本論文提出具有可調漏感整合式變壓器的LLC諧振式轉換器並應用於高功率的電源轉換器上。並且分析LLC諧振式轉換器的整流測電路結構，並且根據電壓、電流應力、整流開關導通損耗以及變壓器的繞線方式後，選擇全橋整流架構。此外為了達到高效率和高功率密度的目標，本論文採用增加磁路形式的可調漏感整合式變壓器取代諧振電感，並提出新型的鐵芯結構降低銅線損耗。為了進一步優化變壓器的鐵芯損耗以及銅線損耗，本論文將鐵芯尺寸以全參數化的形式進行分析，最終根據變壓器的總損耗以及變壓器的占地面積進行比較，選擇最具效益的設計點作為最終設計，並且使用磁性模擬軟體Maxwell針對變壓器的功能進行驗證。最終本論文提出應用於LLC諧振式轉換器的可調漏感整合式變壓器，利用漏感取代諧振電感進行設計。最終實現切換頻率操作於1 MHz、輸入電壓380 V、輸出電壓19 V、輸出功率為190 W，最高效率可以達到XX%的LLC串聯諧振式轉換器。

In this study, a high power adaptor containing an integrated transformer with controllable leakage inductance in a high-frequency isolated LLC resonant converter was proposed as an laptop power converter. The secondary-side topological structures were analyzed from the perspectives of component loss and component stress, and a full-bridge structure was selected for secondary-side circuit architecture of the LLC resonant converter. Additionally, to achieve high power density and high efficiency, controllable leakage inductance with novel core structure was achieved through an additional reluctance length, and the added resonant inductor was replaced with the transformer leakage inductance. To optimize the transformer, the parameter of core size structure was proposed to get the optimal point between total loss and footprint of transformer and the feasibility of the new core design was verified using ANSYS Maxwell software. Finally, this paper proposes an integrated transformer without any additional resonant inductor in the LLC resonant converter. An LLC resonant converter with a 380 V input voltage, 19 V output voltage, 190W output power, and 1 MHz switching frequency was created, and a maximum efficiency of XX% was achieved.

[1] W. -. Gu and R. Liu, A study of volume and weight vs. frequency for high-frequency transformers, Proceedings of IEEE Power Electronics Specialist Conference - PESC '93, Seattle, WA, USA, 1993, pp. 1123-1129.
[2] X. Huang, Z. Liu, Q. Li and F. C. Lee, Evaluation and Application of 600 V GaN HEMT in Cascode Structure, in IEEE Transactions on Power Electronics, vol. 29, no. 5, pp. 2453-2461, May 2014.
[3] C. Lee, W. Lin, Y. Lee and J. Huang, Characterizations of Enhancement-Mode Double Heterostructure GaN HEMTs With Gate Field Plates, in IEEE Transactions on Electron Devices, vol. 65, no. 2, pp. 488-492, Feb. 2018.
[4] J. L. Lu, R. Hou and D. Chen, Opportunities and design considerations of GaN HEMTs in ZVS applications, 2018 IEEE Applied Power Electronics Conference and Exposition (APEC), San Antonio, TX, 2018, pp. 880-885.
[5] J. Xiang, X. Ren, Y. Wang and Y. Zhang, Investigation of cascode stucture GaN devices in ZCS region of LLC resonant converter," 2017 IEEE Energy Conversion Congress and Exposition (ECCE), Cincinnati, OH, 2017, pp. 1374-1378.
[6] R. Watson, F. C. Lee, and G. C. Hua, “Utilization of an active-clamp circuit to achieve soft switching in flyback converters,” IEEE Transactions on Power Electronics, vol. 11, no. 1, pp. 162-169, Jan. 1996.
[7] S. Larousse, H. Razik, R. Cellier, N. Abouchi, and P. Volay, “Active dead-time optimization for wide range flyback active-clamp converter,” in Proc. PCIM Europe, International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 2016.
[8] T. LaBella, B. York, C. Hutchens and J. Lai, "Dead time optimization through loss analysis of an active-clamp flyback converter utilizing GaN devices," 2012 IEEE Energy Conversion Congress and Exposition (ECCE), Raleigh, NC, 2012, pp. 3882-3889.
[9] X. Huang, W. Du, F. C. Lee and Q. Li, "A novel driving scheme for synchronous rectifier in MHz CRM flyback converter with GaN devices," 2015 IEEE Energy Conversion Congress and Exposition (ECCE), Montreal, QC, 2015, pp. 5089-5095.
[10] M. A. Bakar, K. Bertilsson and R. Ambatipudi, "High frequency (MHz) soft switched flyback dc-dc converter using GaN switches and six-layered PCB transformer," 8th IET International Conference on Power Electronics, Machines and Drives (PEMD 2016), Glasgow, 2016, pp. 1-6.
[11] Z. Zhang, K. D. T. Ngo and J. L. Nilles, "A 30-W flyback converter operating at 5 MHz," 2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014, Fort Worth, TX, 2014, pp. 1415-1421.
[12] J. Li, F. B. M. van Horck, B. J. Daniel and H. J. Bergveld, "A High-Switching-Frequency Flyback Converter in Resonant Mode," in IEEE Transactions on Power Electronics, vol. 32, no. 11, pp. 8582-8592, Nov. 2017.
[13] J. S. Yoo, T. Ahn, G. Yu, J. Lee and J. Lee, "A study on novel active clamp snubber applied DC-DC quasi resonant flyback converter to effectively reduce switch voltage surge," 2017 20th International Conference on Electrical Machines and Systems (ICEMS), Sydney, NSW, 2017, pp. 1-5.
[14] X. Huang, J. Feng, W. Du, F. C. Lee and Q. Li, "Design consideration of MHz active clamp flyback converter with GaN devices for low power adapter application," 2016 IEEE Applied Power Electronics Conference and Exposition (APEC), Long Beach, CA, 2016, pp. 2334-2341.
[15] R. Perrin, N. Quentin, B. Allard, C. Martin and M. Ali, "High-Temperature GaN Active-Clamp Flyback Converter With Resonant Operation Mode," in IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 4, no. 3, pp. 1077-1085, Sept. 2016.
[16] J. -. Jung and S. Ahmed, "Flyback converter with novel active clamp control and secondary side post regulator for low standby power consumption under high-efficiency operation," in IET Power Electronics, vol. 4, no. 9, pp. 1058-1067, November 2011.
[17] J. Zhang, X. Huang, X. Wu and Z. Qian, "A High Efficiency Flyback Converter With New Active Clamp Technique," in IEEE Transactions on Power Electronics, vol. 25, no. 7, pp. 1775-1785, July 2010.
[18] N. Quentin, R. Perrin, C. Martin, C. Joubert, B. Lacombe and C. Buttay, "GaN Active-Clamp Flyback Converter with Resonant Operation Over a Wide Input Voltage Range," PCIM Europe 2016; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Nuremberg, Germany, 2016, pp. 1-8.
[19] Y. T. Yau, W. Z. Jiang and K. I. Hwu, "Light-load efficiency improvement for flyback converter based on hybrid clamp circuit," 2016 IEEE International Conference on Industrial Technology (ICIT), Taipei, 2016, pp. 329-333.
[20] J. H. Kim, M. H. Ryu, B. D. Min and E. H. Song, "A Method to Reduce Power Consumption of Active-Clamped Flyback Converter at No-Load Condition," IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics, Paris, 2006, pp. 2811-2814.
[21] D. Murthy-Bellur and M. K. Kazimierczuk, "Active-clamp ZVS two-switch flyback converter," 2011 IEEE International Symposium of Circuits and Systems (ISCAS), Rio de Janeiro, 2011, pp. 241-244.
[22] Y. Yang, D. Huang, F. C. Lee and Q. Li, "Analysis and reduction of common mode EMI noise for resonant converters," 2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014, Fort Worth, TX, 2014, pp. 566-571.
[23] X. Huang, J. Feng, F. C. Lee, Q. Li and Y. Yang, "Conducted EMI analysis and filter design for MHz active clamp flyback front-end converter," 2016 IEEE Applied Power Electronics Conference and Exposition (APEC), Long Beach, CA, 2016, pp. 1534-1540.
[24] A. Nabih, M. Ahmed, Q. Li and F. C. Lee, "Transient Control and Soft Start-up for 1 MHz LLC Converter with Wide Input Voltage Range using Simplified Optimal Trajectory Control," in IEEE Journal of Emerging and Selected Topics in Power Electronics, doi: 10.1109/JESTPE.2020.2973660.
[25] C. Fei, Q. Li and F. C. Lee, "Digital Implementation of Light-Load Efficiency Improvement for High-Frequency LLC Converters With Simplified Optimal Trajectory Control," in IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 6, no. 4, pp. 1850-1859, Dec. 2018, doi: 10.1109/JESTPE.2018.2832135.
[26] W. Feng and F. C. Lee, "Optimal Trajectory Control of LLC Resonant Converters for Soft Start-Up," in IEEE Transactions on Power Electronics, vol. 29, no. 3, pp. 1461-1468, March 2014, doi: 10.1109/TPEL.2013.2261094.P. L. Dowell, "Effects of eddy currents in transformer windings," in Proceedings of the Institution of Electrical Engineers, vol. 113, no. 8, pp. 1387-1394, August 1966.
[27] P. L. Dowell, "Effects of eddy currents in transformer windings," in Proceedings of the Institution of Electrical Engineers, vol. 113, no. 8, pp. 1387-1394, August 1966.
[28] L. H. Dixon, "Eddy current losses in transformer winding and circuit wiring", Unitrode/TI Magnetics Design Handbook, 2000.
[29] Z. Ouyang, O. C. Thomsen and M. A. E. Andersen, "Optimal design and tradeoffs analysis for planar transformer in high power DC-DC converters," The 2010 International Power Electronics Conference - ECCE ASIA -, Sapporo, 2010, pp. 3166-3173.
[30] G. Liu, D. Li, J. Q. Zhang, B. Hu and M. L. Jia, "Bidirectional CLLC resonant DC-DC converter with integrated magnetic for OBCM application," 2015 IEEE International Conference on Industrial Technology (ICIT), Seville, 2015, pp. 946-951.
[31] M. A. Bakar and K. Bertilsson, "An improved modelling and construction of power transformer for controlled leakage inductance," 2016 IEEE 16th International Conference on Environment and Electrical Engineering (EEEIC), Florence, 2016, pp. 1-5.
[32] J. Zhang, Z. Ouyang, M. C. Duffy, M. A. E. Andersen and W. G. Hurley, "Leakage Inductance Calculation for Planar Transformers With a Magnetic Shunt," in IEEE Transactions on Industry Applications, vol. 50, no. 6, pp. 4107-4112, Nov.-Dec. 2014.
[33] Liang Yan-ping, Zhang Fang, Zhang Hai-ting and An Zhen, "Leakage inductance calculation and simulation research of extra-high voltage magnetically controlled shunt reactor," 2010 International Conference on Mechanic Automation and Control Engineering, Wuhan, 2010, pp. 4025-4028.
[34] B. Li, Q. Li and F. C. Lee, "A novel PCB winding transformer with controllable leakage integration for a 6.6kW 500kHz high efficiency high density bi-directional on-board charger," 2017 IEEE Applied Power Electronics Conference and Exposition (APEC), Tampa, FL, 2017, pp. 2917-2924.