Research On Control Algorithm Of Electro-magnetic Levitation System Based On PLC

With the continuous expansion of megacities,the emerging areas,urban clusters and sub-centers of megacities are far away from the main urban areas,so the traffic problems in these areas must be solved.Due to the requirements of environmental protection in some specific areas,under the premise of practicality and environmental protection,adopting low-speed maglev according to local conditions will better improve the layout of urban rail transit.Levitation control is one of the core technologies of maglev train,which is the premise to ensure the safe operation of the train.The robustness of the suspension system in the face of parameter perturbation and the anti-interference ability in the face of complex disturbances are very important.How to ensure the robustness and anti-disturbance ability of suspension controller has become a hot research topic.This paper firstly analyzes the basic principle of maglev control,deduces the mathematical model of single electromagnet system,and establishes the mathematical model of multiple electromagnet system combining the mechanical structure characteristics of suspension frame.Taking cascade control as the core idea,the stability of traditional PD control of air gap outer loop was analyzed by using the current control scheme of air gap outer loop.Secondly,the new levitation control algorithm is studied.When maglev train runs,the suspension system will face the interference of various factors,such as the timevarying normal force of traction system,electromagnetic coupling,large range of load variation,track irregularity,track steps and so on.In this paper,a generalized predictive active disturbance rejection control algorithm is designed which is insensitive to model parameters and has strong anti-interference ability to various perturbations.In order to eliminate the synchronization error between electromagnets,a synchronous controller is designed based on the closed-loop control of each single electromagnet.Then the algorithm is simulated and analyzed in MATLAB/Simulink simulation software.The control performance of the new algorithm is compared under load mutation,given air gap mutation and uncertain disturbance.Finally,PLC maglev controller is designed and experimented.Compared with DSP,RAM,FPGA and other common suspension control core,PLC has industrial-level reliability,and the system development difficulty is small,the cycle is short.This paper designs a suspension controller with PLC as the core,which realizes the stable suspension of single electromagnet,single side of suspension frame and whole suspension frame,and verifies the effectiveness of generalized predictive active disturbance rejection control.At the same time,the control effects of the three control algorithms in several classical conditions are compared.