本論文提出一新型高效率單級式功因校正之交/直流轉換器，在架構上結合一降壓型功因校正電路與一耦合式升降壓型直/直流轉換電路，當兩級電路工作在不連續導通模式時，直流母線電壓不受輸出功率影響。同時利用電路將一部分輸入功率直接傳遞到輸出端，而非先儲存在直流母線電容，可避免功率損耗，進而提升系統效率與功率因數，並具低直流母線電壓應力。為提升不連續導通模式下轉換器效率，本論文亦整合一能量回收緩震電路。由於利用多繞組變壓器且不需外加鐵心、主動開關及其驅動器，因此本論文所提出的電路具低成本與體積的優點。本論文詳述轉換器操作原理、穩態分析與參數設計，並實際製作一額定功率100 W、輸入電壓90 Vrms到260 Vrms，輸出電壓19 V的雛型電路驗證本論文架構之可行性。

The thesis proposes a new high-efficiency, single-stage power factor correction (PFC) AC/DC converter by integrating a buck-type PFC cell with a coupled buck-boost dc/dc cell. When both cells are operated in discontinuous conduction mode (DCM), the DC bus voltage is independent of the output power. Simultaneously, the techniques of transferring a part of the input power directly to the output side instead of storing the DC bus capacitor lead to preventing power dissipation, enhancing efficiency and power factor, and achieving low DC bus voltage.
To further improve the efficiency of the converter, especially operating in DCM, an energy recycling snubber is proposed to integrate a multi-winding transformer without additional magnetic core, active switch and driver. Therefore, the proposed converter has the advantages of lower cost and smaller size. The operation principle, steady-state analysis, design guideline of the proposed circuit are presented in the thesis. The proposed converter has been verified in the thesis by implementing a 100 W, laboratory prototype circuit with output voltage of 19 V and the input voltage varying from 90 Vrms to 260 Vrms.

[1]W. F. Ray and R. M. Davis, “The definition and importance of power factor for power electronic converters,” Proc. European conference on Power Electronics and Applications (EPE), 1989, pp. 799-805.
[2]M. T. Madigan, R. W. Erickson and E. H. Ismail, “Integrated high-quality rectifier–regulators,” IEEE Trans. Ind. Electron., vol. 46, no. 4, pp. 749–758, Aug. 1999.
[3]M. Daniele, P. K. Jain, and G. Jo´os, “A single-stage power factor corrected ac/dc converter,” IEEE Trans. Power Electron., vol. 14, no. 6, pp. 1046–1055, Nov. 1999.
[4]C. Qiao, and K. M. Smedley, “A topology survey of single-stage power factor corrector with a boost type input-current-shaper,” IEEE Trans. Power Electron., vol. 16, no. 3, pp. 360–368, May. 2001.
[5]J. M. Alonso, M. D. Costa and C. Ordiz, “Integrated buck-flyback converter as a high-power-factor off-line power supply,” IEEE Trans. Ind. Electron., vol. 55, no. 3, pp. 1090–1100, Mar. 2008.
[6]S. K. Ki, and D. D. Lu, “Implementation of an efficient transformerless single-stage single-switch ac/dc converter,” IEEE Trans. Ind. Electron., vol. 57, no. 12, pp. 4095–4105, Dec. 2010.
[7]J. J. Lee, J. M. Kwon, E. H. Kim, and B. H. Kwon, “Single-stage single-switch PFC flyback converter using a synchronous rectifier,” IEEE Trans. Ind. Electron., vol. 55, no. 3, pp. 1352–1365, Mar. 2008.
[8]Q. Zhao, F. C. Lee, and F. S. Tsai, “Voltage and current stress reduction in single-stage power factor correction ac/dc converters with bulk capacitor voltage feedback,” IEEE Trans. Power Electron., vol. 17, no. 4, pp. 477–484, Jul. 2002.
[9]H. Ma, Y. Ji, and Y. Xu, “Design and analysis of single-stage power factor correction converter with a feedback winding,” IEEE Trans. Power Electron., vol. 25, no. 6, pp. 1460–1470, Jun. 2010.
[10]H. Y. Li, H. C. Chen, and L. K. Chang, “Analysis and design of a single-stage parallel ac-to-dc converter,” IEEE Trans. Power Electron., vol. 24, no. 12, pp. 2989–3002, Dec. 2009.
[11]H. Y. Li and H. C. Chen, “Dynamic modeling and controller design for a single-stage single-switch parallel boost-flyback–flyback converter,” IEEE Trans. Power Electron., vol. 27, no. 2, pp. 816-827, Feb. 2012.
[12]J. Y. Lee, “Single-stage ac/dc converter with input-current dead-zone control for wide input voltage ranges,” IEEE Trans. Ind. Electron., vol. 54, no. 2, pp. 724-732, Apr. 2007.
[13]A. Lázaro, A. Barrado, V Salas, and E Olías “New power factor correction ac-dc converter with reduced storage capacitor voltage,” IEEE Trans. Ind. Electron., vol. 54, no. 1, pp. 384-397, Feb. 2007.
[14]J. Zhang, D. D. Lu, and T Sun “Flyback-based single-stage power-factor-correction scheme with time-multiplexing control,” IEEE Trans. Ind. Electron., vol. 57, no. 3, pp. 1041-1049, Mar. 2010.
[15]N. Golbon, and G Moschopoulos “A low-power ac–dc single-stage converter with reduced dc bus voltage variation,” IEEE Trans. Power Electron., vol. 27, no. 8, pp. 3714-3724, Aug. 2012.
[16]E. H. Ismail, A. J. Sabzali, and M. A. Al-Saffar “Buck–boost-type unity power factor rectifier with extended voltage conversion ratio,” IEEE Trans. Ind. Electron., vol. 55, no. 3, pp. 1123-1132, Mar. 2008.
[17]M. A. Al-Saffar, E. H. Ismail, and A. J. Sabzali “Integrated buck–boost–quadratic buck PFC rectifier for universal input applications,” IEEE Trans. Power Electron., vol. 24, no. 12, pp. 2886-2896, Dec. 2009.
[18]K. Yao, Y. Qie, M. Xu, and F. C. Lee “A novel winding-coupled buck converter for high-frequency, high-step-down dc–dc conversion,” IEEE Trans. Power Electron., vol. 20, no. 5, pp. 1017-1024, Sep. 2005.
[19]T. J. Peng, and K. I Hwu, “A novel inductor-coupled step-up-down Converter,” IEEE ICSET Nepal., pp. 361–363, 2012.
[20]Z. Hossain, K. J. Olejniczak, K. C. Burgers, and J. C. Balda, “Design of RCD snubbers based upon approximations to the switching characteristics,” IEEE TA2, 6.l–6.3, 1997.
[21]G. R. Kamath, N. Mohan, and T. M. Undeland, “Non-dissipative undeland snubber for electric vehicle drive inverters using GaAs anti - parallel diodes,” IEEE Conf., pp. 748–752, 1997.
[22]K. Fujiwara, and H. Nomura “A novel lossless passive snubber for soft-switching boost-type converters,” IEEE Trans. Power Electron., vol. 14, no. 6, pp. 1065-1069, Nov. 1999.
[23]R. H. Li, and H. S. Chung “A passive lossless snubber cell with minimum stress and wide soft-switching range,” IEEE Trans. Power Electron., vol. 25, no. 7, pp. 1725-1738, Jul. 2010.
[24]A. Abramovitz, T. Cheng, and K. Smedley “Analysis and design of forward converter with energy regenerative snubber,” IEEE Trans. Power Electron., vol. 25, no. 3, pp. 667-676, Mar. 2010.
[25]A. Abramovitz, C. S. Liao, and K. Smedley “State-plane analysis of regenerative snubber for flyback converters,” IEEE Trans. Power Electron., vol. 28, no. 11, pp. 5323-5332, Nov. 2012.
[26]Y. C. Li, and C. L. Chen “A novel single-stage high-power-factor ac-to-dc LED driving circuit with leakage inductance energy recycling,” IEEE Trans. Ind. Electron., vol. 59, no. 2, pp. 793-802, Feb. 2012.
[27]Y. Jang and M. M. Jovanovi´c “Bridgeless high-power-factor buck converter,” IEEE Trans. Power Electron., vol. 26, no. 2, pp. 602-611, Feb. 2011.
[28]Application Note, “UC3854 controlled power factor correction circuit design,” Texas Instruments Incorporated, 1999.
[29]Datasheets, “SG3525A: Pulse width modulator control circuits,” Motorola Incorporated, 1996.
[30]Datasheets, “TL431: Programmable precision references,” Motorola Incorporated, 1998.
[31]Datasheets, “PC817: High density mounting type photo coupler,” Sharp Electronic components, 1996.