This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Thermal Simulation of Power Devices in the Power Supply for Automobiles
Published October 22, 2006 by Society of Automotive Engineers of Japan in Japan
A methodology of modelling thermal contact resistance in thermo-fluid analysis software is developed to estimate power device's temperature, the most important value in thermal management of automobile power supply, with accuracy.
To reduce thermal contact resistance of power device, silicon rubber sheet is used for insulation. Rubber sheet can't fill air gap in contact surface completely, so contact pressure has a big influence on thermal contact resistance. The thermal contact resistance was modeled by three steps; 1) Obtain the contact pressure profile by contact simulation, 2) Calculate thermal contact resistance from empirical formula, 3) Fill the contact surface with 250 small plate objects, and change its thermal conductance by importing thermal contact resistance table.
Contact region was tested by impact paper. The reacted area was wider than simulation result in some points, but it agreed on the whole. The difference seems to be caused by the unevenness of the package surface. The developed thermal contact resistance model was applied to the prediction of the power device temperature of DC-DC converter. Even though there were some differences in contact area, predicted chip and cupper flange temperature agreed well with measurement.