本論文主要研製一台具同步整流之多諧振式轉換器，其變壓器一次側上下橋開關皆具零電壓切換的特性，減少切換損耗；變壓器二次側由同步整流開關取代蕭特基二極體，以減少導通損耗，提升電路整體效率。利用比流器偵測變壓器一次側電流，並透過施密特觸發器產生控制信號來驅動同步整流開關。在保護電路的功能，額外增加諧振元件，解決過載和短路問題，並加入高次諧波(比如三次諧波)，使電流波形更接近方波，有效地降低電流的有效值。
本文介紹多諧振式轉換器之動作原理，並利用數學軟體Mathcad和諧振槽轉移函數繪製出品質因數Q、電感比值K，以利掌握設計參數對諧振槽增益曲線上的變化趨勢，最後實際設計一輸入直流電壓為380 V、輸出直流電壓為12 V / 54 A、最大輸出功率為650 W之半橋多諧振式轉換器。

This thesis presents the study and implementation of a half-bridge multi-element resonant converter with synchronous rectification. The transformer primary-side switches possess the turn-on zero-voltage switching (ZVS) in order to reduce the switching losses. Because of the low output voltage and high output current, the synchronous rectifiers are used instead of the schottky diodes on the secondary side to reduce the conduction losses and improve the overall efficiency. Synchronous rectification control signals are detected by the current transformer. The current transformer detects transformer primary-side current. And control signals are generated by the Schmitt trigger to drive the synchronous rectifier. With an additional resonant element component to solve the current protection issues and injection of higher-order harmonics to reduces rms current.
Firstly, the analysis of basic theories for multi-element resonant converter are discussed. Then, according to the derived transfer function of the resonant tank, a mathematical software Mathcad is used to plot the different parameter curves for quality factor (Q), inductance ratio (K) on the frequency response on the voltage gain of resonant tank. Finally, the output specifications of a half-bridge multi-element resonant converter are an input voltage of 380 V, an output voltage of 12 V, an output current of 54 A and an output power of 650 W was implemented.

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