An Approach to Predicting LED Junction Temperatures With Fluid and Thermal Analysis 2005-01-0864

This study describes a simulation for LED junction temperatures. LEDs will be new light sources for an automotive forward lighting system, for a headlamp. However, some technical problems that have to be addressed still exist for LED applications. Management of the maximum junction temperature on a tip under a phosphor is a fundamental challenge for controlling the LED. Although heatsinks serve as basic and reasonable devices for thermal diffusing, designing an appropriate heatsink generally requires experimentation. As a first step, we created a conduction model for the LED chip in order to apply a Fluid and Thermal Analysis. This allowed us to predict the temperatures of the LED instead of actual testing. We then calculated the LED junction temperatures for three types of heatsinks. We compared them to estimated junction temperatures, based upon measured temperatures underneath the LED, because of the difficulty in measuring the junction temperature directly. Next, for the first generation of LED headlamps, we calculated the junction temperatures of the LED module, which includes a reflector, lens, heatsink, and LED. The result of our study shows that the LED junction temperature is predictable by using the Fluid and Thermal Analysis.