返馳式轉換器因為具元件數量少、成本低、電氣隔離的優勢普遍應用於120W以下的電源轉換裝置。然而，此種架構的開關電壓應力高，且輕載時由於切換損的緣故導致效率低下。本論文基於主動箝位返馳式轉換器的架構提出優化做法，降低開關電壓應力的同時提升了返馳式轉換器的輕載效率。本論文首先介紹了混合箝位返馳式轉換器的原理，並透過時序圖分析各個時段的電路操作模式，比較了兩種箝位模式在輕載時的優劣。其次說明了控制方法，透過偵測輸出電流來進行輕重載切換的調變，使用脈衝寬度調變技術來進行輸出電壓的調節，完成零電壓切換的實現。最後透過模擬以及實測驗證混合箝位返馳式轉換器具備零電壓切換的能力，且有效提升輕載效率。

Flyback power converters are widely used for applications with power ratings below 120W due to their advantages of having few components, low cost, and galvanic isolation. However, this topology faces challenges of high switching voltage stress and low efficiency under light load. This thesis proposes a hybrid clamped flyback converter to reduce switching voltage stress and improve the light load efficiency. The thesis first introduces the operating principles of a hybrid clamped flyback converter and compares the advantages and disadvantages of two clamping modes under different load conditions. Next, the control method is explained, which involves different modulation on light and heavy load switching by detecting the output current to regulate output voltage and achieve zero-voltage switching. Finally, simulation and experimental results confirm the ability of the hybrid clamped flyback converter to achieve zero-voltage switching and to enhance the light load efficiency.

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