| As a new type of semiconductor light source, LED has been widely used in lightingapplications. Compared with conventional automotive headlamps, LED headlamps havevarious advantages, such as more energy saving，longer lifetime, shorter response time,smaller volume, higher color saturation, better shock resistance and so on, therefore areknown as the next generation of automotive headlamps. LED based headlamps currentlypresent a good development trend, and have some applications in high-end automotivemodels. However the design of LED headlamp is difficult which involves several physicalfields. Consequently the mass applications of LED headlamps still have a way to go. Thisthesis has conducted researches of the key technologies of light sources, optical, electric, andthermal on LED headlamps, and the specific efforts are summarized as follows:Firstly, the packaging structure，optical, electric and thermal characteristic of LED arestudied. Then the characteristics and the developments of integrated LED module are studied,and the connections of LED module are analyzed. At last the LED headlamp lighting sourcefor the low beam is designed based on these efforts.Secondly, the important theories and requirements in the national regulations of LEDheadlamps optical design are illustrated. Then the low beam is designed the simulated opticalresults of which by ASAP satisfies the requirements in the national regulations.Thirdly, various methods of LED driver design are studied and a high performance LEDdriver with EMC circuit for the low beam is designed. In order to enrich the function of theLED headlamp, the PWM dimming circuit is proposed.Fourthly, the significance and methods of heat dissipation of LED headlamp have beenresearched and analyzed. Then this thesis designs circuits for thermal management bycontrolling the work conditions of the fan according to the temperature of the heat sink.Lastly, taking the tendency of intelligent control for automotive forward lighting intoaccount, the AFS is researched, and the auto-start function is designed as the earliest attempt. |
