Research On Electromagnetic Topology For Aperture And Cable Couplings In Locomotive

Electromagnetic Topology (EMT) was raised by the United States'C.E. Baum in the mid-1970s, which was primarily used to prevent high-power electromagnetic pulse (EMP) from disturbing and damaging modern electronic systems. After decades of research and development, EMT begins to be applied to other magnetic field topology. However, the application of EMT is still at an early stage when coming down to power electronic equipment in locomotive. Based on EMT method, this thesis studies Electromagnetic Compatibility (EMC) of power electronic equipment in locomotive, focusing on aperture coupling and near-field cable coupling.Firstly, the status of EMT, analysis method and its advantages are briefly introduced. Then the internal and external electromagnetic environment of railway power electronic system is analyzed as well, especially the widespread aperture coupling and near-field coupling. Specific EMT models of these two couplings are built to provide convenience for solving such kinds of problems.General EMT method is used in aperture coupling problem in railway locomotive system. EMT regards radiated source as a node which travels through the aperture on the shielding wall and couples to the transmission line on the other side of the wall. For the convenience of analysis, an extra equivalent coupling node is added which is equivalent to the effect of radiated source on the transmission line. At last, the interference on the two ends of transmission line is qualitatively analyzed to judge aperture coupling interference. Based on EMT model, field-circuit topology model is established to determine state functions of the nodes and transfer functions of the transmission channels. Universal significant conclusion is derived using BLT equation and extended BLT equation, with mathematical model set up to fulfill the simulation. Finally the research results are verified with existed principles and the designed corresponding experiments.For the general existed near-field coupling problems in railway locomotive system, the same analyzing thought as aperture coupling is applied. At first, circuit structure graph is drawn which is consisted of distributed parameters. After that EMT graph is abstracted. Then nodes and transmission channels are determined. On the derivation of transmission function, combined with existed theoretical results, a specific equation is derived systematically starting from telegraph equation with related knowledge of advanced mathematics and matrix analysis. Near-field BLT equation is firstly formulized and applied in practice. Based on multi-conductor transmission lines, mathematical model in Matlab is built and simulated after the derivation of equations. At last, the result is verified with the designed corresponding experiments.The main contribution of this thesis is the modelization of aperture coupling and near-field coupling in railway locomotive system, which facilitates the analysis of entire locomotive system in the use of EMT approach. Meanwhile these two issues are verified experimentally, which confirms the validity of the theoretical analysis.