本文旨在分析及製作應用於三相市電併網之雙向功能的三相換流器。市電併網需要角位置的估測，本文採用數位鎖相迴路，能有效地估測市電電壓角位置。在三相換流器方面，採用直流鏈電壓及交流側電流的閉迴路控制，維持直流鏈電壓固定，不受電源及負載變動的影響並使電流與市電電壓同相位，具有功率補償及提高直流鏈電壓響應速率，以及改善電流諧波及提高功率因數之優點。本文的三相換流器皆採用同步旋轉座標直、交軸電流閉迴路控制，並完成電流調節器增益的設計，具有快速電流響應的性能。
本文採用32位元之數位訊號處理器TMS320F28335為整體系統之控制核心，完成三相換流器之實體製作，其控制策略皆由軟體程式完成。此系統已完成二組換流器的整合，具有雙向功率轉換功能，且用控制區域網路匯流排作通信介面，以完成二組換流器的通信。當第一組三相換流器將功率饋入直流側，則另一組換流器的功率由直流側饋至市電側，反之亦然。市電側電壓為220V，60Hz，直流鏈電壓為380V，系統整合操作於3kW時，穩態的電流諧波失真率為6.19%，功率因數為0.996；系統整體效率為89%。

This thesis is concerned with the analysis and implementation of bidirectional power flow three-phase inverters for three-phase grid-connected power systems. The digital phase-lock loop (PLL) technique is used to calculate the phase-angle for grid-connected system.
In the three-phase inverter, the dc voltage and ac current closed-loop control strategy is adopted to maintain the dc voltage stable under the power supply or load variation, and make the current in phase with the grid voltage in ac side. The advantages of this strategy are better input-output power balance and faster dc voltage response, reducing the current harmonics and improving power factor. The direct and quadratic axis current closed-loop control strategy with synchronous frame and the design of current controller are used for the three-phase inverters to
improve the current response speed.
In this thesis, a 32-bits digital controller is used as the control core to implement the bidirectional three-phase inverters, and all strategies are accomplished by software. The integration of two inverters with bidirectional power flow conversion is completed by CAN-bus that serves as an interface between two inverters. One of the three-phase inverters transmits power to the dc side while the other three-phase inverter converts power from the dc side to the grid, and vice versa. A prototype of 3kW power conversion system is developed under grid-connection. The dc voltage is 380V and the grid voltage is 220V, 60Hz. Experimental results show that the efficiency of the system reaches 89% with current harmonic distortion of 6.19% and power factor of 0.996.

[1]X. Tang, and Z. Qi,“Energy storage control in renewable energy based microgrid,”Power and Energy Society General Meeting, pp.1-6, 22-26 ,2012.
[2]Y. Chen, and X. M. Jin, “Modeling and control of three-phase voltage source PWM rectifier”, International Power Electronics and Motion Control Conference, vol. 3, no. 1, pp. 427-432, 2006.
[3]Y. Chen, and K. Smedley, “Three-phase boost-type grid-connected inverter”, IEEE Transactions on Power Electronics, vol. 23, no. 5, pp. 2301-2309, 2008.
[4]A. L. Julian, G. Oriti, and T. A. Lipo, “Elimination of common-mode voltage in three-phase sinusoidal power converters, ” IEEE Transactions on Power Electron, vol. 14, no. 5, pp. 982-989, 1999.
[5]簡君哲, ”微電網之三相變頻器併聯控制策略研製”, 國立台灣科技大學電機工程研究碩士論文，民國一百零一年七月。
[6]S. K. Chung, “Phase-locked loop for grid-connected three-phase power converter systems,” IEEE Proceedings Electronic Power Applications, vol. 147, no. 3, pp. 213-219, 2000.
[7]S. A. O. da Silva, E. Tomizaki, R. Novochadlo and E. A. A. Coelho, “PLL structures for utility connected systems under distorted utility conditions,” IEEE Industrial Electronics Conference, vol. 4, no. 1, pp. 2636-2641, 2006.
[8]P. Rodriguez, R. Teodorescu, I. Candela, A. V. Timbus, M. Liserre, and F. Blaabjerg, “New positive-sequence voltage detector for grid synchronization of power converters under faulty grid conditions,” Power Electronics Specialists Conference, pp.1-7, 18-22, 2006.
[9]G. Siyu, and M. Barnes, “Phase-locked loop for AC systems: analyses and comparisons,” IET International Conference on Power Electronics, Machines and Drives, pp.1-6, 27-29, 2012.
[10]G. Carpinelli, F. Iacovone, A. Russo, P. Varilone, and P. Verde, “Analytical modeling for harmonic analysis of line current of VSI-fed drives,” IEEE Transactions on Power Delivery, vol.19, no.3, pp.1212-1224, 2004.
[11]H. Wang, C. V. Nayar, J. Su, and M. Ding, “Control and interfacing of a grid-connected small-scale wind turbine generator,” IEEE Transactions on Energy Conversion, vol.26, no.2, pp.428-434, 2011.
[12]R. Melicio, V. M. F. Mendes, and J. P. S. Catalao, “Electrical grid integration and power quality studies of a variable-speed wind energy conversion system,” PowerTech., pp.1-6, 2009.
[13]M. R. Abedi, and B. M. Song, “Specialized predictive SVPWM current control of back-to-back converters for wind power generation systems,” Power Electronics and Machines in Wind Applications, pp.1-7, 16-18, 2012.
[14]J. Alcala, E. Bárcenas, and V. Cárdenas, “Practical methods for tuning PI controllers in the DC-link voltage loop in Back-to-Back power converters,” Power Electronics Congress, pp.46-52, 22-25 ,2010.
[15]B. Lin, and C. Huang, “Single-phase AC/DC/AC converter based on capacitor clamped topology,” IEE Proceedings Electric Power Applications, vol.152, no.3, pp.464-472, 2005.
[16]A. G. Abo-Khalil, and D. C. Lee, “DC-Link capacitance estimation in AC/DC/AC PWM converters using voltage injection,” IEEE Transactions on Industry Applications, vol.44, no.5, pp.1631-1637, 2008.
[17]D. C. Lee, and Y. S. Kim, “Control of single-phase-to-three-phase AC/DC/AC PWM converters for induction motor drives,” IEEE Transactions on Industrial Electronics, vol.54, no.2, pp.797-804, 2007.
[18]A. E. fadili, F. Giri, H. Ouadi, A. E. Magri, L. Dugard, and A. Abouloifa, “Induction motor control through AC/DC/AC converters,” American Control Conference, pp.1755-1760, 2010.
[19]A. E. Magri, F. Giri, A. Abouloifa, I. Lachkar, and F. Z. Chaoui, “Nonlinear control of associations including synchronous motors and AC/DC/AC converters: A formal analysis of speed regulation and power factor correction,” American Control Conference, pp.3470-3475, 2009.
[20]M. Wu, and R. Zhao, “Method analysis and comparison of SVPWM and SPWM,” Chinese Control Conference, pp.3184-3187, 2010.
[21]H. Bai, Z. Zhao, S. Meng, J. Liu, and X. Sun, “Comparison of three PWM strategies-SPWM, SVPWM & one-cycle control,” The Fifth International Conference on Power Electronics and Drive Systems, vol.2, pp.1313-1316 , 2003.
[22]R. Boopathi, P. Muthukumar, P. M. Mary, and S. Jeevananthan, “Investigations on harmonic spreading effects of SVPWM switching patterns in VSI fed AC drives,” International Conference on Advances in Engineering, Science and Management, pp.651-656, 2012.
[23]B. Wang, K. Huang, J. Cui, and G. Wang, “The performance analysis of double-SVPWM in AC-DC-AC bidirectional converter for AC excited doubly fed generation system,” International Conference on Power System Technology, pp. 22-26 ,2006.
[24]Z. Shu, J. Tang, Y. Guo, and J. Lian, “An efficient SVPWM algorithm with low computational overhead for three-phase inverters,” IEEE Transactions on Power Electronics, vol.22, no.5, pp.1797-1805, 2007.
[25]Z. Shu, N. Ding, J. Chen, H. Zhu, and X. He, “Multilevel SVPWM with dc-link capacitor voltage balancing control for diode-clamped multilevel converter based STATCOM,” IEEE Transactions on Industrial Electronics, vol.60, no.5, pp.1884-1896, 2013.
[26]Robert Bosch GmbH, “CAN Protocol Specifications V 2.0 A&B,” 1991-1992.
[27]T. F. Wu, C. H. Chang, H. C. Wu, J. R. Ciou, and T. S. Lin, “Predictive digital controlled three phase bi-directional inverter with wide inductance variation,” Energy Conversion Congress and Exposition, pp.37-44, 2010.
[28]C. Qiao, T. Jin, and K. M. Smedley, “One-cycle control of three-phase active power filter with vector operation,” IEEE Transactions on Industrial Electronics, vol.51, no.2, pp.455-463, 2004.
[29]A. J. Jin, H. T. Li, and S. L. Li, “An improved control Strategy for the one cycle control three-phase PFC rectifier under unbalanced source," Power Electronics Specialists Conference, pp. 18-22 ,2006.