Study On Cooling Technology Of LED Devices And Lighting

Abstract：With the advantages such as high extraction effiency, long lifetime, firmstructure, low energy consumption and environment friendliness, Light EmittingDiode (LED) which is a kind of solid-state lighting source has been widely used inlighting and instructions fields, and regarded as the fourth-generation light source ofgeneral lighting. However, with the increase of power, the thermal problem has beenmore and more serious. Now it has been the main bottleneck for LED into thegeneral lighting. Therefore, the heat problem of LED devices and lighting is reportedin this paper. Here are the main researches:1. Thermal resistance test method of LEDs is studied. As thermal resistance isone of the important heat characteristic paremeters of LED devices and lighting, it isimportant to test the value of it. At present, infrared thermograpy and electricalparameters are the main methods to test the thermal performance of LEDs. Electricalparameters method is more suitable than infrared thermography. In this paper, thestructure function theory is proposed. We can analyse the internal thermal resistanceof packaging devices from the differential and integral function. Compared withconventional methods, this method has the advantages of high precision and fastspeed. So it is one of the effective means to evaluate the thermal characteristics ofLEDs.2. The experiment that tests the thermal resistance of LED devices and lightingmodule is designed. Utilizing thermal transient tester T3Ster with testing samples andsoftware T3Ster Master with data handling, the differential and integral functioncurves of samples are obtained. The results indicated that the thermal resistance ofthe interface of two different materials is large. Furthmore, the heat resistance of heatsink which contains thermal-conduction resistance and thermal-convection resistancehas accounted for57.42%of total heat resistance. Therefore, the optimal design ofheat sink is very important.3. A new structure of heat sink of LED streetlight is proposed. SoftwareSolidWorks is used for modeling and FLOEFD is used for thermal analysis. From thethermal simulation results of the traditional LED street lamp, it has been found that the high temperature area is between the thermal matrix and fins. Due to thisphenomenon, the working temperature of LED is high. Base on the thermalsimulation of the traditional LED street lamp and the installation method ofstreetlight, getting through the thermal matrix among fins has been suggested. In thisway, the low temperature air under the light source can exchange heat with hightemperature area. The thermal simulation results of LED streetlight using the newstructure heat sink show that the working temperature of light soure is lower about15degree and the high tempareture area lower about12degree than the traditional’s.Compared with the traditional street lamp’s heat sink, the temperature of the newLED streelight’s radiator lower about1.3degree on working. So the cooling capacityof heat sink has been improved.4. To demonstrate the cost advantages of the new LED streetlight, the newsimulation is proposed. According to simulating the traditional LED street lampwhose cooling capacity is comparable to the new LED streetlight, it is concluded thatthe weight of new is lower3.19kg than the traditional’s. Therefore, compared withthe traditional LED street lamp, the cost of new LED streetlight is lower.