Electrical Trees of Silicone Gel Encapsulation Materials in Power Electronic Modules Self-Healing Properties and Influencing Factors

Electric tree is a dendritic channel due to partial discharge, which is a more common form of failure in the insulation system of power electronic modules, and silicone gel is widely used in the package insulation of power electronic modules. On this basis, this article conducts experiments on the growth of electric trees at different frequencies, investigates the initiation and propagation mechanisms of electric tree in silicone gels at high frequencies, and analyzes the mechanism of the effect of frequency on the growth characteristics of electric trees. Furthermore, the self-healing experiments of electric trees at different temperatures and component ratios were carried out to investigate the self-healing behavior of electric trees in silicone gels and its influence mechanism. The experimental results show that Maxwell stress is the main cause of electric tree initiation at high frequencies, and the propagation characteristics of electric trees in silicone gels are different from those of conventional dielectrics. Self-healing in silicone gels can be classified into types I and II, which occur respectively during electric tree propagation and after withdrawal of voltage, and type II self-healing can be further classified into physical and chemical self-healing. The effects of temperature and A-component content on the self-healing properties are also investigated in this article.