Enhancing Breakdown Strength of Silicone Rubber Insulating Composite for High‐Frequency Transformers

ABSTRACT High‐frequency transformers (HFTs) are the core components in power electronic transformers, whose external packaging electrical insulating materials withstand electric and thermal stresses over extended periods. Liquid silicone rubber (LSR) has received considerable attention in electrical insulation packaging owing to its excellent electrical insulation characteristics, wide temperature range, and effective room temperature curing. In this work, the LSR composites were investigated to improve their high‐frequency electrical insulation properties, processing characteristics, and dielectric properties. The results revealed that the LSR composite with 37.5 wt% SiO ₂ and 12.5 wt% Al ₂ O ₃ (50‐3/1) exhibited excellent electrical insulation performance, with a breakdown strength of 37.7 kV/mm under a 20 kHz bipolar square wave. Additionally, the composite featured improved thermal conductivity (0.61 W m ⁻¹ K ⁻¹ ) and easy processing performance. Therefore, the above characteristics of LSR composites make them a potential high‐frequency insulating material.