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SUGAHARA Kengo

    Department of Electrical, Electronic and Communication Engineering　Associate Professor
Last Updated :2024/04/25

Researcher Information

URL

Research funding number

  • 50718963

ORCID ID

J-Global ID

Research Interests

  • Accelerator Physics   Electromagnetic Analysis   

Research Areas

  • Natural sciences / Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics / Accelerator Physics
  • Informatics / Computational science / Electromagnetic analysis

Academic & Professional Experience

  • 2019/04 - Today  Kindai University理工学部 電気電子工学科准教授
  • 2014/04 - 2019/03  Kindai UniversityFaculty of Science and Engineering, Department of Electric and Electronic Engineering講師
  • 2010/10 - 2014/03  三菱電機株式会社神戸製作所
  • 2001/04 - 2010/09  Mitsubishi Electric Corporation先端技術総合研究所

Education

  • 2007/09 - 2007/09  Hosei University  Graduate School
  • 1999/04 - 2001/03  Kyoto University  理学研究科  物理学・宇宙物理学専攻
  • 1995/04 - 1999/03  Keio University  Science and Technology  Physics department

Association Memberships

  • IEEE   THE INSTITUTE OF ELECTRICAL ENGINEERS OF JAPAN   

Published Papers

  • Yasuhito Takahashi; Koji Fujiwara; Kengo Sugahara; Tetsuji Matsuo
    IEEE Transactions on Magnetics Institute of Electrical and Electronics Engineers (IEEE) 59 (5) 1 - 4 0018-9464 2023/05 [Refereed]
     
    A method for efficiently deriving a reduced-order model of a cage induction motor (IM) with skewed rotor slots is proposed based on the multiport Cauer ladder network (CLN) method. This article presents several formulations of the multiport CLN method for the skewed rotor, in which the continuity of the bar currents and the space harmonics included in the air-gap flux density waveform are treated differently. The effectiveness of the developed methods was verified from the viewpoints of computational accuracy and cost through application to a practical cage IM with skewed rotor slots.
  • Magnetic Moment Method with the Idea of Magnetic Surface Charge Method
    Journal of the Magnetics Society of Japan 2023/03 [Refereed]
  • Tetsuji Matsuo; Yasuhito Takahashi; Kengo Sugahara
    IEEE Transactions on Magnetics Institute of Electrical and Electronics Engineers (IEEE) 1 - 1 0018-9464 2023 [Refereed]
  • Kengo Sugahara; Naoto Tanimoto; Yasuhito Takahashi; Tetsuji Matsuo
    IEEE Transactions on Magnetics Institute of Electrical and Electronics Engineers (IEEE) 1 - 1 0018-9464 2023 [Refereed]
  • Yoshiki Hane; Tomoki Urata; Yoshitake Onchi; Kengo Sugahara; Kenji Nakamura; Yoshihiro Ishi
    IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING WILEY 18 (4) 500 - 505 1931-4973 2022/12 [Refereed]
     
    To further improve the control accuracy of the magnetic field generated by particle accelerator electromagnets, it is necessary to model not only the magnetic hysteresis behavior but also the magnetic after effect, which has never been studied in the previous literature. In this paper, the gap magnetic field of an accelerator magnet was measured under various excitation conditions to acquire the experimental data required for modeling. Consequently, it was clarified that the magnetic after effect may influence the magnetic hysteresis behavior. Moreover, it was accordingly indicated that a novel modeling technique is required in addition to the conventional hysteresis models developed in the electric machine field. (c) 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.
  • Kengo Sugahara
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 58 (9) 0018-9464 2022/09 [Refereed]
     
    The idea of the Kelvin transformation is extended to analyze the eddy current testing (ECT). The Kelvin transformation was originally proposed to solve the Poisson equation on the entire unbounded domain. When it was first applied to electromagnetic quasi-static problems, it was assumed that the analysis domain is surrounded only by air and nothing is inside the exterior domain. The analysis domain is truncated by a circular boundary in two dimensions and spherical in three dimensions, and another circular/spherical domain for emulating the exterior domain is connected through unknown equivalent boundary conditions. In this article, the Kelvin transformation is reformulated to derive the conductivity and permeability in the exterior domain, which conserves the conformal symmetry of Maxwell's equations. Utilizing the derived conductivity and permeability, the materials can be both in the interior and exterior domains or even across the truncated boundaries. Some numerical examples are demonstrated to validate the proposed method. As an application of the proposed method, the electromagnetic analysis of the ECT model is performed.
  • Yasuhito Takahashi; Koji Fujiwra; Kengo Sugahara; Tetsuji Matsuo
    IEEE Transactions on Magnetics IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 58 (8) 0018-9464 2022 [Refereed]
     
    This study investigated an efficient procedure for developing an accurate behavioral model of a cage induction motor (IM) based on the multiport Cauer ladder network (CLN). The CLN method was applied to a cage IM with semi-closed rotor slots as a model order reduction technique and a method for selecting the appropriate space harmonics included in the air-gap flux density, which is necessary for a multiport CLN method for induction machines, was discussed. Then, the developed approach was applied to the transient analysis of the cage IM coupled with a control system, and its effectiveness in terms of computational accuracy and cost was investigated.
  • Y. Hane; K. Sugahara; K. Nakamura
    Journal of the Magnetics Society of Japan 45 (4) 112 - 117 0285-0192 2021 [Refereed]
     
    In previous research, we have developed a reluctance network analysis (RNA) to calculate various electric machines’ characteristics, including electric motors, with high accuracy and high speed. However, those researches were limited to the closed magnetic circuits. This paper presents a novel RNA model for open magnetic circuits with the Kelvin transformation concept. The proposed method applies to analyzing the particle accelerator magnets, wireless power transfer systems, etc.
  • Yuji Shindo; Ryoma Yamamoto; Kengo Sugahara; Tetsuji Matsuo; Akihisa Kameari
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 56 (12) 0018-9464 2020/12 [Refereed]
     
    As an extension of the Cauer ladder network method, this article presents the equivalent circuit for an eddy current field including a translational mover. The speed voltages for the inductors in the equivalent circuit are obtained by using the directional derivatives of the inductors in the direction of mover displacement. These directional derivatives are determined by using the fact that the electromagnetic force can be represented in two forms, namely, Maxwell's stress tensor and the virtual work principle. This result is also verified by using the theory of continuum mechanics. Finally, numerical examples of an electromagnet are presented.
  • Tetsuji Matsuo; Kengo Sugahara; Akihisa Kameari; Yuji Shindo
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 56 (3) 1 - 4 0018-9464 2020/03 [Refereed]
     
    In this article, a method for motor model order reduction is developed using the Cauer ladder network (CLN). The analyzed domain is decomposed into stator and mover domains, where the multiport CLN of each domain is constructed independently of the other. The two domains are connected through electromagnetic field modes at the boundary. The boundary condition is derived from the coordinate transformation. The reduced model accurately reconstructs the induction motor property affected by slot harmonics.
  • Hassan Ebrahimi; Kengo Sugahara; Tetsuji Matsuo; Hiroyuki Kaimori; Akihisa Kameari
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 56 (3) 1 - 4 0018-9464 2020/03 [Refereed]
     
    Significant advances have been made to the Cauer ladder network method, an attractive method recently proposed for the model order reduction of linear eddy-current problems. However, these developments are often discussed in the context of simple 2-D problems with solid conductors only. The 3-D implementation of the method with general coil connections requires further treatment and deserves detailed discussion. This article reformulates the method for 3-D implementation with stranded coils (with no eddy current) as well as solid conductors with arbitrary connections between coils and external resistors.
  • Tetsuji Matsuo; Takayuki Fujiwara; Kenta Kuriyama; Kengo Sugahara; Akihisa Kameari; Tadashi Tokumasu; Yuji Shindo
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 56 (2) 1 - 5 0018-9464 2020/02 [Refereed]
     
    To achieve efficient multi-port model order reduction, a multi-port Cauer ladder network (CLN) method is formulated that directly yields resistance and inductance matrices that constitute the network elements in the matrix Cauer form. The eddy-current field driven by multiple power sources is accurately reconstructed using a small number of network elements. The matrix Cauer form achieves faster convergence of the transfer function than a single-port CLN method and almost the same convergence as a block Pade via Lanczos (PVL) method.
  • Kenta Kuriyama; Akihisa Kameari; Hassan Ebrahimi; Takayuki Fujiwara; Kengo Sugahara; Yuji Shindo; Tetsuji Matsuo
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 55 (6) 0018-9464 2019/06 [Refereed]
     
    The Cauer ladder network ( CLN) method provides an efficient representation of eddy-current fields. This paper proposes a reformulation of the CLN method that considers expansion points using the magnetic/current vector potential. To cover a wide range of frequencies, the expansion point may be changed at a later stage of the network. Only a few stages of the ladder network are required for the eddy-current field to be reconstructed accurately around the target frequency using the expansion points.
  • Satoshi Azuma; Daisuke Itoh; Takahito Ishida; Akihiko Iwata; Kengo Sugahara; Shigeo Morimoto
    IEEJ Transactions on Industry Applications The Institute of Electrical Engineers of Japan 139 (5) 495 - 502 0913-6339 2019 [Refereed]
     
    This paper proposes countermeasures to reduce radiated AM radio frequency noise caused by the VVVF (variable-voltage/variable-frequency) inverter system incorporated with an electric railway car. First, the common-mode current flowing through a cooling fin earth line is studied, and the connection change of the line shows good attenuation of the 1.26 MHz resonance component. Second, the common-mode current flowing though the motor earth line with a capacitor is focused upon, and the modified connections of the line to the outside of the input common-mode core achieves fine noise reduction in the range from 500 kHz to 1.5 MHz. In such cases, the existing input common-mode core is utilized to establish the impedance, which is efficient in both the noise reduction and the countermeasure cost reduction. Finally, a current simulation model which is paid attention to the AM radio frequency range is examined with the measured impedance data of the VVVF inverter system. The currents flowing thorough the cooling fin earth line and the motor earth line is simulated, and these simulated currents show good agreement with the measured one.
  • Tetsuji Matsuo; Akihisa Kameari; Kengo Sugahara; Yuji Shindo
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 54 (11) 0018-9464 2018/11 [Refereed]
     
    A matrix formulation of the Cauer ladder network (CLN) method is derived using the finite-element method to clarify the mathematical aspects of the CLN method. The CLN method directly yields orthogonal expansions of electric and magnetic fields that ensure the equivalence of the Cauer network to the eddy-current field. The CLN method is as exact as the Pade approximation via the Lanczos (PVL) process but more efficiently provides the circuit parameters and the orthogonal expansion than the PVL.
  • Y. Hibino; K. Sugahara; Y. Muro; H. Tanaka; T. Sato; Y. Kondo
    Journal of Magnetic Resonance 294 128 - 132 1090-7807 2018/09 [Refereed]
     
    We have been working on developing a low-cost tabletop NMR system. We reported that a field homogeneity as high as 50 ppm was achieved with a simple NMR magnet by employing two facing ferrite magnets with iron disks in between (Chonlathep et al., 2017). In this paper, we report two improvements added to our previous system: (1) an FPGA based signal processing unit to improve the S/N ratio and (2) a simple shimming mechanism to improve the field homogeneity. We obtained as high as 1 ppm field homogeneity in the best case. The signals from hydrogen nuclear spins in a methyl and carboxy group in acetic acid were resolved in NMR spectra.
  • K. Sugahara; A. Kameari; H. Ebrahimi; Y. Shindo; T. Matsuo
    IEEE Transactions on Magnetics Institute of Electrical and Electronics Engineers Inc. 54 (3) 0018-9464 2018/03 [Refereed]
     
    In this paper, open boundary techniques are employed to represent the Cauer ladder network (CLN) for unbounded eddy-current problems. Recently, a novel and effective model order reduction method, called the CLN method, has been proposed in which linear eddy-current fields are represented by a CLN. The CLN method was initially formulated for closed domain eddy-current problems. This paper demonstrates that the CLN method can be extended to unbounded-domain problems when combined with conventional open boundary techniques. The CLN network parameter extractions of two parallel busbars are demonstrated as a numerical example.
  • A. Kameari; H. Ebrahimi; K. Sugahara; Y. Shindo; T. Matsuo
    IEEE Transactions on Magnetics Institute of Electrical and Electronics Engineers Inc. 54 (3) 0018-9464 2018/03 [Refereed]
     
    A novel model order reduction method for efficient analysis of linear eddy-current problems is proposed in which the quasi-static electromagnetic fields are expressed by a weighted sum of a sequence of static electric- A nd magnetic-field modes. The modes are calculated sequentially by static electric and static magnetic computations using the conventional finite-element method, and the time-dependent weights are the voltages and currents of an equivalent Cauer ladder network of the problem. In this paper, the formulation of the method and a numerical test problem are presented, and the accuracy and enormous efficiency of the method are demonstrated by solving a 3-D nonlinear inductor model with a voltage excitation by a dc-dc converter, linearized around the dc current using frozen differential permeability.
  • Yuji Shindo; Akihisa Kameari; Kengo Sugahara; Tetsuji Matsuo
    IEEJ JOURNAL OF INDUSTRY APPLICATIONS INST ELECTRICAL ENGINEERS JAPAN 7 (4) 305 - 313 2187-1094 2018 [Refereed]
     
    This paper presents a novel dynamical modeling method for magnetic actuators. The magnetic field is decomposed into orthogonal distribution functions by using the Cauer ladder network representation of eddy-current fields. The linearized transfer function of the magnetic force is derived by using the Maxwell's stress tensor and distribution functions. The numerical example of an electromagnet is presented to show the effectiveness of this method. It is revealed that the eddy current not only reduces the main flux but also induces a repulsive force at the air gap. The details of the Cauer ladder network representations are also clarified.
  • Kengo Sugahara
    IEICE Trans. Electron. IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG 101-C (1) 52 - 55 1745-1353 2018 [Refereed]
     
    Strategic Dual Image method (SDI) for three-dimensional magnetic field problems is proposed. The basic idea of the SDI method is that the open boundary solution is in-between the Dirichlet and Neumann solutions. The relationship between the specific topology (e.g. sphere, and ellipsoid) of the boundary and the averaging weight has been discussed in the previous literature, however no discussions on the arbitrary topology. In this paper, combined with "the perturbation approach using equivalence theorem", the methodology to derive the averaging weight of Dirichlet and Neumann solutions on the arbitrary topology has been proposed. Some numerical examples are also demonstrated.
  • K. Sugahara
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 53 (6) 0018-9464 2017/06 [Refereed]
     
    Improvised Asymptotic Boundary Conditions (IABCs) in ellipsoidal and elliptic cylindrical coordinates have been derived. The IABCs are among the simplest techniques to emulate the open boundary condition, which can be improvised in virtually any finite-element program. The IABC was first proposed with the circular in 2-D, and spherical in axisymmetric 3-D domains. This work extends the IABC formulation to ellipsoidal and elliptic cylindrical domains.
  • K. Chonlathep; T. Sakamoto; K. Sugahara; Y. Kondo
    JOURNAL OF MAGNETIC RESONANCE ACADEMIC PRESS INC ELSEVIER SCIENCE 275 114 - 119 1090-7807 2017/02 [Refereed]
     
    We have developed a simple, easy to build, and low-cost magnet system for NMR, of which homogeneity is about 4 x 10(-4) at 57 mT, with a pair of two commercially available ferrite magnets. This homogeneity corresponds to about 90 Hz spectral resolution at 2.45 MHz of the hydrogen Larmor frequency. The material cost of this NMR magnet system is little more than $100. The components can be printed by a 3D printer. (C) 2016 Elsevier Inc. All rights reserved.
  • K. Sugahara
    2016 PROGRESS IN ELECTROMAGNETICS RESEARCH SYMPOSIUM (PIERS) IEEE 2478 - 2483 2016 [Refereed]
     
    The perturbation method for open boundary problems based on the equivalence theorem has been proposed. Most of the open boundary techniques in electromagnetic analysis are approximate, whereas more accurate techniques require large computational resources. In order to improve the accuracy of the open boundary solution, the equivalence theorem has been employed as a perturbation correction to the electromagnetic analysis with the approximate open boundary conditions. In this manuscript, the proposed method has been verified with numerical examples.
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  • K. Sugahara
    2016 PROGRESS IN ELECTROMAGNETICS RESEARCH SYMPOSIUM (PIERS) IEEE 1152 - 1155 2016 [Refereed]
     
    The performance of the Improvised Absorbing Boundary Conditions (IABC) is studied when applied to wireless power transfer (WPT) systems. The IABC is one of the approximated techniques to solve the unbounded electromagnetic problems. It was recently proposed to solve quasi- static problems and extended to the high frequencies. Non- radiative WPT based on the magnetic resonance and near- field coupling of two- loop resonators was first reported by Tesla and nowadays, it has attracted interest from industry and academic researchers. The frequency used in non- radiative WPT systems are rather low and therefore, high frequency electromagnetic techniques e. g., radiation boundary conditions and PML are not applicable to analyze the WPT systems. In this manuscript, the advantages of the IABC is discussed.
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  • K. Sugahara
    Proceedings of the 2015 International Conference on Electromagnetics in Advanced Applications, ICEAA 2015 1094 - 1097 2015/10 [Refereed]
     
    Improvised absorbing boundary conditions for high frequency electromagnetic problems have been studied. This method approximated unbounded space as series of isotropic spherical shells so as to emulate open boundaries without the need for additional code to any finite element solver. Previous work addressed applications of this technique to magnetostatic and electrostatic problems. This present work studies the wide-range frequency dependence of the IABC when applied to three-dimensional electromagnetic radiation problems.
  • Kengo Sugahara
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 49 (11) 5399 - 5403 0018-9464 2013/11 [Refereed]
     
    A simple and efficient method for solving open boundary axisymmetric magnetic field problems is proposed. This technique uses two ellipsoidal analysis domains which are connected through the periodic boundary conditions. One of the domains acts as an exterior region which produces no reflection of low-order multipoles. The harmonic solutions of the Laplace equation in an oblate spheroidal coordinate have been investigated and a formula for the axis ratio of the ellipsoidal boundary and the permeability of the exterior region has been derived. To verify the formula, we have demonstrated some numerical examples and compared with spectrum-domain solutions. Based on the results, we concluded that the methodology is proven to be valid.
  • Kengo Sugahara
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 49 (9) 4944 - 4950 0018-9464 2013/09 [Refereed]
     
    During the early 1990s, the strategic dual image (SDI) method for axisymmetric open boundary magnetic field problems was proposed. Although the method is powerful, the specific axis ratio of the ellipsoidal boundary has not been clarified, and therefore no further research has been done so far. Our aims are to clarify the relationship between the specific axis ratio of the ellipsoidal boundary and the harmonic solutions of Laplace equation, and to extend the strategic dual image method in general form. We have investigated the harmonic solutions of the Laplace equation in the oblate spheroidal coordinate to derive the explicit formula regarding the axis ratio and the averaging factor of Dirichlet and Neumann boundary value problems. Numerical analyses have also been carried out to verify the formula. We have determined the explicit formula regarding the axis ratio and averaging factor of Dirichlet and Neumann solutions, thus extending the SDI method in general form. Utilizing the derived formula, one can obtain the open boundary solutions of axisymmetrical magnetic field problems without alternating the existing software which are widely distributed through the Internet.
  • Kengo Sugahara
    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 22 (4) 1 - 7 1051-8223 2012/08 [Refereed]
     
    A technique for magnetic field reconstruction is proposed with the use of a generalized electrical image method (GEIM). The basic idea behind the GEIM is that by understanding fundamental properties of the strategic dual image (SDI) method and applying the equivalence principle on the SDI boundary, a simple form of the interior/exterior magnetic field can be determined. As an example of this technique, a field reconstruction of a quadruple magnet is demonstrated.
  • K. Yamamoto; H. Tanaka; H. Harada; K. Sugahara; H. Inoue; S. Kawasaki; T. Nagayama; S. Ueda
    Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 269 (24) 2875 - 2878 0168-583X 2011/12 [Refereed]
     
    Alternating phase focusing (APF) is known as a beam focusing method it was applied to an interdigital H-mode structure and successfully accelerated high current proton beams up to the desired energy for a medical synchrotron injector. A high-current APF linac was achieved by the optimal design of the cavity and the drift tubes themselves, as well as drift tube arrangement based on the co-iteration of a precise electromagnetic field and space charge beam dynamics. A proton injector for a medical accelerator complex was fabricated with the newly developed APF linac. The injector consists of an electron cyclotron resonance ion source, a radio-frequency quadrupole linac and the APF linac. The experimental results showed that over 10 mA proton beams were accelerated up to 7.4 MeV. © 2011 Elsevier B.V. All rights reserved.
  • AZUMA Satoshi; ITOH Daisuke; SUGAHARA Kengo
    IEEJ Transactions on Industry Applications The Institute of Electrical Engineers of Japan 129 (4) 399 - 405 0913-6339 2009/04 [Refereed]
     
    A novel double-series resonant filter is implemented in order to reduce the high-frequency return current noise generated by AC-powered electric cars with AC/DC PWM converters and inverters. The double-series resonant filter is placed between a main transformer and a converter. The resonant filter is tuned so that the noise signal due to the return current is attenuated at the exact noise frequency; for example, the 105-kHz component of an ATS (Automatic Train Stop) signal is attenuated by this filter. The filter has two LCR resonant circuits, one of which is in parallel with a resistance. This filter design helps achieve good attenuation at the noise frequency and helps limit unnecessary amplification at other frequencies. First, a test filter is realized, and the inductance and capacitance of this filter are in good agreement with the corresponding values in the filter design. Then, the filter is included in a full-scale test system with a main transformer and a converter. Then it is confirmed that a 5-dB reduction in the return current noise is achieved by using the proposed filter. Finally, the return current noise in the test system is confirmed to be well below the desired regulation level. This is expected to help realize simple methods for dealing with the effects of impedance at high frequencies in the main transformer.
  • Kengo Sugahara
    IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 56 (3) 722 - 727 0018-926X 2008/03 [Refereed]
     
    We have found that a boundary integral equation n x H = J(s) results in an inaccurate solution on torus-shaped perfect conducting surfaces. Although, constraining a boundary condition n x H = J(s) automatically satisfies E x n = 0 on a closed polyhedron-shaped conductor, there exists a solution which only satisfies the boundary condition n x H = J(s) but not the other boundary condition E x n = 0 on a torus-shaped conductor. We have introduced a virtual magnetic current M, in the system equation as another degree of freedom and employed E x n = 0 at one point on the perfect conducting surface so as to obtain the accurate solution. To verify the proposed discussion, we have formulated an axially-symmetric method of moments based on n x H = J(s) and compared with other electromagnetic field solvers.
  • Kengo Sugahara; Hiroaki Yamamoto; Hirofumi Ouchi; Yuji Nakano
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 43 (8) 3375 - 3379 0018-9464 2007/08 [Refereed]
     
    We propose a numerical method for analyzing near-field magnetic fields for automobile electronic key systems. The surface of an automobile body is divided into triangular patches and a modified inductance matrix formulation is employed. A large inductance matrix equation is solved using a Block Gauss-Seidel method. A source magnetic field produced by a ferrite bar antenna is analyzed using a magnetic moment method to formulate a right-hand vector of the matrix equation. We have made a simplified automobile model and measured leakage of magnetic fields from windows of the model. Analyzed results agreed with the measured results with an error of 10%.
  • Yasuhiro Shiraki; Kengo Sugahara; Yuichiro Murata; Shinya Nishi
    ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS SCRIPTA TECHNICA-JOHN WILEY & SONS 90 (9) 1 - 10 8756-663X 2007 [Refereed]
     
    In this paper, a highly accurate equivalent circuit is constructed that can calculate the transmission characteristics of the vias connecting the layers in multilayered printed circuit boards. Various factors of the vias affecting the transmission characteristics are discussed. The present equivalent circuit is based on the physical structure and the equivalent circuit parameters are determined by an optimization method. The equivalent circuit is applied to the vias in printed circuit boards with more than 10 layers. The results of evaluation of the transmission characteristics in the gigahertz range are verified by the FDTD method and by measurement so as to verify their validity. Further, by using the present equivalent circuit, the effects of various factors of the vias on the transmission characteristics are studied. It is demonstrated that the time needed for study by the equivalent circuit is less than that needed for numerical analysis. (c) 2007 Wiley Periodicals, Inc.
  • Kengo Sugahara; Kiyoshi Yoda
    IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 54 (12) 3833 - 3839 0018-926X 2006/12 [Refereed]
     
    We have proposed a numerical method for calculating low-frequency electromagnetic scattering from three-dimensional arbitrarily shaped perfectly conducting bodies using an inductance matrix. The surface of the perfectly conducting scatterer and its apertures are modeled by a set of triangular patches. The current on each patch is computed by solving a coupled inductance matrix equation. Scattering from various conducting bodies with apertures is calculated to compare with the other methods. The proposed method well agrees with finite element method in electromagnetic field distribution.
  • K Sugahara; K Yoda
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 42 (5) 1555 - 1559 0018-9464 2006/05 [Refereed]
     
    We have proposed a numerical method for calculating low-frequency electromagnetic scattering from axially symmetric conducting bodies with and without apertures. The surface of the perfectly conducting scatterer is modeled by a set of inductively coupled coil elements, and the current in each coil element is computed by solving an inductance matrix equation. A disadvantage of a conventional method for a scatterer with apertures is discussed. Scattering from various axially symmetric conducting bodies with or without apertures is calculated and the resulting fields are in good agreement with those obtained by finite-element method.
  • K Sugahara; S Tanabe; M Yamaguchi
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 41 (10) 3529 - 3531 0018-9464 2005/10 [Refereed]
     
    We have proposed a method for identifying a wide-band equivalent circuit model for ferromagnetic radio frequency (RF) integrated inductors. The equivalent circuit parameters have been extracted from measured S-parameters by using a multiobjective simplex method, which sequentially switches three different cost functions, given by the average of error in Y-parameters, Z-parameters, and S-parameters. With this method, the optimization converged to the global minimum without being trapped at a local minimum. Calculated Y-parameters, Z-parameters, and S-parameters were in good agreement with the measured results in the range of dc to 20 GHz.
  • SHIRAKI Yasuhiro; SUGAHARA Kengo; TANABE Shinji; WATANABE Tetsushi; NAKAMOTO Katsuya
    The transactions of the Institute of Electronics, Information and Communication Engineers. B The Institute of Electronics, Information and Communication Engineers 88 (7) 1319 - 1328 1344-4697 2005/07 [Refereed]
     
    自動車では, 車載電子機器(ECU)から発生する不要電磁波放射(EMI)がFMラジオの受信特性に影響を与えるため, 設計段階EMI評価を行うため数値計算が必要である.本論文では給電部の電流測定, 二次元モーメント法, 伝送線路解析法及びFDTD法を組み合わせて連携させた電磁界解析法を用いて, ECUから発生するEMIによる自動車車室内の電磁界分布を明らかにすることにより, 自動車車室内のEMI設計に電磁界解析を適用する方法の検討を行った.このような人体や車室内構造品を考慮した実際の自動車にほぼ等しい条件で, EMI設計に電磁界解析を適用した報告は見当たらない.まず実際の自動車において, 測定ケーブルに不要電流が重畳しない実測方法を用いて, 車室内の電磁界解析結果を検証し, 本連携解析が自動車のEMI解析に有用であることを示した.更に本手法がEMIの影響を受けにくいFMアンテナ位置の最適設計に効果的な手法であることを明らかにした.また, 車体ボディ材質, 人体の有無によりFMアンテナのEMIが異なることを示した.
  • Shirakii Yasuhiro; Sugahara Kengo; Murata Yuichiro; Nishi Shinya
    Proceedings of the IEICE General Conference The Institute of Electronics, Information and Communication Engineers 2004 (2) 90 - 90 2004 [Refereed]
  • A Konrad; S Tanabe; R Jafari; K Sugahara; M Yamaguchi
    IEEE TRANSACTIONS ON MAGNETICS IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 39 (5) 3079 - 3084 0018-9464 2003/09 [Refereed]
     
    Design and equivalent circuit of an inductor with ferromagnetic film is described. High-frequency circuit simulation including inductances is carried out by two methods: 1) a SPICE-based simulation in which the distributed linear circuit is converted into GCRL equivalent circuit and 2) a harmonic balance method in which the nonlinear active part of the circuit is solved in terms of sinusoidal harmonics in frequency domain. High-frequency circuits including inductors and active elements such as low noise amplifiers are analyzed by these methods.

Conference Activities & Talks

MISC

Industrial Property Rights

Awards & Honors

  • 2021/08 J. Magn Soc. Jpn MSJ Distinguished Paper Award
     A Novel Reluctance Network Model Applicalble for Open Magnetic Circuits. 
    受賞者: Yoshiki Hane;Kengo Sugahara;Kenji Nakamura
  • 2020/11 IEEE EEE-IAS TSC Fist Prize
     
    受賞者: 三菱電機;東聖;伊藤大輔;菅原賢悟
  • 2019/05 日本電気協会関西支部 第66回電気関係功績者表彰
     電磁界解析における開領域問題解法に関する研究
  • 2016/03 電子情報通信学会 エレクトロニクスシミュレーション研究会 優秀論文発表賞
     等価定理による摂近似 
    受賞者: 菅原賢悟

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2023/04 -2026/03 
    Author : 菅原 賢悟; 佐藤 孝洋; 日高 勇気; 半田 久志
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2020/04 -2023/03 
    Author : 松尾 哲司; 菅原 賢悟; 高橋 康人
     
    (1) 誘導モータ解析の非線形化 電源磁束，空隙部磁束をパラメータとして飽和度を表現し，小さなパラメータ次元で精度よく飽和度を表現する手法を開発することにより，固定子の非線形化を実現した。トルクなどモータ諸量を時間変化を含めて精度よく効率的に算出することに成功している。 (2) 簡易モデルの開発 空間高調波数の相互作用を無視することにより，周波数領域における縮約モデルを開発し，トルクなどの平均量を過渡解析なしに算出する簡易モデルを構築した。従来の簡易等価回路より高精度なモデル化を実現している。 (3) スキューを考慮したモデル縮約 マルチポートCLN法に基づいて，かご形誘導モータのスキューを考慮したビヘイビアモデルを導出した。スキューを近似的に模擬した多段の回転子のモデル縮約と各段間のロータバー電流の接続を考慮することにより，トルク波形を含むモータ諸量を高精度に再現する効率的な縮約モデルを開発した。 (4) 誘導加熱問題への拡張 CLN法を誘導加熱問題に拡張した。等価なカウア回路の変換により，物理的意味が明確な等価回路を構成した。 (5) FP-CLN法の近似解の誤差評価 Fixed-Point法を用いた新たな非線形CLN法について，その誤差を評価する方法を検討した。 (6) 固有関数展開を用いたCLN法の誤差解析 固有関数展開と連分数展開との関係を議論することにより，カウア回路の段数と誤差の関係を理論的に導出した。予備的な1次元問題による検討により，誤差評価法の有効性を示した。
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2020/04 -2023/03 
    Author : 菅原 賢悟; 石 禎浩; 藤原 耕二; 中村 健二; 羽根 吉紀
     
    粒子加速器による磁場制御の精度をさらに向上させるためには、これまで粒子加速器分野で研究されてこなかった磁気ヒステリシスや磁気残効をモデル化することが必要である。本論文では、モデル化に必要な実験データを取得するため、電磁石の磁場測定環境の構築及び磁場測定を行い，測定した基礎データの分析を行った．測定結果より，磁気余効の時定数より十分に長い待機時間を設けた場合，渦電流などによる磁場の遅れが増加するという現象と真逆の現象を確認した． この現象の原因については今後の研究で明らかにしていく必要がある．また，電気機器の分野において提案されたヒステリシスモデリング手法は，そのままの形では加速器の分野に適用できないことを明らかにした．したがって，これらの現象を考慮した新たなモデリング手法の確立も必要である．

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