Modular Modeling And Simulation Research Of Conducted Electromagnetic Interference In Train Traction System

The train traction system is an AC drive system controlled by a variable voltage inverter,which is the main source of conductive electromagnetic interference during the operation of high-speed trains.As trains become faster and faster,traction power continues to increase,and electrical lines become denser and more complicated.The analysis accuracy of conducted electromagnetic interference is becoming higher and more difficult.In order to ensure the safe and reliable operation of trains,it is necessary to simulate,predict and analyze system conducted electromagnetic interference.This article takes the traction system of a subway line as the object,builds its conducted EMI simulation platform,and use the simulation platform to predict and analyze specific issues related to the cable shielding layer.First,the working principle of the train traction system is studied,the main coupling path of its conducted EMI and the parasitic parameters that play a key role in the path are analyzed.Secondly,the interference source is analyzed,the structural resonance method is used to extract the common mode parasitic capacitance of the IGBT module;the genetic algorithm is designed to establish the high-frequency equivalent model of the traction motor based on the measurement results of the impedance analyzer;vector matching method is used to establish port equivalent models of other discrete devices;and the three-dimensional structure is used to extract high-frequency parasitic parameters of cables and other structural parts,and their models are built based on the conduction relationship.All parts are connected to build a full circuit EMC simulation model of the traction system.Thirdly,the traction system is tested on the bench to measure the conducted EMI on the DC input side and the three-phase output side of the traction converter box,the test and simulation results are compared to verify the accuracy of the model,and the error is analyzed.Finally,the calculation results of the built simulation model is used to analyze the impact of specific issues such as the single and double end grounding of the cable shielding layer and the discontinuity of the shielding layer on the conducted EMI.After analysis,the built model can effectively reflect the changing trend of traction system conducted EMI in the 150 k Hz-30 MHz frequency band,which verifies the validity of the model.The simulation results of the model under different conditions of the cable shielding layer provide a reference for specific measures to suppress the conducted EMI of the traction system.