本論文主要為研製一高功因與高效率之LLC諧振轉換器。此電源供應器之電路架構前級採用升壓型功率因數修正器，來減少電流諧波成份並使輸入電流與輸入電壓同相位，以提高電路之功率因數，後級採用半橋LLC諧振轉換器，利用功率開關之寄生電容及二極體使其達成零電壓切換，來降低切換損失，以達到高功率密度及高轉換效率之要求。本論文除了說明兩個電路架構的動作原理外，並詳述電路之設計考量與所選用之元件參數，而LLC諧振電路分析是使用一階諧波近似法，並搭配Matlab來模擬電壓增益對頻率響應圖，了解品質因數與電感比率對電路特性的影響。本論文實作出一台250W之AC/DC電源供應器，其輸入電壓為90 ~ 264 VAC，輸出直流電壓53V，滿載輸出電流4.72A，整體平均功因達0.94以上，平均效率可達90%且最高效率接近94%，最後，以實驗結果驗證理論分析，並研擬未來研究方向。

This thesis focuses on the design and implementation of a high power factor and efficiency LLC Resonant Converter. The front-end part of the converter is a boost power factor corrector (PFC), used not only to eliminate the current harmonics but also to raise the power factor (PF). The second stage is a half-bridge LLC Resonant Converter. To achieve high power density and high conversion efficiency requirements, the LLC resonant converter utilizes the parasitic capacitances and diodes of the power switch to achieve ZVS, which reduces the switching loss. Besides, this thesis explains the operating principle of the two circuit architectures, and the detail design considerations of component parameters. All the analysis, design and simulation of the LLC resonant circuit are based on the first harmonic approximation (FHA) of the circuit. This thesis designs a 250W AC to DC converter with ac input voltage is 90 ~ 264VAC, output voltage and rated current are 53V and 4.72A respectively. The overall PF is above 0.94. The overall average efficiency can reach 90% and its maximum efficiency is close to 94% for the full load condition. Finally, experiment results are given to verify theoretical analysis. Moreover, future research directions are indicated.

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