本論文提出以空間向量脈衝寬度調變(SVPWM)為基礎，透過解耦合分切合整直接數位控制實現的LCL濾波型三相三線轉換器。本研究為縮小濾波元件的體積，選用LCL架構作為濾波器，並根據所使用的開關切換頻率來設計LCL濾波器之諧振頻率，以達到最大的切換漣波衰減特性。本研究的開關切換頻率為19.2 kHz，因此選用Renesas的RX62T微控制器做為控制核心，以滿足多組訊號回授轉換與控制運算的需求。
解耦合分切合整直接數位控制藉由空間向量的觀念，將一個切換週期分切成數個區間，並計算切換週期內開關狀態電壓平均值，進而推導出三相開關責任比率。此控制法可省略三相控制常見的abc至dq框轉換，還可將電感值隨電流值衰退量納入計算，使輸出波形更加精準。而三相轉換器會透過直流鏈電壓穩壓控制，使其能夠雙向傳送能量。除此之外，本論文提出一種電容電流補償控制方法，當電網電壓有諧波成分時，可以利用重複控制的原理計算出電網諧波產生的濾波電容電流，並將其加入至轉換器側電感電流命令中，藉此消除電網諧波對電網側電感電流的影響。
本研究的主要貢獻如下：第一、採用分切合整方法推導之解耦合直接數位控制法，可考慮電感值變化且降低控制方法的複雜程度，並降低濾波元件的體積與成本。第二、使用比例-積分控制器作為直流鏈電壓穩壓控制方式，使三相轉換器能雙向操作。第三、提出電容電流補償機制，能夠消除電容電流對電網側電感電流的影響，使其總諧波失真降至最低。第四、實作一台12 kW三相三線LCL雙向轉換器，並實測電容電流補償機制的補償效果。

This thesis presents a three-phase three-wire LCL bidirectional converter system with SVPWM-based decoupled direct digital control with the division-summation (D-Σ) process. In order to reduce the size of filter, this research chooses LCL as the filter circuit. This research designs the resonant frequency of LCL filter depending on the switching frequency of the converter, in order to obtain the best ripple attenuation performance. The switching frequency is 19.2 kHz. For the requirement of feedbacking many kinds of signals and complex calculation, Renesas RX62T is chosen as the control kernel for its multiple A/D conversion channels and high operating frequency.
Based on the concept of space vector, decoupled direct digital control with the D-Σ process divides one switching cycle into several time intervals, calculates the average value of the switching-state voltage over one switching cycle, and determines the duty ratios of switches. This control method can leave over the traditional abc-to-dq frame transformation processing and take the filter inductance variation into consideration. Based on the dc-bus voltage regulation method, the converter system can bidirectionally transfer power. Besides, this thesis presents a compensation method for grid voltage distortion. When the grid-voltage is distorted, based on the concept of repetitive control, we can use the filter capacitor voltage to estimate the capacitor current. With this estimated capacitor current, the effect of grid-voltage distortion on the grid-side inductor current can be eliminated.
The major contributions of this research are as follows: First, adopting the D-Σ digital control can take the filter inductance variation into consideration and reduce the complexity of control method. Secondly, adopting PI control method to regulate the dc- bus voltage, making the converter be able to transfer energy bidirectionally. Thirdly, presenting a compensation method for grid-voltage distortion. Eliminating the effect of grid-voltage distortion on the grid-side inductor current. Lastly, constructing a 12 kW three-phase three-wire bidirectional converter with LCL filter, and testing the effect of capacitor current compensation method.

摘要 i
Abstract ii
誌謝 iv
目錄 v
圖目錄 viii
表目錄 xii
第1章 緒論 1
1-1 研究背景與動機 1
1-2 文獻回顧 2
1-2-1 轉換器控制策略 2
1-2-2 電容電流補償策略 5
1-3 論文大綱 7
第2章 系統架構與控制策略 8
2-1 三相三線式轉換器系統架構 8
2-2 三相解耦合分切合整直接數位控制 9
2-3 直流鏈穩壓機制 13
2-4 電容電流補償機制 15
2-4-1 補償機制推導 15
2-4-2 穩定性分析 19
第3章 轉換器周邊電路 26
3-1 輔助電源 26
3-2 開關驅動電路 28
3-3 電壓/電流回授電路 29
3-3-1 直流鏈電壓 29
3-3-2 濾波電容電壓 30
3-3-3 電感電流 32
3-3-4 電網電壓 33
3-4 保護電路 35
3-4-1 過壓/過流保護電路 35
3-4-2 電壓箝位保護電路 36
3-5 繼電器與預充電路 36
第4章 系統韌體架構與控制流程 38
4-1 系統韌體架構 38
4-2 微控制器RX62T簡介 39
4-3 轉換器控制流程 42
4-3-1 轉換器主程式 42
4-3-2 轉換器類比/數位中斷副程式 44
4-3-3 直流鏈電壓穩壓程式 46
4-3-4 電容電流補償程式 47
第5章 系統模擬與實測驗證 48
5-1 電氣規格 48
5-2 實務考量 49
5-2-1 電感值變化 49
5-2-2 直流鏈穩壓比例-積分控制參數 51
5-3 Matlab/Simulink模擬 52
5-4 模擬與實測波形比較 54
5-4-1 功率測試 54
5-4-2 電容電流補償測試 59
5-4-3 電網諧波瞬間變化 75
5-5 損耗分析 79
5-5-1 電感損耗 79
5-5-2 功率開關損耗 82
5-5-3 總損耗與效率 83
第6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

[1] "IEEE Recommended Practice and Requirements for Harmonic Control in Electric Power Systems," IEEE Std 519-2014 (Revision of IEEE Std 519-1992) , vol., no., 11 June 2014 , pp.1-29.
[2] W. Taha, A. R. Beig, and I. Boiko, "Design of PI Controllers for a Grid-Connected VSC Based on Optimal Disturbance Rejection," IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society, 2015, pp. 001954-001959.
[3] J. Selvaraj, N. A. Rahim, and C. Krismadinata, "Digital PI Current Control for Grid Connected PV Inverter," 2008 3rd IEEE Conference on Industrial Electronics and Applications, 2008, pp. 742-746.
[4] P. C. Loh and D. G. Holmes, "Analysis of Multiloop Control Strategies for LC/CL/LCL-Filtered Voltage-Source and Current-Source Inverters," IEEE Transactions on Industry Applications, vol. 41, no. 2, March-April 2005, pp. 644-654.
[5] Z. Xin, X. Wang, P. C. Loh, and F. Blaabjerg, "Grid-Current-Feedback Control for LCL-Filtered Grid Converters With Enhanced Stability," IEEE Transactions on Power Electronics, vol. 32, no. 4, April 2017, pp. 3216-3228.
[6] Y.-Y. Tzou and S.-Y. Lin, "Fuzzy-Tuning Current-Vector Control of a Three-phase PWM Inverter for High-Performance AC Drives," IEEE Transactions on Industrial Electronics, vol. 45, no. 5, Oct. 1998, pp. 782-791.
[7] S. Hafsi, M. Dhaoui, and L. Sbita, "Fuzzy Logic Control of Grid-Connected PWM Rectifiers with LCL Filters," 2017 International Conference on Green Energy Conversion Systems (GECS), 2017, pp. 1-6.
[8] T.-F. Wu, Y.-H. Huang, Y.-T. Liu, and M. Misra, "Decoupled Direct Digital Control with D-Σ Process and Average Common-Mode Voltage Model for 3Φ3W LCL Converters," 2019 IEEE Applied Power Electronics Conference and Exposition (APEC), 2019, pp. 601-606.
[9] T. Hua, H. Lin, and X. Wang, "Improved Feedforward Based on Lead Compensation for LCL Grid-connected Inverter," 2020 IEEE 9th International Power Electronics and Motion Control Conference (IPEMC2020-ECCE Asia), 2020, pp. 2420-2425.
[10] W. Li, D. Pan, X. Ruan, and X. Wang, "A Full-Feedforward Scheme of Grid Voltages for a Three-Phase Grid-Connected Inverter with an LCL Filter," 2011 IEEE Energy Conversion Congress and Exposition, 2011, pp. 96-103.
[11] Z. Xin, P. Mattavelli, W. Yao, Y. Yang, F. Blaabjerg, and P. C. Loh, "Mitigation of Grid-Current Distortion for LCL-Filtered Voltage-Source Inverter With Inverter-Current Feedback Control," IEEE Transactions on Power Electronics, vol. 33, no. 7, July 2018, pp. 6248-6261.
[12] X. Zhou and S. Lu. (2020). A Novel Inverter-Side Current Control Method of LCL-Filtered Inverters Based on High-Pass-Filtered Capacitor Voltage Feedforward. IEEE Access. PP. 1-1. 10.1109/ACCESS.2020.2967122.
[13] 吳俊毅，三相三線LCL高切頻雙向換流器研製，國立清華大學電機工程研究所碩士論文，2020 年 7 月。
[14] S. Yang, B. Cui, F. Zhang, and Z. Qian, "A Robust Repetitive Control Strategy for CVCF Inverters with Very Low Harmonic Distortion," APEC 07 - Twenty-Second Annual IEEE Applied Power Electronics Conference and Exposition, 2007, pp. 1673-1677.
[15] T.-F. Wu, M. Misra, Y.-Y. Jhang, and C.-Y. Lin, "Virtual Impedance Based Stability Analysis for Direct Digital Controlled Single-Phase Grid-Connected Inverter with LCL Filter Having Wide Inductance Variation," 2018 IEEE Applied Power Electronics Conference and Exposition (APEC), 2018, pp. 963-968.
[16] Mean Well, LRS-150-24 Datasheet.
[17] LEM, LAX100-NP Datasheet.
[18] Renesas Electronics, RX62T Group User’s Manual, Dec. 2011.
[19] 米達爾，具寬電感值變化單相LCL併網逆變器之直接數位控制，國立清華大學電機工程研究所博士論文，2019 年 7 月。
[20] Chang Sung Corporation, Magnetic Powder Cores.
[21] CREE, C2M0025120D Datasheet.