A Novel Isolated High Step-Down DC/DC Converter

[[abstract]]本論文提出一種新型隔離式高降壓直流/直流電能轉換器，可應用於通信系統的電源、電動車的電池充放電系統、伺服器的供電系統等場合中。整體電路架構僅使用一個主動開關，且不需極端的責任週期比與匝數比就能達到高降壓比的轉換。此外，無需使用任何的主動或被動箝位電路，即可達到漏感與激磁感能量的回收，因此，減少電路複雜度與成本。因為能回收這些寄生元件的能量，故可有效地抑制主動開關上的突波，進而降低開關耐壓，提升轉換器整體的效率。在論文中針對所提之新型轉換器做工作模式說明、理論分析與公式推導，並且透過軟體模擬，來驗證理論的正確性。論文中，實際製作一輸入400 V、輸出12 V、功率200 W的雛型，藉由硬體來量測以印證所提之新型轉換器的可行性。在量測中，當負載於140 W時，可得最高轉換效率可達93 %。[[abstract]]This thesis presents a novel isolated high step-down dc/dc converter to serve as a power supply for communication power system hybrid electric vehicle (HEV) battery bank and computer server The proposed converter which only requires an active switch can achieve high step-down feature without extreme switch duty cycle or transformer turns ratio In addition the energy stored in leakage inductor can be inherently recycled without the use of any active or passive clamp circuits Accordingly voltage spike on switch converter can be suppressed and conversion efficiency is improved The operation principle theoretical analysis and mathematical derivation of proposed converter are thoroughly described in this thesis To verify the correctness and feasibility of proposed converter a 200-W prototype with 400-V input and 12-V output is implemented and tested From experimental results it is demonstrated that the peak efficiency is up to 93% at 140-