Researches On Led Intelligent Illu- Mination Systems Based On The Solar

As a kind of clear, renewable and inexhaustible energy source, the solar energy is getting more and more popular around the world. It has become a tendency that the countries all over the world are all propelling the development and utilization of solar energy, especially in the realm of lighting application. However, due to a variety of reasons, the solar lighting systems are not as sustainable and intelligent as expected. Therefore, this thesis has designed an optimized solar lighting system to improve the sustainability and intelligence of the solar lighting system. Compared with the similar solar lighting system, the lighting system designed in this thesis adopts well-selected lighting devices and well-designed software system to achieve the best system performance. The detailed design of this solar lighting system can be summarized as follows:(1) This thesis has introduced the working principle of solar cells and analyzed how the V-A characteristic curve, maximum power point, open circuit voltage, short circuit current, environment temperature and light intensity effect on the performance of solar cells.(2) This thesis has discussed on the selection of lighting devices and energy-storage equipment and analyzed the advantage and working principle of white LED. Through analysis and comparison, the lithium iron phosphate battery and white LED is eventually adopted as the energy-storage equipment and lighting device. The characteristic and working principle of both the lithium iron phosphate battery and white LED are introduced in this thesis.(3) The LPC2103 embedded micro processor is adopted as the controller of the solar lighting system to realize the intelligent adjustment of lighting intensity, system logic control and the charge-discharge control of lithium iron phosphate batteries. The MAX16834 is adopted as the high-brightness LED driver and served as a constant current source. The circuit for MPPT control has also been designed and implemented in this thesis.(4) The thesis has designed the software system and Perturbation & Observation Maximum Power Point Tracking (Perturbation & Observation MPPT) algorithm for the solar lighting system. The LED lighting intensity can be adjusted according to the environment while the MPPT algorithm ensured the best performance of the solar lighting system. Computer simulation by MATLAB has proven the effectiveness of Perturbation & Observation MPPT algorithm.(5) The thesis has summarized all the work aforementioned at the last chapter and discussed about the outlook of solar lighting system. Additionally, a real solar lighting system has been set up for evaluation.The solar lighting system designed in the thesis has adopted white LED and lithium iron phosphate battery as the lighting device and power-storage equipment respectively. The LED lighting intensity and charge-discharge process of lithium iron phosphate battery is under the control of programs to eventually achieve intelligent light intensity adjustment according to different time of the day.