出版者・発行元：2025 Energy Conversion Congress and Expo Europe Ecce Europe 2025 Proceedings  

Wireless power transfer offers a convenient solution for public electric vehicle charging by eliminating physical connectors, enabling seamless operation. However, traditional single-coil inductive power transfer systems suffer from sensitivity to misalignment, reducing power transfer efficiency (PTE) and limiting real-world viability. This study proposes a multi-coil transmitter design to enable free-position parking, improving adaptability to vehicle misalignment and receiver variations. A blackbox optimisation framework is implemented, leveraging a neural network-based surrogate model trained on simulation data, achieving a 9000 × speedup while maintaining prediction errors below 2.5%. A scenario-based stochastic optimisation formulation solved via the meshadaptive direct search algorithm ensures adaptability across real-world receiver conditions. The optimised four-coil design achieves an average PTE of 86.93% while minimising material costs, balancing efficiency and affordability. These findings confirm the feasibility of a scalable, user-friendly universal wireless charging system for commercial parking environments.

DOI： 10.1109/ECCE-Europe62795.2025.11238918

Scopus

出版者・発行元：14th International Conference on Renewable Energy Research and Applications Icrera 2025  

The electrification of vehicles has increased the operating voltage of automotive electric compressors, raising concerns about the self-decomposition of HFO refrigerants. This study models the current and voltage waveforms of arc discharges during phase-to-phase short circuits and quantitatively evaluates the resulting discharge energy. Compressor parameters obtained through teardown were incorporated into a motor drive circuit model including overcurrent protection (OCP). Shortcircuit tests conducted at 300 V and 400 V with motor speeds ranging from 850 to 3500 rpm showed that discharge energy increases with voltage but remains unaffected by motor speed. Simulation results were consistent with experimental data, confirming the validity of the model.

DOI： 10.1109/ICRERA66237.2025.11283919

Scopus

出版者・発行元：2025 IEEE Energy Conversion Congress and Exposition Asia Shaping A Greener Future with Power Electronics Ecce Asia 2025  

Silicon carbide (SiC) power semiconductors have high switching speeds which can lead to high common-mode (CM) noise. Flip chip design can be utilized to reduce CM noise by placing the pulsating node above the substrate. This paper details the manufacturing process of a flip chip module and evaluates its performance through simulations and experiments. Simulations assess the impact of epoxy materials and solder thickness on thermomechanical reliability, revealing that optimization of epoxy selection and solder thickness reduced stress with minimal thermal impact. Experimental CM noise measurements demonstrated a 12dBμV reduction at low frequencies and a 3-4dBμV reduction at higher frequencies compared to a conventional design. Thermal cycling tests (TCT) confirmed the robustness of the module, with no observed delamination from the gate pads of the flipped chips.

DOI： 10.1109/ECCE-Asia63110.2025.11112121

Web of Science

Scopus

記述言語：英語   出版者・発行元：一般社団法人 電気学会  

This paper introduces a practical approach for transformer design optimization using a novel hybrid Dowell artificial neural network (HDANN) model. This model is a highly efficient and accurate method to estimate leakage inductance, which is an important parameter that affects the performance of transformers and power converters. The model combines the conventional hybrid Dowell’s model, which uses analytical equations, and an artificial neural network, which uses machine learning techniques. It is integrated into an optimization program to optimize the design of a transformer in terms of its size and loss. We investigated the HDANN design scope by testing various transformer conditions. The results provided an in depth understanding of the capabilities and limitations of the HDANN model for transformer design. By understanding the HDANN design scope, the optimization program was implemented in a multidomain circuit simulation, which includes electric and magnetic circuits. This allows a high-speed co-simulation using the optimized transformer design that considers the geometry and material characteristics for the desired circuit specification. It showed that the HDANN offers significant advantages over existing design optimization methods, including improved ease of application, accuracy, and efficiency. The effectiveness of the optimization using the HDANN with the defined geometric parameters was demonstrated by the circuit analysis results of a phase-shift full-bridge converter. Summarizing, the proposed method can potentially revolutionize how transformers are designed and implemented for various applications, leading to increased design reliability as well as reduced power loss and size.

DOI： 10.1541/ieejjia.23009691

Open Access

Web of Science

Scopus

CiNii Research

出版者・発行元：2024 14th International Workshop on the Electromagnetic Compatibility of Integrated Circuits EMC Compo 2024  

Compound power semiconductor devices such as Silicon Carbide (SiC) and Gallium Nitride (GaN), are increasingly being adapted into automotive, renewable energy, and energy management applications to advance carbon neutrality. These devices offer the advantage of operating at higher switching frequencies than their silicon-based devices, attributed to their superior switching speed and reduced on-resistance. The ability to operate at elevated switching frequencies also enables the realization of high-power density in DC/DC converters. However, with the widespread application of compound semiconductor devices capable of high-frequency operation, the importance of noise reduction generated from power converters is significantly increasing towards safe and secure societies. Consequently, this paper presents the latest advancements in noise reduction methods based on a comprehensive literature review. This paper introduces strategies for common-mode noise reduction in high-power and high-frequency applications without necessitating an increase in the converter’s volume.

DOI： 10.1109/EMCCompo61192.2024.10742027

Web of Science

Scopus

記述言語：日本語   出版者・発行元：一般社団法人エレクトロニクス実装学会  

DOI： 10.11486/ejisso.38.0_14a2-2

CiNii Research

出版者・発行元：2024 IEEE Energy Conversion Congress and Exposition Ecce 2024 Proceedings  

Silicon carbide (SiC) semiconductors have higher switching speeds compared to their Silicon counterparts, which increases common mode (CM) noise. This study proposes a new configuration of power module which utilizes flip chip and copper lead bonding techniques to reduce CM capacitance. The low side bare dies are flipped, allowing the pulsating terminal to be placed above the direct bonded copper (DBC) as a copper lead. The prototype module was able to achieve a 90% reduction in CM capacitance. A double pulse test proved a 77% reduction in peak CM current during turn off and a 40% reduction during turn on. Thermal cycling tests confirmed the reliability of the gate pad connection of the flipped chips.

DOI： 10.1109/ECCE55643.2024.10861124

Web of Science

Scopus

出版者・発行元：13th International Conference on Renewable Energy Research and Applications Icrera 2024  

This paper explores wireless power transfer (WPT) systems for public electric vehicle charging, focusing on optimising the transmitter design to enhance interoperability across various receiver coil geometries and alignment conditions. Due to the complex non-linear relationships inherent to WPT systems, traditional optimisation methods are computationally expensive. Therefore, this study proposes an approach using artificial neural networks (ANNs) trained on finite element method (FEM) data to develop a surrogate model of the WPT system. This model is integrated into a blackbox optimisation solver, enabling faster identification of improved transmitter designs. The proposed method achieves computational speeds 6,000 times faster than traditional FEM simulations, with post-validation on the final solutions verifying prediction errors below 0.6%. The results demonstrate a significant acceleration in the optimisation process, establishing this method as an effective framework for developing practical WPT systems for public charging applications.

DOI： 10.1109/ICRERA62673.2024.10815548

Web of Science

Scopus

記述言語：日本語   出版者・発行元：一般社団法人 電気学会  

DOI： 10.1541/ieejias.143.nl9_14

CiNii Research

記述言語：英語   出版者・発行元：一般社団法人 電気学会  

This study proposes strategies for improving the accuracy and usefulness of leakage inductance modeling using the Dowell model (DM). As the analytical method of modeling the leakage inductance model considers geometrical factors, it is vital for front-loading transformer design. DM is one such widely used one-dimensional magnetic field-based approach for analytically modeling both AC resistance and leakage inductance. It is more accurate and requires less computational work than other analytical approaches proposed in previous studies. However, some approximations may cause errors and eventually lead to inaccurate results. Therefore, this study aims to ascertain the conditions that result in inaccurate leakage inductance modeling. Additionally, a simple exponential-based model and an artificial neural network are developed to increase the accuracy of inaccurate modeling. The results clarify the conditions that result in a frequency-dependent and bias error. Moreover, the intended findings indicate that the proposed strategies effectively improve modeling accuracy while simultaneously providing some extra advantages for transformer design.

DOI： 10.1541/ieejjia.22007452

Open Access

Web of Science

Scopus

CiNii Research

出版者・発行元：Conference Proceedings IEEE Applied Power Electronics Conference and Exposition APEC  

This research investigates the accuracy of Dowell model (DM) and builds an accurate and practically useful semi-analytical method for leakage inductance modeling of foil winding transformers. As a widely used model for AC resistance and leakage inductance, DM is well known for its high applicability and high accuracy compared to the other modeling methods. However, it is found that transformers with certain geometrical conditions are used in most works of literature for implementing DM. Although some analyses about the modeling accuracy were conducted, the applicability of DM for some geometry is still unclear. Therefore, in this research, the accuracy of the modeling is analyzed, focusing on the frequency and geometry dependency of foil winding. Some results show the modeling error of DM has frequency dependency. Furthermore, modeling using DM with Artificial Neural Network (ANN) is implemented to achieve more practically usable modeling. As a result, the utility could be proved with accurate modeling results of the transformer samples. Some advantages are also discussed to show more possibility of developing this method.

DOI： 10.1109/APEC43580.2023.10131441

Web of Science

Scopus

出版者・発行元：Icpe 2023 Ecce Asia 11th International Conference on Power Electronics Ecce Asia Green World with Power Electronics  

An equivalent circuit model of lithium-ion batteries which has a nonlinear resistor governed by Butler-Volmer's equation and a constant phase element was investigated. The current dependence of the real battery could be reproduced well by the contribution of the nonlinear resistor, and the transient response of voltage could be reproduced well by the contribution of the constant phase element.

DOI： 10.23919/ICPE2023-ECCEAsia54778.2023.10213775

Scopus

出版者・発行元：2023 IEEE CPMT Symposium Japan Icsj 2023  

Recently WBG (Wide Band Gap) power semiconductors such as SiC and GaN, which have been attracting attention, are being applied in power electronics field because of their high switching speed and low losses compared to existing Si power devices. SiC is spreading from industrial applications to main traction systems of N700S SHINKANSEN bullet trains, and GaN is spreading to low-voltage applications such as AC adapters, DC/DC converters and LED drivers etc.. On the other hand, there are problems such as surge noise due to current path stray inductance Ls by high current reduction rate, di/dt, at turn-off. To reduce the turn-off voltage surge, it is necessary to optimize structure of main current path to minimize Ls. In optimizing the structure, loop inductance can be reduced by forming a return path in which current distribution could cancels leakage magnetic flux. However, depending on the switching mode of the power converter topology, such as a three phase inverter, the main current may not always be a return path that cancels the leakage magnetic flux. This time, in order to confirm the usefulness of Power Device Embedded Module (POWER DEM) packaging process, a prototype of SiC bare die embedded half-bridge circuit has been prototyped. Inductance analyzed results of circuit structure using ANSYS Q3D Extractor® before prototyping, have been comparatively evaluated. As a result, loop inductance was 5.5 nH in Q3D analysis, 3.6 nH in impedance analyzer, and calculated inductance from actual surge voltage was 10.03 nH. Finally, turn-off voltage surge, turn-on loss, turn-off loss, turn-on time and turn-off time have been reduced approximately 40 % to 80 % compared to similar half bridge circuit using conventional TO-247 packages. Further works are to optimize current path constructions for actual cases of circuit topologies i.e. three phase inverter etc., modeling of three dimensional structure including dielectric insulating material and analyze methods.

DOI： 10.1109/ICSJ59341.2023.10339574

Scopus