Research On EMC Characteristics Of Real-Time Ethernet And Wireless Channels In High-Speed Railway

With the continuous development of electrified railroads,high-speed railway generally uses 100 BASE-TX Ethernet communication technology for data transmission,and wireless communication technology will also be gradually used in the future on-board network.As a key link for communication between devices,physical channel is also an important coupling path for electromagnetic energy to enter electronic devices,and once it fails,the consequences are very serious.In this paper,the EMC characteristics of the real-time Ethernet and wireless channels of high-speed railway are studied in depth to provide a modeling method and theoretical basis for the analysis and design of the EMC of high-speed railway.The specific research contents of this paper are summarized as follows:(1)By reviewing the relevant domestic and international literature on this topic,the current status of research on the electromagnetic compatibility of cables,connectors and antennas are described.(2)For the study of real-time Ethernet and wireless channel electromagnetic theory,the electromagnetic harassment coupling mechanism,transmission line theory,shielded cable transfer impedance theory,cable crosstalk theory and the basic theory of vehicle antennas are analyzed.(3)Research on the physical channel modeling of 100 BASE-TX Ethernet,establish the simulation model of in-vehicle Ethernet signal,driver circuit,in-vehicle connector and invehicle communication cable,simulate and calculate the normal and strong interference conditions;collect data on the physical signal of 100 BASE-TX Ethernet in real vehicles,compare and analyze the simulation value of normal conditions with the collected data,and verify the accuracy of the simulation model in this paper.(4)The interference mechanism and simulation modeling of in-vehicle cables are studied,and an analytical method optimization model for calculating the transfer impedance of invehicle double-layer shielded cables is proposed.The quantitative relationship between shielding effectiveness and transfer impedance is derived,and the effect of braiding angle on shielding effectiveness is analyzed.The validity of the optimization model is verified by comparing the CST simulation values with the theoretical calculation values in MATLAB.An analytical model and analysis method are proposed for analyzing the crosstalk problem of shielded cables in vehicles,and the validity of the analysis model and analysis method is verified by comparing the CST simulation values with the theoretical calculation values in MATLAB.(5)The simulation of wireless communication antenna layout of high-speed railway is studied,and the integrated model of train body and antenna is established.The comparative simulation analysis of the wireless communication quality in different antenna layout and with or without onboard interior conditions is carried out,and the analysis process and conclusions obtained can provide reference for the onboard wireless communication antenna layout.