Effects of nanoparticles on reducing partial discharge induced degradation of polyimide/Al2O3 nanocomposites
Effects of nanoparticles on reducing partial discharge induced degradation of polyimide/Al2O3 nanocomposites
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DOI：
10.1109/tdei.2018.006807
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发表时间：
2018-04
影响因子：
3.1
通讯作者：
Xin Zhong;Guangning Wu;Yan Yang;Xuhui Wu;Y. Lei
中科院分区：
文献类型：
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作者：
Xin Zhong;Guangning Wu;Yan Yang;Xuhui Wu;Y. Lei
聚酰亚胺（PI）薄膜广泛应用于变频电机的匝间绝缘，但在双极性连续方波脉冲电压（BCSIV）作用下，PI薄膜的局部放电性能普遍下降。本文将纳米Al 2 O3分散在PI（质量分数分别为0、2、5和8%）中，制备PI/Al 2 O 3纳米复合材料。为了从物理、化学和电学的角度了解纳米粒子对PI/Al 2 O3纳米复合材料降解的影响，研究了不同PD老化时间下PI和PI/Al 2 O3纳米复合材料的PD老化特性、微观形貌、键合结构、表面电导率和陷阱能级分布。PD老化结果表明，NC 8（PI/Al_2O_3，质量分数为8%）的寿命比NC 8（PI/Al_2O_3，质量分数为8%）的寿命长Al_2O_3）比PI提高了215.8%（从19.6到61.9min）。微观形貌分析结果表明，纳米粒子的加入可以有效地防止PI在PD老化过程中同一局部点被连续侵蚀。基于键合结构分析，发现纳米粒子/聚酰亚胺界面区域形成的新键首先被破坏，通过吸收PD能量，有助于减少聚酰亚胺分子中其他化学键的解离。研究还发现，在降解过程中产生的导电酸是负责的表面电导率的增加。陷阱能级分布表明，PI/Al 2 O3纳米复合材料的陷阱密度和能量均随降解的进行而降低，而PI的趋势则相反。结果表明，PI/Al_2O_3纳米复合材料的电性能较PI有所改善，从而使PI/Al_2O_3纳米复合材料的电性能得到改善。
Polyimide (PI) films, which are widely used in turn-to-turn insulation of inverter-fed motors, are generally degraded by bipolar continuous square impulse voltage (BCSIV) induced partial discharge (PD). In this paper, Al2O3 nanoparticles were dispersed into PI (with 0, 2, 5 and 8 wt.%) to prepare PI/Al2O3 nanocomposites. In order to understand the effects of nanoparticles on reducing the degradation of PI/Al2O3 nanocomposites from the physical, chemical and electrical point of view, PD aging characteristics, micromorphology, bonding structure, surface conductivity and trap level distribution of PI and PI/Al2O3 nanocomposites under different PD aging time were studied. The PD aging results showed that the lifetime of NC8 (PI/Al2O3 with 8 wt.% of Al2O3) increased by 215.8% (from 19.6 to 61.9 min) compared with that of PI. The micromorphology results indicated that nanoparticles could prevent the same local point of PI from being eroded continuously during PD aging. Based on the bonding structure analysis, it was found that new bonds formed in the nanoparticle/polyimide interfacial region would be destroyed firstly, which helped reduce dissociations of other chemical bonds of polyimide molecules, by absorbing PD energy. It was also found that the conductive acids generated during the degradation process were responsible for the increase of surface conductivity. Besides, the trap level distribution showed that both trap density and energy in PI/Al2O3 nanocomposites decreased as degradation, while the trend of PI was opposite. It indicated the degradation of PI/Al2O3 nanocomposites was mitigated compared with PI, which could be attributed to the improved electrical characteristics of PI/Al2O3 nanocomposites.