近年來隨著油價高漲與環保之重視，使得世界各國均積極推動再生能源與潔淨能源的開發，而其中光伏電池與燃料電池亦扮演一甚為重要的角色；然而這兩類電源之輸出電壓較低，因此需要依高升壓比之電源轉換器，作為此二類新能源系統之介面，將其提升至較高電壓以作為後級應用。因此本文之重點，即在研發一高升壓比高效率直流轉換器，以作為此兩類電源系統之應用。
本論文的主要貢獻有三點。文中首先針對高升壓比及高效率之目標，提出一新型多相升壓型直流轉換器，新型轉換器可以有效地降低主動開關之耐壓與輸出電壓漣波，並可於較寬廣的負載變動範圍維持高效率。第二點貢獻則是針對新型轉換器進一步推導出其小信號數學模型，以作為閉迴路控制器設計之依據，使得轉換器擁有較好的穩定性及暫態響應特性。第三點貢獻則依據理論分析的結果實際製作一輸入電壓24V、輸出電壓200V以及輸出功率100W之雛型系統以驗證新型轉換器的可行性。電路模擬與實測結果顯示本論文所研製之新型轉換器，其電源轉換效率於40W至100W的負載情況下均為93%以上，最高可達到94%，而其主動開關跨壓與輸出電壓漣波比較2007年提出的一新型倍壓式轉換器，可分別降低25%及16.7%。

In recent years, with global energy shortage and strong environmental movements, many countries are encouraging and promoting the development of distributed energy sources such as fuel cells and renewable energies. As important roles in new energy, however, the output voltage of the solar cells and the fuel cells is rather low. Hence, a high step-up dc/dc converter is normally required as an interface to increase voltage for back-end applications. Therefore, emphasis of this thesis is placed on developing a high efficiency and high step-up dc/dc converter for these two new energy systems.
Basically, the main contributions of this thesis can be summarized as follows. First, a new high efficiency and high step-up dc/dc converter is proposed. It can effectively reduce the voltage stress of active switches and the output voltage ripple of the converter. Moreover, it is able to maintain rather high efficiency in wide load range. Second, the mathematical model of the proposed converter is derived. According to the model, a close-loop controller is designed to achieve better stability and transient response of the converter. Finally, a 200V/100W laboratory prototype is constructed and corresponding simulations as well as experimental results are provided to verify the feasibility of the proposed converter. It is seen that the resulting efficiency curve can be maintained rather flat and above 93% for a load varied from 40W to 100W. Furthermore, the voltage stress of active switches and the output voltage ripple are 25% and 16.7%, respectively, lower than that of the voltage doubler proposed in 2007.

[1]S. R. Bull, “Renewable energy today and tomorrow,” Proceedings of the IEEE, Vol. 89, No. 8, pp. 1216-1226, Aug. 2001.
[2]G. Connor and H. W. Whittington, “A vision of true costing [renewable energy],” Engineering Science and Education Journal, Vol. 10, No. 1, pp. 4-12, Feb. 2001.
[3]M. Begovic, A. Pregelj, A. Rohatgi, and C. Honsberg, “Green power: status and perspectives,” Proceedings of the IEEE, Vol. 89, No. 12, pp. 1734-1743, Dec. 2001.
[4]H. Falk, “Prolog to renewable energy today and tomorrow,” Proceedings of the IEEE, Vol. 89, No. 8, pp. 1214-1215, Aug. 2001.
[5]T. Gilchrist, “Fuel cell to the fore,” IEEE Spectrum, Vol. 35, No. 11, pp.35-40, 1998.
[6]M. W. Ellis, M. R. Von Spakovsky, and D. J. Nelson, “Fuel cell system: efficient, flexible energy conversion for the 21st century,” Proceedings of the IEEE, Vol. 89, No. 12, pp. 1808-1818, 2001.
[7]F. Blaabjerg, Z. Chen, and S. B. Kjaer, “Power electronics as efficient interface in dispersed power generation systems,” IEEE Trans. Power Electronics, Vol. 19, No. 5, pp. 1184-1194, 2004.
[8]R. J. Wai and R. Y. Duan, “High-efficiency power conversion for low power fuel cell generation system,” IEEE Trans. on Power Electronics, Vol. 20, No. 4, pp. 847-856, July 2005.
[9]J. S. Lai and Douglas J. Nelson, “Energy management power converters in hybrid electric and fuel cell vehicles,” Proceedings of the IEEE, Vol. 95, No. 4, pp. 766-777, April 2007.
[10]R. J. Wai, W. H. Wang, and C. Y Lin, “High-performance stand-alone photovoltaic generation system,” IEEE Trans. on Industrial Electronics, Vol. 55, No. 1, pp. 240-250, Jan. 2008.
[11]R. J. Wai and W. H. Wang, “Grid-connected photovoltaic generation system,” IEEE Trans. on Circuits and Systems I: Fundamental Theory and Applications, Vol. 55, No. 3, pp. 953-964, April 2008
[12]Dragan Maksimovic and Slobodan Cuk, “Switching converters with wide DC conversion range,” IEEE Trans. on Power Electronics, Vol. 6, No. 1, pp. 151-157, Jan. 1991.
[13]R. Gules and N. Barbi, “A high efficiency isolated DC-DC converter with high-output voltage for TWTA telecommunication satellite applications,” IEEE Power Electronics Specialists Conference, pp. 1982-1987, 2001.
[14]I. Barbi and R. Gules, “Isolated DC-DC converters with high-output voltage for TWTA telecommunication satellite applications,” IEEE Trans. on Power Electronics, Vol. 18, No. 4, pp. 975-984, July 2003.
[15]T. Filchev, D. Cook, P. Wheeler, and J. Clare, “Investigation of high voltage, high frequency transformers/voltage multipliers for industrial applications,” IET Power Electronics, Machines and Drives Conference, pp. 209-213, 2008.
[16]J. A. Martin-Ramos, A. M. Pernia, J. Diaz, F. Nuno, and J. A. Martinez, “Power supply for a high-voltage application,” IEEE Trans. on Power Electronics, Vol. 23, No. 4, pp. 1608-1619, July 2008.
[17]R. Gules, L. L. Pfitscher, and L. C. Franco, “An interleaved boost DC-DC converter with large conversion ratio,” IEEE International Symposium on Industrial Electronics, pp. 411-416, 2003.
[18]J. Wen, T. Jin, and K. Smedley, “A new interleaved isolated boost converter for high power applications,” IEEE Applied Power Electronics Conference, pp. 79-84, 2006.
[19]W. Li and X. He, “ZVT interleaved boost converters for high-efficiency, high step-up DC-DC conversion,” IET Electric Power Applications, Vol. 1, No. 2, pp. 284-290, March 2007.
[20]P. Thounthong, P. Sethakul, S. Rael, and B. Davat, “Design and implementation of 2-phase interleaved boost converter for fuel cell power source,” IET Power Electronics, Machines and Drives Conference, pp. 91-95, 2008.
[21]T. J. Liang, and K. C. Tseng, “Analysis of integrated boost-flyback step-up converter,” IEE Proceedings-Electric Power Applications, Vol. 152, No. 2, pp. 217-225, March 2005.
[22]K. C. Tseng, and T. J. Liang, “Novel high-efficiency step-up converter,” IEE Proceedings-Electric Power Applications, Vol. 151, No. 2, pp. 182-190, March 2004.
[23]O. Krykunov, “Analysis of the extended forward converter for fuel cell applications,” IEEE International Symposium on Industrial Electronics, pp. 661-666, 2007.
[24]Y. T. Jang and M. M. Jovanovic, “Interleaved boost converter with intrinsic voltage-doubler characteristic for universal-line PFC front end” IEEE Trans. on Power Electronics, Vol. 22, No. 4, pp. 1394-1401, July 2007.
[25]Lazslo Balogh, “Design and application guide for high speed MOSFET gate drive circuits”, Texas Instruments Incorporated. Application Note, Power Supply Design Seminar, pp. 2-1~2-39, 2002.
[26]S. S. Ang, Power Switching Converters. Marcel Dekker, Inc. 1995.
[27]R. W. Erickson and D. Maksimovics, Fundamentals of Power Electronics. Kluwer Academic Publisher, Inc. 2001.
[28]George C. Chryssis, High-Frequency Switching Power Supplies. McGraw-Hill, Inc, 1989.
[29]U. S. Department of energy, Fuel cell handbook 7th, Morgantown: EG&G Services, 2004.
[30]C. S. Wang and M. H. Nehrir, “Load transient mitigation for stand-alone fuel cell power generation systems,” IEEE Trans. on Energy Conversion, Vol. 22, No. 4, pp. 864-872, Dec. 2007.
[31]S. Y. Choe, J. W. Ahn, J. G. Lee, and S. H. Baek, “Dynamic simulator for a PEM fuel cell system with a PWM DC/DC converter,” IEEE Trans. on Energy Conversion, Vol. 23, No. 2, pp. 669-680, June 2008.
[32]X. Yu, M. R. Starke, L. M. Tolbert, and B. Ozpineci, “Fuel cell power conditioning for electric power applications: a summary,” IET-Electric Power Applications, Vol. 1, No. 5, pp.643-656, Sept. 2007
[33]E. Koutroulis, K. Kalaitzakis, and N. C. Voulgaris, “Development of a microcontroller-based, photovoltaic maximum power point tracking control system,” IEEE Trans. on Power Electronics, Vol. 16, No. 1, pp. 46-54, Jan. 2001.
[34]N. Kasa, T. Iida, and L. Chen, “Flyback inverter controlled by sensorless current MPPT for photovoltaic power system,” IEEE Trans. on Industrial Electronics, Vol. 52, No. 4, pp. 1145-1152, Aug. 2005.
[35]S. Jain and V. Agarwal, “Comparison of the performance of maximum power point tracking schemes applied to single-stage grid-connected photovoltaic systems,” IET-Electric Power Applications, Vol. 1, No. 5, pp. 753-762, Sept. 2007.
[36]Lazslo Balogh, “Agilent 2.5 Amp output current IGBT gate drive optocoupler,” Agilent Technologies. Application Note, April 2005.