鐵路電池供電系統種類繁多，故其電力來源電壓範圍極大，寬輸入範圍直流轉換器因可滿足不同設施的備貨需求，因此廣泛地應用在鐵路運輸工業中。本論文研製具十倍輸入電壓範圍的兩級式轉換器。第一級轉換器為擁有三模式控制方案的雙開關降壓/升壓轉換器，分別在不同的輸入電壓條件下，使用降壓、升壓和降/升壓模式將寬範圍輸入調整至固定的電壓；第二級轉換器為雙開關返馳式轉換器，為系統提供電氣隔離，並具漏感能量回收機制可有效提升系統效率。本論文首先分析上述兩種轉換器之動作原理，並進行系統參數設計及討論三模式控制方案之設計準則。最後，實作一輸入電壓範圍在16~160 VDC、輸出為5 V/30 A之實驗雛形，以驗證三模式控制方案，實驗結果顯示其於輸入電壓40 V輸入並操作於升壓控制模式時可達最高效率87.5 %。

Railway applications are powered from various railway storage battery system with the wide voltage range. So, the wide input range DC-DC converters are always be adopted in transportation industry applications to reduce inventory requirements. In this thesis, a two-stage converter with a 10:1 input voltage range is implemented. The first-stage is buck/boost converter with a three-mode control scheme. It regulates the wide-range input into fixed voltage via three different modes—buck, boost and buck-boost—based on different input conditions. The second-stage is two-switch flyback converter providing isolation and recycling leakage inductance energy. The operating principles of both converters are analyzed, the system parameters are designed, and the control scheme is discussed in detail. Finally, a two-stage converter is implemented and the three-mode control scheme is verified. The specifications of the input and output voltage range are 16 VDC to 160 VDC and 5 V/30 A, respectively. As the experimental results show, the highest efficiency is 87.5% when the input voltage is 40 V and the converter is operated in boost mode.

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