固体介质空间电荷与松弛电流的同步测量及应用研究

Simultaneous Measurement and Application of Space Charge and Relaxation Current for Solid Dielectric

为克服固体介质内空间电荷和电导分立测量导致实验数据关联性弱的缺陷,基于电声脉冲法原理设计了一套片状试样空间电荷和电导同步测量系统,以获得同片试样在不同电场下的空间电荷和电导动态响应。首先,通过空间电荷测量中电脉冲响应的仿真计算,分析了电脉冲对同步测量时电导的干扰,并采用空间电荷和电导快速分时切换测量的模式解决电脉冲干扰。然后,基于IEC/TS62758-2012空间电荷测量技术校验规范,采用有机玻璃试样对该系统进行了系统验证,以评估空间电荷测量的准确性。最后,采用该系统对低密度聚乙烯(low density polyethylene-LDPE)试样在室温下进行了不同电场时的空间电荷和电导的同步测量,并根据空间电荷时空分布信息计算出位移电流和传导电流分布。结果表明:高(50kV/mm)电场下,半导电/LDPE试样/铝测量结构中LDPE内的位移电流明显低于传导电流,且传导电流的载流子主要源于电极的表面注入,杂质在高场下的解离对传导电流影响不明显。

To overcome the defect that the weak correlation of experimental results caused by individually measuring space charge and conduction current of solid dielectric, a new type of measuring system based on pulse electro acoustic method（PEA） was designed to perform simultaneous（fast time division） measurement of space charge and conduction current for plate sample in various electric fields. Firstly, electric pulse response during space charge measurement was simulated, the interference to conduction current measurement caused by electric pulse was also analyzed. To handle this problem, fast time division technique was employed to eliminate the interference of electric pulse. And then, to make sure that this system can realize the function of simultaneous measurement of space charge and conduction current, theoretic analysis and experiment verification of PMMA based on IEC/TS62758 technical specification were adopted. Finally, this paper presented the measurement results of space charge distribution and high electric field current in Low density polyethylene（LDPE） plate sample at various electric fields under room temperature. And then the displacement and conduction current distribution were calculated according to spatial and temporal distribution of space charge. The experimental results show that in high（50k V/mm） electric fields, displacement current density is much lower than conduction current density in the measuring structure of semiconducting layer/ LDPE sample and aluminum electrode. And the carrier flow which constitutes conduction current stems from electrode surface injection rather than impurity dissociation.