Modeling And Simulation Research For Train-to-Wayside Communication System Based On Cross Induction Cable Loop

With the rapid development of urban rail transit in China, communication based train control system is applied more and more in the subway and light railway, and it plays an important role in ensuring the safety and reliability of train operation. As a kind of important information transmission medium of train-to-wayside communication system, the cross induction cable loop is coupled with vehicle antennas through the electromagnetic induction principle to realize continuous real-time information transmission between vehicle and ground. Train-to-wayside communication system based on cross induction cable loop is an important equipment to ensure the safety and reliability of train operation, and the stability of information transmission is very important. On the basis of modeling and simulation with physical theory and electromagnetic simulation software, this paper studies the performance of the communication system, then analyzes and optimizes the parameters that affect the performance of the system.This paper adopts the idea of "theoretical modeling-software modeling and simulation-optimization and analysis". Firstly, studying and analyzing train-to-wayside communication system from two aspects of the actual and model. Further, researching based on the combinative method of electromagnetic field theory modeling and software modeling simulation. The main research contents are as follows:(1) Theoretical modeling. The communication principle of TWC (Train-to-Wayside Communication) system is electromagnetic induction principle, then, according to electromagnetic field theory and based on Maxwell equations with wave equations, modeling and deducing the induction voltage between the vehicle receiving antenna and the cross induction cable loop. First, because the electromagnetic field generated by the cross induction cable loop is time-varying electromagnetic field, so based on quasi stationary condition, the time-varying electromagnetic field is equivalent to quasi stationary electromagnetic field to solve. Then, analyzing and determining the vehicle receiving antennas are mainly affected by the magnetic field distribution of one cross loop, and then, deducing the magnetic induction intensity generated by one cross loop and calculating the formula of induction voltage.(2) Software modeling and simulation. First of all, using ANSYS Maxwell electromagnetic simulation software to build the models of uplink communication system and downlink communication system, after a series of modeling and simulation steps, the correct simulation results are obtained, mainly including magnetic field strength distribution, magnetic induction intensity distribution, flux linkage, induction voltage, and so on. Proving the accuracy of simulation results through detailed analysis and research. Secondly, analyzing the metal objects such as rails and steel bars having a slightly weakened effect on the signal strength. Finally, carrying out the spectrum analysis of the actual line data and the simulation result data to verify the correctness and applicability of the system model.(3) Optimization and analysis. Optimizing and analyzing the performance parameters such as size, number of windings, installation height of the vehicle receiving antenna and transmit antenna, and analyzing the influence of antenna lateral offset on the signal strength of train-to-wayside communication. After the software simulation and post-processing and MATLAB drawing, respectively obtaining the optimal values of various performance parameters and the effect curves.