一般的串聯諧振轉換器(Series Resonant Converter, SRC)在輕載操作時，諧振電流不夠大造成開關無法零電壓導通，本論文提出一種半橋SRC電路操作在輕載時其中一個開關也能零電壓導通的控制策略。整體電路架構中，前級為主動式功率因數修正器，後級為半橋式串聯諧振轉換器，上下半橋開關由自製的控制板驅動，輕載時有一個開關可以達成零電壓導通減少切換損，二次側使用同步整流技術以MOSFET代替二極體，其優點為重載時可減少導通損。論文中將和市售的IC CM6900比較，以及闡述如何實現驅動波形。最後將實作一穩壓器(Adaptor)，輸入電壓AC 115 ~ 230V、輸出電壓12V、輸出電流20A、功率開關切換頻率範圍為50 kHz ~ 150 kHz，實驗結果證明輕載時效率確實能夠提升，驗證了理論分析之正確性與可行性。

This thesis is devoted to design an AC-to-DC adaptor for raising the conversion efficiency of a DC-to-DC series resonant converter (SRC) and decreasing the power loss at light-load condition. The front-end part of the adaptor is an active power factor correction circuit to improve the input power factor. The second stage is a half-bridge series resonant converter that utilizes zero–voltage switching and synchronous rectification to achieve high conversion efficiency. The low power consumption at the light-load condition is obtained by using the proposed asymmetric one-sided duty cycle modulation control method. One of the two power switches in the half-bridge SRC features the zero-voltage turn-on at light load. The comparisons will be made between the proposed controller and the commercial IC CM6900. Experimental results are recorded for a prototype converter with an AC input voltage rang from 115 to 230V, an output voltage of 12 V and an output current of 20 A, operating at switching frequency from 50 kHz to 150 kHz.

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