本論文旨在研製啟動控制策略，以期抑制全橋LLC諧振轉換器在啟動時的湧浪電流。本論文的作法是將全橋LLC諧振轉換器開關在啟動時以半橋的形式切換，僅提供諧振槽一半的輸入電壓，在啟動過程中結合變頻及相移控制，以限制諧振槽的能量。除此之外，藉由狀態平面分析探討切換頻率、諧振電流和輸出電壓之間的關係式，得到其頻率特性曲線。根據此曲線調整操作頻率來限制諧振電流。論文最後以480 W的全橋串聯諧振轉換器，輸入電壓為400 V、輸出電壓為48 V、諧振頻率在100 kHz作為測試平台，並將此方式與一般常用方式作比較，實驗結果證明了此方法優點是可以使用較低頻率啟動且有效抑制啟動時的湧浪電流。

This thesis aims to study and develop a start-up surge-current-restraining strategy for a full-bridge LLC resonant converter. The idea of this thesis is to first operate the full-bridge LLC converter at half-bridge mode, therefore halve the resonant tank voltage into half of input voltage. Afterwards, frequency modulation control and phase-shift modulation control are also applied to suppress resonant tank energy. In addition, the relationship between resonant current, output voltage, and switching frequency based on state plane analysis is investigate to obtain the frequency adjusting curve under the consideration of resonant current limitation. The operating frequency consequently is modulated according to the curve to limit resonant current. At the end of this thesis, a full bridge series resonant converter with 480W, input voltage 400 V, the output voltage 48 V, and the resonant frequency 100 kHz is used as the test platform to compare the method with general method. The experimental results show that the advantage of this method can use lower initial frequency, and be effective to suppress the surge current during start-up moment.

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