Infrared thermography applied to the validation of thermal simulation of high luminance LED used in automotive front lighting

Abstract

Automotive front lighting evolved toward digital and adaptive high definition beams. In order to create such functions, multiple LED designs are replaced with new LED concepts involving only one high luminance LED. The luminous energy emitted by such a semiconductor light source, up to 3000 lm (i.e. 10 W), induces high density of energy up to 40 W that requires to be thermally managed. Indeed, optical performances and reliability of components are directly linked to the LED temperature. Thus, accurate and efficient numerical models must be developed. In this paper, the validation of the high luminance LED thermal model is achieved by comparing numerical simulations with experimental data. The full characterization of the components is managed in order to build the corresponding thermal model. Then, a well-designed experimental set-up was developed to proceed to LED temperature measurement thanks to IR thermography, involving a camera equipped with a macro lens G1. A temperature uncertainty calculation is performed to introduce a tolerance range for the validation of the software. Finally, the commercial FVM software FloEFD™ is used to compute the LED thermal model. Numerical simulations are compared to experimental data. The agreement between computations and IR thermography is fair, which reinforces the use of the developed model with acceptable accuracy.