| In 2017,the National Development and Reform Commission issued the “Implementation Plan for the Industrialization of Rail Transit Equipment Technology” which clearly requires the development of the new generation of 600-km/h-class high-speed magnetic levitation(maglev)trains.Maglev train is a typical representative of advanced rail transit technology,which has the advantages of none-contact operation,high speed,environmental friendliness,safety and reliability.Maglev train can be divided into two types: Electromagnetic Suspension(EMS)and Superconducting Electrodynamic Suspension(EDS).The null-flux EDS train was applied to the Japanese Yamanashi test line due to its advantages of large suspension gap,self-stability,high lift/drag ratio and other key parameters of the maglev system.In 2015,it created a record of 603 km/h which is the highest speed of manned rail transportation,and fully verified its great potential and advantages in high-speed and ultrahigh-speed applications.The electromagnetic force calculation is essential for the understanding of EDS.At present,the finite element method is the main method to calculate the electromagnetic forces,and there is a lack of relevant research in analytical method.In order to improve the solution efficiency of the system and promote its application in the future high-speed maglev transportation,this thesis took the EDS field-circuit-motion coupled model as the core.The comprehensive research method combining the analytical calculation,numerical simulation and experimental test was used to study the electromagnetic forces,dynamic characteristics of the EDS train and the law of induced current.First,based on the dynamic circuit theory,the magnetic coupling calculation was carried out between onboard superconducting magnets and ground coils.The equivalent dynamic circuit models with cross connection and without cross connection structure were established respectively.The mutual inductance and magnetic field distribution were calculated by discretizing the continuous coils.This method also can be used to solve the problem of mutual inductance between coils of any shape,as well as the magnetic field distribution and electromagnetic force of permanent magnet.The time-step iteration method was utilized to solve the induced current governing equation of the ground coil under different operating conditions.And based on MATLAB,a electromagnetic force calculation APP was established for the purpose of convenient and fast solution.Secondly,the mathematical model of E-J nonlinear characteristic relationship of high temperature superconducting(HTS)material was established from the point of view of material characteristics,thus the mathematical expression of power-law model was derived.Because there is no test line for the verification of EDS train in China,this paper is based on the relevant parameters of MLX01 superconducting EDS train in Japan.Three-dimensional finite element simulation models of cross connected and no cross connected structures were established respectively,to realize the motion simulation of superconducting EDS train.The testing data of Japanese Yamanashi test line was then used to verify the finite element simulation model and field-circuit-motion coupled model.The variation of levitation force,drag force and guidance force with the speed was analyzed.On the other hand,based on the unit structure,the causes of the variation of induced current and electromagnetic force were analyzed.The influence of the electric parameters of the ground coil on the levitation force,drag force and guidance force was explored,which can provide reference for improving the performance of the levitation and guiding system of the EDS train.Finally,this thesis proposed a new EDS testing method.This method can replace the traditional rotating motion method to realize the prediction of the operating performance of superconducting EDS trains.In addition,the prototype of the test system was built.This EDS testing system was introduced in detail from three aspects: principle,structure and construction process.The following research can be based on this platform to carry out the dynamic performance test of EDS train under different working conditions. |
