Cooling Structure Study Of High-power LED Light And Car Headlamp

Along with the increasingly tensing of energy, the new cold light source LED has causedmore and more attention with high efficiency, low power consumption and long life.High-power LED light source not only can save energy, but also can shorten the responsingtime, therefore it be regarded as the fourth-generation light source.Along with the progressingof technology, to enhance the luminous flux of LED chip and heat dissipation become thekey- issues, which hinder the promotion and popularity of high-power LED lights. As thebrightness of the chip is improved, the chip’s temperature will be also improved. Excessivetemperature can shorten the life of the high- power LED lights or even lead to failure. In orderto solve these problems, the paper studied and optimized the design on cooling devices ofhigh-power LED lights and headlamps.The paper start from the development of LED in the world, discussed the develop historyof LED and automotive lights sources, and their significant research results and key issuesrespectivly. In theoretical level of LED, we first summarized the principles of LED, then weanalysis the optical properties, electrical properties and thermal characteristics of LED step bystep, especially on the LED junction temperature and thermal resistance. And we establishedthermal models. Then we discussed cooling means, cooling fins’efficiency and fin’s formingmethod respectivly.On the basis of theoretical analysis, we developed four kinds of high- power LED lightswith HengGuang Technology Co., Ltd., which have the same light sources, but different coolingdevices. The research methods used here were: 1) we regulated the four lights, and detectedthe temperature and thermal effect at a constant room;2)we used AUTO CAD2004 to design 2Ddrawings and use CATIA V5R17 to design 3D models, which can be imported into the ANSYS11.0 software to simulate. After repeatedly changing the material parameters, wecontrasted the results and found the relationships among cooling area, fin efficiency, powerof unit area and PN junction export-side temperatures. Finally, we calculated the thermalresistances of the four high-power LED lights, and we got relationship between externalresistances and chips’temperature.On the basis of the conclusion: the simulation values can reflect the actual temperaturedistribution and the factors,which can affect cooling device design,we used―LEAF‖headlights as the light source to design two kinds of cooling devices: The device with onlycooling fins and the device with cooling fins and semiconductors. After temperaturefield simulations of twocooling systems, which showed that: the cooling device with convectionalone is insufficient to meet the cooling demand of automotive headlamps’high-power LEDchips, but the increased semiconductor cooling device can effectively reduce the temperatureof the LED chips. Then we replaced of the cooling fin material, the heat sink materialand the MCPCB material and resimulated and obtained the relationship among heatsinkmaterial, MCPCB material, cooling fins material and the chip temperatures. On the basisof the conclusions, we designed air circulating cooling loop in front part of automotive, whichcan efficiently use of convection and reduce the chips’temperature more effectively.This paper ultimately concluded that: the computer simulation can in some extent reflectthe actual temperature distribution.In the design process of high-power LED lights and carheadlamps cooling devices, not only should we enhance the characteristics of the material itself,but also should we consider the combined effects of heat sink fins arrangement, the heat coolingarea and the fin efficiency. Rational cooling device design not only can greatly reduce the chiptemperature, but alsocan improve the life of chips. The experiments and simulations in thispaper can significantly reduce the time and improve the factory’s working efficiency, whichwill provide new ideas and a strong theoretical basis to factories.