本論文提出一具效率優化之多輸出電池充電系統，充電系統之第一級為具同步整流及零電壓切換之隔離全橋諧振轉換器，第二級以三組具同步整流之降壓型轉換器分別對三組電池充電。本研究依據三組電池的電壓，使用權重效率法分析輸入電壓對降壓型轉換器的影響，並考慮全橋諧振轉換器的效率，調節全橋諧振轉換器輸出電壓以優化整體充電系統效率。本論文首先分析全橋諧振轉換器與降壓型轉換器之特性，並分析電路等效電阻對效率之影響。最後實作以數位訊號處理器控制之充電系統，實作系統規格如下：全橋諧振轉換器的輸入電壓為390 V、輸出電壓範圍為8-12 V、額定功率為1.2 kW；降壓型轉換器之輸出電壓為1-7 V、電池最大充電電流為50 A、額定功率為350 W，以驗證本論文所提出的效率優化與設計之可行性。

In this thesis, the design and implementation of a multiple-output battery charging system with optimized efficiency is proposed. The first stage is an isolated full-bridge resonant converter with zero voltage switching. In second stage, there are three buck converters which are used to charge three independent battery. And two stages are both with synchronous rectifier to improve the conversion efficiency. According to the battery voltage, the output voltage of the full-bridge resonant converter is modulated to optimize the overall efficiency of the charging system. Not only the efficiency of first stage is calculated at different output voltage, but also the efficiency of three buck converters are calculated by the weighted-efficiency method. Finally, a prototype is built to validate the feasibilities of the proposed method where first stage input voltage is 390 V, output voltage is 8-12 V with rated power of 1.2 kW, and the second stage output voltage is battery voltage of 1-7 V, rated output current is 50 A with rated power of 350 W.

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