本論文主要為研製一高效率LLC諧振轉換，電路拓樸中包含半橋功率級、諧振槽、變壓器與輸出整流的部份，使用兩個電感與一個電容做為諧振槽元件。LLC諧振式轉換器具有許多優點，它充分利用寄生電容及諧振槽使其達成零電壓切換，降低開關切換損失同時也減少寄生元件引起的不良效應，當輸入電壓下降時亦可透過變頻方式提高電壓增益，維持輸出端穩定。電路分析使用一階諧波近似方法，設計出最佳化得元件參數，搭配MATLAB模擬出電壓增益值對頻率響應圖，了解品質因數(Qe)與電感比值(K)對電路影響。本論文研製出一台150W之轉換器，其輸入電壓為375~405 VDC，輸出電壓53VDC，額定輸出電流2.83A，以實驗結果驗證理論分析，並藉由實驗結果顯示LLC諧振轉換器可提供高效率電源給網通設備、LED照明設備及未來節能應用等使用。

This thesis presents a high efficiency LLC converter including a half bridge stage, a resonant tank, a transformer, and a rectifier. The resonant tank includes two inductors and a capacitor. LLC resonant converter uses parasitic capacitances and the resonant tank to achieve ZVS, which can reduce the switching loss and also can eliminate bad influences from parasitic elements. The voltage drop of an electrical circuit can increase voltage gain by adjusting the switching frequency to let the output voltage stable. The thesis uses first harmonic approximation (FHA) as analysis method. FHA method can optimize element parameters. This thesis uses MATLAB to simulate circuit the relation between gain and frequency, and also shows that quality factor and the rated inductors are how important for the circuit. This thesis implies on 150W LLC resonant converter, output voltage and rated current are 53V and 2.83A respectively. Also experiment results are given to verify theoretical design. The proposed design can be used in Power of Ethernet (POE), power supply of LED and green energy equipment in the future.

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