近年來隨著油價高漲與環保議題受到關注，使得世界各國均積極推動分散式替代能源及再生能源的開發。而在分散式再生能源發電系統中，雙向直流轉換器扮演著甚為重要的角色，因為它具有雙向能源傳遞及彈性控制供電能力，當再生能源無法正常供應或故障時，雙向轉換器可發揮功能提供備用電源迴路。本文針對高效率之目標，提出一新型具低開關跨壓及自動均流特性之交錯式高轉換比雙向直流轉換器，可運用於直流微電網系統。首先，以非隔離型二相交錯式轉換器結合新型四倍壓電路架構作為原理說明。再者基於相同的電路操作原理，所提新型轉換器的電路架構可拓展至非隔離四相、非隔離六相交錯式電路以及另一種隔離型二相交錯式電路，更衍生為廣義隔離型n相交錯式電路。上述這些轉換器，其基本工作原理為內建電容式切換電路基於電容電壓分壓原理，使得電力轉換器不僅能將能量儲存在阻隔電容以達到雙向高轉換比的效果，且能有效的降低各個開關於截止時所承受的跨壓，因此，可選用較低耐壓開關元件以減少開關之切換損失及導通損失，增加轉換器之轉換效率。此外利用交錯式切換技術分散開關的電流應力，可使轉換器具有低電流漣波的特色，進而降低開關的切換及導通損失以提升轉換器之電能轉換效率。另外，本電路具有主動分流特性而不需要額外輔助電路或複雜的控制方法，故在各分路電感電流可以達到主動均流，如此可減少電感導通損失，增加轉換器之轉換效率。最後，依據理論分析的結果，實際製作一組規格為低壓側電壓24V、高壓側電壓400V、輸出功率500W之硬體電路雛型用以實驗驗證轉換器性能。

With global energy shortage and strong environment movements, many countries are encouraging and promoting the development of distributed alternative energy and renewable energy sources. It is well-known that bidirectional dc-dc converters (BDC) play an important role in the renewable energy generation systems. BDC has bidirectional power flow capability with flexible control between the source and load sides that can provide the backup power when the main source is not available or has failed. For this reason, the main objective of this dissertation is therefore to develop a high efficiency high conversion ratio BDC as an interface for DC-based nanogrid applications. In this dissertation, a novel interleaved high conversion ratio BDC with low switch voltage stress and uniform current sharing characteristics is proposed. As an illustration, a two phase interleaved NBDC with a new voltage quadrupler circuit configuration is first given for demonstration. Furthermore, topological extensions which include a four-phase interleaved NBDC, the extended six-phase NBDC, another two-phase interleaved IBDC and generalized configuration using the new voltage quadrupler module for higher bidirectional conversion applications. In these proposed converter topologies, based on the concepts of the voltage division of the capacitor voltage, the energy can be stored in the blocking capacitor set of the BDC converter for increasing the voltage conversion ratio and for reducing the voltage stresses of the switches. As a result, the proposed converter topology possesses the low switch voltage stress characteristic. This will allow one to choose lower voltage rating MOSFETs to reduce both switching and conduction losses, and the overall efficiency is consequently improved. In addition, due to the charge balance of the blocking capacitor, the converter features automatic uniform current sharing characteristic of the interleaved phases without adding extra circuitry or complex control methods. Finally, a 24V low voltage side, 400V high voltage side, and 500W output power prototype circuit is implemented in the laboratory to verify the performance.

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