Study on High Frequency Surface Discharge Characteristics of SiO2 Modified Polyimide Film

Abstract

Polyimide (PI) can be used as a cladding insulation for high frequency power transformers, and along-side discharge can lead to insulation failure, so material modification techniques are used. In this paper, different doped nano-SiO2 are introduced into polyimide for nanocomposite modification. The results of testing the life time of high-frequency electrical stress along-side discharge show that the 10% SiO2 doping has the longest life time. The results show that: for composites prone to corona, their flashover causes more damage, and both positive half-cycle and polarity reversal discharges are more violent; compared to pure PI, the positive half-cycle and overall discharge amplitude and number of modified films are smaller, but the negative half-cycle is larger; at creeping development stages, the number of discharges is smaller, and the discharge amplitude of both films fluctuates in the mid-term, with the modified films having fewer discharges and the PI films discharging more violently in the later stages. The increase in the intensity of the discharge was greater in the later stages, and the amplitude and number of discharges were much higher than those of the modified film, which led to a rapid breakdown of the pure polyimide film. Further research found that resistivity plays an important role in the structural properties of the material in the middle and late stages, light energy absorption in the modified film plays an important role, the distribution of traps also affects the discharge process, and in the late stages of the discharge, the heating of the material itself has a greater impact on the breakdown, so the pure polyimide film as a whole discharges more severely and has the shortest life.

Corona Resistance Mechanism of Nano-Modified Polyimide

“…Researchers all over the world are focusing on the research of corona-resistant insulation materials. Experiments show that [21][22][23][24][25][26][27][28][29][30][31][32] inorganic oxides can improve the properties of the matrix to a certain extent, and adding a certain amount of inorganic nano-oxide to a polyimide matrix can greatly improve the corona resistance of polymer insulation materials, thus meeting the operation requirements of the variable frequency motor and ensuring its service life. At the same time, the urgent problem to be solved is clarifying the mechanism of PI film corona resistance as soon as possible, which can provide a feasible technical route for industrial production.…”

DC Surface Flashover Characteristics of Polyimide Containing Polyhedral Oligomeric Silsesquioxane (POSS) in the Main Chains under Vacuum

“…Another method is to carry out molecular modification of polyimide, introducing specific elements such as silicon and phosphorus into diamine monomer or dianhydride monomer, and introducing it into the molecular structure of polyimide through polymerization. Ding and Xing [16,17] used SiO 2 nanoparticles and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (GAPD) to separate polyimide. It showed that both modification methods can obtain the better basic physical and chemical properties of polyimide such as thermal and mechanical properties.…”

Localized Surface Hydrophilicity Tailoring of Polyimide Film for Flexible Electronics Manufacturing Using an Atmospheric Pressure Ar/H2O Microplasma Jet

“…Diverse methods have been proposed to modify PI surfaces, such as chemical processing, photo-irradiation, and plasma treatments [12][13][14]. Among them, plasma treatment is considered the most effective and eco-friendly method due to the advantages of its dry process, low cost, easy operation and rich of various active species.…”