本論文提出應用於電池充電系統的12 V - 48 V非隔離雙向直流-直流轉換器，電路架構採用兩相耦合電感升壓轉換器，耦合電感可使兩相的磁通抵銷，並可以透過耦合係數來調整降低磁通量，當鐵芯流過越小的磁通時，則會有越低的鐵芯損耗。同時切換頻率也會影響鐵芯大小，因此切換頻率設計於400 kHz，開關使用寬能隙元件氮化鎵元件。本論文探討非隔離轉換器的理論基礎，並分析各個區間的電路動作原理與動作區間等效電路的轉換推導，並透過損耗分析針對選用的開關元件進行分析與比較。同時將電感的鐵芯尺寸以參數化的形式表示，並在眾多鐵芯參數組合中得到電感損耗與其體積的最佳平衡點，最後提出採用分散式氣隙鐵芯以及Pot鐵芯來做優化比較的結構。最終實現輸入電壓12 V、輸出電壓48 V、切換頻率400 kHz、輸出功率為1 kW、升壓模式最高效率為97.55%、降壓模式最高效率為97.68%的非隔離雙向轉換器，以因應高效率電池充電應用需求。

This thesis discusses a bidirectional DC/DC converter used in battery charger between 48 V system and 12 V system. A two-phase interleaved converter with coupled inductor is designed. Coupled inductor can adjust coupling coefficient to reduce the flux of each phase. In the meantime, lower flux make the size of core become smaller. Furthermore, due to the superior performance of GaN devices, the switching frequency can be pushed to 400 kHz and the core volume are reduced. Under different combinations of switches, choose best combination which can have low-est loss. Analyze the relationship between equivalent inductance and each interval. Moreover, use ANSYS Maxwell to parametrize the core and se-lect the design point based on the balance of loss and footprint. The com-parison of distributed airgap and Pot core will be presented. As a result, a bidirectional converter achieved with the switching frequency operating at 400 kHz, an input voltage of 12 V, an output voltage of 48 V, an output power of 1 kW, the highest efficiency in boost mode is 97.55%, and the highest efficiency in buck mode is 97.68%.

[1] E. Ceuca, G. Brezeanu, and V. Trifa, “Study for developing the energy recovering circuit for modern e-bike controller,” in 2015 International Semiconductor Conference (CAS), 12-14 Oct. 2015 2015, pp. 245-248, doi: 10.1109/SMICND.2015.7355221.
[2] S. Biswas, E. A. Jones, M. d. Rooij, and J. S. Glaser, “GaN-based High Current Bi-directional DC-DC Converter for 48 V Automotive Applications,” in PCIM Europe 2019; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 7-9 May 2019 2019, pp. 1-7.
[3] Z. Liu, X. Huang, M. Mu, Y. Yang, F. C. Lee, and Q. Li, “Design and evaluation of GaN-based dual-phase interleaved MHz critical mode PFC converter,” in 2014 IEEE Energy Conversion Congress and Exposition (ECCE), 14-18 Sept. 2014 2014, pp. 611-616, doi: 10.1109/ECCE.2014.6953451.
[4] X. Huang, Z. Liu, Q. Li, and F. C. Lee, “Evaluation and Application of 600 V GaN HEMT in Cascode Structure,” IEEE Transactions on Power Electronics, vol. 29, no. 5, pp. 2453-2461, 2014, doi: 10.1109/TPEL.2013.2276127.
[5] U. K. Mishra, P. Parikh, and W. Yi-Feng, “AlGaN/GaN HEMTs-an overview of device operation and applications,” Proceedings of the IEEE, vol. 90, no. 6, pp. 1022-1031, 2002, doi: 10.1109/JPROC.2002.1021567.
[6] J. Millán, P. Godignon, X. Perpiñà, A. Pérez-Tomás, and J. Rebollo, “A Survey of Wide Bandgap Power Semiconductor Devices,” IEEE Transactions on Power Electronics, vol. 29, no. 5, pp. 2155-2163, 2014, doi: 10.1109/TPEL.2013.2268900.
[7] 陳允彥，三相交錯式耦合電感設計與研製，國立臺灣科技大學電子工程系碩士論文，2021年。
[8] B. Li, W. Qin, Y. Yang, Q. Li, F. C. Lee, and D. Liu, “A High Frequency High Efficiency GaN Based Bi-Directional 48V/12V Converter with PCB Coupled Inductor for Mild Hybrid Vehicle,” in 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA), 31 Oct.-2 Nov. 2018 2018, pp. 204-211, doi: 10.1109/WiPDA.2018.8569067.
[9] DMR53 datasheet. [Online]. Available : https://www.dianyuan./uplo-ad/community/2017/09/05/1504577498-77035.pdf
[10] Y. Yang, J. Ma, C. N. M. Ho, and Y. Zou, “A New Coupled-Inductor Structure for Interleaving Bidirectional DC-DC Converters,” IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 3, no. 3, pp. 841-849, 2015, doi: 10.1109/JESTPE.2015.2443178.
[11] A. Arruti, F. J. Perez-Cebolla, J. Anzola, I. Aizpuru, and M. Mazuela, “Analytical, FEM and Experimental Study of the Influence of the Airgap Size in Different Types of Ferrite Cores,” in 2022 24th European Conference on Power Electronics and Applications (EPE'22 ECCE Europe), 5-9 Sept. 2022 2022, pp. 1-8.
[12] J. Muhlethaler, J. W. Kolar, and A. Ecklebe, “A novel approach for 3d air gap reluctance calculations,” in 8th International Conference on Power Electronics - ECCE Asia, 30 May-3 June 2011 2011, pp. 446-452, doi: 10.1109/ICPE.2011.5944575.
[13] S. Saeed, J. Garcia, M. S. Perdigão, V. S. Costa, B. Baptista, and A. M. S. Mendes, “Improved Inductance Calculation in Variable Power Inductors by Adjustment of the Reluctance Model Through Magnetic Path Analysis,” IEEE Transactions on Industry Applications, vol. 57, no. 2, pp. 1572-1587, 2021, doi: 10.1109/TIA.2020.3047593.
[14] C. Fei, M. H. Ahmed, F. C. Lee, and Q. Li, “Two-Stage 48 V-12 V/6 V-1.8 V Voltage Regulator Module With Dynamic Bus Voltage Control for Light-Load Efficiency Improvement,” IEEE Transactions on Power Electronics, vol. 32, no. 7, pp. 5628-5636, 2017, doi: 10.1109/TPEL.2016.2605579.
[15] D. Lin, P. Zhou, W. N. Fu, Z. Badics, and Z. J. Cendes, “A dynamic core loss model for soft ferromagnetic and power ferrite materials in transient finite element analysis,” IEEE Transactions on Magnetics, vol. 40, no. 2, pp. 1318-1321, 2004, doi: 10.1109/TMAG.2004.825025.
[16] Z. Yu et al., “A Novel Pyramid Winding for PCB Planar Inductors With Fewer Copper Layers and Lower AC Copper Loss,” IEEE Transactions on Power Electronics, vol. 37, no. 10, pp. 11461-11468, 2022, doi: 10.1109/TPEL.2022.3164994.
[17] H. H. Cui, M. H. Kao, L. L. Xue, and K. D. T. Ngo, “Enhanced Inductance and Winding Loss Model for Coupled Inductors,” in 2020 IEEE Energy Conversion Congress and Exposition (ECCE), 11-15 Oct. 2020 2020, pp. 3518-3523, doi: 10.1109/ECCE44975.2020.9235673.
[18] J. Cros, A. J. Perin, and P. Viarouge, “Soft magnetic composites for electromagnetic components in lighting applications,” in Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344), 13-18 Oct. 2002 2002, vol. 1, pp. 342-347 vol.1, doi: 10.1109/IAS.2002.1044110.