時至今日，雙向直流轉換器在許多電源系統高低壓匯流排之間扮演一關鍵的介面角色，例如：電動車輛、再生能源系統、不間斷電源系統以及電信系統與計算機系統等相關應用，並持續發揮著相當重要的作用。其雙向功率潮流能力致使操作在如太陽能光伏系統與混合動力電動車輛，將使之系統更可靠與靈活。事實上，本文針對再生能源系統提出具電氣隔離以及柔性切換之高升降壓轉換比雙向直流轉換器。
基本上，本論文之主要貢獻茲分述如下：首先本文提出雙向直流轉換器電路拓檏由半橋電路、耦合電感、全橋電路以及諧振電容器和輸出電容器所組成，其具有雙向高轉換比、電氣隔離與柔性切換能力等特點。另外對於各類不同的應用，耦合電感器之耦合係數選擇度提供了很大的設計彈性。第二點貢獻則為針對本文所提雙向直流轉換器，提出一些設計準則以利於設計製作轉換器。最後，本論文實際製作一額定功率為250W，高壓側以匯流排電壓200V而低壓側以電池電壓24V之雙向直流轉換器，並利用數位控制器DSP TMS320F28335變頻操控。由實測結果可知，轉換器工作於降壓模式最高效率約93.3%，而升壓模式最高效率約為92.5%。

Today, bidirectional DC converters (BDC) are playing a much more important role of key component to interface between a high-voltage bus and a low-voltage bus in power systems such as electric vehicles, renewable energy sources, uninterrupted power supplies, telecom and computer systems. The bidirectional power flow capability enables one to operate the corresponding power system such as photovoltaic systems and hybrid electric vehicles more reliably and flexibly. In fact, a BDC with galvanic isolation and high step up/down ratio as well as with soft switching characteristic for renewable energy systems is focused in this thesis.
Basically, the major contributions of this thesis can be summarized as follows. First, a BDC topology consisting of a half bridge, a coupling inductor, a full bridge together with a resonant capacitor and an output capacitor is proposed to achieve high step up/down ratio, galvanic isolation and soft switching capability. The choice of the coefficient of coupling of the coupled inductors can provide one with one more degree of design flexibility for different applications. Second, some design guidelines are also provided for easy design of the BDC. Finally, a 250W prototype with 200V dc bus voltage and 24V battery voltage is implemented with a digital controller using DSP TMS320F28335 to verify the validity of the proposed converter. It is seen that a maximum efficiency of 93.3% can be achieved for forward step-down operation mode, and a maximum efficiency of 92.5% can be obtained for reverse step-up operation.

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