Research On Electromagnetic Disturbance Characteristics Of Mining Frequency Converter Based On Frequency Domain Analysis

In recent years,with the continuous improvement of the scientific and technological level of coal mine equipment,the underground electrical equipment tends to be diversified.Among them,frequency converter has been widely used in underground high-power ventilator,shearer,roadheader,conveyor,hoist and other electromechanical equipment because of its characteristics of energy saving,high efficiency and intelligence.However,the mining frequency converter will produce a lot of electromagnetic disturbance when working,and the disturbance spectrum is wide,which may cause the abnormal operation of the safety monitoring system,sensors and other surrounding electrical equipment,and the electromagnetic problems are more complex.Therefore,it is of great significance to study the electromagnetic disturbance characteristics of mining frequency converter in frequency domain.Taking a typical ZJT series mine flameproof and intrinsically safe AC frequency converter as the research object,this paper studies the electromagnetic disturbance characteristics in the frequency domain.Firstly,the working principle,basic circuit structure and special structure of mining frequency converter are analyzed;According to the circuit structure of mining frequency converter,it is clear that the main electromagnetic disturbance source is IGBT device in inverter circuit.It is analyzed that the high du/dt and di/dt produced at the moment of IGBT breaking can cause a lot of electromagnetic disturbance;Aiming at the two coupling paths of conduction and radiation,the radiated electromagnetic disturbance is studied in this paper.Secondly,the electromagnetic disturbance characteristics of IGBT,the main electromagnetic disturbance source of mining frequency converter,are studied,and the influence of radiator on the electromagnetic disturbance characteristics of IGBT is explored.The electromagnetic field simulation software based on finite integral theory is used to build the simulation model of single IGBT module and the combination of IGBT and radiator;The change of IGBT breaking process is simulated by applying the changing excitation source waveform,and the solver is used to solve it.The time-frequency simulation results of electromagnetic disturbance 100 mm above the center of the model are obtained.The simulation results verify the established model at the same time;By comparing the disturbance time-frequency results of the above two models,the influence of the radiator on the characteristics of IGBT electric field disturbance and magnetic field disturbance is obtained.Then,according to the modeling and Simulation of the whole mining frequency converter,the electromagnetic disturbance characteristics of the mining frequency converter in the 0-200 MHz frequency domain,input and output terminals,near-field tangent plane and far-field are obtained,and analyzed in combination with the field measured data.The variation of electromagnetic disturbance amplitude with frequency is obtained by simulation calculation.The electromagnetic disturbance intensity at the input and output of the frequency converter is compared,and the variation trend of electromagnetic disturbance amplitude with distance at the near-field position of the frequency converter is studied;The maximum disturbance amplitude of the near-field tangent plane at 0.6m around the frequency converter is obtained by simulation calculation,and it is proposed to pay attention to the electromagnetic disturbance at the output end;Observe the variation of amplitude and direction of electromagnetic disturbance at typical frequency points with frequency in the far-field simulation cloud image;The test scheme of mining frequency converter is described.The spectrum diagram is derived based on Matlab software,and then compared with the analysis results of measured data to verify the correctness of modeling and Simulation of mining frequency converter.Finally,the characteristic parameters and statistical analysis of the measured electromagnetic disturbance data are carried out.Analyze and summarize the characteristic parameters for each group of disturbance data;The normality test is carried out by W test method to verify the availability of data,and the Bessel statistics and 80%/80% criterion are used for statistical analysis.The results have certain guiding significance for formulating the immunity test standard of equipment or system around mining frequency converter.