Faculty Profiles - IMAOKA Jun

Papers - IMAOKA Jun

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Active Gate Driver with a Current Source to Reduce Surge and Turn-on Switching Losses in SiC-MOSFETs Reviewed Open Access

Kiyotaka Ono, Sihoon Choi , Yu Yonezawa, Jun Imaoka, Masayoshi Yamamoto

IEEJ Journal of Industry Applications Vol. advpub ( 0 ) 2026.4

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electrical Engineers of Japan

<p>Active gate drivers (AGDs) enhance the trade-off between switching losses and voltage surges by actively controlling switching transitions. However, conventional AGDs, that vary gate resistance to adjust switching behavior, are limited in their capability to operate at high speed. This paper proposes a novel AGD architecture that combines a current source for the turn-on transition and an active gate resistor for the turn-off phase. The current source enables faster switching compared to resistance-based control and the active gate resistor employed during the turn-off phase is similar to conventional AGDs. The results of double-pulse testing show that the proposed AGD reduced turn-on losses by up to 32.4% compared to traditional gate drivers and by 6.55% compared to existing AGDs, while maintaining similar turn-off losses.</p>

DOI： 10.1541/ieejjia.20250462

Open Access

CiNii Research

A Simultaneous Prediction Method for Multiple Characteristics of a Power Converter using Multiple-Output Hybrid Model Reviewed Open Access

Yasumichi Omoto, Yuji Nagira, Shusuke Furui, Koichi Shigematsu, Jun Imaoka, Masayoshi Yamamoto

IEEJ Journal of Industry Applications page： 1 - 11 2026.4

Circuit-Balanced Flyback Converter Eliminating the Need for an Isolated Auxiliary Supply for Gate Driver IC Reviewed

Naoya Miyata, Yuta Imaeda, Silumin Sandaru Seneneyak, Sihoon Choi, Yu Yonezawa, Jun Imaoka, Masayoshi Yamamoto, Hayato Nakamura, Naoki Yoshizawa, Masashi Sawada

Proc. of IEEE Applied Power Electronics Conference and Exposition (APEC) page： 3362 - 3367 2026.3

Design and Analysis of Leakage Inductance Integrated Transformer Structures Utilizing Interleaved Windings Reviewed

Kota Okada, Sihoon Choi, Jun Imaoka, Masayoshi Yamamoto, Takayuki Ikari, Akinori Okubo,Yuichi Iwasaki, Takahiro Tokita

Proc. of IEEE Applied Power Electronics Conference and Exposition (APEC) page： 3190 - 3196 2026.3

Design and Integration of a Novel Insulated NTC Thermistor for Enhanced Temperature Sensing in Power Modules Reviewed

Keigo Yoshida, Jiyoon Choi, Thiyu S. Warnakulasooriya, Sihoon Choi, Jun Imaoka, Masayoshi Yamamoto, Hideyuki Suzuki. Yuka Kamada, Tsuyoshi Kawaguchi, Minoru Kobayashi

Proc. of IEEE Applied Power Electronics Conference and Exposition (APEC) page： 1500 - 1505 2026.3

Flatwise Windings for Improved Thermal Management in High Power Transformer Applications Reviewed International coauthorship

Karl Raymond D. Roque, Itsuki Masuda, Sihoon Choi, Masayoshi Yamamoto, Jun Imaoka, Matti Kauhanen, Kengo Tashiro

Proc. of IEEE Applied Power Electronics Conference and Exposition (APEC) page： 2641 - 2647 2026.3

A New Winding Structure for Balance Technique Considering Soft Saturation Characteristics of Powder Cores Reviewed

Gaku Kondo, Yota Omizu, Sihoon Choi, Jun Imaoka, Masayoshi Yamamoto

Proc. of IEEE Applied Power Electronics Conference and Exposition (APEC) page： 2597 - 2602 2026.3

Vertical Shunt Resistor for Double-Sided Cooling Power Modules Reviewed

Sihoon Choi, Thiyu S. Warnakulasooriya, Jiyoon Choi, Jun Imaoka, Masayoshi Yamamoto, Keishi Nakamura, Susumu Toyoda, Koji Shigesawa

Proc. of IEEE Applied Power Electronics Conference and Exposition (APEC) page： 1822 - 1826 2026.3

Low-Profile Vertical Shunt Resistor Integration in High-Current Power Modules Reviewed International coauthorship

Thiyu S. Warnakulasooriya, Jiyoon Choi, Sihoon Choi, , Jun Imaoka, Masayoshi Yamamoto , Leonard Henrichs, Jan Ückerseifer, Jan Marien

Proc. of IEEE Applied Power Electronics Conference and Exposition (APEC) page： 1816 - 1821 2026.3

Transfer-Molded Power Module for Low Common-Mode Capacitance and Enhanced Thermo-Mechanical Reliability Reviewed

Jiyoon Choi, Thiyu S. Warnakulasooriya, Sihoon Choi, Jun Imaoka,Masayoshi Yamamoto

Proc. of IEEE Applied Power Electronics Conference and Exposition (APEC) page： 1557 - 1561 2026.3

Utilizing Silicone Gel Encapsulation in Power Semiconductor Module to Improve Manufacturability While Reducing Common-Mode Noise Reviewed International coauthorship

Sihoon Choi, Jiyoon Choi, Thiyu Warnakulasooriya, Jong-Won Shin, Jun Imaoka, Masayoshi Yamamoto

IEEE Transactions on Power Electronics Vol. 41 ( 3 ) page： 3308 - 3318 2026.3

A computation method for voltage conversion gains of an LLC converter using physics model and machine learning Reviewed Open Access

Yasumichi Omoto, Koichi Shigematsu, Jun Imaoka, Masayoshi Yamamoto

IEICE Transactions on Communications Vol. E109.B ( 1 ) page： 9 - 16 2026.1

Modeling of Short-Circuit Faults and Estimation of Arc Discharge Energy in Motor Drive Circuits Reviewed

Kengo Nagai, Koichi Shigematsu, Yota Omizu, Jun Imaoka, Masayoshi Yamamoto, Takashi Usui

Proc. of 2025 14th International Conference on Renewable Energy Research and Applications (ICRERA) page： 1783 - 1788 2025.10

Stacked-Plate Heatsink Design for Effective Thermal Management of Power Semiconductor Modules Reviewed

Jiyoon Choi, Sihoon Choi, Jun Imaoka, Kazuhiro Umetani, Masayoshi Yamamoto

Proc. of 2025 14th International Conference on Renewable Energy Research and Applications (ICRERA) page： 1765 - 1769 2025.10

Active Gate Driver for Current Stress Reduction in Si/SiC Hybrid Switch Reviewed

Shunki Hashimoto, Kiyotaka Ono, Sihoon Choi, Jun Imaoka, Masayoshi Yamamoto

Proc. of 2025 14th International Conference on Renewable Energy Research and Applications (ICRERA) page： 1704 - 1709 2025.10

Analysis Method for Turn-off Oscillation Considering Turn-off Voltage Reviewed

Kota Okada, Sihoon Choi, Kazuhiro Umetani, Jun Imaoka, Masayoshi Yamamoto, Hironari Takase

Proc. of 2025 14th International Conference on Renewable Energy Research and Applications (ICRERA) page： 1795 - 1800 2025.10

Synchronous Pulse Width Modulation for Single-Inverter Mode in Dual-Inverter Systems with Split-Switch DC Link Reviewed International coauthorship Open Access

Chon Chaeduck, Jun Imaoka, Masayoshi Yamamoto

IEEJ Journal of Industry Applications Vol. 14 ( 5 ) page： 670 - 678 2025.9

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electrical Engineers of Japan

<p>This paper presents the driving modes of a dual-inverter system with a split switch and addresses the voltage imbalance issues that arise during single-inverter mode operation in the overmodulation region. The dual-inverter system serves as the structural foundation; a synchronous pulse width modulation (PWM) technique, specifically applied to the single-inverter mode. In this configuration, structural asymmetries such as unbalanced current return paths and elevated common-mode voltages can reduce the efficiency, electromagnetic interference, and circulating currents. The proposed optimal synchronous PWM strategy, incorporating direct memory access, eliminates the timing jitter during real-time switching events. This approach enables precise voltage vector control and ensures consistent PWM pulse generation, which is particularly important at higher operating speeds. Compared to conventional CPU-based implementations, the proposed method shows enhanced current ripple behavior and harmonic suppression over a wide modulation index range. Simulation and experimental validations demonstrate that the method helps lower harmonic distortion and inverter power loss. Furthermore, by improving waveform symmetry, the technique indirectly aids the suppression of common-mode disturbances. This study offers a practical and scalable PWM control strategy for inverter systems that require high fidelity under real-time constraints and structural sensitivity.</p>

DOI： https://doi.org/10.1541/ieejjia.24012226

Open Access

CiNii Research

Other Link： https://www.jstage.jst.go.jp/article/ieejjia/14/5/14_24012226/_article/-char/ja

A Leakage Inductance Integrated Transformer Utilizing Interleaved Windings Reviewed

Kota Okada, Jun Imaoka, Sihoon Choi, Masayoshi Yamamoto, Takayuki Ikari, Akinori Okubo, Yuichi Iwasaki, Takahiro Tokita

Proc. of IEEE Energy Conversion Congress and Expo (ECCE Europe2025) page： 1 - 5 2025.8

Unlocking Free-Position Electric Vehicle Charging: A Neural Network-Driven Approach for Optimisation of Multi-coil Wireless Power Transfer Systems Reviewed International coauthorship

Hannah Merrigan, Yu Hsin Wu, Antoine Lesage-Landry, Koichi Shigematsu, Masayoshi Yamamoto, Jun Imaoka

Proc. of IEEE Energy Conversion Congress and Expo (ECCE Europe2025) page： 1 - 6 2025.8

Design and Analysis of Low-Loss Compensation Topologies for Class-E Inverter Reviewed

Itsuki Masuda, Sihoon Choi, Mitsuru Masuda, Jun Imaoka, Masayoshi Yamamoto

Proc. of IEEE Energy Conversion Congress and Expo (ECCE Europe2025) page： 1 - 6 2025.8

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Papers - IMAOKA Jun