Thermo-optical coupling applied to high luminance LED used in automotive front lighting

Abstract

Automotive front lighting evolved towards high definition beams. To create such function, up to several light source per square millimeters are involved. The current trend tends to replace multiple LED designs with only one high luminance LED. The 10W-optical power emitted by this optoelectronic source induces high energy density that requires to be thermally managed. Moreover, when this LED is integrated within its optical system, the radiation concentration can lead to the system self-heating, leading to early damage or failure. The strategy adopted in this paper to avoid the component failure consists in developing an accurate and robust multi-physics simulation to predict heat transfer in a LED lighting system. In this paper, the validation of a high luminance LED thermo-optical coupling model is achieved by comparing numerical simulations with experimental results. The full optical characterization of LED has been performed to build its opto-thermal model. Then, an experimental set-up has been designed and consists in positioning a black plate in front of the LED, to capture its self-heating induced by light energy absorption using infrared thermography. The agreement between thermo-optical simulation and IR thermography is fair, which reinforces the use of the model with an error lower than 10%.