Design And Application Of Traction Converter Device For CRH2 EMU

With the rapid development of the national economy,the demand for high-speed trains is gradually increasing due to the large population,and the passenger transport capacity need to be further improved.To adapt to the rapid economic development,high-speed trains are an inevitable trend.Therefore,control technologies for high-speed trains must be well studied,which is very important to the rapid development of the national economy.The key technologies for the high-speed electric multiple units(EMU),such as the starting acceleration,the maximum braking distance,the sustainable maximum operating speed,and smoothness of operations,depend largely on the performance of the traction converter.The prospect of the high-speed trains is bound to be promoted by the rapid development of the traction converter.The development of the high-speed train technologies has always centered on speed improvement.After several years of innovative practices,China's high-speed trains have made tremendous achievements in research and application.Now,china already has the capabilities of developing and manufacturing higher-speed trains.The development of the world's high-speed EMU technologies cannot be separated from the in-depth study of the high-power IGBT traction converter.The main contents of this paper are as follows:1.The background and significance of the research on the high-power IGBT traction converter of the high-speed EMU are described.The structure of the traction system of the modified CRH2 high-speed EMU is briefly introduced.2.The components and structure of the traction converter are introduced in detail,especially the control strategies and characteristics of the topologies for different main circuits of the traction converter.The advantages and disadvantages of the two-level structure and three-level structure are compared.According to the technical requirements of the modified CRH2 EMU,the two-level structure traction converter is selected as the core component of the traction driver.3.According to the technical requirements of the traction converter of the modified CRH2 EMU,the parameters and model of the converter is determined through the selection of the input impedance,intermediate support capacitors and the secondary resonant circuit of the two-level traction converter.4.The input impedance of the traction converter is mixed and matched with different voltages and percentages of short-circuit impedance.Simulation results show the rationality of the hardware selection of the traction converter.5.Ground tests show that the harmonics of the modified CRH2 EMU will exceed the standard level if the load is unbalanced.Based on the simulation,several control strategies are proposed,such as multiple phase dislocation control,changing the switching frequency,and increasing the intermediate voltage,which can limit the excessive current harmonics at corresponding points.Field tests show that the presented control strategies are effective and feasible,which provides the theoretical basis for the future research and development of high-speed EMU in China.