Faculty Profiles - TAKEMOTO Masatsugu

Papers - TAKEMOTO Masatsugu

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A New Active Power-Decoupling Topology and Control Mechanism to Extend the Lifespan and Reduce the Number of Passive Components Reviewed

S. Hwang, S. Ogasawara, K. Orikawa, M. Takemoto

IEEJ Transactions on Electrical and Electronic Engineering 14 ( 5 ) 780 - 791 2019.5

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

In this article, a new active power-decoupling (APD) circuit without an additional discharging inductor is proposed for single-phase power systems. In an APD circuit, a small film capacitor is used to extend the lifespan and remove ripple power derived from power systems. However, to manipulate power pulsation, additional circuits such as inductors, capacitors, and switches are required, which increase the manufacturing cost and parametric uncertainties. In the proposed circuit, rectification and a decoupling function are conducted on a coupled-inductor at the same time to reduce the number of passive elements. Furthermore, a sliding mode control is used to ensure stable operation under parameter variation and disturbance. A design example is presented and the operation of the proposed topology is also verified with a simulation study and experimental results. The results show that the proposed APD method was able to remove passive components and reduce the withstand voltage of a buffer capacitor and insulated gate bipolar transistors (IGBT) while ensuring that both the input current and output voltage of the converter were well regulated under load variation. (c) 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

DOI： 10.1002/tee.22865

Common-mode voltage attenuation of an active common-mode filter in a motor drive system fed by a PWM inverter Reviewed

Shotaro Takahashi, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Michio Tamate

IEEE Transactions on Industry Applications 55 ( 3 ) 2721 - 2730 2019.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

© 1972-2012 IEEE. The switching speeds of next-generation power semiconductor devices, such as those made of silicon carbide and gallium nitride are roughly ten times those of conventional devices (e.g., silicon insulated-gate bipolar transistors). This increases the frequency range of the electromagnetic noise accompanying the switching operations of pulsewidth modulated (PWM) converters and worsens the influence of radiated noise. The authors have previously proposed an active common-mode filter (ACF) that reduces the radiated noise from the power cables connected to a PWM converter and evaluated its effect in reducing radiated noise by using a function generator as a common-mode (CM) noise source. In this paper, the ACF is applied to a motor drive system fed by a three-phase PWM inverter, and the attenuation characteristics of the CM voltage are evaluated. To avoid saturating the ACF, the combination of an active common-noise canceller and the ACF is discussed. The experimental results show that the system constructed in this paper can suppress the CM voltage produced by the PWM inverter over a wide frequency range from 100 to 100 MHz.

DOI： 10.1109/TIA.2019.2892364

Increasing the Operating Speed of a Consequent Pole Axial Gap Motor for Higher Output Power Density Reviewed

T. Ogawa, T. Takahashi, M. Takemoto, S. Ogasawara, H. Arita, A. Daikoku

IEEJ Journal of Industry Applications 8 ( 3 ) 497 - 504 2019.5

Language：English Publishing type：Research paper (scientific journal) Publisher：INST ELECTRICAL ENGINEERS JAPAN

In this study, we examine how to increase the operating speed of a consequent pole axial gap motor to achieve higher output density. Our research group has been developing a consequent pole axial gap motor with field windings as the traction motor for electric vehicles. A smaller and lighter traction motor is required for better fuel economy and layout of such vehicles, and it is profitable to manufacture a smaller motor with an increased operating speed. To achieve high-speed operation, it is necessary to suppress the line-to-line voltage, and to that end, we examine the slot/pole combination. Moreover, because the rotor outer diameter of an axial gap motor is larger than that of a radial gap motor, the rotor strength should also be considered. We study the use of non-magnetic high-tensile-strength steel for the component that supports the rotor. We present the motor design and the results of spin burst tests, and we confirm that the motor can operate at the target maximum speed and output power density.

DOI： 10.1541/ieejjia.8.497

A Hybrid Common-Mode Voltage Canceleration Using an Passive Filter and an Active Feedback Circuit for PWM Inverters Reviewed

Shunsuke Ohara, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Yushin Yamamoto

2019 IEEE 4TH INTERNATIONAL FUTURE ENERGY ELECTRONICS CONFERENCE (IFEEC) 2019

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper proposes a hybrid common-noise canceler to improve the common-mode (CM) voltage suppression performance by using an active feedback circuit. First, the operating principles of a passive canceler and the hybrid canceler are presented. The passive canceler is composed of a non-zero sequence choke and a CM transformer. The CM voltage suppression performance of the passive canceler is degraded by leakage inductances of the non-zero sequence choke and the CM transformer. The proposed hybrid canceler achieves higher CM voltage suppression than the passive canceler because the active feedback circuit reduces the effects of the leakage inductance. Finally, the hybrid canceler performance is evaluated by simulations.

Multi-phase Interleaved AC to DC Buck-boost Converter with Active Power Decoupling Function and Sliding-mode Control Strategy Reviewed

Soonhwan Hwang, Satoshi Ogasawara, Koji Orikawa, Masatsugu Takemoto

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

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper proposes an interleaved AC/DC buck-boost converter with active power decoupling(APD) using the modular design method. It also introduces the control method using the sliding mode control (SMC) strategy for the proposed circuit. The contribution of this paper was first proposed by AC/DC Interleaved Converter circuits with APD functions, which allowed the size of input filters and magnetic cores to be reduced. Additionally, we have applied SMC strategies to the control system to be robust for the disturbance or model uncertainty. The effectiveness of the proposed circuit and control method is shown by simulations using MATLAB/SIMULINK.

A Frequency Multiplying Circuit Containing a High-frequency Output Inverter and an Impedance Matching Transformer Reviewed

Koji Orikawa, Satoshi Ogasawara, Masatsugu Takemoto, Jun-ichi Itoh

45TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY (IECON 2019) 6603 - 6608 2019

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

We propose a frequency multiplying circuit containing a high-frequency output inverter and an impedance matching transformer that contains magnetic materials with an operation frequency lower than the output frequency. The operation principle and power loss of the proposed circuit and a conventional circuit are compared. Simple theoretical analysis shows that the proposed circuit can reduce the iron loss of magnetic materials. However, the conduction loss of semiconductor devices and the copper loss of primary windings in the proposed circuit are higher those in the conventional circuit because the number of phases in the half-bridge inverter is five times that in the conventional circuit. Experimentally, it is revealed that Mn-Zn ferrite can be used at an output frequency of 2.5 MHz, which exceeds the operation frequency of the material.

A Proposal of a Delta-Type Salient Pole Variable Flux Memory Motor Having Large Flux Barrier for Traction Applications Reviewed

Ren Tsunata, Masatsugu Takemoto, Satoshi Ogasawara, Koji Orikawa

2019 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 6054 - 6061 2019

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this paper, a novel variable flux memory motor (VFMM) employing delta-type permanent magnet (PM) arrangement and extended flux barriers is proposed. Conventional VFMMs have three main drawbacks as follows: At first, positive and negative current pulse for magnetizing the variable flux PMs are asymmetry due to the diamagnetic field from Neodymium sintered PM as a constant flux PM. As a result of asymmetric magnetizing current, the inverter capacity is increased. Secondly, variable flux PMs are unintentionally demagnetized when applying maximum load current. Thirdly, iron loss is tend to be increased when magnetization reversal is caused by negative magnetizing current pulse because the harmonic flux becomes larger. The proposed VFMM in this paper overcomes the above challenging points at the same time because of delta-type PM arrangement and the extended flux barrier. In addition, the proposed VFMM can achieve lower iron loss and voltage than the target motor mounted in TOYOTA PRIUS fourth-generation. It is obvious that the proposed VFMM has very high performances in terms of magnetization characteristic, efficiency, and torque density.

Experimental consideration of radiated EMI caused by air-conditioner piping - Modal analysis based on measured current distribution - Reviewed

Kanako Tsushima, Satoshi Ogasawara, Koji Orikawa, Masatsugu Takemoto, Kenji Koyama

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

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper deals with electromagnetic interference radiated from air-conditioner piping that acts as an antenna and emits electromagnetic noise. The current distribution on the piping is measured by using a near-field magnetic probe, and the distribution mode is analyzed. The results show that the piping resonates at the frequencies where the piping length accords with lambda/4, 3 lambda/4, and 5 lambda/4, and radiates electromagnetic noise as a monopole antenna. This radiation mechanism is confirmed by simulations using the CST EMC Studio electromagnetic field simulator.

A simple technique for estimating the winding stray capacitance of high-frequency three-phase common-mode inductors Reviewed

Shotaro Takahashi, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Michio Tamate

IEEJ Transactions on Industry Applications 139 ( 3 ) 339 - 347 2019

© 2019 The Institute of Electrical Engineers of Japan. The switching speed of next-generation power devices based on wide-bandgap semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN), are more than ten times those of conventional silicon insulated-gate bipolar transistors (Si-IGBT). This may increase the frequency range of electromagnetic noise produced by pulse-width-modulated converters. Further, the operating frequency ranges of noise filters are limited by the parasitic components of passive elements, so it is difficult to realize a high-frequency (HF) noise filter whose operating frequency exceeds several tens of megahertz. This paper proposes a novel and simple analytical method to calculate the winding stray capacitance of an HF three-phase common-mode (CM) inductor for the purpose of estimating its operating frequency range at the design stage. Results of measuring the CM impedance confirm that the proposed method can estimate the operating frequency range of an HF three-phase CM inductor while ensuring practically sufficient precision. Furthermore, the obtained results also show that the reduction in the number of turns does not always contribute to the enhancement of the operating frequency ranges of filter inductors.

DOI： 10.1541/ieejias.139.339

High-Frequency Noise Suppression in a Buck-Converter System Based on SiC Devices Reviewed

Shotaro Takahashi, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Michio Tamate

2019 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 2859 - 2866 2019

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

High switching speed in next-generation power devices such as silicon carbide allows increased switching frequencies in power converters. Higher switching frequencies increase power densities, but also increase frequencies of electromagnetic noise accompanying switching operations, resulting in more serious electromagnetic interference (EMI). Radiated EMI will thus soon become a major concern when developing power converters. Most previous works have focused on conducted EMI, resulting in a dearth of research on radiated EMI from power converters. We thus investigated the generation mechanism of radiated noise from power converters to identify effective reduction methods. We identify two propagation paths of high-frequency (HF) common-mode (CM) noise currents, primary CM (PCM) and secondary CM (SCM). SCM constructs a large propagation loop, thus becoming a major source of radiated noise. To suppress HF CM current flow through each mode, we fabricate two types of CM inductors (CMI). HF CM currents are measured in a simple buck converter system. CM current measurements verify the effectiveness of CMI for reduction of HF CM currents and clarify how SCM voltage source is generated. The described generation mechanism of SCM voltage source and radiated noise is verified by measurements of radiated noise in a fully anechoic chamber.

Development of a Consequent Pole PM type Axial-Gap Motor with DC Field Winding Reviewed

Tomohira Takahashi, Masatsugu Takemoto, Satoshi Ogasawara, Toru Ogawa, Hideaki Arita, Akihiro Daikoku

2019 IEEE INTERNATIONAL ELECTRIC MACHINES & DRIVES CONFERENCE (IEMDC) 766 - 773 2019

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

Permanent magnet synchronous motors (PMSM) for electric vehicles (EV) requires three properties; high torque, high efficiency at low torque region, and constant output in wide speed range. However, these have a relation of a trade-off at magnitude of field magnetic flux. In this paper, consequent pole PM type axial-gap motor with the ferrite PMs and the field windings, which has structure variable field magnetic flux, is introduced. Also, in order to examine operation characteristics of the proposed motor, a prototype is produced and tested. Experimental results show that the proposed structure is effective in realizing all of three properties; high torque, high efficiency at low torque region, and constant output in wide speed range.

Experimental Evaluation of the Relationship between Filter Inductor Impedances and Dimensional Resonances of MnZn Ferrites Reviewed

Shotaro Takahashi, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Michio Tamate

2019 IEEE 4TH INTERNATIONAL FUTURE ENERGY ELECTRONICS CONFERENCE (IFEEC) 2019

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper explores the relationship between filter inductor impedance and dimensional resonance in magnetic cores. Experimental results were obtained showing multiple factors behind the resonances that appear in the frequency characteristics of inductor impedances: the inherent characteristics of a magnetic material, the self-inductance of an inductor and stray capacitance in its winding, and the winding acting as a distributed constant line. Next, based on the measurement results, the dimensional dependencies of the complex permeabilities ( dimensional resonance) and the influence of dimensional resonance on inductor impedance are discussed in detail. Finally, this paper shows that the effect of dimensional resonance on complex permeability can be mitigated and filter inductor impedance can be increased in the high frequency range by a core lamination. These results are verified by the experiments described in this paper.

Lyapunov-function Based control of an AC/DC buck-boost converter with active power decoupling circuit Reviewed

Soonhwan Hwang, Satoshi Ogasawara, Koji Orikawa, Masatsugu Takemoto

2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

© 2018 EPE Association. Active power decoupling(APD) method is a suitable solution to increase the lifetime of power conversion systems by replacing electrolytic capacitors(E-Caps) with film capacitors using an auxiliary circuit. However, due to the increased non-linearity and uncertainty of the entire circuit, conventional control methods cannot guarantee global stability. This paper proposes nonlinear control strategy based on Lya-punov's direct method for AC/DC buck-boost converter with an APD circuit. The contribution of this paper is to guarantee global stability of the APD circuit based converters. The effectiveness of the proposed method is shown by experiments using a 100 W drive.

A Study of Soft Magnetic Composite Suitable for High Efficiency of an Axial Gap Motor Reviewed

Keisuke Nakamura, Masatsugu Takemoto, Koji Orikawa, Satoshi Ogasawara, Tatsuya Saito, Asako Watanabe, Tomoyuki Ueno

Proceedings - 2018 23rd International Conference on Electrical Machines, ICEM 2018 32 - 38 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

© 2018 IEEE. An axial gap motor using neodymium bonded magnet, which our research group has proposed, achieved high torque density and high efficiency at high torque region in the previous paper. However, further improvement in efficiency is required in a wide operation range including not only high torque region but also low torque region. Hence, this paper discusses soft magnetic composite (SMC) suitable for high efficiency of the proposed axial gap motor. In the SMC, there is a trade-off relationship between low iron loss characteristic and high magnetic permeability. Therefore, at low torque region, the efficiency of the axial gap motor using the SMC was lower than that of the radial gap motor using the electromagnetic steel sheet. The proposed axial gap motor adopts a coreless rotor structure. Thus, it is possible to suppress the torque reduction, because the magnetic circuit of the proposed axial gap motor is hardly affected by the magnetic permeability of the stator core due to the large magnetic reluctance of the coreless rotor. For the proposed axial gap motor, HX3 of the newly material having lower iron loss characteristic than the electromagnetic steel sheet is developed, even though the magnetic permeability decreases. Consequently, improvement of efficiency and high torque are compatible by HX3. In this paper, we show the material properties of HX3 and the experimental results of a prototype machine of the proposed motor using HX3 of the newly material. From the experimental results, we report that the proposed motor can achieve improvement of efficiency around low torque region.

DOI： 10.1109/ICELMACH.2018.8507200

The Examination of Increasing Operation Speed of Consequent Pole Type Axial Gap Motor for Higher Output Power Density Reviewed

Toru Ogawa, Toru Ogawa, Tomohira Takahashi, Masatsugu Takemoto, Satoshi Ogasawara, Hideaki Arita, Akihiro Daikoku

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 2796 - 2801 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

© 2018 IEEJ Industry Application Society. This paper presents an examination of increasing operation speed of consequent pole type axial gap motor to achieve higher output density. Our research group has been developing consequent pole type axial gap motor with field windings for traction motor of electric vehicles. From the point of fuel economy and layout, smaller and lighter traction motor is required. It is profitable to increase operation speed for reducing the size of motor. It is necessary to suppress line to line voltage to achieve high speed operation, and we examined pole-slot combination. Moreover, as rotor's outer diameter of axial gap motor is larger than that of radial gap motor, the strength of rotor should be considered. We studied the adoption of non- magnetic high tensile strength steel for rotor supporting component. Motor design and the result of spin burst test are presented and we confirmed the operation of target maximum speed and output power density can be possible.

DOI： 10.23919/IPEC.2018.8507510

A Study on Reduction Techniques of a Wideband Common-Mode Voltage Produced by a PWM Inverter Reviewed

Shotaro Takahashi, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Michio Tamate

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 3315 - 3322 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

© 2018 IEEJ Industry Application Society. Switching speed of next-generation power devices such as silicon carbide is about ten times faster than those of silicon devices. This aspect may increase the frequency ranges of common-mode (CM) voltage accompanied by switching operations. Meanwhile, operating frequency ranges of noise filters typically limited by parasitic effects and frequency dependencies of magnetic components. Thus, it is difficult to suppress a wideband noise by installing only conventional passive noise filter. This paper studies about the combination of a conventional low-frequency passive filter and a high-frequency passive filter (HF-PF) which consists of a high-frequency magnetic material such as nickel-zinc ferrite. Furthermore, the proposed active CM voltage feedback circuit is applied for improving the performance of the HF-PF. An insertion effect against CM voltage produced by a pulse-width-modulated inverter is evaluated experimentally. Experimental results show that the constructed system effectively reduce CM voltage in the frequency range from 100 kHz to 100 MHz.

DOI： 10.23919/IPEC.2018.8507810

Three-Phase to High-Frequency Single-Phase Matrix Converter : A Frequency Control Suitable for Soft Switching Reviewed

Wataru Kodaka, Satoshi Ogasawara, Koji Orikawa, Masatsugu Takemoto, Takashi Hyodo, Hiroyuki Tokusaki

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 2589 - 2595 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

© 2018 IEEJ Industry Application Society. Insulated AC/DC converters using matrix converters (MCs) have higher efficiency, smaller size, and longer lifespan compared with conventional ones. For downsizing of high-frequency (HF) transformers in these converters, developments of HF output MC control methods are active. It is expected to improve efficiency by applying soft switching techniques for these converters. However, to achieve soft switching, phase difference between an output voltage and a current is required. As a result, output power factor decreases. In this paper, a relationship between soft switching conditions and output power factor is revealed. Considering this relationship, the authors propose a new MC control method to achieve soft switching and maximum output power factor. Additionally, this method enables to suppress the distortion of input currents and reduce ripple of the output current. Also, the MC can control the output current and instantaneous reactive power. The authors confirm that experimental results show validity of the method.

DOI： 10.23919/IPEC.2018.8507605

Development of an SiC High-Frequency PWM Inverter Using a Thick Multilayer PCB to Minimize Stray Inductance Reviewed

Kohsuke Ishikawa, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 2725 - 2731 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

© 2018 IEEJ Industry Application Society. Inverters using SiC or GaN power devices can realize high frequency and high efficiency operation. To achieve high efficiency, the switching characteristics of these power devices are important, because stray inductances in inverter main circuit have strong influence on the switching characteristics. To reduce the switching loss and surge voltage, minimization of stray inductance in the main circuit is required for high-frequency PWM inverter. This paper describes design guidelines for high-frequency inverters that realize low inductance. The PCB design guideline on the thick multilayer PCB is derived from the inductance calculation using 3D-FEA. It is shown experimentally, that the stray inductance of designed PCB can be reduced to the same level as the inductance inside the power devices. Experimental results verify that a prototype can achieve high speed switching and can suppress surge voltage. A load test is demonstrated to evaluate main circuit efficiency in half-bridge inverter at 100 kHz.

DOI： 10.23919/IPEC.2018.8507376

The Examination of Slot and Pole Number Combinations of Consequent-Pole-Type Ferrite PM Axial Gap Motor with DC Field Windings Reviewed

小川徹, 小川徹, 高橋朋平, 竹本真紹, 小笠原悟司, 有田秀哲, 大穀晃裕

電気学会論文誌 D 138-D ( 8 ) 659 - 668 2018.8

Development and Evaluation of an Axial Gap Motor Using Neodymium Bonded Magnet Reviewed

Ren Tsunata, Masatsugu Takemoto, Satoshi Ogasawara, Asako Watanabe, Tomoyuki Ueno, Koji Yamada

IEEE Transactions on Industry Applications 54 ( 1 ) 254 - 262 2018.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers Inc.

In general, radial gap motors employing neodymium sintered permanent magnet (Nd sintered PM) are used to achieve high torque density in many applications. However, the motors are not suited to a flat, disk-like shape because the dead space, such as the coil ends, occupies most of the motor volume. Therefore, axial gap motors are frequently used for flat shape instead of radial gap motors. Nd sintered PM is a well-known high-performance magnet that has high residual magnetic flux density, but eddy current loss easily occurs in the magnet because of its high conductivity. In axial gap motors for industrial applications, it is difficult to take measures against eddy current loss of Nd sintered PM in terms of cost. Therefore, general axial gap motors employing Nd sintered PM often have unsatisfactory characteristics, such as low efficiency, even though the motor produces high torque. On the other hand, radial gap motors can take measures to suppress eddy current in PMs easily if radial gap motors employ interior permanent magnet structure. Accordingly, this paper discusses an axial gap motor employing neodymium bonded permanent magnet (Nd bonded PM) for flat shape. Compared with Nd sintered PM, Nd bonded PM has lower residual magnetic flux density, but also lower cost. In addition, Nd bonded PM has extremely low eddy current loss due to its low conductivity. It is found from three-dimensional finite element analysis and experimental results that the axial gap motor employing Nd bonded PM can achieve higher torque and higher efficiency compared with the radial gap motor employing Nd sintered PM with the same PM weight and a flat shape.

DOI： 10.1109/TIA.2017.2710123

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