潔淨式能源如太陽能電池模組及燃料電池皆為低電壓直流電源，在應用上，往往需要經過一高升壓比直流轉換器，再藉由降壓型反流器以滿足負載或市電併聯的需求，故本文提出一新型單級高升壓比直交流轉換器，以作為此二類能源之介面，俾使系統轉換效率得以提升。
基本上，本論文之主要貢獻茲分述如下：首先，以電容並聯充電、串聯放電之概念，提出一新型單級高升壓比直交流轉換器，所提之新型轉換器具多相電流分擔能力，進而減少開關電流應力，且可有效地降低直流側開關跨壓，故可選用低電壓應力及低導通電阻之開關元件，達到導通損失的降低，進一步提高電路轉換效率。此外，此新型轉換器具高電壓轉換之增益，使其更適用於大電流之低壓潔淨式能源。第二點貢獻則是針對本論文所提之新型轉換器推導其完整數學模型，其中包含直流模型以及交流小訊號模型，此點可做為將來控制器設計之指標，並輔以電路模擬軟體驗證其正確性。第三點貢獻則依據理論分析實際製作一 直流輸入、 有效值交流輸出，以及額定功率 之雛型系統，以驗證新型轉換器的可行性。由實測結果顯示，其轉換效率於 至 的負載情況下均在 以上，最高點可達 ，且低壓側主動開關跨壓較傳統邱克型單級直交流轉換器減少 。由電路模擬與實測結果可驗證本論文所提轉換器之可行性與優越性。

For clean distributed energy resources such as photovoltaic (PV) and fuel cells, their output voltages are rather low. Thus, a step-up DC/DC converter is normally required for boosting to a higher voltage level for the following cascaded inverter. Hence, for further improving the overall conversion efficiency, a novel single-stage high step-up inverter as an interface for these new energy systems is proposed in this thesis.
Basically, the contributions of this thesis can be summarized as follows. First, a novel single-stage inverter topology is proposed for PV or fuel cell systems. The special features include automatic parallel charging and series discharging of two capacitors to provide a rather high step-up ratio, and decrease the electrical stress of the active switches as well with galvanic isolation between input and output. Second, both dc and ac mathematical models are derived for simplifying the design of close loop control. Finally, a 200W, 20V DC input and 110Vrms AC output prototype is implemented. It is seen that the voltage drop across the active switches on low voltage side is 41.7% lower than that of the conventional Ćuk type single-stage inverter, which enables one to use lower RDS(on) MOSFETs. It turns out that the overall efficiency is higher than 90% from 50W to 200W loading. In fact, the highest efficiency, 93%, can be achieved when the load is 150W. Furthermore, both simulation and experimental results indeed verify the effectiveness of the proposed converter.

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