Faculty Profiles - IMAOKA Jun

Papers - IMAOKA Jun

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EMI Prediction and Reduction of Zero-crossing Noise in Totem-pole Bridgeless PFC Converter Reviewed

Baihua Zhang, Qiang Lin, Jun Imaoka, Masahito Shoyama, Satoshi Tomioka, Eiji Takegami

Journal of Power Electronics Vol. 19 ( 1 ) page： pp. 278-287 2019.1

A Novel Transformer Structure Used in a 1.4 MHz LLC Resonant Converter with GaNFETs

Tengfei Ou, Mostafa Noah, Koichi Morita, Mamoru Tsuruya, Seiji Namiki, Jun Imaoka, Masayoshi Yamamoto

Proc. of IEEE International Power Electronics and Application Conference and Exposition (PEAC) page： pp. 1-5 2018.11

ターンオフ遅延時間を考慮したピーク電流モード制御 DC-DC コンバータの限界動作周波数 Reviewed

藤原和也, 右手凌, 今岡淳, 庄山正仁

電子情報通信学会論文誌 Vol. J101–B ( 11 ) page： 950–957 2018.11

Fundamental Experiment of 3-phase Electric Resonant Coupling Wireless Power Transfer Reviewed

Fumiya Hattori, Jun Imaoka, Masayoshi Yamamoto, Mitsuru Masuda

Proc. of 7th International Conference on Renewable Energy Research and Applications (ICRERA) page： pp. 1417-1422 2018.10

Current-Mode Digital Control Method for High Frequency DC-DC Converter with Reduced Number of Sampling in One Switching Cycle Reviewed

Atsushi Mishima, Reo Takiguchi, Jun Imaoka, Masahito Shoyama, Akihiro Yamaguchi, Tomonori Kimura

Proc. of IEEE Energy Conversion Congress & Exposition (ECCE 2018) page： pp.1423-1427 2018.9

Effect of Inductor Parasitic Resistances on the Voltage-Gain of High Step-Up DC-DC Converters for Electric Vehicle Applications Reviewed Open Access

Wilmar Martinez, Camilo Cortes, Jun Imaoka, Masayoshi Yamamoto

IET Power Electronics Vol. 11 ( 10 ) page： 1628–1639 2018.8

Magnetic Design and Experimental Evaluation of a Commercially available Single Integrated Transformer in Three-phase LLC converter Reviewed Open Access

Mostafa Noah, Shota Kimura, Jun Imaoka, Wilmar Martinez, Shun Endo, Masayoshi Yamamoto, Kazuhiro Umetani

IEEE Transactions on Industry Applications Vol. 54 ( 6 ) page： 6190 - 6204 2018.6

Review of Current Balance Mechanism in Multiphase LLC Resonant Converters Reviewed

Mostafa Noah Power Electronics Laboratory, Nagoya University, Nagoya, Aichi, Japan, Jun Imaoka, Yuki Ishikura, Kazuhiro Umetani, Masayoshi Yamamoto

Proc. of 2018 IEEE 27th International Symposium on Industrial Electronics (ISIE) page： pp. 1031-1036 2018.6

Limit Operating Frequency of Peak Current-Mode Control DC-DC Converter Considering Turn-Off Delay Time Reviewed

Ryo Ute, Kazuya Fujiwara, Jun Imaoka, Masahito Shoyama

Proc. the 2018 International power Electronics conference-ECCE ASIA- (IPEC-Niigata 2018) page： 3773-3779 2018.5

A Leakage Flux Cancellation Technique for Series- Parallel Combined Resonant Circuits with Asymmetric Rotary Transformers Used for Ultrasonic Spindle Drive Reviewed

Jun Imaoka, Masahito Shoyama

Proc. the 2018 International power Electronics conference-ECCE ASIA- (IPEC-Niigata 2018) page： 1554-1561 2018.5

A Magnetic Design Method Considering DC-Biased Magnetization for Integrated Magnetic Components Used in Multiphase Boost Converters Open Access

Jun Imaoka, Kenkichiro Okamoto, Shota Kimura, Mostafa Noah, Wilmar Martinez, Masayoshi Yamamoto, Masahito Shoyama

IEEE Transactions on Power Electronics Vol. 33 ( 4 ) page： 3346 - 3362 2018.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers Inc.

High power density and high efficiency in dc/dc converters are required in various applications such as the automotive application. Interleaved multiphase circuits with integrated magnetic components can fulfill these requirements because passive components occupying significant space in power converters can be downsized without high-switching frequency driving of power devices. However, dc-biased magnetization is a drawback of integrated magnetic components because of unbalanced inductor average currents. This imbalance arises from the tolerance among the phase components. To overcome this problem, inductor average current control is implemented in interleaved multiphase dc/dc converters. Nevertheless, the imbalance cannot be completely eliminated because the current sensors inserted into each phase have gain errors. The purpose of this paper is to present a magnetic design method to improve the immunity to unbalanced currents. A comprehensive analysis is carried out with two main objectives: to prevent magnetic saturation, which may arise due to the current unbalance and to downsize the magnetic components by selecting the optimal coupling coefficient taking into consideration the maximum permissible percentage of unbalanced currents. Simulation case studies are presented to support the analysis. Finally, a 1-kW prototype of the interleaved boost converter is built to validate the accuracy of the design method.

DOI： 10.1109/TPEL.2017.2707385

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Lagrangian dynamics model and practical implementation of an integrated transformer in multi-phase LLC resonant converter

Mostafa Noah, Kazuhiro Umetani, Jun Imaoka, Masayoshi Yamamoto

IET Power Electronics Vol. 11 ( 2 ) page： 339 - 347 2018.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Institution of Engineering and Technology

In conventional arrangements of three-phase LLC converters, there are at least three magnetic components that occupy a considerable volume and mass of the power converter. Although, the three-phase LLC topology has many advantages over the single-phase one, circuit designers tend to select the single-phase topology because it has the minimal number of magnetic components. The purpose of this study is to reduce the number of the magnetic components of the three-phase topology, by integrating the three-discrete transformers into a single magnetic core, based on a theoretical framework. Lagrangian dynamics is applied to theoretically prove that it is possible to replace the three-discrete transformers by a single integrated transformer. The Lagrangian dynamics theory allowed us to derive a physically motivated model for the integrated transformer, in which each component of the integrated transformer has its own Lagrangian parameter. The Lagrangian model reveals that in a symmetrical design, there is no interphase coupling, and as a result the magnetic components can be downsized owing to the ac flux cancellation. Along with the theoretical discussion, the practical merits of implementing the integrated transformer is reported. Furthermore, the experimental tests are conducted utilizing a 500 W-390 V/12 V-200 kHz prototype.

DOI： 10.1049/iet-pel.2017.0485

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Winding Orientation Method to Minimise the Secondary Leakage of a Gapped Transformer Utilised in LLC Resonant Converter Reviewed

Mostafa Noah, Kazuhiro Umetani, Masayoshi Yamamoto, Jun Imaoka

Electronics Letters Vol. 53 ( 3 ) page： 157-159 2018.2

A Current Sharing Method Utilizing Single Balancing Transformer for a Multiphase LLC Resonant Converter with Integrated Magnetics Reviewed

Mostafa Noah, Shun Endo, Hiroki Ishibashi, Kimihiro Nanamori, Jun Imaoka, Kazuhiro Umetani, Masayoshi Yamamoto

IEEE Journal of Emerging and Selected Topics in Power Electronics Vol. 6 ( 2 ) page： 977-992 2018

Core Loss Evaluation in Powder Cores: A Comparative Comparison between Electrical and Calorimetric Methods

Ishikura Yuki, Imaoka Jun, Noah Mostafa, Yamamoto Masayoshi

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1087-1094 2018

Modeling, Magnetic Design, and Simulation Methods Considering DC Superimposition Characteristic of Powder Cores Used in Power Converters

Imaoka Jun, Okamoto Kenkichiro, Shoyama Masahito, Ishikura Yuki, Noah Mostafa, Yamamoto Masayoshi

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1095-1102 2018

Allowable Power Analysis and Comparison for High Power Density DC-DC Converters with Integrated Magnetic Components Reviewed

Shota Kimura, Kimihiro Nanamori, Taichi Kawakami, Jun Imaoka, Masayoshi Yamamoto

IEEJ Journal of Industry Applications Vol. 6 ( 6 ) page： 463-472 2017.11

Derivation of Transfer Function of LLC Current Resonant Converter Using Numerical Calculation Reviewed

Masahito Shoyama, Takuma Sagara, Yusuke Yamashita, Jun Imaoka, Yu Yonezawa, Yoshiyasu Nakashima

Proc. IEEE Energy Conversion Congress & Expo (ECCE) page： 3056-3062 2017.10

Analytical Investigation of Interleaved DC-DC Converter using Closed-Coupled Inductor with Phase Drive Control Reviewed

Daigoro Ebisumoto, Shota Kimura, Kimihiro Nanamori, Mostafa Noah, Masataka Ishihara, Jun Imaoka, Masayoshi Yamamoto

Proc. International Communications Energy Conference (INTELEC) page： 526-529 2017.10

Conducted Noise Prediction for Zero-crossing Issue in Totem-pole Bridgeless PFC Converter Reviewed

Baihua Zhang, Qiang Lin, Jun Imaoka, Masahito Shoyama, Satoshi Tomioka, Eiji Takegami

Proc. International Communications Energy Conference (INTELEC) page： 396-401 2017.10

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Papers - IMAOKA Jun