Medium-speed Maglev Train Hybrid Suspension System Of Electromagnet Protection Against Suspension Contact Technology Research

As the rail transit is developing rapidly,the research and construction of mid-speed maglev train,which the maximum speed is 200 kph,is on the schedule.Our school has taken on this project.Mid-speed maglev train adopts permanent magnet-electromagnet hybrid suspension system,which decreases the power dissipation and electromagnetic heat when comparing with electromagnetic suspension system.However,with the speed of maglev train is increasing,the potential safety hazard of suspension contact to the track of permanent magnet-electromagnet hybrid suspension system is getting serious.What’s worse,while in the suspension contact situation,the maglev train cannot get rid of it,thus making it unable to rescue.A new kind of hybrid magnet,which is able to prevent suspension contract and decrease the levitation power dissipation,is strongly needed.This essay puts forward two new types of schemes of hybrid magnet preventing suspension contract based on conventional hybrid electromagnet analysis and does research on this project.The main work for the essay is:(1)This article presents two new kinds of constructions of hybrid suspension electromagnet which are able to reversibly magnetize and analyses two schemes.Firstly,the magnetizing principle is introduced and puts forward two structures of reversibly magnetizing PM-EM hybrid suspension magnet focusing on solving the problem of suspension contract as well as based on the principle of magnetize and dimagnetize.The related mathematical models are constructed.According to the stability demand of NdFeB and SrFeO in two working conditions of suspending normally as well as suspension contact,the feasibility of the two schemes are verified.Because during the magnetizing period of SrFeO,NdFeB is demagnetizing,therefore,cascade type is dismissed and parallel type is chosen.(2)The structure parameters of double permanent parallel PM-EM hybrid suspension magnet are designed.Firstly,the article anal yses the relationship of the working point and maximum magnetic energy point and figures out that,while working in the maximum magnetic energy point,the use ratio is the biggest,that is to say,the usage of the permanent magnet can be reduced and the cost may be reduced.The constraint condition which the parameters of parallel reversibly magnetizing hybridsuspension magnet need to meet in order to reduce the energy cost as well as increase controllability.Finally,in three typical working conditions,t he simulation and comparison of parallel reversibly magnetizing hybrid suspension magnet and electromagnetic magnets is taken and the results shows that parallel reversibly magnetizing hybrid suspension magnets have favorable controllability,its floating current in full carriage condition is smaller than EM magnets,what’s more,parallel hybrid suspension magnets can achieve floating in zero current.(3)A PID bi-loop controller for parallel reversely magnetizing hybrid suspension magnet is designed and stiffness degradation of the whole system is analyzed.First of all,the physical models of the parallel reversely magnetizing hybrid suspension magnet is built,in order to be easy to analyze system’s performance and design the control system,the physical model is linearized.The stability,controllability,observability of the open-loop system is analyzed,there exists one pole in the right half s-plane,thus the open-loop system is unstable.As the inductance of the parallel reversely magnetizing hybrid suspension magnet is huge and the time constant of current response is big,the current loop need to be designed to increase the response speed.Then,gap-loop control is designed and PID controller is used to make the system stable as well as satisfied the demand of steady-state error and dynamic response.The simulation result shows that the bi-loop control can satisfy the control demand of suspension system.Finally,the stiffness degradation is analyzed and the influence of structure parameters and PID controllers to the stiffness is shown.Therefore,this bi-permanent parallel reversely magnetizing hybrid suspension magnet is new type of levitation electromagnet,which is able to reach the function of preventing suspension contract and,at the same time,has the ability of levitating in zero current and good control performance,the goal is reached and a new solution to enhance the ability of avoiding suspension contact is provided.