基于电荷等效法的电容短路放电微观特性数值模拟研究

Numerical Simulation Research on Microscopic Characteristics of Capacitor Short-Circuit Discharge Based on Charge Equivalent Method

为了研究基于IEC火花试验装置的容性电路短路放电的微观特性,该文建立了以钨为阳极材料、镉为阴极材料的二维平行极板仿真模型。在仿真区域充满了空气以及体积分数为8.5%的甲烷混合气体,根据电荷等效原理对该模型采用粒子法(PIC/MCC)进行数值模拟研究,着重分析了极间电压、极间距离及外接电容对电容短路放电过程的影响,得到了在击穿后放电过程中极间电压、电流、各种粒子浓度、平均电子能量的变化情况。模拟结果表明:随着极间电压的增大,平均电子能量也逐渐增大,极间电压对N2的电离影响程度远大于对O_(2)和CH_(4)的电离;当电极间距变大时,击穿所需要的时间变长,电极间气体介质越难以击穿;外接电容容值的改变,对气体电离基本不会产生影响,但外接电容的改变影响极间电流变化,击穿后的极间电流随着电容的增大而增大;随着极间电场强度的增大,气体电离会越剧烈,电流密度会越大,平均电子能量也会逐渐变大。

In order to study the microscopic characteristics of the capacitive circuit short-circuit discharge based on the IEC spark test device,this paper established a two-dimensional parallel plate simulation model with tungsten as the anode material and cadmium as the cathode material.The simulation area was filled with air and the concentration was 8.5%.According to the principle of charge equivalence,the model adopts the particle method(PIC/MCC)to carry out numerical simulation research.The effect of the voltage between the electrodes,the distance between the electrodes and the external capacitor on the short-circuit discharge process of the capacitor is analyzed.Changes in voltage,current,various particle concentrations,and average electron energy during the discharge process after breakdown.The simulation results show that with the increase of the voltage between electrodes,the average electron energy also gradually increases.The influence of the voltage between electrodes on the ionization of N2 is much greater than that on O_(2) and CH_(4);when the electrode spacing becomes larger,the breakdown needs the longer the time,the more difficult it is for the gas medium between the electrodes to break down;the change in the capacitance of the external capacitor will basically have no effect on gas ionization,but the change in the external capacitor affects the change of the inter-electrode current,and the inter-electrode current increases after breakdown with the capacitance increasing;as the inter-electrode field strength increases,the more intense the gas ionization,the greater the current density,and the average electron energy will gradually increase.