Simulation Research On Electromagnetic Field Distribution Characteristics Of Rain In Transient Electromagnetic Environment

With the continuous development of high-speed passenger transportation,heavy freight transportation and autonomous equipment of China’s rail transit system,the complex multi-source and dynamic electromagnetic environment and its effects faced by the cros s-line operation of rail transit system have been of great concern.As a major infrastructure in China,it is important for the national strategic security to study the electromagnetic environment effect of rail transit system,improve its electromagnetic environment adaptability and guarantee its electromagnetic safety.In this thesis,a model of high-speed passenger trains and high-speed freight trains is used as the research object,focusing on the electromagnetic field coupling characteristics of high-speed trains and their distribution laws under the transient electromagnetic environment,and carrying out simulation calculations and analytical research.The main research contents and innovation points of the thesis are as follows:(1)The time-frequency domain characteristics of typical transient electromagnetic signals such as double exponential pulses and high-power microwaves are analyzed and studied.Four typical mathematical models of transient electromagnetic radiation sources are established with d ifferent parameter settings,and the to-target field strengths of different types of transient electromagnetic radiation sources on trains and their time-domain waveforms are calculated with the given emission power and action distance,laying the foundation for the subsequent three-dimensional full-wave simulation calculations.(2)A full-size three-dimensional electromagnetic simulation model of a type of high-speed passenger train was established,and the electromagnetic field distribution characteristics in and around the train and at typical locations under the action of typical transient electromagnetic radiation sources,as well as the current distribution law on the train surface,were simulated and calculated.The simulation results show that: under the action of four typical electromagnetic pulse excitation,the electromagnetic coupling is easily generated in the train windows and apertures,resulting in the field intensity in the train cockpit is significantly higher than that in the on-board cabinet,etc.;when the four typical radiation sources are irradiated from the front of the train cockpit and the left side of the train respectively,the radiation coupling in the cockpit is the largest when the electromagnetic wave incident direction is at an angle of 60° between the front of the train cockpit and the ground;at Under the given radiation intensity,the maximum values of coupling voltage of long double exponential pulse,short double exponential pulse,broadband HPM and narrowband HPM on GSM-R antenna are 280 V,549.14 V,16.77 V and 8.88 V,respectively.(3)A full-size three-dimensional electromagnetic simulation model of a freight high-speed train was established to study the electromagnetic field distribution characteristics inside and outside the train under the irradiation of typical transient electromagnetic radiation sources.Simulation results show that: four typical electromagnetic pulse excitation,the field strength in the freight train cockpit is significantly higher than the field str ength at the onboard cabinet;and the same type of radiation source,freight trains compared with passenger trains,the difference between the field strength at similar locations in the cockpit of the two is not large,but the field strength at the on-board cabinet of the former is significantly smaller than the latter,mainly because the passenger train car windows are relatively more openings.The main reason is that the windows of passenger train cars have more openings.