| As one of the key technology of high-speed train,the braking system is the assurance of high speed,safe and stable operation of train.In the future with the development of high-speed train technology,train operation speed will be further improved.At present,the braking mode used in the EMU is an composite braking combined with air brake and electric brake.Both air brake and electric brake are adhesive brake,which is limited by adhesion,another frequently used air brake under the condition of high speed will accelerate the abrasion of brake disc.In this paper,the linear track eddy current braking is the electromagnetic force produced by the electromagnet and rail,which belongs to non stick braking.Firstly,this paper introduces the development of high-speed railway technology in China,studies the background and significance of eddy current braking,and the research status of eddy current braking technology at home and abroad.Secondly,the overall layout of the eddy current braking system is presented and its working principle is analyzed.According to the working principle,the eddy current braking system is divided into two parts:electromagnetic system and mechanical system.The electromagnetic system of rectifier,DC chopper and excitation circuit part of the circuit and control principle are analyzed;According to analysis of the function characteristics of the mechanical system,we present the scheme of a mechanical system,and draws the schematic diagram of two and three dimensions.Thirdly,Based on the eddy current braking mechanism,a three-dimensional model of electromagnet and rail is established.Based on the theory of electromagnetic field,the theoretical formula of eddy current power and electromagnetic attraction is deduced and analyzed by Matlab.The influence of speed,excitation current and the length of air gap on the braking force and attraction are analyzed by simulation results.Then,according to the characteristics of the train braking modes,the braking force distribution scheme is established,and the braking force distribution model is established by using Matlab/Simulink software.At the same time,according to the principle of eddy current braking system,the circuit simulation model is established,and the performance of each part is analyzed.The braking force distribution model and the electromagnetic system model are combined to form the eddy current braking system simulation model.Afterwards.Based on the simulation model of eddy current braking system,the variation curves of excitation current,eddy current braking force,braking deceleration and speed are analyzed in 8 common braking systems.At the same time,the simulation model is used to simulate the two kinds of special operation conditions,such as the switching condition of power system and the fault condition of catenary.At last,according to the simulation model of the eddy current braking system,the change of the node value of the train speed,the maximum of the exciting current and the length of the air gap are analyzed.The simulation results show that the optimal values of the three parameters are obtained.The optimal value is brought into the model for simulation analysis.The simulation results show that the eddy current braking performance can be improved by optimizing the parameters. |
