掺杂含量对环氧纳米复合电介质陷阱与空间电荷的影响

环氧纳米复合电介质具有抑制空间电荷积聚、高电阻率、高击穿强度等优异性能,对直流电力设备的发展具有重要的作用.但纳米粒子含量对纳米复合电介质陷阱、电导率和空间电荷的影响机理尚不清楚.本文在纳米复合电介质交互区结构模型的基础上提出了计算交互区浅陷阱和深陷阱密度的方法,得到了浅陷阱和深陷阱密度随纳米粒子含量的变化关系.随着纳米粒子含量的增加,浅陷阱密度逐渐增大,深陷阱先增加然后由于交互区重叠的影响而逐渐减少.研究了纳米粒子含量对浅陷阱控制载流子迁移率的影响,发现随着纳米粒子的增多,浅陷阱大幅增多,浅陷阱之间的平均间距迅速减小,导致载流子更容易在浅陷阱间跳跃迁移,浅陷阱控制载流子迁移率增大.建立了纳米复合电介质的电荷输运模型,采用电荷输运模型计算研究了环氧/二氧化钛纳米复合电介质的空间电荷分布、电场分布和电导率特性.发现在纳米粒子添加量较小时,交互区的深陷阱对电导的影响起主导作用;纳米粒子添加量进一步增加,浅陷阱对电导的影响将起到主要作用.

Influence of filler content on trap and space charge properties of epoxy resin nanocomposites

Epoxy resin nanocomposites have excellent properties such as the suppression of space charge accumulation, high resistivity, and high electrical breakdown strength, which play an important role in developing the direct current power equipment. However, the influencing mechanisms of filler content on trap, conductivity, and space charge of nanocomposites have not been clear to date. In the present paper, a method to calculate the densities of shallow traps and deep traps in interaction zones is proposed based on the multi-region structure model of interaction zones, and the dependence of shallow traps and deep traps on filler content is obtained. It is found that the shallow trap density increases with the increase of filler content, while the deep trap density first increases and then decreases with increasing the filler content, which is caused by the overlap of interaction zones. Then, the relation between the shallow trap controlled carrier mobility and the filler content is investigated. With the filler content increasing, the density of shallow traps increases and their mean distance decreases, leading to an increase in the shallow trap controlled carrier mobility. Considering the charge injection from cathode into dielectrics, carrier hopping in shallow traps, charge trapping into and detrapping from deep traps, a unipolar charge transport model is established to study the conductivity and distributions of space charges and electric field in epoxy resin nanocomposites. At relatively low filler content, the charge transport is dominated by deep traps in interaction zones and the conductivity decreases with the increase of filler content. However, the charge transport is determined by shallow traps at relatively high filler content and the conductivity increases.