Keiji Wãda

Signal Processing Method to Remove Electromagnetic Noise Superimposed on AM Radio in Moving Electric Vehicles

Retsu Sugawara, Yuji Matsuda, Jun Takahashi, Keiji Wãda

Electric vehicles (EVs) emit electromagnetic noise, which can cause radio interference. The radio interference from EVs is especially noticeable in terms of AM radio. To prevent radio interference from occurring, several countermeasures have been proposed on the radio side. One promising method …

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イワホリコツブムシ体表に生息するウミミズムシ科の1新種

Noboru Nunomura, Keiji Wãda, 優子 村田

和歌山県田辺湾のイワホリコツブムシSphaeroma wadai体表に生息するウミミズムシ科Iais属の１種を新種，Iais tanabensis n. sp.として記載した．本新種は顎脚の底節の鉤刺が2本である点でシンガポールなどから知られているIais singaporensis Menzies and Barnard, 1951と類似しているが，体型がより細く，後方に向かって特別に太くならないこと，頭部前方に張り出しが弱いこと，第2触角が比較的短く，鞭数が12までしかないこと，第2小顎基節内葉の歯の数が少ないこと，第4胸脚指節に3本の爪があること，腹尾節が丸いこと，オスの１腹肢の先端がいくぶん分離していること，オスの第2腹肢内肢が大きいことにより区別される．本種の宿主当たりの共生密度，抱卵雌の割合の経月変化も示した．

Development and validation of an in vivo pain assessment method for 28-day exposure to intermediate frequency magnetic fields

S. Ohtani, Akira Ushiyama, Keiji Wãda, Masateru Ikehata et autres

The objective of this study was to establish guidelines for evaluating the health effects of electromagnetic fields (EMFs). To achieve this, a comprehensive evaluation of EMF effects on living organisms from both engineering and biological perspectives is essential. As part of this …

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Wireless High-Precision Time Synchronization for QZSS-Integrated Power Modules

Keiji Wãda, Satoshi Mikami, Ryosuke Ota, Shigeyoshi Goka

In wireless control of converters, a major chal-lenge is control timing mismatch or synchronization error, which occurs due to the lack of a common clock source. This paper proposes a half-bridge power module with integrated GNSS time synchronization functionality. Long-term measurements between …

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LLM-Driven Circuit Simulator-Based Multi-Objective Parameter Optimization System for Power Converter Circuit Design

Qingyang Tan, Keiji Wãda

This paper presents a multi-objective parameter optimization system that integrates a large language model (LLM) with circuit simulation, targeting automated design tasks in power electronics. By simply specifying initial parameter ranges and design objectives, users can enable the system to autonomously explore …

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Developing an AI Assistant Platform for Electrical and Electronic Engineering Courses in Universities

Keiji Wãda, Yukihisa Suzuki

This paper proposes developments of an intelligent AI assistant platform for university students. The platform leverages lecture videos as data sources. It offers interactive features such as automated lecture video summarization, chapter generation, advanced question-answering capabilities, and personalized practice question creation. Verification …

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Gate Oxide TDDB Lifetime Evaluation of SiC MOSFETs by HTGB Test Using Square Wave Voltage

S. Hayashi, S. Muraoka, Junya Yamazaki, Keiji Wãda

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EMI Noise Mitigation for Multiple Inverters of Hybrid Electric Aircraft Propulsion Systems

Ryo Shirai, Keiji Wãda

This paper investigates power electronics system architecture and control methodology for hybrid electric aircraft (HEA) focusing on the electro-magnetic interference (EMI) noise suppression. Simulations are performed to characterize the common-mode (CM) noise of two-level (2L) full bridge and three-level (3L) active-neutral-point-clamped (ANPC) …

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Power Density Analysis of Dual Multilevel Inverters for Hybrid-Electric Aircraft Propulsion Systems

Keiji Wãda, Katsuya Shingu, Ryo Shirai, Ryosuke Ota et autres

Research and development for practical implementation of electric aircraft is being actively pursued. Weight reduction is particularly crucial for electric aircraft applications. This paper proposes a design platform to analyze the relationship between circuit topologies, modulation strategies, and inverter weight for a …

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Design and Development of LCCL Resonant Circuit-Based 85 kHz Magnetic Field Generator for Biological Research

Ryosuke Ota, Keiji Wãda, Yukihisa Suzuki

Recently, research and development on wireless charging technology for automobiles has been actively advancing. However, experimental verification ofb iological effects from leakage magnetic fields from p ower t ransmission c oils h as not been sufficiently conducted. This p aper p roposes …

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Buck-Converter-Based Inductor Loss Emulator for Multiple Power Electronics Applications

Yuto Saito, Koushi Takano, Keiji Wãda

This paper proposes a method for evaluating iron losses in inductors by using a DC chopper circuit to emulate the waveforms of power converter circuits. The proposed method accurately reproduces parameters such as duty ratio, magnetic flux density ripple, and average current …

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Experimental Verification of the Switching Loss Reduction Effect and Characteristic Fluctuation of SiC MOSFETs Dependent on Gate Drive Voltage

Takahide Sagae, S. Hayashi, Keiji Wãda

ABSTRACT The switching frequency of silicon carbide (SiC) metal–oxide–semiconductor field‐effect transistors (MOSFETs) should be increased to maximize their benefits in power conversion circuits. However, the switching loss increases when the switching frequency is increased. Generally, the gate resistance is designed to be …

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