近年來由於能源危機導致各國致力於推動再生能源，其中燃料電池與太陽光伏系統等潔淨式能源，所產生之輸出電壓變動範圍較大，故須透過一升降壓轉換器將其升降至額定電壓。然而，由於切換式電源供應器之切換特性，造成轉換器電壓電流漣波較大的問題，在設計上常需加入漣波消除技術，如主動式濾波器、耦合電感、交錯式架構等，但其往往增加額外成本，也使控制更加複雜。因此，本文針對指導教授為紀念其父潘恭先生(Mr. Kung Pan)百年冥誕所提之低輸出漣波升降壓型直流轉換器(稱低輸出電壓漣波升降壓型KP直流轉換器)進一步探討其特性並推導其數學模型。
本論文之主要貢獻茲分述如下: 本文首先詳加說明低輸出電壓漣波升降壓型KP直流轉換器之工作原理並分析其穩態特性。此轉換器架構簡單，其不僅在一個切換週期內皆有能量由輸入端送至輸出端，更具低輸出電壓漣波的特性。其次，本文推導該轉換器連續導通模式下與不連續導通模式下之數學模型，於連續導通模式下，部份數學模型以自耦變壓器方式而非傳統隔離型變壓器呈現，如此將更貼切顯示該轉換器之特性，即該轉換器有部份能量可以不必經由開關切換而直接傳送至輸出端，因此可以獲得較高效率。最後，實際製作一額定功率200W、輸出電壓48V、輸入電壓40/65V之雛型電路。經實測結果顯示，此轉換器輸出電壓漣波可降至0.1%以下。而其效率於升壓模式時，從10%負載至滿載皆達92.5%以上，最高可達96.89%；於降壓模式時，其效率從10%負載至滿載皆達94%以上，最高為96.78%。

Due to energy crisis and environmental protection demand, a lot of efforts have been made by many countries to promote alternative energy resources. For clean fuel cell (FC) energy and photovoltaic (PV) renewable energy sources, step up/down converters are normally required to regulate the varied generated voltage to a stabilized output voltage. However, the inherent unavoidable voltage and current ripples of switching converters will not only degrade the output power quality but also cause EMI problems. Thus, some ripple reduction techniques have been proposed in literature which will increase the cost and complexity of the system. From the reasons outlined above, this thesis is mainly focused on the further study of a low output voltage ripple step up/down KP DC converter which was proposed by Prof. Pan in memory of his father, Mr. Kung Pan (KP).
The main contributions of this thesis can be summarized as follows. First, the operation principle and some steady state characteristics of the low output voltage ripple step up/down KP converter are presented. It can be seen that both input and output currents of the KP converter are continuous which will not only reduce EMI but also increase the conversion efficiency. Also, from the derived analytic expression of the output voltage ripple, it is seen that the output voltage ripple of the converter can be made very small easily even adopting a small output capacitor. Secondly, models of the converter for both CCM and DCM are derived. For CCM, an auto-transformer model instead of an isolation transformer model is adopted which can explicitly feature the special characteristic of the converter. In other words, part of the energy can be transferred to the output without switching mode operation and hence the converter efficiency can be increased. Finally, a 200W rating prototype with 48V output and 40/65V input is constructed to verify the effectiveness of the converter. Experimental results show that the worst case output voltage ripple is less than 0.1% for both step-up and step-down modes. Furthermore, for step-up mode, the highest efficiency is 96.89% and for step-down mode is 96.78%.

Chinese Abstract............................................I
Abstract....................................................II
Acknowledgement.............................................IV
Contents....................................................V
List of Figure Captions.....................................VII
List of Table Captions......................................XIII
CHAPTER 1 Introduction......................................14
1.1 Motivation..............................................14
1.2 Literature Survey.......................................15
1.3 Contributions of the Thesis.............................16
1.4 Outline of Contents.....................................17
CHAPTER 2 Reviews of Step Up/Down Converters...............18
2.1 Introduction............................................18
2.2 Basic Characteristics of Buck-Boost Converter...........18
2.3 Basic Characteristics of Cuk Converter..................22
2.4 Basic Characteristics of Novel Buck-boost Combining KY and Buck Converters.............................................27
CHAPTER 3 Analysis of Low Output Voltage Ripple Step Up/Down KP Converter...................................................36
3.1 Introduction............................................36
3.2 Circuit Configuration and Operation Principle...........38
3.3 Converter Characteristic Analysis in CCM................50
3.4 Converter Characteristic Analysis in DCM................62
CHAPTER 4 Modeling of Low Output Voltage Ripple Step Up/Down KP Converter...................................................68
4.1 Introduction............................................68
4.2 State-Space Average Model Derivation in CCM.............68
4.3 PWM Switch Model Derivation in DCM......................75
4.4 Converter Open-Loop Transfer Functions and Simulations ............................................................79
CHAPTER 5 Implementation and Experimental Results...........86
5.1 Introduction............................................86
5.2 Design Considerations of Power Circuits.................88
5.3 Hardware Implementation.................................92
5.4 Simulation and Experimental Results.....................94
5.5 Loss Analysis...........................................111
CHAPTER 6 Conclusions.......................................121
6.1 Conclusions.............................................121
6.2 Suggested Future Research...............................122
References..................................................124

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