Research On The Optimization Method Of High Color Rendering White LED Light Mixing Based On PWM Dimming

With the development of LED technology,it has been become a research hotspot in recent years to simulate the full spectrum white light-emitting diode?LED?which is similar to the solar spectrum.Based on pulse width modulation,the optimization dimming method of mixed Light for white light emitting diode with high color rendering index is studied and an intelligence dimming control system is built.The main work are as follows in the dissertation:Firstly,this paper proposes a method of white light mixed for red/green/blue/warm-white?R/G/B/WW?light emitting diode?LED?based on PWM.According to the principle of linear superposition of the relative spectral power distribution?SPD?of a multi-color white LED,the proposed model adopts 1931CIE-XYZ tristimulus to determine the relationship between the color coordinates and the rate of contribution of each channel of the LED clusters.When the color rendering performance is optimized,the function relationship between the luminous flux and duty cycles of the mixed light is established.And the experimental verification is carried out with R/G/B/WW LED clusters.The experimental results show that R/G/B/WW LED module can realize that the color rendering index R_ais larger than95 and its maximum relative error of 1.35%,the correlation color temperature?T_c?,the luminous flux and the luminous efficiency change in the range of 3000?7000 K,200?1000 lm,170?240 lm/W,respectively.Secondly,on the basis of the above-mentioned mixed light-emitting diode?LED?the model of a red/green/blue/cyan/yellow/warm white?R/G/B/C/Y/WW?LED cluster is proposed.Following the principle of the spectral combination of multi-color LEDs,The proposed method adopts 1931 CIE-XYZ tristimulus value to determine the relationship between the color coordinates and the contribution ratio?_G+WW?r₁?,?_B+C?r₂?,?_R+Y?r₃?for each component,i.e.,G+WW,B+C,and R+Y,respectively.Using an optimized traversal range under different flux contribution ratios,i.e.,r₁,r₂,and r_3,a maximum color rendering index of 96.4,97.0,97.3 and 97 is attainable when the correlation color temperatures of the synthesized white LED cluster are 2700,4000,5500 and 7000 K,respectively.Furthermore,experimental verification was conducted with R/G/B/C/Y/WW LEDs.Results show that R/G/B/C/Y/WW LED module can realize tunable white light in a wide range of T_c?2700-?7000 K?.When the luminous flux is set to 500 lm,the maximum relative error of T_cand R_aare 1.96%and 1.24%,respectively,and the luminous efficiency varies in the range 146.81?152.40 lm/W.Finally,based on the above research results,the intelligent lighting control system is established and tested in the office environment.The system functions are as follows:select the current environment through the mobile phone app,and the light source automatically adjusts to the default illumination and color temperature of the required environment based on the optimal color rendering.The test results show that the average illuminance value of the office working face is 337.0 lx,the relative error between the color temperature test value and the set value is not more than 0.56%,and the color rendering index of each area is above 95.2.