of Magnetic Suspension Rotor

In recent years,with the rotational speed of rotating machinery(such as aero-engine,turbine-machine rotor)continuously improved,more stringent damping requirements are put forward in industrial production and application,and the magnetic bearing of high speed rotor system has the advantages of no pollution,no abrasion and high controllability,which arouses the keen interest of scientists and industry engineers.It is very important to study the supercritical characteristics of magnetic levitation rotor under active control because it becomes an unavoidable challenge for high-speed rotors.Firstly,in this paper,the dynamic characteristics of flexible rotors are analyzed,the mathematical model of flexible rotors is established,and the critical characteristics of three-supported rotor systems are analyzed by SAMCEF ROTOR,the influence of the intermediate support stiffness and damping on the critical characteristics of three-support rotor system is obtained,and a new method of active variable support magnetic levitation rotor system for passing through the first critical speed was described.Then,introduces the working principle of the magnetic levitation rotor and establishes its simulation model,and analyzes the influence of the control parameters on the equivalent stiffness and equivalent damping of the magnetic suspension bearing,and the mathematical model of the variable-supported magnetic levitation rotor system is established.Aiming at the load characteristics of each support in the model,the calculation formula and the elevation sensitivity matrix of the support load of the multi-support rotor system are deduced by combining the transfer matrix method and the lumped mass method,which solves the problem of bearing load distribution of the suspension rotor system with variable support.Finally,the co-simulation platform model of the variable support magnetic levitation rotor system is established by Solidworks,Adams,ANSYS and MATLAB,based on the platform,the influence of incomplete differential PID control strategy parameters and different support numbers on the critical characteristics of the magnetic levitation rotor system are analyzed.At the same time,the critical characteristics of the variable support magnetic levitation rotor system are simulated and analyzed: Through the switching time,the equivalent stiffness and its change rate,the characteristics of the incomplete differential PID variable support magnetic levitation rotor crossing the first-order critical speed are analyzed in detail,and the simulation results show that the critical amplitude of the magnetic levitation system with variable support is reduced by 39.6% comparing with the traditional two-bearing rotor system,and the critical amplitude of the rotor is suppressed effectively.The critical amplitude of the variable supported maglev rotor system under fuzzy PID control is reduced by 52.6%,which has better inhibition effect.Aiming at the problem of the excessive vibration and instability when rotor pass through the critical speed,a new method of active variable support magnetic levitation rotor system for passing through the first critical speed is presents,and the mathematical model is established.Taking the first-order critical speed as an example,the load analysis and optimization of the variable support model are carried out,and the parameter analysis and optimization of the active control system under different control strategies;The simulation results show that the fuzzy control strategy and working parameters have good optimization effect on the supercritical characteristics of the magnetic levitation rotor.