Faculty Profiles - YAMAMOTO Masayoshi

Papers - YAMAMOTO Masayoshi

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Analysis of Common Mode Noise Reduction Mechanism in A Shielded Inductor

Sasaki Mamoru, Imaoka Jun, Yamamoto Masayoshi, Nakano Akira, Fuse Koji

2020 IEEE 29TH INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS (ISIE) page： 660 - 665 2020

Comparison of switching performance between GaN and SiC MOSFET via 13.56MHz Half-bridge Inverter

Xiong Yi, Oyane Aoi, Ou Tengfei, Thilak Senanayake, Imaoka Jun, Yamamoto Masayoshi

2020 IEEE 29TH INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS (ISIE) page： 672 - 676 2020

Temperature Dependency Modeling, Simulation and Experimental Validations of DC Superimposition Characteristics for Gapped-Ferrite Inductor Including Saturation Region

Imaoka Jun, Aoki Tatsuya, Shigematsu Koichi, Yamamoto Masayoshi

2020 IEEE 29TH INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS (ISIE) page： 1466 - 1473 2020

Voltage Balancing Control Method Using Variable Capacitors with Simple Turn-on Adjusting Function for Multi-Stage FET Bidirectional Converter

Ishikura Yuki, Hosotani Tatsuya, Noah Mostafa, Imaoka Jun, Yamamoto Masayoshi

2020 THIRTY-FIFTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2020) page： 2944 - 2949 2020

Energy Management Storage System with a Multi-stage FET Bidirectional Converter

Ishikura Yuki, Hosotani Tatsuya, Yamamoto Masayoshi

Journal of the Japan Institute of Power Electronics Vol. 46 ( 0 ) page： 44 - 50 2020

Language：Japanese Publisher：The Japan Institute of Power Electronics

This paper presents an energy management storage system with a multi-stage FET bidirectional converter. The
proposed system is constructed by a bidirectional converter using series connected FETs, and it realizes highly energy management that maximizes battery performance. By calculating the power loss using the converter performance index FOM (Figure of merit), it is shown that the proposed configuration can be possible to reduce the power loss 70% compared to the conventional configuration. In the proposed system, using a power control method that reduces the charging current, the battery charging losses can be reduced 60%. The analysis results show that the proposed system can achieve a charging energy efficiency of 96.9%, and reduce the yearly CO2 emission of 33%.

DOI： 10.5416/jipe.46.44

CiNii Research

Dielectric Characteristics Analysis of Aluminum Electrolytic Capacitors Based on Linear Response Function Reviewed International journal

Mukaiyama Daisaku, Yamamoto Masayoshi

JOURNAL OF THE ELECTROCHEMICAL SOCIETY Vol. 166 ( 16 ) page： E554 - E563 2019.12

Modeling, Magnetic Design, Simulation Methods, and Experimental Evaluation of Various Powder Cores Used in Power Converters Considering Their DC Superimposition Characteristics Reviewed International coauthorship International journal

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

IEEE TRANSACTIONS ON POWER ELECTRONICS Vol. 34 ( 9 ) page： 9033 - 9051 2019.9

Comprehensive Analysis of Coupled Inductors with Powder Cores Used in Interleaved Converter: Measurement, Modeling, Design Methods, and Experimental Evaluation

Aoki T., Imaoka J., Yamamoto M., Yoshimoto K.

Proceedings of the International Conference on Power Electronics and Drive Systems Vol. 2019-July 2019.7

Language：Japanese Publisher：Proceedings of the International Conference on Power Electronics and Drive Systems

One of the best techniques for downsizing power converters is to use coupled inductors in multiphase circuits. Meanwhile, from a magnetic material perspective, powder core material is well known as an attractive magnetic material with superior features such as high saturation flux density. However, since the relative permeability of power cores depends on the magnetic field intensity, designing coupled inductors is difficult, and the modeling method is not well discussed in the relevant literature. The purpose of this research is to model coupled inductors with powder cores and present a simple magnetic design method. A model of coupled inductors is created by a novel measurement method of the dc superimposition characteristic unique to the coupled inductor of two-phase interleaved circuits. Furthermore, a design method based on a theoretical analysis using a magnetic circuit model had been established. The validity and effectiveness of the proposed methods are confirmed from simulation and experimental tests. This research is helpful in the field of the model-based development of coupled inductors.

DOI： 10.1109/PEDS44367.2019.8998883

Scopus

Effects of secondary leakage inductance on the LLC resonant converter - Part II: Frequency control bandwidth with respect to load variation

Noah M., Shirakawa T., Umetani K., Imaoka J., Yamamoto M., Hiraki E.

Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC Vol. 2019-March page： 1408 - 1414 2019.5

Publisher：Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC

Resonant converters rely on a precise knowledge of leakage inductance of the equipped transformers. Resonant circuit topologies such as LLC usually utilize the transformer leakage as an inductive component in the resonant tank, allowing for a drastic reduction in the converter weight, size and volume. The existence of the secondary leakage inductance affects the whole operation of the LLC resonant converter. This paper reveals that placing the secondary winding near the air gap would increase the resonant tank input impedance, vertically shrink the voltage-gain curve of the converter, and consequently minimize the frequency range (i.e frequency bandwidth with respect to load variation). On contrary, placing the secondary winding in a close contact with the magnetic core would decrease the resonant tank input impedance, vertically stretches the voltage-gain curve of the converter, and widen the frequency variation range. It has been reported that the winding location with respect to the air gap has an impact on the leakage inductance value. In other words, placing the secondary winding in a close contact with the magnetic core (zero mmf position) would maximize the leakage energy storage originated from the secondary winding, and hence maximize the secondary leakage inductance and vice versa. The theoretical discussion is presented which is merely based on Ampere's law and Dowell's model. Furthermore, transformer prototypes had been constructed and tested in a 390V/12V-220W LLC converter prototype to evaluate the proposed analysis.

DOI： 10.1109/APEC.2019.8722190

Scopus

Effects of secondary leakage inductance on the LLC resonant converter - Part i: Transformer voltage gain and efficiency

Noah M., Shirakawa T., Umetani K., Imaoka J., Yamamoto M., Hiraki E.

Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC Vol. 2019-March page： 780 - 786 2019.5

Publisher：Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC

Minimizing the transformer magnetizing inductance is essential for the soft switching operation of the LLC resonant converter, despite the fact that it results in higher values of magnetizing current, which deteriorates the converter efficiency. Furthermore, it is a well-known practice to utilize the transformer leakage as an inductive component in the resonant tank to improve the power destiny. This paper reveals that the transformer voltage gain can be improved when the transformer leakage inductance in concentrated on the secondary side to avoid the voltage drop inflicted by the relatively large value of the magnetizing current (im), especially at light load condition. The theoretical discussion relies on the asymmetry of the EI core by placing the secondary winding in a close contact with the magnetic core and placing the primary winding in the vicinity of the air gap. Moreover, noise absorber had been utilized to control the leakage inductance value. The proposed transformer design maximizes the value of the secondary leakage inductance and minimizes the primary leakage inductance. Alongside with the theoretical discussion, experimental tests had been conducted to evaluate the proposed method using a 390V-12V, 220W LLC resonant converter.

DOI： 10.1109/APEC.2019.8721980

Scopus

Bidirectional Converter with Balancing Capacitor using Multi-stage FET Driving Technique

Ishikura Y., Imaoka J., Noah M., Yamamoto M.

2019 IEEE 3rd International Conference on DC Microgrids, ICDCM 2019 2019.5

Language：Japanese Publisher：2019 IEEE 3rd International Conference on DC Microgrids, ICDCM 2019

This paper proposes a bidirectional converter with balancing capacitor using multi-stage FET driving technique. The proposed converter is constructed by implementing series-connected low voltage Si-FETs in multi-stages. The balancing capacitor can average the applied voltage on FETs in the transient state of the switching operation and tackle the voltage unbalance between the series-connected FETs. The proposed driving circuit is using multi-stage FET driving technique and can drive all the series-connected FETs using only one power supply. The effect of the balancing capacitor and the proposed driving technique are clarified and presented using the circuit simulator and the converter equivalent circuit. The proposed topology improves the converter power conversion efficiency. The experimental results show that the proposed driving technique allows the bidirectional converter to achieve a maximum power conversion efficiency of 99.2%.

DOI： 10.1109/ICDCM45535.2019.9232896

Scopus

Cooperative Control of Multi-Input Modular DC/DC Converter for Electric Off-Highway Vehicles

Piao Q., Konoto M., Kakisaka T., Imaoka J., Yamamoto M.

2019 IEEE 3rd International Conference on DC Microgrids, ICDCM 2019 2019.5

Language：Japanese Publisher：2019 IEEE 3rd International Conference on DC Microgrids, ICDCM 2019

This paper proposes a cooperative control used in a power conversion system consists of several energy sources and modular DC/DC converters. The proposed cooperative control method has attractive features of realizing constant dynamic characteristics even when each input voltage fluctuates or in case of the output power of each input voltage source is limited. The proposed cooperative control method has dual control loops with current control as an inner loop and voltage control as the outer loop. In addition, feed-forward control of the input voltage and the compensators for each control loop are implemented to suppress the influence of input voltage fluctuation or power capacity limit on dynamic characteristics. The effectiveness of the proposed control is validated by simulation test.

DOI： 10.1109/ICDCM45535.2019.9232868

Scopus

Magnetic Design Method for Multi-Material Powder Core Inductor to Improve Efficiency of Bidirectional DC/DC Converter within Wide Load Range

Imaoka J., Ishikura Y., Ito K., Aoki T., Noah M., Yamamoto M.

ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia 2019.5

Publisher：ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia

Utilizing powder cores in many power electronics applications have been gaining much attention due to their attractive magnetic properties. However, it is quite challenging for the circuit designer to choose the proper core, as there are many kinds of magnetic powder cores available in the market. Therefore, due to the limitation of a single magnetic material property, it is often difficult to realize high power conversion efficiency within wide load ranges, including light and heavy load conditions. This paper proposes a novel design method of the multi-material inductor which combines multiple powder cores having different material properties. The aim of this work is to provide improved efficiency over the entire load range of power converters. The experimental results have proven that the inductor with multi-material powder cores can improve the efficiency over wide load range. The validity and effectiveness of the proposed magnetic design method are confirmed from theoretical analysis, simulation and experimental tests.

Scopus

東海支部における地域貢献活動紹介

山本真義

電気学会誌 Vol. 139 ( 4 ) page： 244 - 244 2019.4

Introduction: Applications Roadmap of GaN Power Semiconductor Devices

YAMAMOTO Masayoshi

The Journal of The Institute of Electrical Engineers of Japan Vol. 139 ( 2 ) page： 76 - 79 2019.2

Comparative Evaluation of Electrical and Calorimetric Methods to Estimate Core Loss in Powder Cores

Ishikura Yuki, Imaoka Jun, Noah Mostafa, Yamamoto Masayoshi

IEEJ Journal of Industry Applications Vol. 8 ( 3 ) page： 386 - 393 2019

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

<p>The utilization of powder cores for many power electronic applications has drawn a significant amount of attention owing to their attractive magnetic properties. However, because of their low relative permeability characteristics, a precise measurement of the core loss is very difficult to obtain. Imprecise estimation of the core loss may lead to an inaccurate thermal design of power converters. Measuring and calculating the accurate value of the core loss allows the circuit designer to design a more efficient system. This paper discusses the revalidation of electrical measurement by comparing the electrical method with the calorimetric method in powder cores. The calorimetric method is one of the most promising methods to accurately measure the core loss; however, it is time consuming. A difference less than 10% has been reported for the core loss measurement error while comparing the electrical method and the calorimetric method in various conditions. These results indicate that the electrical method using the B-H analyzer is effective for measuring the core losses in some conditions for powder cores. Along with the theoretical discussion, simulation and experimental tests are also conducted.</p>

DOI： 10.1541/ieejjia.8.386

Web of Science

Scopus

CiNii Research

Magnetic Design Method for Multi-Material Powder Core Inductor to Improve Efficiency of Bidirectional DC/DC Converter within Wide Load Range Reviewed International coauthorship International journal

Imaoka J., Ishikura Y., Ito K., Aoki T., Noah M., Yamamoto M.

2019 10TH INTERNATIONAL CONFERENCE ON POWER ELECTRONICS AND ECCE ASIA (ICPE 2019 - ECCE ASIA) 2019

Effects of Secondary Leakage Inductance on the LLC Resonant Converter-Part II: Frequency Control Bandwidth with respect to Load Variation Reviewed International coauthorship International journal

Noah Mostafa, Shirakawa Tomohide, Umetani Kazuhiro, Imaoka Jun, Yamamoto Masayoshi, Hiraki Eiji

THIRTY-FOURTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2019) page： 1408 - 1414 2019

Effects of Secondary Leakage Inductance on the LLC Resonant Converter-Part I: Transformer Voltage Gain and Efficiency Reviewed International coauthorship International journal

Noah Mostafa, Shirakawa Tomohide, Umetani Kazuhiro, Imaoka Jun, Yamamoto Masayoshi, Hiraki Eiji

THIRTY-FOURTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC 2019) page： 780 - 786 2019

Comprehensive Analysis of Coupled Inductors with Powder Cores Used in Interleaved Converter: Measurement, Modeling, Design Methods, and Experimental Evaluation

Aoki Tatsuya, Imaoka Jun, Yamamoto Masayoshi, Yoshimoto Kosuke

2019 IEEE 13TH INTERNATIONAL CONFERENCE ON POWER ELECTRONICS AND DRIVE SYSTEMS (PEDS) 2019

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Papers - YAMAMOTO Masayoshi