Thermodynamic Property Improvement of Silicone Rubber for Traction Transformer Based on Molecular Simulation

The traction transformer is the energy core of electric multiple units and the largest single electrical equipment in terms of weight and volume. In order to achieve lightweight electric traction, a new solution of using a dry-type onboard traction transformer (OBTT) has been proposed to replace the commonly used oil-immersed OBTT. Currently, the surface of the dry-type OBTT winding is mostly covered with epoxy resin (EP) for insulation, relying on train airflow for cooling. However, this approach has drawbacks such as poor heat resistance and difficulty in recycling. Therefore, in this study, a green, recyclable, and more heat-resistant silicone rubber is chosen as the matrix material. Hexagonal boron nitride (h-BN) is selected as a thermal conductive filler to modify the silicone rubber. Molecular simulations are employed to analyze the effects of h-BN content and temperature on the thermodynamic properties of the silicone rubber. The results indicate that when the h-BN loading reaches 40phr, the composite silicone rubber material meets the heat dissipation requirements of the dry-type OBTT.