本論文提出混合切換技術搭配主動式箝位SEPIC (Single Ended Primary Inductor Converter)，以增加零電壓切換之範圍，輸出二極體有零電流切換和切換損失最小化，使轉換器達到輕、薄、短、小、高效率之次世代產品需求。混合切換技術就是在一個週期內將傳統脈波寬度調變的線性電感電流與諧振電路的諧振電感電流做結合，也就是在傳統的定頻脈波寬度調變控制轉換器加入諧振元素，並同時保留定頻的脈波寬度調變轉換器和諧振電路之優點。
論文中詳細介紹與分析混合切換技術，接著介紹主動式箝位SEPIC結合混合切換技術，SEPIC輸入為連續電流，因此傳導性的電磁干擾相對較低，而輸入電感會影響開關零電壓切換之範圍，所以針對輸入電感對開關零電壓切換條件做詳細討論，該架構輸出二極體有零電流切換和最小責任週期損失，此技術不需在原架構上增加元件，其控制為定頻脈波寬度調變，所以控制簡單且可靠度高。
最後以實驗結果證明混合切換主動式箝位SEPIC可行性，再將提出的架構與傳統的做比較，以驗證實用性以及改進後的性能。

This thesis proposes a hybrid-switching technique for active-clamp single-ended primary-inductor converter (SEPIC) in order to increase the range of zero-voltage-switching (ZVS), and enables the output diode to operate in zero-current-switching (ZCS) and minimizing the switching loss. Given the high efficiency and high power density requirements of the switch-mode power supply, the proposed technique is an attractive design for future off-line applications. The hybrid-switching technique incorporates resonant operation into the conventional pulse-width modulation (PWM) circuit in a single switching cycle, while preserving the merits of both PWM and resonant operations.
First, the hybrid-switching technique is introduced and analyzed. Then, the proposed technique integrated into active-clamp SEPIC is discussed. The input current of SEPIC is continuous, therefore the conducted emission is low electromagnetic interference (EMI) features. However, the range of ZVS operation highly depends on the input inductor. Detail analysis is given regarding the relationship between input inductance and range of the ZVS operation. This converter still preserves the ZCS turn-off operation of the output diode and the minimized duty loss. The technique does not require additional components into the original topology. Furthermore, the control scheme is fixed frequency PWM. Therefore, the control is simple and straight forward, while still being highly reliable.
The experimental results of the active-clamp SEPIC integrating the proposed technique are presented. Finally, the performance comparisons between the proposed converter and the conventional converter are shown to verify the feasibility and highlight the improved performance.

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