臺灣博碩士論文加值系統

輸入電容的電壓平衡問題普遍存在於傳統多階變流器，因此本論文提出一新型具耦合電感雙降壓式五階換流器。此電路包含一輸入電容、一雙降壓式模組、一組耦合電感及一全橋模組。其中，利用耦合電感技術，可確保供給負載的電壓為較佳的弦波; 此外， 雙降壓模組可透過解決現有電路中的直通電流(shoot-through current)問題以增強系統可靠度。雙降壓式模組包含兩個二極體與兩個功率開關元件，其可產生三階電壓，再由全橋模組轉換成五階的弦波電壓。文中將分析與探討調變方法以及開關切換模態，並提出一最佳化的調變方法應用於本文電路，其可除去激磁電流中的直流成分，以避免鐵心磁飽和發生。
本文透過一實體電路以評估所提出變流器之效能，其輸入直流電壓380 V、輸出交流電壓220 Vrms且輸入額定功率為1.5 kW。根據實驗結果顯示，所提出電路其滿載時電壓總諧波失真率為1.2%，且最高系統效率可達94.7%，此驗證了本文所提出電路的可行性與效能。

The input capacitors used in conventional multilevel inverters commonly experience a voltage-imbalance problem. Accordingly, the thesis proposes a new dual-buck inverter with coupled inductors to realize a five-level inverter, consisting of single input capacitor, a dual-buck module, and a full-bridge module. With the coupled inductors, the inverter ensures an improved sinusoidal voltage to the load. In addition, the dual-buck module enhances system reliability by solving the shoot-through problem existing in conventional circuits. The proposed dual-buck module, comprising two diodes and two power switches, generates a three-level voltage which is then converted to a five-level sinusoidal voltage by the full-bridge module. A modulation method is developed accordingly for the proposed inverter with various switching patterns analyzed. Via the presented modulation method, no dc offset exists in the magnetizing inductor currents, and problems of core saturation can thus be avoided.
The performance of the proposed converter is evaluated by the implemented prototype circuit with an input dc voltage of 380 V, an output ac voltage of 220 Vrms, and an input power of 1.5 kW. The experimental results show that the output voltage total harmonic distortion (THD) of 1.2 % at full load condition and a highest efficiency of 94.7% have been achieved to validate the feasibility and effectiveness of the proposed multilevel inverter.

摘 要...I
ABSTRACT...II
誌 謝...III
CONTENTS...IV
LIST OF TABLES...VII
LIST OF FIGURES...VIII
CHAPTER 1. INTRODUCTION...1
1.1. Backgrounds and motivations...1
1.2. Literature review...2
1.3. Research objectives and contribution of the thesis...4
1.4. Organization of the thesis...6
CHAPTER 2. REVIEW OF MULTILEVEL INVERTERS AND MODULATION METHODS...7
2.1. Introduction...7
2.1.1. H-bridge inverter...7
2.1.2. Diode-clamped inverter...9
2.1.3. Flying-capacitor inverter...11
2.1.4. Simplified five-level inverter...13
2.1.5. Dual-buck five level inverter...13
2.1.6. Three-arm five-level inverter with coupled inductors ...15
2.2. SPWM modulation method...16
2.3. Summary...17
CHAPTER 3. THE PROPOSED FIVE-LEVEL INVERTER...18
3.1. Introduction...18
3.2. The proposed single-phase five-level inverter...18
3.3. Operating principles of the proposed inverter analysis...20
3.3.1. The role of coupled inductors...20
3.3.2. Mode analysis...23
3.4. Analysis and modulation method of the proposed inverter...34
3.4.1. Analysis of switching states...34
3.4.2. Control methods...38
3.4.3. PD modulation...41
3.5. Design of the inverter...42
3.5.1. Coupled inductors...42
3.5.2. LC filter...43
3.6. Summary...43
CHAPTER 4. SIMULATION AND EXPERIMENTAL RESULTS...44
4.1. Specifications of the proposed prototype circuit...44
4.2. Simulation results...46
4.3. Experimental results...50
4.4. The output voltage and current THD analysis...57
4.5. Efficiency of the proposed inverter...58
4.6. Power loss analysis...59
4.7. Comparisons with the existing circuits...60
4.8. Summary...61
CHAPTER 5. CONCLUSIONS...63
5.1. Conclusions...63
5.2. Future works...64
REFERENCES...65

[1]D. Zhong, B. Ozpineci, L. M. Tolbert, and J. N. Chiasson, “DC-AC Cascaded H-Bridge Multilevel Boost Inverter with No Inductors for Electric/Hybrid Electric Vehicle Applications, IEEE Trans. Industry Applications, vol. 45, no. 3, pp. 963-970, Jun. 2009.
[2]L. M. Tolbert, P. Fang Zheng, and T. G. Habetler, “Multilevel converters for large electric drives, IEEE Trans. Industry Applications, vol. 35, no. 1, pp. 36-44, Feb. 1999.
[3]J. S. Lai and F. Z. Peng, “Multilevel converters-a new breed of power converters, Conference Record of IEEE IAS, vol.3, pp. 2348-2356, Oct. 1995.
[4]L. G. Franquelo, J. Rodriguez, J. I. Leon, S. Kouro, R. Portillo, and M. A. M. Prats, “The age of multilevel converters arrives, IEEE Industrial Electronics Magazine, vol. 2, no. 2, pp. 28-39, Jun. 2008.
[5]S. Daher, J. Schmid, and F. L. M. Antunes, “Multilevel Inverter Topologies for Stand-Alone PV Systems, IEEE Trans. Industrial Electronics, vol. 55, no. 7, pp. 2703-2712, Jul. 2008.
[6]S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of single-phase grid-connected inverters for photovoltaic modules, IEEE Tran. Industry Applications, vol. 41, no. 5, pp. 1292-1306, Oct. 2005.
[7]J. Rodriguez, L. Jih-Sheng, and P. Fang Zheng, “Multilevel inverters: a survey of topologies, controls, and applications, IEEE Trans. Industrial Electronics, vol. 49, no. 4, pp. 724-738, Aug. 2002.
[8]N. A. Rahim, K. Chaniago, and J. Selvaraj, “Single-Phase Seven-Level Grid-Connected Inverter for Photovoltaic System, IEEE Trans. Industrial Electronics, vol. 58, no. 6, pp. 2435-2443, Jun. 2011.
[9]S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, W. Bin, et al., “Recent Advances and Industrial Applications of Multilevel Converters, IEEE Trans. Industrial Electronics, vol. 57, no. 8, pp. 2553-2580, Aug. 2010.
[10]Z. X. Li, P. Wang, Y. H. Li, and F. Q. Gao, “A Novel Single-Phase Five-Level Inverter With Coupled Inductors, IEEE Trans. Power Electronics, vol. 27, no. 6, pp. 2716-2725, Jun. 2012.
[11]S. Vazquez, J. I. Leon, J. M. Carrasco, L. G. Franquelo, E. Galvan, M. Reyes, et al., “Analysis of the Power Balance in the Cells of a Multilevel Cascaded H-Bridge Converter, IEEE Trans. Industrial Electronics, vol. 57, no. 7, pp. 2287-2296, Jul. 2010.
[12]Y. S. Lai and F. S. Shyu, “Topology for hybrid multilevel inverter, IEE Proceedings - Electric Power Applications, vol. 149, no. 6, pp. 449-458, Oct. 2002.
[13]Y. Hinago and H. Koizumi, “A Single-Phase Multilevel Inverter Using Switched Series/Parallel DC Voltage Sources, IEEE Trans. Industrial Electronics, vol. 57, no. 8, pp. 2643-2650, Aug. 2010.
[14]Y. H. Liao and C.M. Lai, “Newly-Constructed Simplified Single-Phase Multistring Multilevel Inverter Topology for Distributed Energy Resources, IEEE Trans. Power Electronics, vol. 26, no. 9, pp. 2386-2392, Sep. 2011.
[15]J. J. Shi, W. Gao, H. Yuan, T. F. Zhao, and A. Q. Huang, “Research on voltage and power balance control for cascaded modular solid-state transformer, IEEE Trans. Power Electronics, vol. 26, no. 4, pp. 1154-1166, Apr. 2011.
[16]P. W. Sun, C. Liu, J. S. Lai, and C. L. Chen, “Cascade Dual Buck Inverter With Phase-Shift Control, IEEE Trans. Power Electronics, vol. 27, no. 4, pp. 2067-2077, Apr. 2012.
[17]J. F. Liu, K. W. E. Cheng, and Y. Ye, “A Cascaded Multilevel Inverter Based on Switched-Capacitor for High-Frequency AC Power Distribution System, IEEE Trans. Power Electronics, vol. 29, no. 8, pp. 4219-4230, Aug. 2014.
[18]N. S. Choi, J. G. Cho, and G. H. Cho, “A general circuit topology of multilevel inverter, IEEE Power Electronics Specialists Conference, pp. 96-103, Jun. 1991.
[19]B. P. McGrath and D. G. Holmes, “Multicarrier PWM strategies for multilevel inverters, IEEE Trans. Industrial Electronics, vol. 49, no. 4, pp. 858-867, Aug. 2002.
[20]A. Nabae, I. Takahashi, and H. Akagi, “A New Neutral-Point-Clamped PWM Inverter, IEEE Trans. Industry Applications, vol. IA-17, no. 5, pp. 518-523, Oct. 1981.
[21]A. Shukla, A. Ghosh, and A. Joshi, “Flying-Capacitor-Based Chopper Circuit for DC Capacitor Voltage Balancing in Diode-Clamped Multilevel Inverter, IEEE Trans. Industrial Electronics, vol. 57, no. 7, pp. 2249-2261, Jul. 2010.
[22]G. Ceglia, V. Guzman, C. Sanchez, F. Ibanez, J. Walter, and M. I. Gimenez, “A New Simplified Multilevel Inverter Topology for DC-AC Conversion, IEEE Trans. Power Electronics, vol. 21, no. 5, pp. 1311-1319, Sep. 2006.
[23]K. Hasegawa and H. Akagi, “A New DC-Voltage-Balancing Circuit Including a Single Coupled Inductor for a Five-Level Diode-Clamped PWM Inverter, IEEE Tran. Industry Applications, vol. 47, no. 2, pp. 841-852, Apr. 2011.
[24]Y. Hinago and H. Koizumi, “A Switched-Capacitor Inverter Using Series/Parallel Conversion With Inductive Load, IEEE Trans. Industrial Electronics, vol. 59, no. 2, pp. 878-887, Feb. 2012.
[25]G. Buticchi, E. Lorenzani, and G. Franceschini, “A Five-Level Single-Phase Grid-Connected Converter for Renewable Distributed Systems, IEEE Tran. Industrial Electronics, vol. 60, no. 3, pp. 906-918, Mar. 2013.
[26]J. M. Shen, H. L. Jou, J. C. Wu, and K. D. Wu, “Five-Level Inverter for Renewable Power Generation System, IEEE Tran. Energy Conversion, vol. 28, no. 2, pp. 257-266, Jun. 2013.
[27]S. J. Park, F. S. Kang, M. H. Lee, and C. U. Kim, “A new single-phase five-level PWM inverter employing a deadbeat control scheme, IEEE Trans. Power Electronics, vol. 18, no. 3, pp. 831-843, May 2003.
[28]J. Salmon, A. M. Knight, and J. Ewanchuk, “Single-Phase Multilevel PWM Inverter Topologies Using Coupled Inductors, IEEE Tran. Power Electronics, vol. 24, no. 5, pp. 1259-1266, May 2009.
[29]D. Floricau, E. Floricau, and G. Gateau, “New Multilevel Converters With Coupled Inductors: Properties and Control, IEEE Trans. Industrial Electronics, vol. 58, no. 12, pp. 5344-5351, Dec. 2011.
[30]B. Axelrod, Y. Berkovich, and A. Ioinovici, “A cascade boost-switched-capacitor-converter - two level inverter with an optimized multilevel output waveform, IEEE Trans. Circuits and Systems I: Regular Papers, vol. 52, no. 12, pp. 2763-2770, Dec. 2005.
[31]Z. G. Pan and F. Z. Peng, “A Sinusoidal PWM Method With Voltage Balancing Capability for Diode-Clamped Five-Level Converters, IEEE Trans. Industry Applications, vol. 45, no. 3, pp. 1028-1034, Jun. 2009.
[32]K. Sano and H. Fujita, “Voltage-Balancing Circuit Based on a Resonant Switched-Capacitor Converter for Multilevel Inverters, IEEE Trans. Industry Applications, vol. 44, no. 6, pp. 1768-1776, Nov. 2008.
[33]N. A. Rahim and J. Selvaraj, “Multistring Five-Level Inverter With Novel PWM Control Scheme for PV Application, IEEE Trans. Industrial Electronics, vol. 57, no. 6, pp. 2111-2123, Jun. 2010.
[34]A. Roshan, R. Burgos, A. C. Baisden, and F. Wang and D. Boroyevich, “A D-Q Frame Controller for a Full-Bridge Single Phase Inverter Used in Small Distributed Power Generation Systems, IEEE Proceedings - Applied Power Electronics Conference and Exposition, pp. 641-647., Mar. 2007.
[35]D. Dong, T. Thacker, R. Burgos, D. Boroyevich, and F. Wang, “On Zero Steady-State Error of Single-Phase PWM Inverters Voltage Control and Phase-Locked Loop System, IEEE Proceedings - Energy Conversion Congress and Exposition, pp. 892-899, Sept. 2009