Simulation And Characteristic Analysis Of Electromagnetic Radiation Interference Based On Converter In Coal Mine

At present,China is vigorously promoting the transformation of coal mine and production to intelligence and information.Intelligent equipment and electronic equipment are widely used in coal mine production.The problem of electromagnetic interference is difficult to ignore.Aiming at the problem of abnormal operation of gas sensor in coal mine caused by electromagnetic radiation interference of nearby ventilator converter,after investigating the research status of mine electromagnetic interference and mine converter radiation interference,this dissertation takes the converter of local ventilator as the research object to analyze the electromagnetic radiation interference,which has positive significance for coal mine safety production and accelerating transformation.Based on the electromagnetic theory and the principle of electromagnetic compatibility,summarize the relevant literature research methods,the technical path of this thesis is determined as follows:investigate the electromagnetic environment of the research object,analyze the mechanism of electromagnetic radiation interference,and establish the antenna model according to the structure,use the electromagnetic field simulation software based on the method of moments to solve the electromagnetic field,test the electromagnetic radiation of the converter on the spot,compare the simulation and experimental data to verify the effectiveness of the model,and analyze the electromagnetic radiation characteristics of the converter.This thesis analyzes the radiation interference mechanism of mine-used converter from the perspective of three elements of electromagnetic interference,and determines that the interference source of converter is IGBT,the coupling path is radiation coupling,and the sensitive equipment is sensors and other equipment.The internal electronic components and metal casing of converter will affect its radiation.The working principle of converter includes three parts:converter topology circuit,modulation strategy and speed regulation principle.In order to obtain IGBT interference signal,the FF300R17KE3 module inside the converter is tested on the high-voltage IGBT dynamic test platform,and its dynamic parameters are obtained.The generation of high-frequency pulse in IGBT switching process is described in detail.The converter model is built in MATLAB to simulate the voltage signal generated during IGBT switching process,and the frequency domain signal is obtained by Fourier transform.At the same time,the antenna model of IGBT module is established to solve its electromagnetic radiation level.The influence of the number of grids and the size of excitation source on the simulation results is analyzed by using the control variable method.Based on the antenna theory,the simulation model of ZJT-75/660SF mine-used converter is established in this thesis.The excitation source is set to the IGBT voltage signal obtained from the simulation,and the triangular mesh is used to divide the model.Using the method of moments to calculate the far field radiation and near field radiation of the converter at typical frequency points.The radiation level of the converter is tested on site by using antenna and spectrum analyzer,and the spectrum diagrams of multiple positions near the casing are obtained.Compared with the measured data,the effectiveness of the model is verified.Combined with the simulation data and the measured data,the interference characteristics of the electromagnetic radiation of the converter are analyzed.The near-field data shows that the high field strength area is distributed inside the converter,the case has a shielding effect on the radiation of the converter,and the electromagnetic radiation level at the case is higher than the external environment of the converter.The farther away from the converter,the lower the radiation field strength.From the calculation results of the far field,the converter mainly radiates electromagnetic energy in the direction ofθ=-25~°～0~°,and some frequency points will have side lobes with the slightly lower radiation level and the concentrated direction atθ=±60~°orθ=±70~°.When arranging cables or secondary equipment downhole,try to avoid arranging them in the strong radiation area of the converter.