本論文旨在呈現主動箝位返馳式轉換器電路操作原理，並經由文中介紹的設計流程完成實體電路，透過模擬以及實作驗證設計方法之可行性；開關選用上使用了氮化鎵元件而非矽功率開關，以期待未來達成更高切換頻率；輔助開關以及箝位電容可回收儲存在變壓器漏電感中的能量，以減少出現在變壓器一次側的電壓突波，除此之外，主動箝位電路也可以使主開關達到零電壓切換，以減低出現在主開關上的電壓應力。
　　經過原理介紹及設計流程，完成一開關切換頻率為300kHz的主動箝位返馳式轉換器實作電路，於輸入電壓為127V至380V的範圍內，輸出19V/65W的規格，藉此驗證電路系統的運作表現。

The purpose of this thesis is to present the operation principle of Active Clamp-Flyback converter. By the design rule in the content, we can make a circuit, and check the availability by simulation and experimental result. For the expectation of high frequency operation in the future, we use GaN device rather than using traditional Silicon device for all the switches in the circuit. Auxiliary switch and clamp capacitor in the circuit can recycle the energy in the leakage inductor of transformer. In this way, we can eliminate the voltage spike appear in the primary side of transformer and achieve Zero-Voltage-Switching for the main switch so as to reduce the voltage stress on the main switch.
After the introduction of operating principle and design rule, we made an active clamp flyback circuit whose switching frequency is 300kHz, input voltage is 127V to 380V, and output specification is 19V/65W. By the experimental result, we can prove the performance of the circuit.

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