為了使主動箝位順向式轉換器之主開關與輔助開關實現零電壓切換,本論文將詳細地介紹與分析一種經改善後的主動箝位零電壓切換(ZVS)順向式轉換器之方法。 轉換器的組成是由傳統ZVS順向式轉換器和一個輔助電路所組成,其中包括一個箝位電容及一個電感,藉由輔助電路,轉換器開關能輕易地實現ZVS效果於寬廣負載變動範圍,同時二次側使用同步整流技以降低導通損失。除了電路分析之後,文中並使用IsSpice軟體作為電路模擬於驗證理論分析之正確性。 最後在研究室中研製了一組輸入電壓為48 V、輸出為5 V/ 3.5 A與切換頻率為200 kHz之主動箝位順向式轉換器。在實作結果與理論分析相互驗證下,均呈現良好的符合結果。
In order to achieve zero voltage switching (ZVS) for the both primary switching and auxiliary switch in the active clamp forward converter, an improved active clamp ZVS forward converter is presented and analyzed in detail in this thesis. The converter is composed of a conventional ZVS forward converter and an auxiliary network which consists of a clamp capacitor and an inductor. With the help of auxiliary network, the switches could easily achieve ZVS and reduce the switching losses in wide-load range. Furthermore, the synchronous rectification (SR) is used at low side to reduce the conduction losses. In addition to the circuit analysis, the IsSpice simulation is also applied to verify the accuracy of theoretical analysis. Finally, the prototypes of an active clamp forward converter with an input of 48 V, on output of 5 V/ 3.5 A, and the switching frequency of 200 kHz has been implemented in the laboratory. In general, good agreement is observed between the theoretical and experimental results.