Research On Heat Dissipation Of High Power LED Light Source

At present, the LED is a mainstay in many field of lighting, but in automotive lighting, it has much more difficulty, especially the application of the headlamp. The main reason is that the problem of LED optical design and heat dissipation is difficult to solve. This paper has made a series of experiments which researched and tested the heat dissipation. we hope to provide some helps for the heat dissipation of the LED headlamp.Through the experiments, the three ways of heat transfer have been researched and analyzed. Firstly, the heat conduction dominated the whole process of heat dissipation of LED devices. In order to spread the heat from the LED junction to the surrounding environment, the heat conduction method was used. The experiment data confirmed the dominant position of heat conduction. Secondly, we studied the heat convection. Through experimental test and curve fitting, it was found that the heat convection curve is the exponential form near the heat source. It was different from the the traditional heat convection’s linear relation, and then a reasonable explanation for this phenomenon was given. Thirdly, we studied the thermal radiation which often be ignored by the people. At last, found it also played an important role in the heat dissipation. For increasing the thermal efficiency, the three kinds of heat transfer methods should be combined reasonably and effectively which resulted in spreading the heat fast when the heat dissipation is hard to deal by LED itself. By researching and analyzing the front three heat dissipation methods, a new type of heat sink structure is put forward finally. This sink adopted the cylindrical metal structure, and combined with heat pipe technology. It was found that the thermal efficiency of the structure was better than the traditional metal structure, and it has small volume, stabilized structure, low price and high cost performance.The last of the paper, there was a research on the effects of temperature to optical parameters of the LED light source. A set of simple experimental device was put forward for testing optical parameters, and it was only used for LED headlamp source. With the experimental research, we has found that there was a linear relationship between the illuminance value and the substrate temperature of LED light source. The value is that illuminance value of three meters away from the light source location, and the value decreases with the temperature increasing. thus, there was also a linear relationship between the substrate temperature of LED light source and the luminous flux or the luminous efficiency.