本論文提出一個具有最大功率追蹤(Maximum Power Point Tracking)及冷啟動功能之能源採集系統，DuraCap。此系統係針對無線感測網路(WSN)及手持電子裝置之供電所設計，使用太陽能板(Solar Panel)進行能源轉換，並利用超級電容(Supercapacitor)儲存電力，可提供長時間且穩定的電源，亦解決無線感測平台長久以來使用電池導致操作時間不足的問題。論文中提出一種邊界控制電路(Bound-Control Circuit)，可經由微控制器設定欲追蹤之最大功率點，邊界控制電路即會自動對PFM Regulator進行操作，進而維持太陽能於最大功率點輸出能源。DuraCap亦包含太陽能曲線追蹤器(I-V Curve Tracer)，可經由微控制器監控太陽能板之狀態，藉此計算即時的最大功率點，以維持系統能源收集之效率。此外，針對太陽能於系統中電源輸出路徑之控制，本論文亦開發兩種電源路徑開關(Enhanced Power Path Switch)，可使用較低的閘極控制電壓進行電源路徑切換之控制。實驗結果顯示，DuraCap採用邊界控制電路(Bound-Control Circuit)、PFM Regulator、曲線追蹤器(I-V Tracer)、電源路徑開關(Enhanced Power Path Switch)及超級電容(Supercapacitor)，可有效的降低系統耗電、提高能源收集效率，並且提供無線感測平台穩定且長久的電源，大幅提升其運作時間。

DuraCap is a solar-powered energy harvesting system that stores harvested energy in supercapacitors and is volage compatible with lithium-ion batteries. The use of supercapacitors instead of batteries enables DuraCap to extend the operational life time from tens of months to tens of years. DuraCap addresses two additional problems with micro-solar systems, namely cold booting and maximum power point tracking (MPPT). Cold booting is when the system starts running from the state of total exhaustion of stored energy, and it can be inefficient due to the long charging time of supercapacitors. We solve this problem by dedicating a smaller supercapacitor to this stage before handing over to the array of larger-value supercapacitors. To enable accurate and efficient MPPT, we propose and evaluate a bound-control circuit for PFM regulator switching. The DuraCap also contains an I-V tracer to obtain the I-V curve and P-V curve of the solar panel to enable self-configuring to match solar panels of different types and sizes. Two types of enhanced switch for power path switching are designed for low voltage control that reduces the power consumption. Experimental results show the DuraCap’s bound-control MPPT circuit, enhanced switch, and supercapacitor array achieve the highest conversion efficiency, thereby enabling low power consumption and long operational life time.

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