- 學位論文
全橋直流�直流轉換器與同軸變壓器之設計與製作
Design and Implementation for Full-Bridge Converter and Coaxial Transformer
摘要
高功率具隔離之直流�直流轉換器被廣泛的應用於各種場合，如電信機地台的電源或伺服器主機的電源供應器等。許多重要的文獻中亦提出提高轉換器之效率與功效率密度的方法。為了此一目的，全橋軟切換轉換器因應而生，此種技巧可利用開關元件的零電壓切換，來有效的降低切換損失。然而這種做法將需要一額外的電感或較大的漏感來達成，將會提高導通損失並造成功率密度的下降。 在本論文中將採用一低漏感之變壓器，並架設於全橋半軟切的電路上，來增加系統的功率密度。在同軸架構下，其耦合係數會較傳統變壓器高，如此可達成變壓器的漏感最小化，因此轉換器之落後臂可進行硬式切換，而不會造成過大的損失。責任週期丟失亦由於同軸變壓器的低漏感特性而減少。除此之外在本論文中，亦討論變壓器之損失估算以及設計考量。全橋半軟式切換電路其主要優點為，簡單的電路架構以及較廣的 ZVS 操作範圍。 本論文中介紹了不同之同軸架構，分別包括了一對一導線與一對二導線。並利用 Ansoft 來模擬變壓器之漏感與磁性分析。並使用 Saber 以近似的轉換器電路架構，來模擬轉換器的操作模式，並驗證回授控制正確性。在實作中，分別製作四組同軸變壓器以及一組傳統變壓器，安裝於實際全橋半軟切電路中，來驗證其系統之整體效率。
並列摘要
High power isolated DC/DC converters have been extensively used in various applications, such as telecommunication power supplies, server power supplies, and so on. Significant research efforts have been devoted to increase the operating efficiency and power density of the converter.Soft switching full bridge converter has been proposed to meet these goals by establishing zero voltage switching condition across the power transistors. However, a significant inductor is required to facilitate the resonance condition,and results in increased loss and reduced power density of the converter. In this thesis, a full bridge converter with limited soft switching capability and a coaxially-wound transformer are presented to improve the power density. With the coaxial winding structure, the coupling coefficient the transformer will be much higher than conventional transformer, and the resulting small leakage inductance enables hard-switching of the slave leg of the converter with little switching loss. The duty cycle loss of the converter is also reduced thanks to the low leakage inductance of the coaxial transformer. The transformer loss estimation and design are also taken into consideration.The advantages of FBSSS converter are simply circuit and wild ZVS range. Various coaxial structures are presented in the thesis. Detailed simulations using ANSOFT are conducted to observe their magnetic characteristics. These coaxial transformers are constructed in the laboratory and tested with the full bridge converter under soft-switching conditions to evaluate the performance of the entire system.