Novel High Efficiency Isolated-Type Three-Port Bidirectional DC/DC Converter for Photovoltaic Systems

[[abstract]]本文提出一應用於太陽能系統之新型高效率隔離型三端雙向DC/DC轉換器，本文所提出的隔離型轉換器結合了太陽能模組升壓至直流匯流排的高昇壓轉換電路及電池的充放電雙向轉換電路，形成一改良型Boost-Flyback轉換器，當有太陽能時，將太陽能模組升壓提供直流匯流排能量，並對電池充電；當夜晚或遮蔭無太陽能時，電池輸出升壓至直流匯流排提供能量，若電池電量不足直流匯流排在此時也可將多餘能量對電池充電。高壓側的阻隔直流電容器在降壓模式下可以降低變壓器上的電壓達到高降壓功能，在升壓模式時可以回收二次側的漏感能量提高效率。最後，本文以模擬與硬體實作驗證所提出的三端雙向轉換器，總功率為500W，太陽能模組升壓最高效率95 2%，電池升壓最高效率為94 2%，降壓效率最高97 6%。[[abstract]]This paper proposed a novel high efficiency isolated three-port bidirectional DC/DC Converter for Photovoltaic Systems The proposed isolated converter contains a high step-up converter from PV modules to DC bus and a bidirectional charge and discharge control circuit for battery to institute into an improved Boost-Flyback converter When the energy supplied from the PV modules is sufficient it can step-up the output of PV modules and provide energy to the DC bus while charging the battery at the same time However the DC bus voltage is provided by the battery while lack of energy supply from the PV modules When the proposed converter is operated at the step-down mode the DC-blocking capacitor in the high-voltage side is used to reduce the voltage on the transformer and achieve a high step-down performance Moreover the energy stored in the leakage inductance is recycled to the DC-blocking capacitor during the step-up mode to improve the system’s overall efficiency Finally a 500W three-port bidirectional converter was implemented to verify the feasibility and practicability The maximum efficiency of the proposed converter operated under high step-up mode for the PV modules is 95 2% while battery step-up mode is 94 2% and step-down mode is 97 6