基于瞬态放电电流法的聚丙烯薄膜中空间电荷密度的动态监测

Dynamic monitoring of space charge density in polypropylene films based on fast-discharge current method

提出了利用过阻尼瞬态放电电流法监测聚丙烯薄膜中空间电荷密度及其演变的方法 .本文研究中首先将聚丙烯薄膜置于40℃烘箱中并在直流电场下极化,极化结束后立即把聚丙烯薄膜串联至含有负载电阻和电感的线路中,同时测量聚丙烯薄膜的短路放电电流.通过比较不同极化电场强度对聚丙烯薄膜过阻尼放电电流波形特性的影响,分析计算得出薄膜样品在放电过程中剩余空间电荷总量和平均电荷密度随时间的变化规律.结果表明:通过瞬态电流法估算获得的薄膜中的剩余电荷密度与热脉冲法测量获得的稳态空间电荷密度相近.因此,认为利用过阻尼瞬态放电电流法可以基本分析出聚丙烯薄膜中空间电荷的分布及变化情况,是一种相比于热脉冲法、激光光强调制法简单而有效的近似方法 .

A method to monitor the space charge density and the evolution of polypropylene film was proposed using Fast-Discharge Current Method. The polypropylene film is placed in the oven at 40 degrees Celsius and polarized under DC electric field. After polarization,the polypropylene film was instantly connected in series to the short circuit that contains load resistance and inductance. Then the short circuit discharge current of the polypropylene film was measured. By comparing the influence of different field strength on the damping discharge current waveform characteristics of polypropylene film,the rule was attained that the remaining amount of space charge and average charge density vary with time of thin film samples. The results show that the residual charge density in the thin films estimated by the Fast-Discharge Current Method is similar to that of the steady state space charge density measured by the Thermal Pulse Method. Therefore,it is inferred that the distribution and change of space charge in polypropylene film can be analyzed by using the Fast-Discharge Current Method,which is a simple and effective approximation method compared to the Thermal Pulse Method and Laser Intensity Modulation Method.