Charge and discharge control of high-performance solar lighting system

• Main Authors: Min-Sheng Wu, 吳民聖
• Other Authors: 黃秉鈞
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/s2m5nb

碩士 === 國立臺灣大學 === 機械工程學研究所 === 93 === A battery charge and discharge control technique for solar lighting system was developed to prevent the battery from being over charged in the daytime and to adjust the discharge power for lighting in order to extend the lighting time at night-time. A linear system dynamics model for battery discharge was first derived in the present study. It is found that a first-order perturbed model can accurately describe the system dynamic behavior of the battery at different operating conditions. A feedback control system utilizing PI control is designed. The closed-loop controller design uses a closed-loop sensitivity function to make a compromise between the disturbance rejection and the system response requirement. The experimental results show that the battery voltage can be controlled within 0.2V for the step change of solar irradiation from 344W/m2 to 862 W/m2. The present study also derives a time-series model for predicting the variation of daily total solar radiation using meteorological data in order to control the discharge power effectively to extend the light hours at night. However, the probability of success in forecasting the daily solar radiation within the range ±2MJ/day m2 is only about 30%. A simple algorithm utilizing the PWM power control technique and open-loop voltage check is thus developed. It is found that the present control system can extend the lighting at night for 5 continuous cloudy and rainy days.