纳秒脉冲同轴结构固体绝缘介质尺寸优化分析

Optimum analysis on solid dielectric insulation dimension in coaxial electrodes under nanosecond pulse voltage

同轴电场沿径向分布不均匀,径向电场降落集中在内电极表面附近一定范围内。在内电极直径不变,外电极直径增加的情况下,内外电极距离大于一定阈值后,电场变化在经过一个快速减小的阶段后明显变缓;在仅仅增加内电极直径,固定内外电极距离,相应增加外电极直径的情况下,内电极直径少量增加大于一定阈值后,同轴电场变化类似地经过一个快速衰减阶段后明显趋于缓和。根据同轴电极结构内外电极间隙距离与内电极直径变化影响电场分布的阈值的存在,利用Ansys数值计算结合纳秒脉冲下同轴电场变压器油中有机玻璃和尼龙1010闪络特性的实验结果,提出同轴结构高功率脉冲功率装置绝缘结构优化概念,并且给出依据闪络距离与内电极直径变化闪络电压的经验公式。

The rapid declining of electric field in the very close vicinity of inner electrode results in non-uniform distribution of coaxial electric field in coaxial electrodes. Under the condition of keeping the inner diameter of electrode constant and increasing the outer diameter, the variation of coaxial electric field is markedly slow down following a stage of rapid decay when the gap between the inner and outer diameters is longer than a threshold. When the gap between inner and outer electrodes is keeping constant but correspondingly increasing the diameter of the outer electrode, then a slight increase of diameter of inner electrode beyond the threshold value, the variation of coaxial electric field will have the same variation as the former case. The appearance of two thresholds about two parameters of the gap between inner and outer electrodes and the diameter of inner electrode implies the optimum conception of the coaxial insulation structure of pulsed power equipments. This paper provides an empirical formula relevant to flashover gap and the inner electrode diameter on the basis of the results of ANSYS software and experiments, and the experimental results is of flashover data of polymethyl methacrylate （PMMA） and nylon 1010 in transformer oil under coaxial electric field under the applied pulsed voltage in the range of nanosecond .