本研究研製半橋三相四線式換流器模組並聯不斷電系統，採用分切合整數位控制法(D-Σ Digital Control)，並結合脈衝寬度調變(SPWM)以實現回授控制。與傳統類比控制法相比，數位控制在系統功能實現上相對簡單，而分切合整數位控制法透過其控制器設計，能抵消系統參數變化，如直流鏈電壓、電感值以及切換週期變化等對受控體的影響，並能直接計算出開關責任週期。本研究亦在控制法中加入負載阻抗估測，透過每一切換週期下的輸出電壓變化量，分別計算電容電流與負載電流變化量，並搭配分切合整數位控制，以輸出穩定電壓至負載。為了平均分配負載，本研究採用外部均流電路，每切換週期皆能得到平均電流值，並利用電流型控制的優勢，令電流誤差值直接加入控制中，以達到瞬時均流目的。最後透過中央控制單元發送載波同步訊號，探討載波交錯與同步時的輸出電壓特性，由模擬與實驗結果顯示，交錯式載波能降低輸出電壓漣波。當應用於整流性負載時，更能有效地改善電壓失真；然而，模組間的開關切換不同步，將產生高頻環流於各模組間流竄，致使均流效果受到些微影響。
本論文主要貢獻包含：(1)採用分切合整數位控制法，不但簡化繁瑣的計算過程，也將感值衰減與直流鏈電壓變化納入考量，且能夠容許寬廣的感值變化，有效地縮小電感鐵芯體積。(2)透過負載阻抗估測法，在每一切換週期下，皆能即時地將電壓誤差值轉換為電流變化量，並透過分切合整數位控制，輸出穩定弦波電壓至負載。(3)藉由外部電流平均電路，能夠即時得到每一切換週期的平均電流值，實現瞬時均流控制。(4)利用各模組的載波相位相互交錯，使輸出電流漣波相互抵消，有效降低輸出電壓總諧波失真(THD)，且能提高系統之動態響應。最後，本研究利用三部三相四線式換流器模組，模擬與實作驗證其均流與漣波消除效果，並可穩定輸出三相弦波電壓至各式負載。

This thesis presents an SPWM-based division-summation (D-Σ) digital control for three 3-Φ four-wire half-bridge voltage source inverters in parallel. These inverters are operated as an uninterruptible power supply. Compared with analog control, it is easier to implement system function with digital control. A controller which is designed from D-Σ digital control can consider DC bus variation, inductance decay and switching period variation. Moreover, it can calculate duty cycle of switches directly. With a load impedance estimation scheme, it can processes variation of capacitor current and load current, and generate sinusoidal voltage to linear and rectified loads by D-Σ digital control. In order to implement load-sharing control, it needs to obtain output current average with current-sharing circuit every switching cycle. With current mode control, error of current can be added into control directly to achieve current-sharing instantaneously. Finally, all carriers of modules are controlled by external trigger generated from central control unit, to investigate the output voltage performance according to synchroneous and interleaved PWM. The results including THD reduction of output voltages and improvement of dynamic response can be found with interleaving fashion. However, it will weaken current-sharing capability.
The main features of this thesis include : (1)With D-Σ digital control, it can not only simplify calculation process significantly, but also consider the variation of inductance and DC bus voltage. Furthermore, D-Σ digital control allows wide inductance variation to reduce the core size of inductor effectively. (2)With a load impedance estimation scheme, the D-Σ digital control which was originally developed for current tracking can be adopted to generate sinusoidal output voltages for loads. (3)With a current distribution circuit, uniform current-sharing can be achieved on nonlinear load instantaneously. (4) The parallel interleaved inverters can reduce current ripple and THD of output voltage.
In the last, simulated and experimental results obtained from three 10 kVA 3-Φ four-wire half-bridge voltage source inverters in parallel have verified the analysis and discussion.

[1]柯嘉閔，單相半橋在線式不斷電系統之研製，國立成功大學-電機工程學系-碩士
論文，民國91年6月。
[2]蘇育生，以數位訊號處理器為基礎之並聯型單相全橋不斷電系統之研製，國立台
灣科技大學-電機工程學系-碩士論文，民國93年6月。
[3]曾國棟，以數位訊號處理器為基礎之不斷電並聯運轉系統，國立中山大學-電機
工程學系-碩士論文，民國91年6月。
[4]Josep M. Guerrero, Luis Garcia De Vicuna, Javier Uceda,
“Uninterruptible Power Supply Systems Provide Protection,” IEEE
Industrial Electronics Magazine, Spring 2007.
[5]Vitor Monteiro, Bruno Exposto, Joao C. Ferreira, Joao Luiz
Afonso, “Improved Vehicle-to-Home (iV2H) Operation Mode:
Experimental Analysis of the Electric Vehicle as Off-Line UPS,”
IEEE Transactions on Smart Grid, vol. pp, No. 99 pp.1-10, Mar.
2016.
[6]H.-L. Jou, J.-C. Wu, C. Tasi, K.-D. Wu and M.-S. Huang, “Novel
Line-interactive Uninterruptible Power Supply,” IEE Proc.-
Electr Appl., Vol. 151, No. 3, May 2004.
[7]J.-K. Park, J.-M. Kwon, E.-H. Kim, and B.-H. Kwon, “High-
Peformance Transformerless Online UPS,” IEEE Transactions on
Industrial Electronics., Vol. 55, pp.2943-2953, No. 8, August
2008.
[8]E.-H. Kim, J.-M. Kwon, B.-H. Kwon, “Transformerless Three-phase
On-line UPS with High Performance,” IET Power Electron., Vol.
2, Iss. 2, pp. 103-112, 2008.
[9]不斷電電源裝置構造:種類與用法，杜光宗 撰，建宏出版，1991.
[10]T.-F. Wu, T.-H. Shiu, P.-H. Lin, L.-C. Lin, and J.-W. Huang,
“Circulating Current Reduction for a D-Σ Digital Controlled
Transformerless UPS,” IEEE Applied Power Electronics
Conference and Exposition (APEC), 2016.
[11]R. Maheshwari, G. Gohil, L, Bede, and S. Munk-Nielsen,
“Analysis and Modelling of Circulating Current in Two
Parallel-connected Inverters,” IET Power Electron., Vol. 8,
pp.1273-1283, No. 7, Jul. 2015.
[12]Z. Xueguang, C. Jiaming, M. Yan, W. Yijie, and X. Dianguo,
“Bandwidth Expansion Method for Circulating Current Control in
Parallel Three-phase PWM Converter Connection System,” IEEE
Transactions on Power Electronics., Vol. 29, No. 12, pp.6847-
6856, Mar. 2014.
[13]W. Yu, D. Xu, and C. Zhou, “Parallel Control of the UPS
Inverters,” IEEE Applied Power Electronics Conference and
Exposition, APEC 2008.
[14]D. Shanxu, M. Yu, X. Jian, K. Yong, and C. Jian, “Parallel
Operation Control Technique of Voltage Source Inverters in
UPS,” IEEE Power Electronics and Drive Systems, 1999.
[15]T. Kawabata, S. Higashino, “Parallel Operation of Voltage
Source Inverters,” IEEE Transactions on Industry Applications,
Vol 24, Mar/Apr 1988.
[16]M. Prodanovic, T.C. Green, H. Mansir, “A survey of Control
Method for Three-phase Inverters in Parallel Connection,” IEEE
Power Electronics and Variable Speed Drives, 2000.
[17]W.-C. Lee, T.-K. Lee, S.-H. Lee, K.-H. Kim, D.-S. Hyun, and
I.-Y. Suh, “A Master and Slave Control Strategy for Parallel
Operation of Three-phase UPS Systems with Different Ratings,”
IEEE Applied Power Electronics Conference and Exposition,
2004.
[18]J.M. Guerrero, Luis Garcia de Vicuna, J. Matas, M. Castilla,
J. Miret, “Output Impedance Design of Parallel-connected UPS
Inverters with Wireless Load-sharing Control,” IEEE
Transactions on Industrial Electronics, Vol. 52, No 4,
pp.1126-1135, Aug. 2005.
[19]G. J. Capella, J. Pou, S. Ceballos, G. Konstantinou, J.
Zaragoza, and V. G. Agelidis, “Enhanced Phase-shifted PWM
Carrier Disposition for Interleaved Voltage-Source Inverters,”
IEEE Transactions on Power Electronics, Vol. 30, No. 3,
pp.1121-1125, March 2015.
[20]G. Gohil, L. Bede, and R. Teodorescu, T. Kerekes, and F.
Blaabjerg, “Flux Balancing Scheme for PD Modulated Parallel
Interleaved Inverters,” IEEE Transactions on Power
Electronics, Vol. 32, No. 5, pp.3442-3457, May 2017.
[21]X. Shi, Z. Wang, Leon M. Tolbert, and F. Wang, “A
Comparison of Phase Disposition and Phase Shift PWM Strategies
for Modular Multilevel Converters,” IEEE Energy Conversion
Congress and Exposition (ECCE), pp.4089-4096, 2013.
[22]F. Yang, X. Zhao, C. Wang, and Z. Sun, “Research on Parallel
Interleaved Inverters with Discontinuous Space-Vector
Modulation,” EPE, Vol. 5 No. 4B, pp.219-225, July 2013.
[23]S. J. Chiang, and J. M. Chang, “Parallel Control of the UPS
Inverters with Frequency-dependent Droop Scheme,” IEEE Power
Electronics Specialists Conference, pp.957-961, 2001.
[24]C. S. Lee, S. Kim, C. B. Kim, S. C. Hong, J. S. Yoo, S. W.
Kim, C. H. Kim, S. H. Woo, and S. Y. Sun, “Parallel UPS with a
Instantaneous Current Sharing Control,” IEEE Industrial
Electronics Society, pp.568-573, 1998.
[25]P. Liu, C. Chen, J. Cai, and S. Duan, “Stability Analysis
of Instantaneous Average Current Sharing Control Strategy for
Parallel Operation of UPS Modules,” IEEE Energy Conversion
Congress and Exposition (ECCE), pp.1238-1242, 2015.
[26]Y. Zhang, M. Yu, F. Liu, and Y. Kang, “Instantaneous
Current-sharing Control Strategy for Parallel Operation of UPS
Modules Using Virtual Impedance,” IEEE Transactions on Power
Electronics, Vol. 28, No. 1, pp.432-440, Jan. 2013.
[27]H. Shi, F. Zhuo, D. Zhang, Z. Geng, and F. Wang, “Adaptive
Implementation Strategy of Virtual Impedance for Paralleled
Inverters UPS,” IEEE Energy Conversion Congress and Exposition
(ECCE), pp.158-162, 2014.
[28]Fairchild,“UC3843 Datasheet,” 2002.
[29]LEM,“LAX 100-NP Datasheet.”
[30]GLOBAL Components & Controls,“DIP REED RELAY Datasheet.”
[31]何嘉偉，具冗於及熱插拔功能之多模組換流器並聯系統研製，國立中正大學-電
機工程學系-碩士論文，民國93年7月。
[32]吳毓恩，加權電流分配控制換流器並聯系統，國立中正大學-電機工程學系-博
士論文，民國93年7月。
[33]TOSHIBA,“TLP-350 Datasheet,” 2014.
[34]Renesas,“RX62T Group Datasheet,” Rev. 1.10, Apr. 2011.
[35]Chang Sung Corporation(CSC), “Magnetic Powder Cores,” ver.14.
[36]美國線規表(AWG),“UL758 Table 5-1.”