Research On Application Of High-power White LED To Automobile Headlamps

LED has already been the best choice of the new generation of automobile illuminant because of its smaller volume, longer life, lower power consumption, anti-shake, quick start-up, environmental protection and so on. The application of high-power white LED to automobile headlamps will be the most important factor of the development in automobile LED markets. Domestic automobile industry has been developed very rapidly and there is a good opportunity to apply high-luminance LED. It is very important to develop LED automobile headlamp for promoting domestic automobile industry. One Foshan Company has been taken as the development base; the author studies mainly the key technologies about photometric design and heat-dissipating design by means of the high-power white LED on automobile headlamp. Because of the application of the LED automobile headlamp on automobiles, the technique about changing the automobile body structure is also discussed; the main research of this dissertation is shown as follows:1. Through the analysis to nervous energy situation and the development of automobile industry, the importance of this project is presented. Based on the analysis to the LED characteristics and the development of automobile lamps, the contents and technologies about this project are established.2. According to the characteristics of LED, the author puts forward the scheme of lamps and lantern system design, in which the photometric design for automobile headlamps depends only on reflectors and has no use for lens. By means of the software for photometric design, Photometric Characteristics of Headlamps for motor vehicles (GB4599-1994) has been analyzed; the photometric difficulty and technique have also been found out. The type of LED adopted in this project is decided. The necessity and importance to establish illuminant model in simulated conditions are analyzed. The relationship of LED and reflector has been established through analyzing their relative positions of the illuminant surfaces and the reflectors.3. By means of the curved free-surface design for automobile headlamp reflectors, the design method for reflectors in this project is put forward. The LED quantity used in this project will be estimated. The approximate paraboloid is taken as the reflector surface. To apply three-dimensional software PRO/E and photometric emulate software TracePro; the simulated design is used for their reflector groups and modules of the near headlight and the bright headlight respectively. The photometric emulate data have been got. The samples of the near headlight and the bright headlight are made up. The photometric tests have been accomplished. The photometric test data and the emulate results are compared with the national standards, and the results indicate the success and shortage of the photometric combination design. Finally the feasibility of this combination system design for lamps and lanterns is also discussed.4. The differences of LED headlamps and traditional headlamps in dissipated heat design for automobiles have been pointed. And P-N junction temperature, thermal resistance and heat-dissipated channels have also been analyzed. According to test results, the design project of the heat-dissipated structure has been established, the radiator design completed, and the methods to reduce the interface resistance put forward. The highest P-N junction temperature of LED lamps has been found out, and its thermal resistance model established. The P-N junction temperatures for LED lamps in conditions of natural convection and forced convection have been computed respectively, the project feasibility of heat-dissipated structure design discussed, and the methods to apply this heat-dissipated structure for automobile headlamps also presented here.5. Based on the author's opinion, the reasons of the domestic research about automobile LED headlamps in the backward condition is Analyzed...