本論文研製一個具有同步整流技術之零電流零電壓轉移(ZCZVT)隔離型順向式電力轉換器，主要係將ZCZVT柔性切換技術(soft-switching)與同步整流技術，同時應用到隔離型順向式電力轉換器，以達到高頻化及高效率的目標。
　　ZCZVT柔切技術係結合了ZVT與ZCT的優點，有效地提升電力轉換器之效率。輔助開關在一個切換週期 內切換為on兩次，產生兩次瞬態共振，使主開關達到零電壓切換(ZVS)及零電流切換(ZCS)，解決傳統PWM電力轉換器的高切換損失及共振式電力轉換器高電壓/大電流的傳導損失等缺點。
　　此外，吾人亦於變壓器二次側引入同步整流技術：主要係在輸出整流二極體兩端，並聯導通電阻極低的主動開關元件MOSFET，並使MOSFET與輸出整流二極體作同步的切換，以降低因輸出整流二極體壓降所造成的高導通損耗問題，改善轉換器操作於低電壓/大電流輸出時的效率。
　　本論文並針對同步整流電路設計提出了系統化的分析及設計方法，且設計穩壓控制器，以降低線電壓及負載變動對輸出電壓的影響。最後，實際製作出一組輸入電壓48V、輸出電壓12V、輸出功率100W且切換頻率300kHz，滿載效率達88.37%的高性能DC/DC電力轉換器。

　　This thesis presents the synthesis and analysis of a zero-current-zero-voltage-transition (ZCZVT) soft-switching isolated forward converter with synchronous rectification (SR). By virtue of the techniques of ZCZVT and SR, an isolated forward converter is well designed to satisfy the specifications of high efficiency with a high switching frequency.
　　The ZCZVT soft-switching converter exhibits the advantages of both ZVT and ZCT converters. It improves the efficiency of the power converters. To achieve zero voltage switching (ZVS) and zero current switching (ZCS) during switching transitions, the auxiliary switch turns on twice, and thus two resonances occur in one switching period. It overcomes the existing problems of high switching losses of the conventional PWM converters and the conduction losses due to high voltage/current stresses of resonance power converters.
　　In addition, synchronous rectification is also applied in the output stage to improve efficiency of the converter, operating in low voltage and high current conditions. The output diodes are paralleled with the MOSFETs that have low conduction resistance. MOSFETs must switch simultaneously with the output diodes to overcome the problem of high conduction losses due to the forward-voltage drop of the output diodes.
　　A systematic design procedure is developed for synchronous rectification in this thesis. Moreover, a voltage controller is then designed to regulate the output voltage despite of the variations of line voltage and load. Finally, a converter switched at frequency of 300kHz, with input 48V and output 12V, is implemented. The overall efficiency with 300kHz has been obtained experimentally at full load.

[BBML90] Barbi, I., J. C. O. Bolacell, D. C. Martin and F. B. Libano, “Buck Quasi-Resonant Converter Operating at Constant Frequency: Analysis, Design and Experimentation,” IEEE Trans. on Power Electronics, Vol. 5, No. 3, pp. 276-283, 1990.
[ChL97] Chen, Y. T. and W. H. Liu, “The Implementation and Analysis for The ZVS PWM Forward Converter Using a Saturable Circuit,” Proceeding of the 18th Symposium on Electrical Power Engineering, R.O.C., pp. 328-333, 1997.
[ErM01] Erickson, R. W. and D. Maksimovic, Fundamentals of Power Electronics, 2nd Ed., Kluwer Academic Publishers, Massachusetts, 2001.
[FrM87] Freeland, S. and R. D. Middlebrook, “A Unified Analysis of Converters with Resonant Switches,” IEEE PESC, pp. 20-30, 1987.
[HKP85] Hower, P. L., G. M. Kepler and R. Patel, “Design, Performance, and Application of a New Bipolar Synchronous Rectifier,” IEEE PESC, pp. 247-256, 1985.
[HLL92] Hua, G., C. S. Leu and F. C. Lee, “Novel Zero-Voltage-Transition PWM Converters,” VPEC Seminar, pp. 81-88, 1992.
[HuL95] Hua, G. and F. C. Lee, “Soft-Switching Techniques in PWM Converters,” IEEE Trans. on Industrial Electronics, Vol. 42, No. 6, pp. 595-603, 1995.
[JTL88] Jovanovic, M. M., W. A. Tabisz and F. C. Lee, “Zero-Voltage-Switching Technique in High-Frequency Off-Time Converters,” IEEE APEC, pp. 23-32, 1988.
[JZL95] Jovanovic, M. M., M. T. Zhang and F. C. Lee, “Evaluation of Synchronous-Rectification Efficiency Improvement Limits in Forward Converters, ” IEEE Trans. on Industrial Electronics, Vol. 42, No. 4, pp. 387-395, 1995.
[KKM97] Kudo, K., K. Kuwabara and E. Miyachika, “Synchronous Rectifier Circuit with DC Biasing Transformer,” IEEE Telecommunications Energy Conference, pp. 40-45, 1997.
[LiC03] Lin, J. L. and C. H. Chang, “Small-Signal Modeling and Control of ZVT-PWM Boost Converters,” IEEE Trans. on Power Electronics, Vol. 18, No. 1, pp. 2-10, 2003.
[LiH00] Lin, J. L. and H. Y. Hsieh, “Dynamics Analysis and Controller Synthesis for Zero-Voltage-Transition PWM Power Converters,” IEEE Trans. on Power Electronics, Vol. 15, No. 2, pp. 205-214, 2000.
[LiL90] Liu, K. H. and F. C. Lee, “Zero-Voltage Switching Technique in DC/DC Converters,” IEEE Trans. on Power Electronics, Vol. 5, No. 3, pp. 293-304, 1990.
[LiS04] Lin, J. L. and C. H. Hsia, “Dynamics and Control of ZCZVT Boost Converters,” to be published in IEEE Trans. on Circuits and Systems, Part I.
[LOL87] Liu, K. H., R. Oruganti and F. C. Lee, “Quasi-Resonant Converter: Topologies and Characteristics,” IEEE Trans. on Power Electronics, Vol. 2, No. 1, pp. 26-71, 1987.
[MaC91] Maksimoric, P. and S. Cuk, “Constant Frequency Control of Quasi-Resonant-Converter,” IEEE Trans. on Power Electronics, Vol. 6, No. 1, pp. 141-150, 1991.
[MNSY93] Murakami, N., H. Namiki, K. Sakakibara and T. Yachi, “A Simple and Efficient Synchronous Rectifier for Forward DC-DC Converters,” IEEE APEC, pp. 463-468, 1993.
[MUR95] Mohan, N., T. M. Undeland and W. P. Robbins, Power Electronics: Converters, Applications, and Design, 2nd Ed., John Wiley & Sons, Inc., New York, 1995.
[SaH95] Sakai, E. and K. Harada, “Synchronous Rectifier for Low Voltage Switching Converter,” IEEE Telecommunications Energy Conference, pp. 471-475, 1995.
[StH00] Stein, C. M. O. and H. L Hey, “A True ZCZVT Commutation Cell for PWM Converters,” IEEE Trans. on Power Electronics, Vol. 15, No. 1, pp. 185-193, 2000.
[TaL88] Tabisz, W. A. and F. C. Lee, “Zero-Voltage-Switching Multi-Resonant Technique: a Novel Approach to Improve Performance of High- Frequency Quasi-Resonant Converters,” IEEE PESC, pp. 9-17, 1988.
[TLC90] Tabisz, W. A., F. C. Lee and D. Y. Chen, “A MOSFET Resonant Synchronous Rectifier for High-Frequency DC/DC converters,” IEEE PESC, pp. 769-779, 1990.
[TsC98] Tseng, C. J. and C. L. Chen, “Novel ZVT-PWM Converters with Active Snubbers,” IEEE Trans. on Power Electronics, Vol. 13, No. 5, pp. 861-869, 1998.
[XiJ03] Xi, Y. and P. K. Jain, “A Forward Converter Topology Employing a Resonant Auxiliary Circuit to Achieve Soft Switching and Power Transformer Resetting,” IEEE Trans. on Industrial Electronics, Vol. 50, No. 1, pp.132-140, 2003.
[XLPP00] Xie, X., C. P. Liu, N. K. Poon and M. H. Pong, “Voltage-Driven Synchronous Rectification in Forward Topology,” IEEE Power Electronics and Motion Control Conference, pp. 100-105, 2000.
[YaL93] Yang, L. and C. Q. Lee, “Analysis and Design of Boost Zero-Voltage-Transition PWM Converters,” IEEE APEC, pp. 707-713, 1993.
[YaL03] Yang, S. P. and J. L. Lin, “Design for a Zero-Current-Zero-Voltage-Transition Soft-Switching Isolated DC/DC Forward Converters,” NCKU/ES CPE-Lab seminar, 2003.
[YMY98] Yamashita, N., N. Murakami and T. Yachi, “Conduction Power Loss in MOSFET Synchronous Rectifier with Parallel-Connected Schottky Barrier Diode,” IEEE Trans. on Power Electronics, Vol. 13, No. 4, pp. 667-673, 1998.
[劉君上96] 劉君上，共振式DC-DC電源轉換器之分析與強健控制器之設計，碩士論文，國立成功大學工程科學系，1996。
[邱士峰97] 邱士峰，半共振式零電流切換型暨PWM電流回授型之DC-DC電源轉換器：製作分析及控制器之設計，碩士論文，國立成功大學工程科學系，1997。
[謝欣穎98] 謝欣穎，零電壓轉移柔性切換電源轉換器之動態模式分析及控制器之研製，碩士論文，國立成功大學工程科學系，1998。
[張景華99] 張景華，升壓型零電壓轉移柔切式電力轉換器之模式分析及控制器設計，碩士論文，國立成功大學工程科學系，1999。
[游志雄00] 游志雄，零電壓轉移高功率因數電力轉換器之模式分析及控制器設計，碩士論文，國立成功大學工程科學系，2000。
[夏存孝01] 夏存孝，零電流零電壓轉移柔切式升壓型電力轉換器之模式分析及控制器設計，碩士論文，國立成功大學工程科學系，2001。
[劉育伶02] 劉育伶，非浮接開關之零電流零電壓轉移柔切式升壓型電力轉換器之分析研製及控制器設計，碩士論文，國立成功大學工程科學系，2002。
[葉怡君03] 葉怡君，新型零電流零電壓轉移柔切式高功因AC/DC整流器，碩士論文，國立成功大學工程科學系，2003。