Improved Electrothermal Properties and High-Frequency Discharge Performance Verification of MWCNT/SiC Complex-Modified Silicone Gel

Abstract

As power electronic devices continue to advance toward higher voltage and power levels, the issue of insulation failure in silicone gel package materials is becoming more noticeable. Therefore, there is a pressing need to develop a high-performance silicone potting material. This research presents the preparation of a silicone gel filled with multiwalled carbon nanotubes (MWCNTs) and micrometer silicon carbide (SiC) using the physical blending method. Then, the composite’s electrothermal properties and high-frequency partial discharge characteristics are explicitly investigated. The experimental findings indicate that when the MWCNT filling ratio increases from 0%vol to 0.7%vol, the modified silicone gel has pronounced nonlinear conductivity properties, reaching a maximum nonlinear coefficient of 9.34. The rise in shallow and deep trap density ratio expedites the dissipation rate of surface charge. Also, the thermal conductivity is also augmented by 59.38%. Nevertheless, the dielectric loss exhibits a progressive increase. Finally, the modified silicone gel was used in the potting package module, and high-frequency partial discharge experiments were conducted. It was found that the silicone gel filled with 0.3%vol MWCNT/9.7%vol SiC could effectively inhibit the partial discharge. This study will provide practical ideas and a theoretical basis for developing new high-performance insulating materials for the insulated-gate bipolar transistor (IGBT) package.