The Design For High-power LED Headlamps Research

The human lifes is changing constantly with the rapid development of science and technology since we human beings came into the electrical age. And mankind has also entered the era of high brightness LED lighting at the same time, with the increase of traffic tools such as cars, LED lamps and lanterns have made great development in the field of automotive lighting. As a new green energy, LED has many advantages such as long working hours, low power consumption, quick changing, starting fastly, good color, high luming efficiency and so on, this is the reason why LEDs become the first choice for the cars by the automobile lamps designer. Nowadays, LED application technology has been mature in the low power lighting, and the LED’s ultimate goal is used for the high power road lighting as the headlamps, but the technology is still far away from the ultimate goal because of the high power LEDs thermal issue. As we all know, LED is very sensitive to temperature changing, which the LED average highest temperature can be only125℃at present. But when the temperature of the LED is more than80℃usually, the luminous flux of LED declines largely, light failure phenomenon is serious, even fail. In this paper, in order to solve high temperature and shorten using problems which caused by the heat dissipation of high-power LED headlamps of car, the text has optimized design in two aspects from the cooling device’s structure and control device hardware. The specific work as follows:First of all, LEDs development in the car field at the present is introduced from the development status of LED, the LEDs applied to the actual situation of automobile headlamps lighting and patent situation are showed detailed, and the heat dissipation ways of high-power LEDs and LED headlamps which exists in the home or abroad are analyzed currently, describing the control contents of LED headlamps simply, and the research contents and technical route of the paper are identified.Secondly, the basic power type LED light-emitting principle is introduced, analyses the optical properties, thermal properties and electrical properties, characteristics of LED light source, the thermal model of high power LED package was set up and simulated, three defferent models of LED headlamps are designed by Pro/E software.Moreover, the heat transfer theory and ANSYS analysis software are introduced, and emphatically analyzes the relation between thermal resistance and junction temperature of LED, the three designed model are simplified, these simplified models are imported into ANSYS for thermal analysis simulation research, comparing the temperature distribution of three LED headlamps under two states which includes the natural convection and forced convection.At the last, three typical kinds of LED driver circuit is introduced, and a LED headlamps drive circuit and PWM dimming technology are designed, building experimental platform and testing the temperature finally. Experiments show that this kind model of lamp coincides basically with the simulation results, the simulation results prove correctly, it can reduce the LED junction temperature by using this kind of lamp model.