本論文提出一具部分功率調節之發光二極體(Light-Emitting Diode, LED) 可調光驅動電路。驅動電路中採用多輸出返馳式轉換器，以多相脈衝寬度調變控制，個別調節三原色LED串列電流，混合成期望的白光色溫。論文內容分析驅動電路的操作模式，推導參數設計方程式。設計兩組實驗電路，分別驅動由相同數目的三原色LED串列組成45-W之LED燈，和三串切入電壓相近的三原色LED串列組成35-W之LED燈。實驗結果顯示，在LED燈可調光範圍中，具部分功率調節功能之驅動電路整體轉換效率比傳統返馳式轉換器高約4%至5%。

An efficient light-emitting diode (LED) driver with dimming control is proposed based on a topology with partial power regulation. The currents on red-green-blue (RGB) LED strings are individually regulated by a multi-output flyback converter. A multi-phase pulse-width modulation scheme is used to dim the RGB LEDs with desired lighting performances. The circuit operation of the driver is analyzed, and then the design equations for designing the circuit parameters are derived accordingly. Two laboratory circuits are designed for a 45-W lamp formed by RGB LED strings with a same number of LEDs and a 35-W lamp with an identical cut-in voltage in three LED strings, respectively. The experimental results show that the overall power conversion efficiency of the driver circuit with partial power regulation is 4% to 5% higher than that of the conventional flyback converter over the dimmable range.

論文審定書 i
中文摘要 ii
Abstract iii
Contents iv
List of Figures vi
List of Tables viii
Chapter 1 Introduction 1
1.1 Research Background and Motivation 1
1.2 Content Arrangement 3
Chapter 2 Introduction to White-Light LEDs and Drivers 4
2.1 White-Light LEDs 4
2.2 Fundamentals of Color Science 8
2.3 Electric Characteristics of RGB LEDs 10
2.4 LED Drivers 12
Chapter 3 Analysis of the Driver with Multi-Phase Dimming 14
3.1 Circuit Configuration 14
3.2 Multi-phase PWM Dimming Control 18
3.3 Power Conversion Efficiency 20
3.4 Circuit Operation 22
3.5 Circuit Analysis 25
3.6 Design Procedure 28
3.7 Feedback Control Circuit 29
Chapter 4 Design and Experiment 32
4.1 Case I: LED Strings with Same Number of LEDs 32
4.1.1 Circuit Specifications 32
4.1.2 Experimental Results 36
4.2 Case II: LED Strings with Same Cut-In Voltage 40
4.2.1 Circuit Specifications 40
4.2.1 Experimental Results 43
4.3 Comparison of Circuit Efficiencies 48
4.4 White-Light Generated with the RGB LEDs 50
Chapter 5 Conclusion and Future Work 53
5.1 Conclusion 53
5.2 Future Work 55
References 56

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