| The applications of light-emitting-diode(LED) develop gradually from the traditional small power(indicator light, background light etc.) to the high power applications(mining lamp, street lamp etc.). Meanwhile, the luminous efficiency is improved and the unit cost decreases. The heat and the optical design, which plays a decisive impact on the luminous efficiency, light quality and service life, are the key problems that blocking the development of high-power LED lighting. Therefore, this paper performs systematic study of heat dissipation and the optical design for the high power LED downlight.For the thermal management, the model of high power LED downlight is firstly built using FloEFD simulation software. The performance of the LED downlight adopting four different heat dissipation solutions were compared through finite element analysis. The results shows that the performance of cannular radiator structure with chimney convection effect is the best. Evaluation was carried out by orthogonal test method, and the thickness of tube wall, the thickness of the thermal conducting substrate and the fin number were evaluated. Secondly, the experimental platform is constructed. the optimization scheme through the actual test of the sample and the simulation data are compared to verify the accuracy of the model. Then, the heat dissipation effects for the radiator surface coated with and without high radiation properties coating are compared. Finally, the chimney tubular radiator convection structure analysis, including the effects direction, the fluid temperature, velocity and trajectory parameters are analyzed through the simulations.For the secondary optical design, a design method for TIR(Total Internal Reflection) Lens with small angle is proposed based on the characteristic curved surface. the distribution of the light between two surfaces appropriately is designed to get the surface of the Lens by using the iterative calculation. And a TIR Lens with small angle is designed using this method. The results show that light distribution angle of the designed small angle light distribution lens is 6 degrees, and the illumination uniformity reaches 97%, the energy utilization rate is 85%. This design method can quickly obtain the shape parameters of the lens, which is suited to the design of small angle light distribution lens.Secondly, for the secondary optical design of high power LED downlight, we design a new reflector by software optimization method according to the target light distribution curve and compared with the traditional reflector. The light distribution angle is 80 degrees. The design can solve the problems such as glare effectively, Finally the lighting simulation of the high-power LED downlight is performed to provide some guidance for practical application. |
