研究者詳細 - 小迫　雅裕

論文 - 小迫　雅裕

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Preparation of fullerene/epoxy resin composite with fine dispersion and its breakdown strength 査読有り

S.Harada, M.Kozako, M.Hikita, T.Igarashi, H.Kaji

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 654 - 656 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. Fullerene is likely to form aggregates so that it is difficult to disperse it well in a polymer matrix, and few reports have been made on electrical insulation properties of fullerene filled composite as electrical insulating material. This paper deals with fullerene dispersion method in conventional epoxy resin (EP) and breakdown strength (BDS) of the composite with different filler loading of fullerene. Composite materials added with fullerenes of 0.1, 0.3, and 0.6 weight% were prepared in a plate shape with a thickness of 0.5 mm using two different dispersion methods, i.e. fullerene dissolved and fullerene direct mixing methods, and neat specimen was also prepared for comparison so as to investigate BDS. As a result, it was found that BDS of fullerene/EP composite with good dispersion greatly increased by 30 %. The increase in BDS of the composite is discussed in terms of the inter-particle distance as an index of the dispersion degree.

DOI： 10.23919/ISEIM.2017.8166575

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Permittivity estimation of hydrocarbon-based thermosetting resin using quantum chemical calculation 査読有り

Y.Fuchi, R.Nakasako, Y.Okubo, M.Kozako, M.Hikita, N.Kamei

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 524 - 527 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. In recent years, development of computers and progress of calculation algorithms promote understanding of the various mechanisms of characteristics of electrical insulating materials using quantum chemical calculation. This paper deals with quantum chemical calculation of the relative permittivity ϵrof dicyclopentadiene and tricyclopentadiene resins expected as the next generation electrical insulating materials based on density functional theory and Clausius-Mossotti's, Onsager's or Kirkwood's equation. As a result, estimated values of the relative permittivity are found to reasonably agree with experimental ones. In addition, we investigate the influence of the number of repeating units in the molecular structure on ϵr. As a result, it is found that the estimated ϵris almost independent of the number of repeating units.

DOI： 10.23919/ISEIM.2017.8166541

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Influence of electrode interface on insulation property of hydrocarbon-based thermosetting composite with silica filler 査読有り

R.Nakasako, Y.Fuchi, Y.Okubo, M.Kozako, M.Hikita, N..Kamei

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 528 - 531 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. We have been studying electrical insulation properties of hydrocarbon-based thermosetting composite as a development of new functional polymeric insulating material. Our previous reports showed that the composite has advantages in high heat resistance, low dielectric constant and low dielectric loss. These evaluations were performed for the specimen with a shape of plane. Practical application of the composite to the insulation system of high voltage power apparatus needs to estimate properties for molded electrode configuration. However, the hydrocarbon-based thermosetting resin has relatively poor adhesiveness with a metallic material such as a high voltage conductor. Thus, poor adhesion to metal material may cause lowering of the insulation properties. This paper deals with influence of the electrode interface on the insulation properties of the composite specimen filled with silica filler. As a result, it was found that both the rough surface treatment on the electrode and the adhesive monomer loading can avoid formation of void at the interface between the electrode and specimen, resulting in relatively high breakdown strength.

DOI： 10.23919/ISEIM.2017.8166542

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Grounding effect on transient earth voltage signal induced by partial discharge in metal box model 査読有り

H.Yoshizumi, T.Koga, M.Kozako, M.Hikita, Y.Fujii, Y.Nakamura, H.Cho

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 555 - 558 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. This paper deals with advancement of insulation diagnosis technology for high voltage equipment by partial discharge (PD) detection using transient earth voltage (TEV) detection method. Our previous study showed that detected TEV signal contains both high-frequency and low-frequency components around 500 MHz and 30 MHz, respectively. To further investigate the principle of detecting the low frequency components, this paper presents experiment and finite difference time domain analysis of TEV signal propagation. Results revealed that the signal intensity detected by TEV sensor with grounding is about five to six times as much as that without the grounding. Furthermore, when grounded, the low frequency components tend to be strongly detected. In other words, it is suggested that PD current including the low frequency component is induced on the surface of the metal box via the ground line, and this component greatly influences the TEV detection intensity.

DOI： 10.23919/ISEIM.2017.8166549

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Evolution of PD properties till breakdown in silicon nitride substrate molded with resin 査読有り

Y.Akinaga, J.Maki, M.Kozako, M.Hikita, Y.Nakamura, K.Taniguchi, T.Ikeda, K.Okamoto

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 664 - 667 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. This paper deals with evolution of partial discharge (PD) occurrence phase and charge (φ-q) characteristics of 0.32 mm thick Si 3 N 4 substrate molded with resin by applying ac 9 kVrms at 60 Hz until breakdown to quantitatively evaluate the degradation degree as well as the lifetime. Experimental results revealed that all specimens broke down just after PD magnitude suddenly increased. This means difficulty to expect the lifetime from only the PD magnitude. On the other hands, it was also found that φ-q characteristics changed continuously until breakdown. Namely, the shape of φ-q characteristics exhibited a rabbit-like pattern a few minutes before breakdown. In addition, the skewness of the pattern of PD distribution was analyzed in the positive and negative phases separately. As a result, the positive and negative skewness has increased three to four times with approaching to the breakdown. Thus, the present research indicates that a statistical parameter skewness of PD occurrence distribution can provide a possibility for expecting the lifetime of Si 3 N 4 insulation substrate molded with resin.

DOI： 10.23919/ISEIM.2017.8166578

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Effects of tracking and erosion resistance of nano-boehmite added silicone rubber 査読有り

R.Inoue, T.Kondo, M.Kozako, M.Hikita

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 1 29 - 31 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

The aim of this study is to develop new room temperature vulcanization (RTV) silicone rubber nanocomposites for application to outdoor polymer insulator. This paper deals with effects of addition of nano-scale boehmite filler on tracking, erosion resistance and arcing resistance of silicone rubber. The inclined plane test and the arc resistance test were performed. As a result, it was elucidated that the addition of small amount of nano-boehmite filler is able to increase tracking, erosion and arcing resistance.

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到達時間差法を用いたパワーモジュール内部の部分放電発生位置評定の高精度化検討査読有り

秋永優也, 真木洵耶, 満留博, 小迫雅裕, 匹田政幸, 岡本健次, 池田良成, 谷口克己, 中村瑤子

スマートプロセス学会誌 6 ( 5 ) 175 - 180 2017年09月

AC Partial Discharge Characteristics and Accumulation Charge after Lightning Impulse in Cast Resin Transformer 査読有り

H.Maruyama, M.Kozako, M.Hikita, K.Iida, T.Umemura, Y.Nakamura, T.Maeda, M.Higashiyama, T.Nakamae

The 20th International Symposium on High Voltage Engineering(ISH2017) ( 416 ) 1 - 5 2017年08月

PARTIAL DISCHARGE INCEPTION VOLTAGE MEASUREMENT AND ITS ESTIMATION BY VOLUME-TIME THEORY FOR SF6/PET INSULATED WEDGE GAP UNDER IMPULSE VOLTAGE 査読有り

K.Maeda, M.Kozako, M.Hikita, S.Yoshida, T.Chigiri

The 20th International Symposium on High Voltage Engineering(ISH2017) ( 441 ) 1 - 6 2017年08月

Dielectric properties and creepage discharge of epoxy/silica nanocomposite in mineral oil 査読有り

M.Kurachi, K.Jang, T.Akahoshi, M.Kozako, M.Hikita

19th IEEE International Conference on Dielectric Liquids 2014 (ICDL2017) 2017-January ( 1196 ) 1 - 4 2017年06月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

UK Manchester 2017年06月25日 - 2017年06月29日

© 2017 IEEE. This paper deals with the effect of the nano filler loading in epoxy resin (EP) on creepage discharge properties of the epoxy/silica nanocomposite (EP/S-NC) in mineral oil under standard lightning impulse voltage application using needle-bar electrode arrangement. Experimental results allow to estimate discharge occurrence probability (Pd) at each voltage level. The relative permittivity and dielectric loss are measured at 50 Hz - 5 MHz for EP/S-NC with a good dispersion of nanoparticles in the base epoxy matrix. As a result, it is found that Pd decreases with increasing the filler loading up to 1 wt%, and then increases. Namely, the nano filler content of 1 wt% produces the best insulation performance in terms of Pd. The relative permittivity of the composite decreases with decreasing the filler loading below 1 wt%, while further increasing nano silica filler loading results in increased έr above 3 wt%.

DOI： 10.1109/ICDL.2017.8124663

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Aging Properties of Monoesters and Comparison with Tri-ester and Mineral Oil 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, T.Suzuki

19th IEEE International Conference on Dielectric Liquids 2014 (ICDL2017) ( 1201 ) 2017年06月

Electrical insulation performance evaluation of PVF wire under thermal and electrical accelerated aging 査読有り

T.Uchimura, T.Kubo, M.Kozako, M.Hikita, K.Shimomura, S.Kawakami, T.Tanaka

19th IEEE International Conference on Dielectric Liquids 2014 (ICDL2017) 2017-January ( 1180 ) 1 - 4 2017年06月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

UK Manchester 2017年06月25日 - 2017年06月29日

© 2017 IEEE. It is crucial to understand degradation factors under actual operation in the lifetime evaluation of the coil winding of transformer. Polyvinyl formal (PVF) wire is used in oil-immersed transformer. Main degradation factor is considered to be oxidation and damage of the insulation coating due to thermal stress and partial discharge (PD). This paper deals with electrical insulation performance evaluation of twisted-pair specimen with PVF wire after thermal and electrical stress in the insulating oil. This research also deals with evaluation of a relation between the thermal stress and PD inception voltage (PDIV). Furthermore, Voltage-time (V-t) characteristics of twisted-pair specimen is investigated.

DOI： 10.1109/ICDL.2017.8124729

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Effect of discharge trace on creeping discharge characteristics in oil/pressboard composite insulation system under impulse voltage application 査読有り

S.Kainaga, S.Yoshida, T.Umemoto, M.Yoshimura, T.Tsurimoto, T.Akahoshi, K.Jang, M.Kurachi, M.Kozako, M.Hikita

19th IEEE International Conference on Dielectric Liquids 2014 (ICDL2017) 2017-January ( 1126 ) 1 - 5 2017年06月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

UK Manchester 2017年06月25日 - 2017年06月29日

© 2017 IEEE. In order to improve the insulation performance of oil-immersed power transformers, the characteristics of the creeping discharge under impulse voltage have been investigated. In this work, by using streak camera, investigations of the influence of the white discharge trace on the creeping discharge characteristics were implemented. The results showed that the velocity of the discharge developing along the white trace was about a thousand times larger than that of the discharge progressing on the pressboard surface. The results also showed that the length of the discharge progressing on the pressboard surface after the white trace formation was shorter than that before the white trace formation. On the other hand, the discharge time delay became larger. These results are thought to be explained by the residual charge generated by the discharge developing along the white trace.

DOI： 10.1109/ICDL.2017.8124708

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High accuracy partial discharge location in power module using multiple loop sensors 査読有り

H.Mitsudome, Y.Akinaga, M.Kozako, M.Hikita, Y.Ikeda, K.Taniguchi, Y.Nakamura, K.Okamoto

IEEE International Workshop On Integrated Power Packaging (IWIPP2017) ( 1009 ) 2017年04月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Netherlands Delft 2017年04月05日 - 2017年04月07日

© 2017 IEEE. Existence of partial discharge (PD) is one of the key issues in high-voltage power module. Thus, identifying a PD location in a power module leads to a higher voltage operation of a power module. An attempt is made to identify PD location in an IGBT power module by measuring electromagnetic wave (EMW) detected by multiple loop sensors. In this paper, a novel technique for identification of PD source is proposed by utilizing the polarity reversal of the first rising part of detected EMW signals and Time of Flight (TOF) method with four loop sensors. As the result, it is found that the method utilizing the polarity reversal of EM waveform allows PD location with accuracy of 1 mm. And it is found that TOF method with sampling frequency of 80 GS/s allows PD location with accuracy of 1 mm.

DOI： 10.1109/IWIPP.2017.7936749

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Investigation of prototype SiC power module structure for low inductance and high heat operation 査読有り

A.Imakiire, K.Nakamura, H.Tanabe, H.Kaisyakuji, T.Kubo, M.Kozako, M.Hikita

IEEE International Workshop On Integrated Power Packaging (IWIPP2017) ( 1032 ) 2017年04月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Netherlands Delft 2017年04月05日 - 2017年04月07日

© 2017 IEEE. This paper deal with structure for low inductance and high heat operation of silicon carbide (SiC) power module, which attracts attention in terms of high withstand voltage, high efficiency and high heat operation in recent years. First, the parasitic inductance of the power module of two types of structure; a conventional structure which forms the current path in a planar manner and a structure formed three-dimensionally is investigated using electromagnetic field analysis. In addition, thermal resistance of two types of power modules are experimentally evaluated from heat radiation performance. Experimental and simulated results reveals that the three-dimensionally formed power module is superior in the current path, resulting in lower parasitic inductance as well as smaller switching loss. Moreover, on state resistance and leakage current are evaluated at the junction temperature of 250 °C and the problems of power module package under high temperature environment is also investigated.

DOI： 10.1109/IWIPP.2017.7936767

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Evaluation on Applicability to Electrical Insulating Material of Hydrocarbon-Based Thermosetting Resin 査読有り

K.Yoshida, M.Kozako, S.Ishibe, M.Hikita , N.Kamei

Electronics and Communications in Japan 100 ( 4 ) 83 - 90 2017年04月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2017 Wiley Periodicals, Inc. This paper deals with dielectric properties of hydrocarbon-based thermosetting resin to evaluate the applicability to electrical insulating materials. Moreover, higher withstand voltage, lower dielectric constant, and lower moisture absorption are required for the electrical insulating materials. One of the candidate polymer materials satisfying such demands is hydrocarbon-based thermosetting resin, that is, polydicyclopentadiene (P-DCP) and polytricyclopentadiene (P-TCP). We measured the dielectric properties such as dielectric constant, dielectric loss, volume resistivity, and breakdown strength (BDS), and other properties such as moisture absorption, viscosity, mechanical strength, glass transition temperature, and coefficient of linear expansion of those specimens. It was found from the results in particular that P-DCP and P-TCP have the lower dielectric constant and the lower moisture absorption as compared with epoxy resin, while the volume resistivity and the BDS of P-DCP and P-TCP are not different to those of epoxy resin. As a result, it is elucidated that two kinds of hydrocarbon-based thermosetting resin have a potential for application to an electrical insulating material.

DOI： 10.1002/ecj.11953

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油/プレスボード複合絶縁系におけるインパルス沿面放電特性に及ぼす白色放電生成物の影響査読有り

赤星卓勇, Jang Kyunghoon, 小迫雅裕, 匹田政幸, 海永壮一朗, 吉田成是, 梅本貴弘, 吉村学, 釣本崇夫

電気学会論文誌A 137 ( 4 ) 188 - 195 2017年04月

記述言語：日本語掲載種別：研究論文（学術雑誌）

© 2017 The Institute of Electrical Engineers of Japan.We have investigated the effect of white discharge trace remaining on pressboard (PB) surface on the impulse creeping discharge characteristics in oil/PB composite insulation system. This paper deals with the effect of the white trace on the partial discharge inception voltage (PDIV), the number of discharge pulses, the discharge charge amount, and the time delay of discharge occurrence under the standard lightning impulse voltage application. Then, we also investigated the mechanism how the white trace affected the creeping discharge characteristics.

DOI： 10.1541/ieejfms.137.188

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Impulse creepage discharge properties of solid coated pressboard/oil composite insulation with rod-plane electrode system 査読有り

K.Jang, T.Akahoshi, M.Kozako, M.Hikita

電気学会論文誌A 137 ( 2 ) 113 - 118 2017年02月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2017 The Institute of Electrical Engineers of Japan.The surface of oil immersed pressboard (PB) influences partial discharge (PD) inception voltage and creepage discharge properties. This paper deals with surface modification of insulating paper by thin solid layer coating such as epoxy resin, Teflon and nano size silica /epoxy resin composites on PB surface to improve electrical insulation properties of oil /pressboard composite insulation system. Five kinds of specimens are prepared with different coating materials to investigate creepage discharge initiation and propagation under positive standard lightning impulse voltage (1.2 /50 μs) using a rod-plane electrode arrangement in mineral oil. Creepage discharge properties of conventional PB in oil/ PB composite insulation system are compared with that of the solid layer coated PB in terms of discharge final propagation length (ld) and PD inception voltage (PDIV) as an inception probability (Pi). The results show that PDIV of the solid layer coated PB increases at all applied impulse voltage levels compared with that of conventional PB. Especially, when the filler content of nano silica added in base epoxy was SP-0.2wt%, PDIV characteristic was improved. The effect of solid layer coating of PB surface on the creepage discharge properties is also discussed in terms of the effects of introduced deep electron traps due to the nano composites coating as well as the drying effect to remove water content and the surface roughness of PB.

DOI： 10.1541/ieejfms.137.113

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Non-empirical (ab initio) molecular orbital method 査読有り

Kozako M.

Advanced Nanodielectrics: Fundamentals and Applications 345 - 351 2017年01月

Low thermal fault gases of various natural monoesters and comparison with mineral oil 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, T.Suzuki

IEEE Transactions on Dielectrics and Electrical Insulation 23 ( 6 ) 3421 - 3428 2016年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2016 IEEE.Natural ester oils began to be implemented in higher voltage of power transformer in 2002. Gases generated by such oils need to be examined in order to anticipate the use of dissolved gas analysis (DGA) method to diagnose the presence of faults in natural ester filled transformer in service. This paper deals with an analysis of the gas generations of natural monoesters of different molecular structures derived from palm and rice bran oils under localized and low thermal faults ranging from 200 to 300 °C. Types of gases and their generation rates at various temperature levels were investigated. An attempt is made to compare the gas generation tendency between tested oils and commercially available natural ester insulation oil reported in the previous literature as well as mineral oil. The phenomenon of ethane generation by fatty acid monoesters having C-C double bond in their hydrocarbon chains and those without C-C double bond are discussed. Due to the expectation of overheating temperature, the possible implementation of CO/CH4 gas ratio is also evaluated.

DOI： 10.1109/TDEI.2016.006068

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