空间电荷

哈尔滨理工大学工学硕士学位论文

摘要

纳米聚合物复合材料作为一种新材料，已经引起了越来越多的关注。通过向聚合物中填加少量的纳米填料，原有的性能将会被改善。纳米氧化镁交联聚乙烯复合介质已经被成功应用于高压直流输电系统中，这种新材料可以提升直流电压下的击穿电压。

在本论文中，将会对外国学者近年来对纳米聚合物复合材料电特性所做的研究和实验结果做总结。它们包括电导率，介电特性，局部放电，电树及空间电荷特性。还会对Toshikatsu Tanaka所提出的用于解释纳米复合材料各种性能的多核模型做介绍。

在实验部分，首先，用电声脉冲法对加入纳米MgO的复合介质做空间电荷测试。发现加入纳米粒子后，空间电荷降低。当填量大于0.5phr时，对空间电荷的抑制作用就会非常明显。

然后，通过光刺激电流法测量了XLPE和MgO/XLPE的陷阱能级。结果发现MgO/XLPE拥有更深的陷阱。

最后，对XLPE和MgO/XLPE的电致发光起始电压及发光光谱进行了测量。结果表明，复合介质提升了EL的起始电压并且降低了发光量。并且XLPE与MgO/XLPE的光谱存在很大的区别。

关键词纳米复合材料，交联聚乙烯，空间电荷，陷阱

- I -

哈尔滨理工大学工学硕士学位论文

Abstract

Polymer nanocomposite materials have been attracting much attention as a new material because the properties of the original material can be drastically improved by adding a few percent of nano-sized filler. It has been found that nano-sized MgO-filler added into XLPE (crosslink polyethylene), which had been developed for HVDC cable insulation, improved the dc breakdown property of conventional XLPE cable.

In this paper, recent topics and their important results will be reviewed on electrical properties of polymer nanocomposite materials. They include characteristics associated with electrical conduction, dielectric properties, partial discharge, electrical treeing and space charge formation. A multi-core model proposed by Toshikatsu Tanaka is discussed to understand various properties and phenomena in nanocomposite.

At first, to investigate the influence of MgO nano-filler on space charge properties, we measured the space charge distributions using PEA (pulsed electro-acoustic method) system under DC electric field. In the case of LDPE with nano-filler, there is less space charge injection than LDPE. It is thought that space charge injection is drastically prevented by adding only more than 0.5phr of MgO to LDPE.

Also, we measured the trap depth of conventional XLPE and MgO/XLPE by using a photo-stimulated discharge system. We found that the trap depth in MgO/XLPE is deeper than in XLPE. Space charge is expected to be closely related to the nature of carrier traps.

Finally, electric field dependence, time variations and the spectra of EL

- II -

哈尔滨理工大学工学硕士学位论文

(electroluminescence) pulses were examined. As the results of these experiments, the addition of MgO nanoparticles in XLPE matrix makes elevate the EL inception level and decrease the number of EL pulses. The EL spectra is different between XLPE and MgO/XLPE.

Keywords: nanocomposite, crosslink polyethylene, space charge, trap, electroluminescence

- III -