本研究旨在對一部單相LCL全橋式併網型換流器進行建模與分析，並利用模擬軟體預測換流器可能面對的問題，最後提出相對應的解決方案，且使用模擬與實測來驗證改善方法的可行性。
在硬體建模方面，拓樸架構與部分硬體參數為已知，可以直接匯入建模軟體中，而剩餘硬體參數必須自行計算與量測，再輸入至建模軟體，例如電磁干擾濾波器串聯漏感值。在韌體建模方面，原系統是使用德州儀器TI TMS320F28069 C2000系列微控制器，為了建立微控制器架構，必須了解載波的生成原理、功率開關切換機制、類比訊號取樣更新邏輯及數位濾波器基本架構。有了以上背景知識，最後才能解析內部控制法，包括鎖相迴路控制、內迴路電流控制及外迴路電壓控制。
由於電網阻抗的關係，單相LCL全橋式併網型換流器可能會有穩定性的問題，尤其是在弱電網的條件下。本研究根據短路比(SCR)研究電網阻抗效應，並在各種SCR下對換流器進行穩定度分析，方法包括根軌跡圖、步階響應、虛擬阻抗及阻抗法分析。
最後提出另一種取樣更新邏輯，並搭配分切合整直接數位控制法，改善當換流器面對電網諧波失真與弱電網時，所產生的輸出電流失真問題。以上解決方法皆使用理論分析、模擬及量測的時域結果證明其效益。
本研究之主要貢獻為：(1)針對一部單相LCL全橋式併網型換流器進行建模，(2)執行系統穩定度分析，了解濾波電感值衰減與電網阻抗變化對系統穩定度的影響，(3)最後針對換流器操作在電網諧波失真與弱電網時，提出有效的解決方案，如分切合整直接數位控制法。
關鍵詞：單相LCL全橋式併網型換流器、換流器建模、穩定度分析、分切合整直接數位控制

This research aims to model and analyze a single-phase LCL full-bridge grid-connected inverter, and use simulation to predict the problems that the inverter may face, and finally propose corresponding solutions.
In hardware modeling, the topology and some hardware parameters are known a priori and can be directly imported into the model. In firmware modeling, the original system uses TI TMS320F28069 C2000 series microcontrollers. In order to build the firmware modeling architecture, it is necessary to understand the carrier generation principle, switching mechanism, analog signal sampling update logic, and the architecture of digital filters. With the above background knowledge, we can finally analyze the internal control methods, including phase-locked loop control, inner-loop current control, and outer-loop control.
Due to line impedance effect, the inverter connected to the grid may cause stability problems, especially under weak grid conditions. This research investigates the grid-impedance effect in terms of short-circuit-ratio (SCR) and conducts stability analysis of the inverter under various SCRs. Then, a direct digital controller for the single inverter is proposed to stabilize the system and reduce current distortion. The modeling and proposed approach are verified with simulated and experimental results.
The main contributions of this research are: (1) modeling a single-phase LCL full-bridge grid-connected inverter, (2) analyzing the system stability to understand the attenuation of the filter inductance and the grid-impedance varation on system stability, and (3) proposing effective solutions are when the inverter is operated under grid-voltage distortion and weak grid, such as the direct digital control method.
Keywords: Single-phase LCL full-bridge grid-connected inverter, inverter modeling, stability analysis, direct digital control

摘要 i
Abstract ii
誌謝 iii
目錄 v
圖目錄 viii
表目錄 xii
第一章 緒論 1
1-1 研究背景與動機 1
1-2 文獻回顧 2
1-2-1 建模軟體 2
1-2-2 以離散域(z域)或連續域(s域)分析換流器系統 4
1-2-3 基本拓樸 6
1-2-4 電感值衰減 7
1-2-5 電網阻抗 8
1-3 論文大綱 11
第二章 系統建模 12
2-1 單相換流器系統架構 12
2-2 硬體參數確認 13
2-3 微控制器簡介 17
2-4 載波生成 19
2-4-1 三角波載波 19
2-4-2 鋸齒波載波 20
2-5 功率開關切換機制 21
2-5-1 單極性電壓切換模式 21
2-5-2 雙極性電壓切換模式 24
2-5-3 切換模式比較與選擇 27
2-6 類比訊號取樣與命令更新邏輯 28
2-6-1 波峰取樣波峰更新 28
2-6-2 波峰取樣波谷更新 29
2-7 數位濾波器 30
2-7-1 二階無限長脈衝響應數位濾波器直接模式二 30
2-7-2 特殊變化型數位濾波器 31
第三章 控制迴路建模 33
3-1 MATLAB/Simulink模擬 33
3-2 鎖相迴路控制 37
3-3 內迴路電流控制 44
3-4 外迴路電壓控制 47
第四章 穩定度分析 49
4-1 絕對穩定度 50
4-1-1 閉迴路增益轉移函數 50
4-2-2 閉迴路增益極零點圖 52
4-2 相對穩定度 54
4-2-1 步階響應 54
4-2-2 虛擬阻抗 56
4-2-3 阻抗法 61
4-3 穩定度分析總結 64
第五章 實測模擬比對與系統改善 65
5-1 電網諧波失真實測與模擬結果 65
5-1-1 電網實測與模擬 65
5-1-2 電網建模結果檢討 68
5-2 電網等效阻抗變化實測與模擬結果 69
5-2-1 電網等效阻抗變化實測與模擬 69
5-2-2 電網等效阻抗變化結果檢討 77
5-3 系統問題預測與改善 78
5-3-1 原換流器系統問題 78
5-3-2 改善方法 79
5-3-3 改善方法模擬驗證 82
第六章 結論與未來研究方向 84
6-1 結論 84
6-2 未來研究方向 85
參考文獻 86

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