本文提出一新型單級交/直流(AC/DC)返馳式轉換器，其包含三個輸出繞組且具有同步整流功能。由於三個輸出繞組以串聯結構堆疊，並採用同步整流開關來取代二極體以實現整流。由此可消除二極體於導通時的傳導損耗，並且因為採同步整流開關之故，使得每組繞組的電流皆可雙向流動。因此，輕載繞組上的漏電感能量可以經由負載較重之繞組消耗掉，因而在輕載繞組中不會出現因漏電感能量釋放而產生之瞬態過電壓現象，無需藉由假負載電阻來消耗漏感能量以改善交互穩壓，因此可大幅降低無載的待機功耗。與現有的文獻解決對策相比，所提出的轉換器只採用低成本的類比IC來實現，不需要昂貴的數位控制器，且其多輸出繞組的總匝數比傳統的方式只需更少的圈數，最終並能有效地改善交互穩壓率於±2.26%之內和提升整體效率可達87%。本文詳細介紹了所提轉換器之電路結構和工作原理，並開發一雛型電路進行實驗，實測結果則驗證所提出的轉換器之可行性與有效性。

This dissertation proposes a single stage AC/DC Flyback Converter which contains three output windings with synchronous rectification function to achieve better cross-regulation and efficiency. Because the three output windings are stacked in a series structure and use synchronous rectification instead of diode rectification, the forward conduction loss of the diode can be eliminated, and the current of each winding can flow bilaterally. The energy of leakage inductance can be dissipated through heavy load winding without transient overvoltage in light load winding. Therefore, there is no need to use a dummy load resistor to consume leakage inductance energy for improving the cross-regulation, which can significantly reduce the no-load standby power consumption. Compared with existing methods in the literature, the proposed converter can be realized by simple analog IC with fewer winding turns. Finally, under the extreme load imbalance condition, the cross-regulation is still within ±2.26 %. The maximum efficiency of the proposed converter reaches 87 %, which is about 3% higher than the conventional Schottky diode solution's efficiency. The circuit structure and operation principle are described. A practical prototype and experiment results are implemented to verify the feasibility of the proposed converter.

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