本論文為了達到寬輸入範圍電壓，提出具雙諧振槽 LLC 諧振轉換器。電路架
構可視為兩個半橋電路串聯。本文轉換器操作於兩種模式，而這兩種模式分別以
半橋 LLC 諧振轉換器之電路動作對應兩種不同輸入範圍電壓，模式一用於低電壓
輸入，模式二用於高電壓輸入。在相同的操作頻率與增益特性下，各個模式運作
於不同的開關切換狀態。本論文討論電路運作及分析，且按照設計流程得到電路
參數。最後製作 480 W 電路，在輸入電壓等級為 230 V 滿載狀態下，可得電路最
高效率為 97.85 %。

To achieve a wide input voltage range, an LLC resonant converter with double
resonant-tanks is proposed. The topology can be conceived as two half-bridge circuits
connected in series. The converter is operated in two modes, both are realized with the
operational behavior of a half-bridge LLC resonant converter for two different input
voltage ranges. Among them, Mode 1 is for low input voltage, while Mode 2 is for high
input. With the same operation frequency range and similar gain characteristics, each
mode is performed under different switching pattern. This thesis discusses the circuit
operation and analysis of the converter, followed by the design procedure to obtain circuit
parameters. A 480 W prototype is implemented to validate the proposed circuit, with
maximum efficiency of 97.85% at an input voltage level of 230 V and full load condition.

Contents
論文審定書 ....................................................................................................................... i
Acknowledgement ........................................................................................................... ii
中文摘要 ......................................................................................................................... iii
Abstract .......................................................................................................................... iv
List of Figures ................................................................................................................ vii
List of Tables ................................................................................................................. viii
Chapter 1 Introduction .................................................................................................. 1
1.1 Research Background and Motivation................................................................... 1
1.2 Content Arrangement.............................................................................................. 3
Chapter 2 LLC Resonant converter ............................................................................. 4
2.1 Series Resonant Converter (SRC) .......................................................................... 4
2.2 Parallel Resonant Converter (PRC) ....................................................................... 8
2.3 Series-Parallel Resonant Converter (SPRC) ....................................................... 10
2.4 LLC Configuration ............................................................................................... 12
2.5 Wide Input-Voltage-Range Applications .............................................................. 14
Chapter 3 Analysis of the LLC Resonant Converter with Double Resonant Tanks
........................................................................................................................................ 16
3.1 Circuit Configuration ......................................................................................... 16
3.2 Circuit Operation ................................................................................................ 17
3.2.1 Steady State Operation of Mode 1 ................................................................ 19
3.2.2 Steady State Operation of Mode 2 ................................................................ 23
3.3 Gain Characteristics ............................................................................................. 26
3.4 Design Procedure .................................................................................................. 31
Chapter 4 Experimental Design and Results ............................................................. 37
4.1 Mode 1: Low Input Voltage Range ....................................................................... 37
4.1.1 Circuit Specifications ..................................................................................... 37
4.1.2 Experimental Results ..................................................................................... 39
4.2 Mode 2: High Input Voltage Range ..................................................................... 41
4.2.1 Circuit Specifications ..................................................................................... 41
4.2.2 Experimental Results ..................................................................................... 44
4.3 Circuit Efficiency and Load Regulation for Mode 1 and 2 Voltage Level .......... 47
Chapter 5 Conclusion and Future Work .................................................................... 50
5.1 Conclusion............................................................................................................. 50
5.2 Future Work .......................................................................................................... 51
References...................................................................................................................... 52

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