能源危機爆發後,尋找替代能源便成為世界各國共同努力的目標。太陽能源有取之不盡、用之不竭及無污染的特色,因而太陽能源成為新一代的發電方式。目前的太陽能發電效率普遍都不高,所以如何增加太陽能的發電效率是值得研究的,雖然國外已提出多種方式可追蹤到其最大功率點(MPP),但是大多還是採用被動的追蹤方式來達到最大功率點(MPP)。 本論文設計的目的是要去實現一採用阻抗匹配法的太陽光能發電系統,經由調整DC-DC轉換器中的主動開關之責任週期,去使得太陽電池看進去的內部阻抗跟其外接的負載阻抗匹配,達成最大功率傳輸。控制電路的部分由單晶片PIC18F452為中心,重點為如何有效的取得太陽電池的開路電壓及短路電流,以便正確計算出太陽電池的內部阻抗。本論文使用阻抗匹配法的最大功率點追蹤技術,將能有效預知下次的最大功率點位置,使系統維持工作在最大功率點上,達到最大功率輸出的目的。 最後,經由實測結果,證明此阻抗匹配法的可行性。
After the energy crisis breaking out, looking for the alternative energy sources has become the goal of countries all over the world. The solar energy has inexhaustible and pollution-free characteristics, so the solar energy becomes one of the most potential source of electrical power. Since the efficiency of solar cell is not high at present, and it is also affected by working conditions, and how to extract maximum energy from photovoltaic energy system has been the hot research object. There are many proposals to make the solar energy system to work on maximum power point(MPP). This research adopts the impedance marching method, by varying duty cycle in a DC-DC converter to make the apparent load impedance matching with current system impedance, and reach the mpp operation. We use the single chip PIC18F452, as the center control circuit, and through the measurement of open circuit voltage and short circuit current to get the current system impedance, then force the apparent load impedance to match it to make the solar system working on maximum power point. Finally, real experimental data has been used to verify the feasibility of this method.