Study on Surface Discharge Characteristics of Silicone Gel in Salt Fog Environment

IGBT (Insulated Gate Bipolar Transistor) power modules are the core components of offshore wind power converters, and the rapid development of the offshore power generation industry has driven a significant increase in their demand. Under long-term operating conditions, IGBT modules are susceptible to corrosion from high salt spray penetration, leading to module failure. As the main insulation material for IGBT devices, silicone gel's insulation performance is also affected by salt fog particles, making it necessary to study its insulation performance in a salt fog environment. In this study, silicone gel was subjected to surface discharge testing at different frequencies under varying salt fog concentrations using a controlled variable method, and surface damage characteristics were investigated. The research findings indicate that the starting voltage and flashover voltage of surface discharge are minimally affected by salt fog concentration. the measurement finds that there is a special frequency-induced inflection point phenomenon of surface breakdown voltage at 15 kHz under the salt fog environment. The surface damage morphology of the silicone gel varies at different frequencies, with the most severe damage observed at 15 kHz frequency. These research results can provide valuable insights for the insulation design of IGBT packaging.