国際会議(査読有)

  1. Takahiro Okamoto, Masataka Ishihara, Kazuhiro Umetani, Eiji Hiraki, “High-Bandwidth Embedded Rogowski Coil on Multilayer Substrate with Minimal Contribution to Power Loop Inductance," in Proc. 2025 IEEE Applied Power Electronics Conference and Exposition (APEC), Atlanta, USA, May. 2025

  2. Yuto Yoshimura, Kenji Funatani, Kazuhiro Umetani, Toshiyuki Zaitsu, Akito Nakagaki, Masataka Ishihara, Eiji Hiraki, “Direct Effective Power Control (D-EPC) for LLC Resonant Converters Operating in Boost Mode using Event-Driven-Timer based Digital Controller," in Proc. 2025 IEEE Applied Power Electronics Conference and Exposition (APEC), Atlanta, USA, May. 2025

  3. Ryoma Yoshida, Eiji Hiraki, Kazuhiro Umetani and Masataka Ishihara, “Prevention Oscillatory False Triggering of Two Paralleled GaN-HEMTs by Optimization Parasitic Capacitance and Common-Source Inductance," in Proc. 2024 13th International Conference on Renewable Energy Research and Applications (ICRERA), Nagasaki, Japan, Nov. 2024

  4. TAkito Nakagaki, Eiji Hiraki, Kazuhiro Umetani, Ishihara Masataka, Yuto Yoshimura, “Actual Circuit Verification of LC Series Resonant Converter with Power Factor Control for Effective Power in Load regulation," in Proc. IECON 2024 - 50th Annual Conference of the IEEE Industrial Electronics Society, Chicago, USA, Nov. 2024

  5. Takuto Hayashi, Kazuhiro Umetani, Masataka Ishihara, Hiroto Sakai, Yuta Okawauchi, Kotaro Kobashi, Eiji Hiraki, “Improvement Turn on Loss Simulation Accuracy by Nonlinear Voltage Dependence Modeling of Gate Source Capacitance," in Proc. 2024 IEEE Energy Conversion Congress and Exposition (ECCE), Phoenix, USA, Oct. 2024

  6. Yuki Fushino, Kazuhiro Umetani, Masataka Ishihara, Eiji Hiraki, “Equivalent Capacitance of Nonlinear Capacitance in GaN-FET for Improving Accuracy in Suppressing Conditions of Oscillatory False Triggering," in Proc. 2024 IEEE Energy Conversion Congress and Exposition (ECCE), Phoenix, USA, Oct. 2024

  7. Kotaro Kobashi, Kazuhiro Umetani, Masataka Ishihara, Hiroto Sakai, Takuto Hayashi, Eiji Hiraki, “Suppression Strategy for Oscillation between Two Paralleled GaN-HEMTs Based on Harmonics of Switching Surge," in Proc. 2024 IEEE 21st International Power Electronics and Motion Control Conference (PEMC), Pilsen, Czech, Oct. 2024

  8. Daichi Buto, Kazuhiro Umetani, Tomohide Sirakawa, Masataka Ishihara, Eiji Hiraki, “Stack integration structure of multiple high-frequency magnetic devices for power applications," in Proc. 2024 Energy Conversion Congress & Expo Europe (ECCE Europe), Darmstadt, Germany, Sep. 2024

  9. Hiroki Seto, Kazuhiro Umetani, Masataka Ishihara, Eiji Hiraki, “Effective Study of Streamlined Fin with Low-Pressure Loss to Improve Heat Dissipation Performance of Heat Sink," in Proc. 2024 IEEE International Communications Energy Conference (INTELEC), Bengaluru, India, Aug. 2024

  10. Kazuhiro Umetani, Fumie Ishitani, Taira Shirahase, Masataka Ishihara, Eiji Hiraki, “Non-isolated interleaved high stepdown DC-DC converter with reduced switched capacitor stages and automatic current sharing," in Proc. 2024 IEEE International Communications Energy Conference (INTELEC), Bengaluru, India, Aug. 2024

  11. Toshiyuki Zaitsu, Yuto Yoshimura, Kazuhiro Umetani, Eiji Hiraki, Kazuhiro Horii, “Compact hardware implementation of power factor control for LLC converter with event-driven-timer based digital controller," in Proc. 2024 IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 2015-2020, Long Beach, CA, USA, Feb. 2024

  12. Kotaro Kobashi, Kazuhiro Umetani, Masataka Ishihara, Hiroto Sakai, Yuta Okawauchi, Takuto Hayashi, Eiji Hiraki, “Parasitic Inductance Network Modeling Method for Power Module Inner Wirings Based on Inductance Matrix Measurement," in Proc. 2024 IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 2530-2536, Long Beach, CA, USA, Feb. 2024

  13. K. Umetani, Y. Takehara, M. Ishihara, and E. Hiraki, “GaN-HEMT power module structure with single-sided and double-sided aluminum-clad printed-circuit boards for small power loop inductance and high cooling performance,” in Proc. 2023 IEEE Energy Conversion Congress and Exposition (ECCE), pp. 5531-5537, Nashville, TN, USA, Oct. 2023

  14. Ryoma Yoshida, Masataka Ishihara, Kazuhiro Umetani, and Eiji Hiraki, “Suppression strategy for oscillatory false triggering between two paralleled GaN-HEMTs based on optimization of parasitic inductance,” in Proc. 2023 IEEE Energy Conversion Congress and Exposition (ECCE), pp. 5406-5413, Nashville, TN, USA, Oct. 2023

  15. Kotaro Kobashi, Akihiro Konishi, Kazuhiro Umetani, Masataka Ishihara, Takuto Hayashi, and Eiji Hiraki, “Origin of common source inductance in power device packages with kelvin source terminal,” in Proc. 2023 IEEE Energy Conversion Congress and Exposition (ECCE), pp. 5510-5510, Nashville, TN, USA, Oct. 2023

  16. Kazuhiro Umetani, Masataka Ishihara, Eiji Hiraki, “Design of Embedded Experiments in Power Electronics Class,” in Proc. 2023 IEEE 10th International Conference on E-Learning in Industrial Electronics, ICELIE 2023 Oct. 2023, Singapore

  17. Eiji Hiraki, Masataka Ishihara, Kazuhiro Umetani, “Introduction of Circuit Simulator to Power Electronics Education in Interdisciplinary Educational Environment,” in Proc. 2023 IEEE 10th International Conference on E-Learning in Industrial Electronics, ICELIE 2023 Oct. 2023, Singapore

  18. Hiromu Saeki, Kazuhiro Umetani, Tomohide Shirakawa,Masataka Ishihara, and Eiji Hiraki, “Rectifier-Integrated Printed-Circuit-Board Winding Structure of Secondary-Side Center-Tapped Transformer for Suppressing Parasitic Resonance between Decoupling Capacitors ,” in Proc. 11th International Conference on Power Electronics – ECCE Asia, May. 2023, ICC Jeju, Jeju, Korea

  19. Toi Nakamura, Kazuhiro Umetani, Daiki Miyake ,Masataka Ishihara, Eiji Hiraki,and Shuichi Ichikawa, “Semi-analytical derivation of heating material distribution for homogenizing heat generation of cylindrical catalyst,” in Proc.Heating by Electromagnetic Sources (HES-23), Barba ,Università di Pavia , Italia, 2023

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  20. Eiji Hiraki,Masataka Ishihara,Kazuhiro Umetani, “Differences in Visibility of Students' Proficiency by Grading Methods in Energy Electronics-related Lectures Based on DX Format,” in Proc. IEEE 2022 Intl. Conf. E-Learning Ind. Electron. (ICELIE2022), Oct. 2022, Brussels, Belgium

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  21. Kazuhiro Umetani,Masataka Ishihara, Eiji Hiraki, “Solution-Oriented Teaching Method of Electric Power Circuit Design for Online On-demand Video Streaming Lecture Course,” in Proc. IEEE 2022 Intl. Conf. E-Learning Ind. Electron. (ICELIE2022), Oct. 2022, Brussels, Belgium

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  22. Masataka Ishihara, Kodai Matsuura, Akihiro Konishi, Kazuhiro Umetani and Eiji Hiraki,“Cross-Interference Free 6.78 MHz Multiple-Transmitter Using Power Factor Based Control for Wide-Area Wireless Power Transfer Systems,” in Proc. IEEE 2022 Energy Converdion Congress & Expo (ECCE2022), Oct. 2022, Detroit, USA.

  23. Kawahara Shota, Umetani Kazuhiro, Ishihara Masataka and Hiraki Eiji,“PFrequency Dependence Deterioration of AC Resistance in Large-Diameter Litz Wire for High Power Induction Heating,” in Proc. IEEE 2022 Energy Converdion Congress & Expo (ECCE2022), Oct. 2022, Detroit, USA.

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  24. Kiwa Nagayasu, Masaki Iida, Kazuhiro Umetani, Mastaka Ishihara, Eiji Hiraki,“Performance Evaluation of Sinusoidal-Flux Reluctance Machine for Improving Power Density with Reduced Torque and Input-Current Ripples,” in Proc. 2022 23nd European Conference on Power Electronics and Applications (EPE2022 ECCE Europe), Sep. 2022, Hannover, Germany.

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  25. Daiki Miyake, Kazuhiro Umetani, Shota Kawahara, Masataka Ishihara, Eiji Hiraki,“High-Efficiency Solenoid Coil Structure for Induction Heating of Cylindrical Heating Object,” in Proc. IEEE 2022 31th International Symposium on Industrial Electronics (ISIE2022), June. 2022, Anchorage, Alaska, USA.

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  26. Hayato Nakamura, Kazuhiro Umetani, Masataka Ishihara, Eiji Hiraki,“Secondary-Side Resonating LLC Converter for Reducing Transformer Voltage in High Power Applications,” in Proc. International Power Electronic Conference (IPEC2022), May. 2022, Himejia, Japan.

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  27. T. Kawakami, K. Umetani, and S. Morimoto, “Cooperation between theoretical and practical education through power electronics circuits,” in Proc. Intl. Conf. E-Learning Ind. Electron,” in Proc. IEEE 2021 Intl. Conf. E-Learning Ind. Electron. (ICELIE2021), Oct. 2021, Virtual.

  28. Eiji Hiraki, Masataka Ishihara, Kazuhiro Umetani,“Tiny Approaches To the Interactive Online Lectures Under the COVID-19 Pandemic,” in Proc. IEEE 2021 Intl. Conf. E-Learning Ind. Electron. (ICELIE2021), Oct. 2021, Virtual.

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  29. Yusuke Hatakenaka, Kazuhiro Umetani, Masataka Ishihara, Eiji Hiraki, Hiroshi Tadano,“Parasitic Inductance Design for Preventing Oscillatory False Triggering of Parallel-Connected GaN-FETs,” in Proc. IEEE 2021 47th Annual Conference of the IEEE Industrial Electronics Society (IECON2021), Oct. 2021, Virtual.

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  30. Kazuhiro Umetani, Kota Shimomura, Kenta Yamada, Taichi Kawakami, Masataka Ishihara, Eiji Hiraki,“A Control Method Based on Power Factor for Improving Output Voltage Stability and Efficiency of LLC Converter in Wide Range of Output Voltage and Load Impedance,” in Proc. IEEE 2021 Energy Converdion Congress & Expo (ECCE2021), Oct. 2021, Virtual.

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  31. Kodai Matsuura, Masataka Ishihara, Akihiro Konishi, Kazuhiro Umetani, Eiji Hiraki,“Multiple-Transmitter with Phase-Shift and Dynamic ZVS Angle Controls at Fixed Operating Frequency for Cross-Interference Free Wireless Power Transfer Systems,” in Proc. IEEE 2021 Energy Converdion Congress & Expo (ECCE2021), Oct. 2021, Virtual.

  32. Masaki Iida, Kazuhiro Umetani, Takayuki Kusumi, Masataka Ishihara, Eiji Hiraki,“Sinusoidal-Flux Reluctance Machine Driven with Three-Phase Inverter for Improving Power Density with Reduced Torque and Input Current Ripples,” in Proc. 2021 23nd European Conference on Power Electronics and Applications (EPE2021 ECCE Europe), Sep. 2021, Virtual.

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  33. Akihiro Konishi, Kazuhiro Umetani, Eiji Hiraki,“Autonomous resonant frequency tuning controller for repeater resonator in resonant inductive coupling wireless power transfer system,” in Proc. IEEE 2021 30th International Symposium on Industrial Electronics (ISIE2021), June. 2021, Kyoto, Japan.

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  34. Koki Abe, Masataka Ishihara, Yusuke Hatakenaka, Kazuhiro Umetani, Eiji Hiraki,“Feasibility of Parasitic Drain Inductance Design for Minimizing Switching Loss in Bridge Circuits Using GaN-FETs,” in Proc. IEEE 2021 30th International Symposium on Industrial Electronics (ISIE2021), June. 2021, Kyoto, Japan.

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  35. Masaki Iida, Takayuki Kusumi, Kazuhiro Umetani, Eiji Hiraki,“Feasibility of Sinusoidal Flux Drive Design of Reluctance Motor for Reducing Torque and Input Current Ripples with Three-Leg Inverter,” in Proc. IEEE 2020 19th International Power Electronics and Motion Control Conference (PEMC2020), Apl. 2021, Gliwice, Poland.

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  36. L. Dunai, J. Martins, K. Umetani, O. Lucia, Y. Ibrahim and G. K. Appuhamillage, “E-learning in industrial electronics during covid-19,” in Proc. IEEE Intl. Conf. Ind. Tech. (ICIT), pp. 1227-1233, March. 2021.

  37. Shota Kawahara, Kazuhiro Umetani, Eiji Hiraki,“AC resistance Prediction of Litz Wire Planer Spiral Coil Based on Litz wire Loss Model,” in Proc. IEEE 2020 23rd International Conference on Electrical Machines and Systems (ICEMS2020), Nov. 2020, Hamamatsu, Japan, .

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  38. Yusuke Hatakenaka, Kazuhiro Umetani, Masataka Ishihara, Eiji Hiraki,“Optimization of Common Source Inductance and Gate-Drain Capacitance for Reducing Gate Voltage Fluctuation after Turn-off Transition,” in Proc. IEEE Energy Conversion Conf. Expo. (ECCE2020), Oct. 2020, Detroit, MICHIGAN, USA, pp. 3155-3162.

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  39. Kodai Matsuura, Masataka Ishihara, Akihiro Konishi, Kazuhiro Umetani, Eiji Hiraki,“Multiple-Transmitter Achieving Load-Independent Transmitter Current and Compensation of Cross-Interference Among Transmitters for Wide Charging Area Wireless Power Transfer Systems,” in Proc. IEEE Energy Conversion Conf. Expo. (ECCE2020), Oct. 2020, Detroit, MICHIGAN, USA, pp. 5474-5481.

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  40. Shota Kawahara, Kazuhiro Umetani, Eiji Hiraki,“Analysis and Prediction of AC Resistance of Litz Wire with Rectangular Cross-Section,” in Proc. IEEE Energy Conversion Conf. Expo. (ECCE2020), Oct. 2020, Detroit, MICHIGAN, USA, pp. 3273-3279.

  41. K. Umetani and E. Hiraki, “Competition-based learning of power converter design emulating product development activity,” in Proc. Annu. Conf. IEEE Ind. Electron. Soc. (IECON2020), Oct. 2020, Singapore, pp. 3339–3344..

  42. Ryo Murata, Tomohide Shirakawa, Kazuhiro Umetani, Eiji Hiraki, Hiroto Mizutani, Takaaki Takahara, Osamu Mori,“Homogenization of Current Distribution in Parallel Connection of Interleaved Winding Layers of High-Frequency Transformers by Optimizing Distance between Winding Layers,” in Proc. IEEE European Conf. Power Electron. Ap.pl. (EPE2020), Lyon, France, Sept. 2020.

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  43. Tomohide Shirakawa, Kazuhiro Umetani, Eiji Hiraki, Wilmar Martinez,“Secondary-Side Center-Tapped Transformer Structure with One-Turn Secondary Coils Integrating Rectifier for Reducing Copper Loss of Forward Converter,” in Proc. IEEE 2020 29th International Symposium on Industrial Electronics (ISIE2020), June. 2020, Delft, Netherlands.

  44. W.-R. Lin, C. Suarez, K. Umetani, W. Martinez, “Gate drivers techniques and solutions for GaN HEMTs in high frequency applications,” in Proc. IEEE Intl. Sym. Ind. Electron. (ISIE2020), Delft, Nederland, Jun. 2020, pp. 674–678.

  45. K. Kamaeguchi, K. Umetani, and E. Hiraki, “Axial heating coil structure for reducing magnetic levitation force of all-metal type induction cookers,” in Proc. IEEE Intl. Conf. Renewable Energy Research Appl. (ICRERA2019), Nov. 2019, Brasov, Romania, pp. 1-7

  46. K. Koki, M. Yoshioka, K. Umetani, and E. Hiraki, “Verification of device model by measuring capacitance and static characteristics for predicting switching waveform,” in Proc. IEEE Intl. Conf. Renewable Energy Research Appl. (ICRERA2019), Nov. 2019, Brasov, Romania, pp. 1-7.

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  47. T. Shirakawa, K. Umetani, E. Hiraki, Y. Itoh, and T. Hyodo, “Optimal winding layer allocation for minimizing copper loss of secondary-side center-tapped forward transformer with parallel-connected secondary windings,” in Proc. IEEE Energy Conversion Conf. Expo. (ECCE2019), Oct. 2019, Baltimore, ML, USA, pp. 6206-6213.

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  48. T. Kusumi, K. Kobayashi, K. Umetani, and E. Hiraki “Analytical derivation of phase current waveform eliminating torque ripple and input current ripple of switched reluctance motors under magnetically saturated operation,” in Proc. IEEE Energy Conversion Conf. Expo. (ECCE2019), Oct. 2019, Baltimore, ML, USA, pp. 6540-6547.

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  49. M. Ishihara, K. Fujiki, K. Umetani, and E. Hiraki, “Automatic active compensation method of cross-coupling in multiple-receiver resonant inductive coupling wireless power transfer systems,” in Proc. IEEE Energy Conversion Conf. Expo. (ECCE2019), Oct. 2019, Baltimore, ML, USA, pp. 4584-4591.

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  50. A. Konishi, K. Fujiki, K. Umetani, and E. Hiraki, “Resonant frequency tuning system for repeater resonator of resonant inductive coupling wireless power transfer,” in Proc. IEEE European Conf. Power Electron. Ap.pl. (EPE2019), Genova, Italy, Sept. 2019, pp., 1–10.

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  51. K. Fujiki, M. Ishihara, K. Umetani, and E. Hiraki, “Experimental verification of impedance matching method for repeater to improve spatial freedom of 6.78 MHz resonant inductive coupling wireless power transfer systems,” in Proc. IEEE European Conf. Power Electron. Appl. (EPE2019), Genova, Italy, Sept. 2019, pp., 1–10.

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  52. R. Murata, T. Shirakawa, K. Umetani, and E. Hiraki, “Volume reduction effect of thinly extended core structure for transformer in isolated DC-DC converter,” in Proc. IEEE Intl. Conf. Power Electron. (ICPE2019), Busan, Korea, May 2019, ThH1-5.

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  53. T. Shiraishi , F. Hattori , M. Ishitobi , and E. Hiraki , “Characteristic Analysis of Integrated Magnetic Component for Forward Converter,” in Proc. IEEE Intl. Conf. Power Electron. (ICPE2019), Busan, Korea, May 2019, TuA2-4.

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  54. M. Noah, T. Shirakawa, K. Umetani, J. Imaoka, M. Yamamoto, and E. Hiraki, “Effects of secondary leakage inductance on the LLC resonant converter—Part II: Frequency control bandwidth with respect to load variation,” in Proc. IEEE Appl. Power Electron. Conf. (APEC2019), Anaheim, CA, USA, Mar. 2019, pp. 1408–1414.

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  55. K. Umetani, J. Acero, H. Sarnago, O. Lucia, and E. Hiraki, “Simple fully analytical copper loss model of Litz wire made of strands twisted in multiple levels,” in Proc. IEEE Appl. Power Electron. Conf. (APEC2019), Anaheim, CA, USA, Mar. 2019, pp. 1257–1264.

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  56. M. Noah, T. Shirakawa, K. Umetani, J. Imaoka, M. Yamamoto, and E. Hiraki, “Effects of secondary leakage inductance on the LLC resonant converter—Part I: Transformer voltage gain and efficiency,” in Proc. IEEE Appl. Power Electron. Conf. (APEC2019), Anaheim, CA, USA, Mar. 2019, pp. 780–786.

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  57. T. Kusumi, K. Kobayashi, T. Hara, K. Umetani, and E. Hiraki, “Core loss modeling based on equivalent circuit for switched reluctance motors,” in Proc. IEEE Intl. Conf. Ind. Tech. (ICIT2019), Melbourne, Australia, Feb. 2019, pp. 1795-1800.

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  58. N.Nanato , T.Adachi and T.yamanishi, “Development of a Single-phase Bi2223 High Temperature Superconducting Transformer for a High Frequency and Large current source and a protection system for the transformer,” in 31th International Symposium on Superconductivity, Ibaraki, Japan, December 2018.

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  59. N.Nanato and H.Aoyama, “Early Detection of Normal Transitions in a High Temperature Superconducting Transformer Wound with a Plurality of HTS Tapes Using the Active Power Method,” in 31th International Symposium on Superconductivity, Ibaraki, Japan, December 2018.

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  60. N.Nanato , M.Kondo and H.Yamada, “Development of an Air-core Bi2223 High Temperature Superconducting Transformer for a Large AC Current Supply and its Self-Protection for Normal Transitions,” in 31th International Symposium on Superconductivity, Ibaraki, Japan, December 2018.

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  61. K. Umetani, T. Mishima, K. Umetani, E. Hiraki, T. Hirokawa, M. Imai, and H. Sadakata, “Improved thin heating coil structure of copper foil feasible for induction cookers,” in Proc. Annu. Conf. IEEE Ind. Electron. Soc. (IECON2018), Washington D.C., USA, 2018, pp. 3503–3508.

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  62. A. Oyane, K. Itakura, K. Umetani, E. Hiraki, T. Ikenari, and S. Kawano, “Soft-switching control circuit based on traveling and reflected waves for high-frequencr resonant inverter applicable to capacitive load impedance,” in Proc. Annu. Conf. IEEE Ind. Electron. Soc. (IECON2018), Washington D.C., USA, 2018, pp. 3051–3056.

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  63. S. Ikegami, K. Umetani, E. Hiraki, S. Sakai, and S. Higashino, “Feasibility study of fractal-fin heat sink for improving cooling performance of switching power converters,” in Proc. IEEE Intl. Telecommunications Energy Conf., Torino, Italy, Oct. 2018 pp. 1–8.

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  64. T. Kusumi, T. Hara, K. Umetani, and E. Hiraki, “Rotor configuration which reduces copper loss of switched reluctance motors with suppression of torque ripple and input current ripple,” in Proc. IEEE Energy Conversion Congr. Expo. (ECCE2018), pp. 6097–6103, Portland, OR, USA, Sept. 2018.

  65. M. Ishihara, K. Umetani, and E. Hiraki, “Impedance Matching to Maximize Induced Current in Repeater of Resonant Inductive Coupling Wireless Power Transfer Systems,”in 2018 IEEE Energy Conversion Congress and Exposition (ECCE), in USA, 2018.

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  66. M. Ishihara, K. Umetani, and E. Hiraki, “Improving Robustness Against Variation in Resonance Frequency for Repeater of Resonant Inductive Coupling Wireless Power Transfer Systems,” in 20th European Conference on Power Electronics and Applications (EPE'18 ECCE Europe), Riga in Latvia, 17-21 Sept. 2018.

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  67. K. Kamaeguchi, K. Umetani, and E. Hiraki, “Application of Automatic Resonant Frequency Tuning Circuit to Induction Heating System,” in 20th European Conference on Power Electronics and Applications (EPE'18 ECCE Europe), Riga in Latvia, 17-21 Sept. 2018.

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  68. M. Hataya, K. Kamaeguchi, E. Hiraki, K. Umetani, T. Hirokawa, M. Imai, and S. Sadakata, “Verification of the reduction of the copper loss by the thin coil structure for induction cookers,” in Proc. IEEE Intl. Power Electron. Conf. (IPEC2018), Niigata, Japan, May 2018, pp. 410–415.

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  69. A. Konishi, K. Umetani, and E. Hiraki, “High-frequency self-driven synchronous rectifier controller for WPT systems,” in Proc. IEEE Intl. Power Electron. Conf. (IPEC2018), Niigata, Japan, May 2018, pp. 1602–1609.

  70. M. Ishihara, K. Umetani, and E. Hiraki, “Automatic resonance frequency tuning method for repeater in resonant inductive coupling wireless power transfer systems,” in Proc. IEEE Intl. Power Electron. Conf. (IPEC2018), Niigata, Japan, May 2018, pp. 1610–1616.

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  71. M. Noah, J. Imaoka, Y. Ishikura, K. Umetani, and M. Yamamoto, “Review of current balance mechanism in multiphase llc resonant converters,” in Proc. IEEE Intl. Sym. Ind. Electron. (ISIE2018), Cairns, Australia, Jun. 2018, pp. 1030–1036.

  72. T. Kusumi, T. Hara, K. Umetani, and E. Hiraki, “Theoretical derivation of phase current profile for switched reluctance motors to suppress radial force ripple and torque ripple,” in Proc. IEEE Intl. Sym. Ind. Electron. (ISIE2018), Cairns, Australia, Jun. 2018, pp. 1037–1042.

  73. R. Matsumoto, K. Aikawa, A. Konishi, K. Umetani, and E. Hiraki, “Evaluation of impact of parasitic magnetic coupling in PCB layout on common source inductance of surface mount package,” in Proc. IEEE Intl. Conf. Power Electron. Drive Syst., Honolulu, USA, Dec. 2017, pp. 559–566.

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  74. M. Ishihara, K. Umetani, and E. Hiraki, “Elucidation of quasi-duality between series-series and series-parallel topologies of resonant inductive coupling wireless power transfer systems,” in Proc. IEEE Intl. Conf. Power Electron. Drive Syst., Honolulu, USA, Dec. 2017, pp. 674–679.

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  75. Y. Tanaka, N. Nanato, M. Kondo, T. Niwase: Study on Configuration of a Single-phase Air-core Bi2223 High Temperature Superconducting Transformer for a Large AC Current Supply, 30th International Symposium on Superconductivity, December 13 - 15, 2017, Tokyo, Japan

  76. T. Ono, T. Adachi, T. Yamanishi, N. Nanato: Protection System for Normal Transitions in a Single-phase Bi2223 Full Superconducting Transformer by the Active Power Method under Flowing Various Frequency Current, 30th International Symposium on Superconductivity, December 13 - 15, 2017, Tokyo, Japan

  77. H. Kumagai, N. Nanato: High Resolution Location of Normal Transitions in A High Temperature Superconducting Coil by Capacitor Type Voltage Terminals, 30th International Symposium on Superconductivity, December 13 - 15, 2017, Tokyo, Japan

  78. S. Tanaka, S. Tenkumo, N. Nanato, Study on a Magnetic Flux Detection Coil for Detection of Normal Transitions in a Hybrid Single-phase Bi2223 Superconducting Transformer by the Active Power Method, 30th International Symposium on Superconductivity, December 13 - 15, 2017, Tokyo, Japan

  79. T. Koyama, T. Honjo, M. Ishihara, K. Umetani, and E. Hiraki, “Simple self-driven synchronous rectifier for resonant inductive coupling wireless power transfer,” in Proc. IEEE Intl. Telecommunications Energy Conf., Gold Coast, Australia, Oct. 2017, pp. 363–368.

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  80. T. Shirakawa, K. Umetani, and E. Hiraki, “Application of extremum co-energy principle for homogenizing current distribution in parallel-connected windings in transformers: design optimization of winding turn allocation among winding layers,” in Proc. European Conf. Power Electron. Appl. (EPE2017), Warsaw, Poland, Sept. 2017, pp. 1–10.

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  81. M. Noah, S. Endo, S. Kimura, M. Yamamoto, J. Imaoka, K. Umetani, and E. Hiraki, “An investigation into a slight-variation of the transformer effective permeability in LLC resonant converter,” in Proc. European Conf. Power Electron. Appl. (EPE2017), Warsaw, Poland, Sept. 2017, pp. 1–7.

  82. T. Kusumi, T. Hara, K. Umetani, E. Hiraki : "Simple analytical derivation of magnetic flux profile eliminating source current ripple and torque ripple of switched reluctance motors for electric vehicle propulsion", 2017 IEEE Applied Power Electronics Conference and Exposition (APEC) pp. 3142 - 3149 (2017)

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  83. K. Aikawa, T. Shiida, R. Matsumoto, K. Umetani, E. Hiraki : "Measurement of the common source inductance of typical switching device packages", 2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia), pp. 1172 - 1177 (2017)

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  84. T. Ozaki, H. Nakaido, K. Umetani, E. Hiraki, T. Ikenari, and S. Kawano, “Compact three-phase AC inductor network for PFC converter using magnetic coupled technique,” in Proc. Annu. Conf. IEEE Ind. Electron. Soc. (IECON2017), Beijing, China, 2017, pp. 958–963.

  85. K. Itakura, H. Kakemizu, H. Nakaido, K. Umetani, E. Hiraki, T. Ikenari, and S. Kawano, “Soft-switching technique applicable to capacitive load for resonant inverter of plasma generator,” in Proc. Annu. Conf. IEEE Ind. Electron. Soc. (IECON2017), Beijing, China, 2017, pp. 1556–1562.

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  86. W. Martinez, C. A. Cortes, J. Imaoka, K. Umetani, and M. Yamamoto, “Current ripple modeling of an interleaved high step-up converter with coupled inductor,” in Proc. Intl. Future Energy Electron. Conf. (IFEEC2017), pp.1-6, Kaohsiung, Taiwan, May 2017.

  87. R. Kadowaki, N. Nanato: Detection Method of Normal transitions in a High Temperature Superconducting Coil wound with a plurality of YBCO superconductors by the Active Power Method and H-coils, 29th International Symposium on Superconductivity, November 13 - 15, 2016, Tokyo, Japan

  88. K. Okura, N. Nanato, Yasunobu Kumagai, Hiroki Aoyama: Locating of Normal Transitions in A Bi2223 High Temperature Superconducting Coil by Using Capacitor Type Voltage Terminals and the Active Power Method, 29th International Symposium on Superconductivity, November 13 - 15, 2016, Tokyo, Japan

  89. S. Nakamura, N. Nanato, S. Tanaka: Detection of Normal Transitions in a Hybrid Single-phase Bi2223 High Temperature Superconducting Transformer by using the Active Power Method and a Magnetic Flux Detection Coil, 29th International Symposium on Superconductivity, November 13 - 15, 2016, Tokyo, Japan

  90. N. Koide, N. Nanato, T. Ono, T. Adachi: Protection System for Normal Transitions in a Single-phase 1 kA Class Bi2223 High Temperature Superconducting Transformer by Using the Active Power Method, 29th International Symposium on Superconductivity, November 13 - 15, 2016, Tokyo, Japan

  91. N. Kishi, N. Nanato, Y. Tanaka, M. Kondo: Development of A large AC Current Supply with A Single-phase Air-core Bi2223 High Temperature Superconducting Transformer, 29th International Symposium on Superconductivity, November 13 - 15, 2016, Tokyo, Japan

  92. Y. Isshiki, K. Umetani, S. Sakai, S. Higashino, M. Yoshino, Y. Hayashi, and E. Hiraki, “Fractal-like geometry for improving heat dissipation of heat sinks,” in Proc. Intl. Forum Heat Transfer (IFHT2016), Sendai, Japan, Nov. 2016, IFHT2016-1866.

  93. W. Martinez, S. Endou, K. Nanamori, S. Kimura, M. Noah, M. Yamamoto, J. Imaoka, and K. Umetani, “Three-phase LLC resonant converter with integrated magnetics,” in Proc. IEEE Energy Conversion Congr. Expo. (ECCE2016), Milwaukee, USA, Sept. 2016.

  94. R. Matsumoto, K. Umetani, and E. Hiraki, “Optimization of the balance between the gate-drain capacitance and the common source inductance for preventing the oscillatory false triggering of fast switching GaN-FETs,” in Proc. IEEE Energy Conversion Congr. Expo. (ECCE2017), Cincinnati, USA, Sept. 2016, pp. 405–412.

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  95. M. Noah, K. Umetani, S. Endo, H. Ishibashi, J. Imaoka, and M. Yamamoto, “A Lagrangian dynamics model of integrated transformer incorporated in a multi-phase LLC resonant converter,” in Proc. IEEE Energy Conversion Congr. Expo. (ECCE2017), Cincinnati, USA, Sept. 2016, pp. 3781–3787.

  96. Y. Sugihara, K. Nanamori, S. Ishiwaki, Y. Hayashi, K. Aikawa, K. Umetani, E. Hiraki, and M. Yamamoto, “Analytical investigation on design instruction to avoid oscillatory false triggering of fast switching SiC-MOSFETs,” in Proc. IEEE Energy Conversion Congr. Expo. (ECCE2017), Cincinnati, USA, Sept. 2016, pp. 5113–5118.

  97. N. Mostafa, S. Kimura, S. Endo, M. Yamamoto, J. Imaoka, K. Umetani, and W. Martinez, “A novel three-phase LLC resonant converter with integrated magnetics for lower turn-off losses and higher power density,” in Proc. IEEE Appl. Power Electron. Conf. (APEC2017), Tampa, FL, USA, Mar. 2016, pp. 322–329.

  98. T. Hara, T. Kusumi, K. Umetani, E. Hiraki : "A simple behavior model for switched reluctance motors based on magnetic energy", 2016 IEEE 8th International Power Electronics and Motion Control Conference (IPEMC-ECCE Asia), pp. 109 - 115 (2016)

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  99. T. Koyama, T. Honjo, K. Umetani, E. Hiraki : "Lagrangian derivation and analysis of a simple equivalent circuit model of wireless power transfer system with dual transmitting resonators", 2016 18th European Conference on Power Electronics and Applications (EPE'16 ECCE Europe), pp. 1 - 10 (2016)

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  100. T. Shirakawa, G. Yamasaki, K. Umetani, E. Hiraki : "Copper loss analysis based on extremum co-energy principle for high frequency forward transformers with parallel-connected windings", IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, pp. 1099 - 1105 (2016)

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  101. T. Kusumi, T. Hara, K. Umetani, E. Hiraki : "Simple control technique to eliminate source current ripple and torque ripple of switched reluctance motors for electric vehicle propulsion", IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, pp. 1876 - 1881 (2016)

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  102. T. Shirakawa, G. Yamasaki, K. Umetani, E. Hiraki : "Extremum co-energy principle for analyzing AC current distribution in parallel-connected wires of high frequency power inductors", 2016 19th International Conference on Electrical Machines and Systems (ICEMS), pp. 1 - 6 (2016)

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  103. T. Honjo, T. Koyama, K. Umetani, E. Hiraki : "Novel receiving coil structure for improving efficiency and power transfer capability of resonant inductive coupling wireless power transfer", 2016 19th International Conference on Electrical Machines and Systems (ICEMS), pp. 1 - 6 (2016)

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  104. M. Hataya, Y. Oka, K. Umetani, E. Hiraki, T. Hirokawa, M. Imai : "Novel thin heating coil structure with reduced copper loss for high frequency induction cookers", 2016 19th International Conference on Electrical Machines and Systems (ICEMS), pp. 1 - 6 (2016)

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  105. W. Martinez, J. Imaoka, M Yamamoto, and K. Umetani, "High step-up interleaved converter for renewable energy and automotive applications," in Proc. Intl. Conf. Renewable Energy Research Appl. (ICRERA2015), pp. 809–814, Palermo, Italy, Nov. 2015.

  106. H. Umegami, M. Ishihara, F. Hattori, M. Masuda, K. Umetani, and M. Yamamoto : "Mid-range kHz electrical resonance coupling wireless power transfer", in Proc. IEEE Energy Conversion Congr. Expo., pp.3197-3202, Montreal, Canada, Sept. 2015.

  107. Kazuhiro Umetani, Eiji Hiraki, Masayoshi Yamamoto : "Passive regenerative turn-off snubber composed of two diodes and a capacitor for two-phase interleaved boost chopper", 2015 IEEE International Telecommunications Energy Conference (INTELEC), pp. 1 - 6 (2015)

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  108. W. Martinez, J. Imaoka, Y. Itoh, M. Yamamoto, and K. Umetani, "A novel high step-down interleaved converter with coupledinductor," in Proc. IEEE Intl. Telecommunications Energy Conf., pp. 348–353, Osaka, Japan, Oct. 2015.

  109. Kazuhiro Umetani, Eiji Hiraki, Masayoshi Yamamoto : "Non-isolated interleaved high step-up converter with reduced voltage multiplier stages and a regenerative turn-off snubber", 2015 IEEE Energy Conversion Congress and Exposition (ECCE), pp. 125 - 132 (2015)

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  110. Shinya Kurachi, Naoki Yamamoto, Hiroaki Yamada, Toshihiko Tanaka, Eiji Hiraki, Yukiharu Yamada, Tatsuya Nagao, Yasuhiro Miyake, Yujiro Noda : "High-frequency induction heating for tiny foreign metals", 2015 9th International Conference on Power Electronics and ECCE Asia (ICPE-ECCE Asia), pp. 2203 - 2208 (2015)

  111. N. Nanato, K. Nishiyama, S. Hesaka, K. Okura: Locating of Normal Transitions in a High Temperature Superconducting Coil by Non-Destructive Voltage Detection Method, 27th International Symposium on Superconductivity, November 25 - 27, 2014, Tokyo, Japan

  112. N. Nanato, Y. Kobayashi, N. Koide, S. Nakamura, N. Kishi: "Detection and Protection System for Normal Transitions in a Single-phase High Temperature Superconducting Transformer by Using the Active Power Method", 27th International Symposium on Superconductivity, November 25 - 27, 2014, Tokyo, Japan

  113. Tint Soe Win, Yoshihiro Hisada, Toshihiko Tanaka, Eiji Hiraki, Masayuki Okamoto, Seong Ryong Lee : "Novel, simple reactive power control strategy with DC capacitor voltage control for active load balancer in three-phase four-wire distribution systems", 2014 IEEE Energy Conversion Congress and Exposition (ECCE), pp. 3916 - 3921 (2014)

  114. Tint Soe Win, Yoshihiro Hisada, Toshihiko Tanaka, Eiji Hiraki, Masayuki Okamoto, Seong Ryong Lee : "Reactive power control strategy based on DC capacitor voltage control for active load balancer in three-phase four-wire distribution systems", 2014 International Power Electronics Conference (IPEC-Hiroshima 2014 - ECCE ASIA), pp. 3292 - 3297 (2014)

  115. Keisuke Yoshizawa, Toshihiko Tanaka, Eiji Hiraki, Masayuki Okamoto : "MHz-class high-frequency soft-switching GaN-based inverter for wireless power transmission via electromagnetic resonance", 2014 International Power Electronics and Application Conference and Exposition, pp. 451 - 455 (2014)