Research on Solar LED color control technique

• Main Authors: Chun-Wei Chen, 陳俊瑋
• Other Authors: 黃秉鈞
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/80522731559088608408

博士 === 國立臺灣大學 === 機械工程學研究所 === 101 === A 24V stand-alone solar direct battery driving full-color lighting system with tri-chromatic RGB-LED as lighting source has been built in this study. The lighting system could be suit for the plant factory which is stable with temperature and for long-term lighting. Useing a microprocessor and PI feedback control technology to create a PWM constant power control system. The microprocessor could control the switch signal of the MOSFET which is in series with R, G, B LED to adjust the average current and power stability. In the change of the driving voltage of 26V to 23V, the maximum controlled driving power error is below 2.7%. Through exploring the illumination characteristics of R, G, B LED, as chromaticity coordinates and spectrum shift, under different driving voltage while PWM duty cycle is changed, a constant power PWM mixing-color technology has been developed. A thousand kinds of mixing color can be generated by the mixing-color data at a fixing RGB-LED driving voltage. Comparing the measured data with the three test points, the results show that the maximum offset between the measured value and the target point Rt is Δu''v''= 0.00203, and point Gt is Δu''v''= 0.00273, and point Bt is Δu''v''= 0.00083. It means the constant power PWM mixing-color system consists of the mixing-color data can reach the wanted chromatic coordinates within criterion drift Δu''v''= 0.0035. The established constant power PWM mixing-color technology provide a evaluation of mixing-color target error by least squares error analysis. While the driving voltage are 23V, 24V, 25V, and 26V, the constant power PWM mixing-color technology control the color difference under Δu''v''=0.00526 from the white light of color temperature 6500K without illumination and chromatic feedback. The technic in this study realize a mixing-color control system with low cost and could be feasible.