Research On Conducted Emi Modeling And Simulation Of Traction Converter System Of High-speed EMU

During the operation of high-speed EMU,the traction converter system will produce strong electromagnetic disturbance which can not be completely avoided,and the traction converter system itself and the surrounding electronic power equipment will be affected by the EMI generated by the traction converter system.Therefore,to further study on the mechanism and characteristics of EMI on traction converter system is one of the key technical issues in terms of the reliable operation of high-speed EMU.However,in the current research on EMI modeling of the traction converter system of EMU,the relevant simulation models and test data are not perfect,and there is a lack of more systematic,comprehensive and in-depth analysis.And in the related research on conducted interference of traction converter system,ideal grounding is just simply adopted without the consideration of influences of EMU grounding system in the simulation model,a key factor in affecting EMC of EMU.Therefore,it is necessary to start from the complete vehicle system of the high-speed EMU and undertake a stimulation study on forecast models of conducted EMI of traction converter system of EMU with complete grounding system.The article introduces structures and working principles of traction converter system and grounding system of a standard EMU and sorts out the mechanisms of conducted EMI caused by traction converter system and the influence of grounding system on EMC of EMU.According to the grounding return path and system impedance parameters,the equivalent circuit network model of the whole vehicle grounding system was established.The distribution characteristics and laws of the grounding current at axle end were simulated and analyzed,and the rationality of the model was verified through experiments.Then the conducted EMI simulation model of traction converter system of the Chinese standard EMU was established,including IGBT dynamic model,main and auxiliary integrated traction converter main circuit,traction converter control strategy,traction transformer and traction motor EMI equivalent model,system distribution parameters and grounding system.Co-simulation and time-domain simulation methods were used to carry out system-level modeling and simulation analysis.The conducted EMI spectrum data of each position of the traction converter system was obtained,and the rationality of the model was verified through experiments.The simulation model established in this thesis can effectively predict and evaluate the distribution characteristics and laws of the grounding current at axle end,and the characteristics and laws of the conducted EMI of the traction converter system.The results of the research show that advantages of mixed grounding for the grounding system of the standard EMU are: the relatively even distribution of grounding current at each axle end of trains during operation,and a small proportion of the grounding current at each axle end on the total working grounding current;while the disadvantages are as follows: first,there are possible rising manufacturing and maintenance costs of the EMU due to the increasing number of grounding cables with the mixed grounding;second,there are greater difficulties in EMC design inside and outside the vehicle caused by increased circulation between the vehicle body and the tracks by the mixed grounding.The frequency spectrum of the common-mode conducted current generated by the traction converter system has an obvious peak in the frequency band of 200-600 k Hz.In this frequency range,the traction converter system will produce greater common-mode conducted disturbance.Because the grounding system of EMU is one of the critical paths for the EMI source to affect the EMC of the sensitive equipment inside and outside the vehicle,the common-mode conducted disturbance current generated by the traction converter system will flow into the vehicle body,and coupled into the rails through the vehicle grounding system,which may cause interference to the sensitive equipment.The research content breaks through the key technology of system-level simulation and prediction of conducted EMI in the traction converter system of EMU,and provides simulation assistance and guidance for the electromagnetic compatibility design,prediction analysis and optimization of the traction converter system and grounding system of EMU.