Simulating light conversion in mid-power LEDs

A good understanding of the optical and thermal properties of mid-power LEDs requires an accurate simulation of the light conversion process in the phosphor layer and a good description of the major materials properties. A ray-tracing model for the light conversion process is developed in LightTools® and the output is used as input for the thermal model in ANSYS®. The thermal resistances of the main resistors in the junction to case heat flow path are measured and implemented in the thermal model. The results of the optical and thermal simulations using key parameters are compared with the measured values. Depending on the effort used to calibrate the model, deviations of less than ten percent can be achieved. This is typically within the error margin of the experiments. The main source of error is most likely missing information on the precise optical die properties.