通用型光伏系統應用於最大功率點追蹤與升壓之兩級式直流-直流轉換器

Abstract

本研究旨在研製一通用型光伏系統應用於最大功率點追蹤與升壓之兩級式直流-直流轉換器。近年來太陽能被列為最具發展潛力的再生能源，但太陽能板容易受照度、溫度、遮蔭以及元件劣化等因素影響，為了發揮其最大效能，目前太陽能系統皆採用最大功率點追蹤之技術，此外，轉換器的輸出電壓必須負荷後端電力系統的負載。有鑑於此，本論文採用的電路架構為兩級式直流-直流轉換器，其中，第一級為最大功率點追蹤電路，第二級為升壓電路以達到負載所需的電壓位準，並且使用Powersim電力電子軟體完成太陽能光伏電池模型以及電路模擬，並以DSP (TMS320F2808) 為核心演算法及控制技術完成實作。此通用型兩級式轉換器主要應用於遮蔭條件下額定功率600VA以內的系統且效率可達到90%以上。

A new two-stage DC-DC converter for maximum power point tracking (MPPT) and voltage boost of a generic photovoltaic system is designed and realized in this study. Photovoltaic (PV) energy has recently become one of the most potential candidates for renewable energy. To maximize power extraction from a photovoltaic panel under varied conditions of illumination, temperature, shading and degradation, a common technique called the maximum power point tracking technique are largely used for maximizing the efficiency of the PV systems in realistic operations. On the other hand, the output voltage of the converter is constantly required to be large to overcome rear loading of the power transmission system. To these ends, a two-stage DC-DC converter is design herein with the first stage performing MPPT while the second-stage responsible for boost to overcome loading. The system modeling and circuit simulation are achieved using Powersim. The algorithms based on DSP (TMS320F2808) used to adjust switching duty are implemented. The PV string voltage boost circuit is applied mainly for rated power 600VA of the system under partial shading conditions. Results are obtained from the experiment and show that the efficiency achieves over 90%, a satisfactory efficiency for a two-stage converter for a generic PV system.