Design And Implementation Of LED Automotive Headlamp Lighting System

As a new type of light source of the21stcentury, high-power LED(Light Emitting Diode)has a lot of advantages, such as small size, long life, high luminous efficiency, energy saving,short response time, and so on. Those make it become the fourth generation light source of theautomotive headlamps. However, the light type of the automotive low-beam is special, itrequires not only a clear cut-off line, but also to have the important points and areas toachieve specific illumination values. Thus, we shall choose an appropriate automotiveheadlamp lighting system. In this thesis, the characteristics of LED light source and opticaldesign methods based on free-form theory are described in detail, meanwhile, muchexploration and research have been carried out on the optical design methods of LEDautomotive headlamp system and its feasibility.Firstly, according to the features of LED light source, a projector low-beam system,which consists of the ellipsoidal reflector, baffle and freeform lens, was presented. Based onnon-imaging optics theory, the correspondence between the angle of the light reflected by theellipsoidal reflector and the coordinates of point in the target plane was established. Thefreeform lens point coordinates calculated according to the correspondence and reflection andrefraction laws was fitted to surface entity by mechanical modeling software. The aboveoptical models are imported into the optical software to simulate by Monte Carlo ray tracingmethod. The results show that light distribution of lens is fully satisfied the national low-beamstandards, and the system has a small size, broad vision, high efficiency of incident rays. Atthe same time, the correctness of the design method has been verified through the abovework.Secondly, we select the most appropriate passive cooling solution by comparing thecooling methods of automotive headlamps and combining with realistic economic conditionsand the difficulty of processing. Import the aluminum radiator model which has brass insideinto the thermal simulation software, it is verified that the radiator can be applied in theautomotive low-beam, the temperature of LED light source does not exceed the maximumjunction temperature, and the LED light source can work normally even in the harsh hightemperature environment.Finally, we design the LED high-beam lighting system. Verification for the LEDautomotive low-beam system is performed. The steps are selecting the actual LED lightsource, producing the above optical components, assembling the components. After the seriesof preparations, the model is been tested in a dark room. The test results show that the nearly bare type gained by the experimental fully satisfied the national low-beam and high-beamstandards, and the important points and regions are able to achieve the specified value. Thus,the design methods are proved to be right, and the feasibility of the methods is been verifiedin practice.