Chromatic, Photometric and Thermal Modeling of LED Systems With Nonidentical LED Devices

Abstract

With the emergence of new color-mixing LED systems based on LED devices of different color temperatures, the need for a new modeling technique for LED systems with nonidentical LED devices becomes imminent. This paper presents a modeling tech- nique for LED systems with LED arrays comprising nonidenti- cal LED devices that have nonidentical optical-thermal-electrical properties. Based on a general 3-D photo-electro-thermal LED node model, LED devices of different kinds can be arranged in var- ious array forms according to their system construction and design. By linking the system matrix to the correlated-color-temperature prediction, the proposed modeling technique provides an accu- rate prediction of the temperature distribution, luminous flux, and correlated color temperature of the LED systems. The tempera- ture distribution and light output of the LED systems have been measured using an infrared imaging system and a spectrophoto- colorimeter with an integrating sphere. The modeling technique has been successfully demonstrated and experimentally verified on several LED systems comprising nonidentical LED devices. It is particularly useful as a modeling tool to study new color-mixing LED systems based on different types of LED devices. Index Terms—Correlated color temperature (CCT), light- emitting diodes (LED), lighting system, nonidentical LEDs, photo- electro-thermal (PET), thermal model.