本論文主要研製與比較主動前位順向式與非對稱半橋交流/直流電源供應器，電源轉換器為雙級架構，前級為主動式功因修正電路，而後級則具有同步整流功能之直流/直流轉換器。其中直流/直流轉換器分別採用主動箝位順向式架構與非對稱半橋架構，並分析與比較電路架構，此二種電路架構操作特性相似，且都具有零電壓切換良好之特性。另外，為減少電源轉換器的空載損失，當轉換器空載時，中斷功因修正器與同步整流電路以減少功率消耗，並使用脈波省略技術降低直流/直流轉換器在空載時的損失。最後，經由實作完成輸出直流12V/8A，滿載效率87%以上，功率因數0.95 以上之二種電源轉換器之原型機作為理論分析之驗證。

　This thesis mainly studies and implements two two-stage AC/DC power converters. The front-stage is a power factor correction circuit and the second-stage is a soft-switching DC/DC converter with synchronous rectifier. The DC/DC converter applies active clamp forward converter and asymmetrical half-bridge converter individually. These two circuits have similar zero-voltage-switching operating features, and the main circuit has the same number of components. A comparison between the two topologies is made in this thesis. The power consumption at no load condition can be reduced by disabling the power factor correction circuit and synchronous rectifier. In addition, the pulse skip scheme is used to reduce the losses of the converter at no load condition. Experimental results show that both these two prototypes can achieve 87% efficiency and 0.95 power factor at DC 12V/8A output condition.

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