Distribution Design Of High Power LED Lighting Based On Freeform Surface

With the development and progress of material science and process technology, the photoelectric conversion efficiency of LED has a continuous improvement-from less than 1m/W to more than100lm/W. In color, we also make a great progress and so far all colors of visible light can be made. All of these technology progresses expand LED's application areas including not only indicator light and display areas in tradition but also lighting area.Before entering lighting area, first and foremost two crucial problems that are light distribution and heat dissipation should be resolved. Traditional light distribution method is to change light's propagation path through deflection system such as spherical lens, aspherical lens and reflection bowl so as to find the global optimal solution of high energy efficiency. These methods are simple but difficult to get high energy efficiency and illumination uniformity at the same time. According to above shortcoming, combining with related theory of non-imaging optics and freeform surface, in this paper, we design a freeform surface lens being used in LED street lamp lighting which is constructed by bidirectional iteration principle and realizes one-to-one correspondence of light ray space and road grid region. It increases not only energy efficiency but also illumination uniformity. The main contents of this paper include as follows:1. Using the basic principle of freeform surface and combining with LED's distribution curve and theory of space reflection law, this paper introduces in detail design scheme of freeform surface being used in LED street lamp lighting, and proposes two ways of road grid dividing-parallel lines and radial lines. Furthermore, we analyze the impact on construction result using these two dividing ways and their advantages and disadvantages respectively. Besides, we improve the way of constructing freeform surface and design a method to construct freeform surface based on radial lines.2. Under the basic of improving the method of freeform surface constructing, we calculate that specific dots'coordination on freeform surface with the help of MATLAB, and furthermore build 3D-model using the software ProE.3. Beginning with LED's luminescence properties, we analyze lighting situation on the road under the traditional distribution ways of LED array, cylindrical lens and trapeziform reflection bowl. After all, we selectively analyze the impact on energy efficiency and illumination uniformity under the method of freeform surface light distribution. The result shows that energy efficiency and illumination uniformity can reach 84% and 77% respectively using lens combination. Besides, we also analyze the impact on energy efficiency on the road because of error, which verify the feasibility of this method.4. Introducing simply heat dissipation related knowledge about power LED and FEM (finite element) thermal analysis theory. According such theory, in this paper, we simulate heat dissipation under several situations using ANSYS and analyze the corresponding results which show heat dissipation design can greatly decrease LED chip's temperature and it plays an important role in LED lighting.