這篇論文主要為以分切合整解耦數位控制來實現LCL濾波型三相三線轉換器，因為LCL濾波器有著較好的切換漣波衰減特性。在這篇論文中，三相轉換器操作在整流模式;此外，以諧振頻率為基底設計LCL濾波器。採用比例－積分控制來穩直流鏈電壓。除了主要的控制之外，本研究還使用零序空間向量脈衝寬度調製（SVPWM）。

為了減少電網電流諧波，本文提出了一種基於「直接數位控制」的LCL濾波器設計和控制方法的改進。該系統工作在整流模式，具有功率因數校正和直流鏈電壓調節功能。透過解耦合直接數位控制，不需要經由abc到d-q軸變換，並且控制法則可以通過一個開關週期內的電感器電流變化來決定。因此，在考慮電感變化的同時，可以將轉換器視為電流源。所以說，可以直接發出電流命令以補償失真的電流波形。本控制以微控制器Renesas RX62T做為系統的控制核心，即使在有限的電網阻抗和電網電壓諧波下，轉換器也可以準確地對電網電流進行調整。所提出的設計和控制方法已經使用MATLAB Simulink模擬驗證，並以12 kW三相三線轉換器操作在整流模式下所量測的實驗結果進行了驗證。

本研究的主要貢獻可概括為：(1)可以納入電網電壓諧波成分並進行功率因數校正，(2)可以調節直流鏈電壓，便於未來結合綠色能源發電系統，例如:太陽能發電和風力發電，(3)本研究提出了以分切合整（D-Σ）方法所推導之解耦合直接數位控制法則，它改良了傳統直接數位控制法則，(4)本研究還提出了基於諧振頻率的LCL濾波器設計。

This thesis presents a decoupled direct digital control with division-summation (D-Σ) processes for a three-phase three-wire (3Φ3W) converter with LCL filters. LCL filters have better switching-ripple attenuation at a reduced cost. In this thesis, control of a three-phase converter in rectification mode, the design of LCL filters based on resonant frequency and a dc-link voltage regulation method using PI control have been explored. This research uses the positive sequence Space Vector Pulse Width Modulation (SVPWM) in addition to the main control laws.

To reduce grid current harmonics, this thesis presents an improvement of LCL filter design and control method based on direct digital control. The system operates in rectification mode with power-factor correction and dc-link voltage regulation. With the decoupled direct digital control, there is no need of abc to d-q frame transformation, and control laws can be directly determined by inductor current variations over one switching period. Therefore, a converter can be regarded as a current source while considering inductance variation. As a result, current commands can be issued directly to compensate distorted current waveforms. The microcontroller Renesas RX62T is used for the control center of the system. The converter can shape the grid current sinusoidally even under finite grid impedance and grid-voltage harmonics. The proposed design and control methods have been verified through simulation using MATLAB Simulink and through experimental results measured from a 12 kW 3Φ3W converter in rectification mode with LCL filters.

The major contributions of this research can be summarized as: it can accommodate the harmonic components present in the grid voltages and conduct power-factor correction. It can regulate dc-link voltage and incorporate green power, such as solar and wind power in the future. Moreover, this research presents the decoupled direct digital control with division-summation (D-Σ) processes, which is an improved version of the conventional direct digital control. Moreover, this research also presents the design of LCL filters based on resonant frequency.

摘要 i
ABSTRACT ii
ACKNOWLEDGMENTS iii
List of Figures viii-x
List of Tables xi

CHAPTER 1. INTRODUCTION 1

1.1 Motivation 1
1.2 Review of Power-Factor Correction 2
1.2.1 Power-Factor Correction 3

CHAPTER 2. HARDWARE ARCHITECTURE AND CONTROL STRATEGIES 9

2.1 Hardware Architecture 9
2.2 Direct Digital Control 10
2.3 Basic Direct Digital Control Law 10
2.4 Improvement of Direct Digital Control Law 12
2.4.1 Decoupled Direct Digital Control with D-Σ Processes 12
2.5 DC-Link Voltage Regulation Method 17

CHAPTER 3. FIRMWARE PLANNING AND PROGRAM FLOW 19

3.1 Introduction to Microcontroller 19
3.2 Firmware Planning and Program Flow 22
3.2.1 Main Program Flow 22
3.2.2 A/D Interrupt Subprogram Flow 23
3.2.3 Dead Time Compensation 25
3.2.4 DC-Link Voltage Regulation Flow 27

CHAPTER 4. PERIPHERAL CIRCUITS 28

4.1 Auxiliary Power Supply 28
4.2 Driver Circuit for Switches 29
4.3 DC-Link Voltage Feedback Circuit 31
4.4 AC Voltage Feedback Circuit 32
4.5 Inductor Current Feedback Circuit 33
4.6 AC Pre-charge and Relay Circuit 34
4.7 Biased Feedback Circuit for vp 36

CHAPTER 5. SIMULATED AND EXPERIMENTAL RESULTS 38

5.1 Determination of Components 38
5.1.1 DC-Link Capacitor 38
5.1.2 LCL Filter 40
5.2 DC-Link Voltage Regulation 46
5.3 Practical Considerations 47
5.3.1 Inductance Variation 47
5.3.2 Decoupling Capacitor 48
5.3.3 Gate Driver Resistor 49
5.3.4 Switch Driver Voltage 50
5.4 Measured Waveforms 51
5.4.1 DC-Link Voltage Regulation 51
5.4.2 Power-Factor Correction 56

CHAPTER 6. CONCLUSIONS AND FUTURE RESEARCH 71

6.1 Conclusions 71
6.2 Future Research 71

REFERENCES 74

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