Faculty Profiles - TAKEMOTO Masatsugu

Papers - TAKEMOTO Masatsugu

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Investigation of Efficiency Enhancement of an Ultra-High-Speed Bearingless Motor at 100,000 r/min by High Switching Frequency Using SiC-MOSFET Reviewed

Yu Fu, Masatsugu Takemoto, Satoshi Ogasawra, Koji Orikawa

2018 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 2306 - 2313 2018

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

This paper introduces the operational characteristics of an ultra-high-speed bearingless motor with 2-pole concentrated motor windings and 4-pole concentrated suspension windings. Experiments with a prototype machine indicate that iron loss is the largest component of losses in the proposed bearingless motor. Therefore, in order to reduce the iron loss, comparison of the experimental results and the 3D-FEM results is discussed. As a result, because it is turned out that iron loss of the switching frequency component accounts for a large proportion in total iron loss, a method of enhancing efficiency of the proposed bearingless motor by means of high switching frequency using SiC-MOSFET is examined. The experimental results with the examined method show that the prototype machine can attain the high efficiency of 94.3% at rated operation of 1.70 kW and 100,000 r/min in spite of including suspension input power for magnetic levitation. In addition, operational characteristics comparison of the bearingless motor at switching frequency of 40 kHz, 80 kHz and 120 kHz is discussed in detail.

Investigation of Secondary Winding Structure in Multi-Core Transformer in MHz Inverter using Frequency Multiplying Reviewed

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

2018 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 1279 - 1286 2018

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

This paper investigates secondary winding structures in a multi-core transformer in a MHz inverter using a frequency multiplying method at the output frequency of 2.5 MHz which is five times of the switching frequency of 500 kHz. The proposed circuit can generate high output frequency by using a multi-phase inverter with phase shift control and the multi-core transformer while the switching frequency and an operational frequency of the multi-core transformer is lower than the output frequency. Therefore, an iron loss of the multi-core transformer is reduced, which results in high efficiency. In this paper, two prototypes of the multi-core transformers which have different secondary winding structures are made and compared from the view point of a leakage inductance and a parasitic capacitance viewed from the secondary side of the multi-core transformer. As a result, it is confirmed that the effect of the parasitic capacitance viewed from the secondary side of the multi-core transformer to a series resonant capacitor connected to the secondary side of the multi-core transformer in series is reduced to 1/4 compared with a loosely-coupled multi-core transformer by a highly-coupled multi-core transformer.

A Modeling Technique for Designing High-Frequency Three-Phase Common-Mode Inductors Reviewed

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

2018 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 6600 - 6606 2018

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

Switching speed of the next-generation power devices based on the wide-bandgap semiconductors such as silicon carbide and gallium nitride are more than ten times faster than the conventional silicon insulated-gate bipolar transistors. This may increase frequency ranges of electromagnetic noise accompanied by switching operations of power converters. Besides, the operating frequency ranges of noise filters are limited due to frequency dependencies of magnetic materials and parasitic components of passive components, thus, the realization of the high-frequency (HF) noise filter with the operating frequency range beyond several ten megahertz is difficult. This paper presents a modeling technique for estimating the operating frequency range of the HF three-phase common-mode (CM) inductors. The proposed method includes a novel simple estimation technique of winding stray capacitance. The CM impedance measurement results validate that the proposing model can estimate the operating frequency range of the HF three-phase CM inductor while securing practically sufficient precision at the design-stage.

Active Power Decoupling Control of Bridge-less SEPIC using Lyapunov-function based Control Strategy Reviewed

Soonhwan Hwang, Satoshi Ogasawara, Koji Orikawa, Masatsugu Takemoto

2018 IEEE 4TH SOUTHERN POWER ELECTRONICS CONFERENCE (SPEC) 2018

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

This paper proposes a new control strategy for active power decoupling(APD) function of a bridge-less single-ended primary inductance converter(SEPIC). Without additional components, a change of control method would enable the implementation of APD functions, replacing an electrolytic capacitor(E-Cap) with a small film capacitor. The contribution of this paper is to apply a Lyapunov-function based control method to the control system to ensure global stability and reduce the number of sensors and parameters required for control. The effectiveness of the proposed control method is shown by simulations using MATLAB/SIMULINK.

Investigation of a 5-axis active control type magnetic suspension pump capable of generating thrust suspension force in both positive and negative direction with only one electromagnet Reviewed

Ryuhei Okumura, Masatsugu Takemoto, Satoshi Ogasawara, Masao Hiragushi

Proceedings IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society 2017-January 2020 - 2026 2017.12

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

© 2017 IEEE. Magnetic suspension pumps have been attracted attention and actively developed. These pumps can realize magnetic suspension and rotation of a rotor shaft integrated with an impeller without mechanical contact. There is now a need to develop a magnetic suspension pump that is capable of 5-axis active control while retaining a small size and low power output. However, conventional structures capable of 5-axis active control are not suited to such requirements. This paper introduces a novel structure of a 5-axis active control type magnetic suspension pump for small size and low power output. The proposed structure reduces pump size by eliminating a dedicated rotor component for a thrust magnetic bearing and generating thrust suspension force in both the positive and negative axial directions with a single electromagnet. 3D-FEM analysis and experiment demonstrate that the proposed structure satisfies requirements for magnetic suspension pump applications.

DOI： 10.1109/IECON.2017.8216340

Operational Characteristics of an IPM-Type Bearingless Motor With 2-Pole Motor Windings and 4-Pole Suspension Windings Reviewed

Tatsuya Matsuzaki, Masatsugu Takemoto, Satoshi Ogasawara, Satoru Ota, Kazunobu Oi, Daiki Matsuhashi

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS 53 ( 6 ) 5383 - 5392 2017.11

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

A bearingless motor (BelM) integrates the characteristics of an electric motor and a magnetic bearing. Typically, a surface-mounted permanent magnet (SPM)-type BelM with a ring magnet magnetized in parallel is employed for high-speed operation. It is noteworthy that a carbon fiber bandage is needed to fix the ring magnet. However, when an SPM-type BelM is applied to a high-output motor, it becomes difficult to generate sufficient suspension force because of the wide magnetic gap arising from the carbon fiber bandage and the ring magnet. In addition, the manufacturing cost for the large-scale ring magnet and the carbon fiber bandage is high. Therefore, to realize a high-output and highspeed BelM at a low cost, we have focused on an interior permanent magnet (IPM)-type BelM with 2-pole motor windings and 4-pole suspension windings. Moreover, a rotor structure for suppressing suspension force ripple arising in the IPM-type BelM has been proposed based on a three-dimensional finite element analysis. In this study, a prototype of the IPM-type BelM with the proposed rotor structure is produced. Experiments with this prototype show that the proposed rotor structure is effective in reducing suspension-force ripple. Additionally, the operational characteristics of the prototype are shown in detail.

DOI： 10.1109/TIA.2017.2746668

Proposal of an Active Common-Mode Filter Capable of Reducing Radiated EMI from Power Cables Reviewed

高橋翔太郎, 小笠原悟司, 竹本真紹, 折川幸司, 玉手道雄

電気学会論文誌 D 137-D ( 8 ) 639 - 646 2017.8

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

S. Takahashi, S. Ogasawara, M. Takemoto, K. Orikawa, M. Tamate

2017 20th International Conference on Electrical Machines and Systems (ICEMS) 2017.8

Size and Weight Reduction of an In-Wheel Axial-Gap Motor Using Ferrite Permanent Magnets for Electric Commuter Cars Reviewed

Tomohira Takahashi, Masatsugu Takemoto, Satoshi Ogasawara, Wataru Hino, Kenichi Takezaki

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS 53 ( 4 ) 3927 - 3935 2017.7

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

In-wheel type permanent-magnet synchronous motors for electric commuter cars are required to be compact and light to use limited wheel space effectively and reduce unspringing weight. Therefore, our previous papers presented a low-cost in-wheel axial-gap motor that uses ferrite permanent magnets. This motor adopted an open slot structure to reduce production costs. However, to achieve further size and weight reduction, we examine here in detail the adoption of a semiclosed slot structure instead of an open slot structure. Experimental results show that the semiclosed slot structure is effective in realizing size and weight reduction.

DOI： 10.1109/TIA.2017.2684739

An active common-mode filter for reducing radiated noise from power cables Reviewed

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

2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia (IFEEC 2017 - ECCE Asia) 2017.6

Investigation of Enhancing Efficiency and Acceleration in a Flat Shape Axial Gap Motor Having High Torque Characteristic Reviewed

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

2017 IEEE INTERNATIONAL CONFERENCE ON MECHATRONICS (ICM) 278 - 283 2017

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

In recent years, flat shape motors are desired for many industrial applications such as robot arm, automobiles and so on. Thus, this paper discusses axial gap motors which have advantage for flat shape. In general, axial gap motors have high torque density with flat shape because of its wide air-gap area. Axial gap motors are therefore used for limited space like disk shape instead of radial gap motors which are the most general motor. However, compared with radial gap motors, the acceleration of axial gap motors is relatively lower because of the larger moment of inertia. In this paper, rotor structure to enhance the acceleration of axial gap motors is proposed and analyzed by 3D-FEA. In addition, material for permanent magnet of axial gap motors is properly selected in order to enhance efficiency at high speed and high torque area. Finally, prototypes of both axial and radial gap motor with flat shape are evaluated by some experiments. It is found that proposed axial gap motor can achieve the higher torque and efficiency compared with the radial gap motor with flat shape. Proposed axial gap motor additionally achieved the slightly larger acceleration compared with the radial gap motor.

A Novel Active Common-Noise Canceler Combining Feedforward and Feedback Control

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

2017 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 2469 - 2475 2017

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

This paper proposes a novel type of an active common noise canceler (ACC) combining feedforward and feedback control. The ACC attenuates the common-mode (CM) voltage and suppresses EMI emissions by adding the CM voltage of reverse polarity to the CM voltage generated by inverters in AC motor drive system. The proposed ACC uses feedforward and feedback control whereas the original ACC [19] uses feedforward control only. Experimental evaluation is presented for comparison between the proposed ACC, a feedforward ACC, and common mode chokes (CMCs) which are widely used as passive filters. The experimental results show that the proposed ACC has large CM voltage attenuation of up to 50 dB in the wide frequency range. The attenuation performance of the proposed ACC is larger than the feedforward ACC and a CMC, which uses the same ferrite core and windings used in the proposed ACC.

Investigation of a High Speed and High Power Density Bearingless Motor with Neodymium Bonded Magnet Reviewed

Yu Fu, Masatsugu Takemoto, Satoshi Ogasawara, Koji Orikawa

2017 IEEE INTERNATIONAL ELECTRIC MACHINES AND DRIVES CONFERENCE (IEMDC) 2017

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

Bearingless motors (BelMs), which can realize magnetic levitation rotation with no mechanical contact, have been proposed and developed. In general, in high speed and high output BelMs, distributed winding structure is adopted in order to suppress iron loss, and neodymium sintered permanent magnet (Nd sintered PM) is employed to achieve a high power density. However, output power fall is caused due to long coil end of the distributed winding structure because a shaft length is limited by primary bending mode under high speed rotation. Furthermore, eddy current loss easily occurs in the Nd sintered PM because of its high conductivity. It is difficult to achieve continuous highspeed and high-output operation due to the temperature raising in a rotor. Therefore, in this paper, a high speed and high power density BelM using concentrated winding stator and neodymium bonded permanent magnet (Nd bonded PM) is proposed in order to suppress output power reduction caused by the coil end and eddy current loss generated in PM. In addition, this paper indicates analysis results of various BelM models using distributed winding structure, concentrated winding structure, Nd sintered PM, and Nd bonded PM, respectively. Comparison of these results is discussed in detail and effectiveness of the proposed structure is clarified.

The Examination of Pole Geometry of Consequent Pole Type Ferrite PM Axial Gap Motor with Field Winding Reviewed

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

2017 IEEE INTERNATIONAL ELECTRIC MACHINES AND DRIVES CONFERENCE (IEMDC) 2017

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

This paper presents the examination of consequent pole type ferrite PM axial gap motor with field winding. Especially the configuration of magnet and rotor core is analyzed with equivalent magnetic circuit and 3D FEA. The prototype was assembled and the comparison between test result and analysis is also provided. It is confirmed that high torque and efficiency characteristic is achieved when the width of magnet and rotor core are 21 deg. and 15 deg. (mechanical angle) respectively.

2017 IEE-Japan industry applications society conference

Satoshi Ogasawara, Masatsugu Takemoto, Satoshi Komada

IEEJ Transactions on Industry Applications 137 ( 7 ) 2017

Novel PWM Schemes With Multi SVPWM of Sensorless IPMSM Drives for Reducing Current Ripple Reviewed

Minglei Gu, Satoshi Ogasawara, Masatsugu Takemoto

IEEE TRANSACTIONS ON POWER ELECTRONICS 31 ( 9 ) 6461 - 6475 2016.9

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

This paper proposes novel pulsewidth modulation (PWM) schemes for multi-space-vector pulsewidth modulation (MSVPWM), which is used in position sensorless control of interior permanent-magnet synchronous motor drives. The estimation of the rotor position is based on magnetic saliency and employs high-frequency components of voltage and current, which are excited by MSVPWM. The difference between the instantaneously applied voltage vector and the reference voltage vector causes current ripple. Since six or four voltage vectors are generated during a PWM period, the sequences of the error voltage vectors lead to different types of current ripples. In this paper, the proposed MSVPWM schemes employ six sequences for zero-/low-speed operation and 24 sequences for high-speed operation to reduce line current ripple. Experimental results confirm that the proposed MSVPWM schemes lead to significant reduction in harmonic current while maintaining high performance of sensorless estimation.

DOI： 10.1109/TPEL.2015.2500364

Novel Structure of Three-Axis Active-Control-Type Magnetic Bearing for Reducing Rotor Iron Loss Reviewed

Tatsuya Matsuzaki, Masatsugu Takemoto, Satoshi Ogasawara, Satoru Ota, Kazunobu Oi, Daiki Matsuhashi

IEEE TRANSACTIONS ON MAGNETICS 52 ( 7 ) 8105404 2016.7

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

Magnetic bearings (MBs) are useful for suspending the rotor shaft of a high-speed, high-output motor because they can do so without mechanical contact. In [2], we have proposed a three-axis active-control-type MB (3-axis AMB) with a cylindrical rotor whose diameter is equal to that of the rotor of a radial MB (RMB) or a motor. The proposed 3-axis AMB integrates an RMB and a thrust MB in one unit. However, the assembly of the conventional 3-axis AMB is complex, and the rotor iron loss is large. Thus, in order to simplify the assembly of the 3-axis AMB and to reduce rotor iron loss, this paper discusses a novel structure for the 3-axis AMB in which small auxiliary permanent magnets (PMs) are inserted in the radial winding slots. The suspension force and the rotor iron loss of the proposed device are evaluated by 3-D finite-element analysis in comparison with a 3-axis AMB without small auxiliary PMs.

DOI： 10.1109/TMAG.2016.2514604

Parameter identification of simplified common-mode equivalent circuit for inverter-fed motor drive systems by applying computer-aided optimization software Reviewed

Yizhanyi Tang, Satoshi Ogasawara, Masatsugu Takemoto, Tsuyoshi Tokiwa, Masaki Kanamori

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 11 ( 2 ) 243 - 249 2016.3

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

This paper deals with common-mode (CM) electromagnetic interference (EMI) in an inverter-fed motor drive system. A simplified CM equivalent circuit including -type equivalent circuit for the motor winding is proposed by using the waveform of the common-mode current flowing in the ground conductor. Moreover, a parameter identification method applying the computer-aided software modeFRONTIER is proposed to decide objectively the circuit parameters of the proposed simplified equivalent circuit. Validity and effectiveness of the proposed equivalent circuit are confirmed by comparing the measured impedance characteristics with the calculated ones. Finally, the possibility of a nonlinear phenomenon is discussed in this system. It is shown that the accuracy of simulation result can be improved by introducing the nonlinear element. (c) 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

DOI： 10.1002/tee.22212

A novel method for making a 2D-FEA model considering three-dimensional effect equivalently in analysis of switched reluctance motors Reviewed

Kazuki Makimura, Masatsugu Takemoto, Satoshi Ogasawara

IEEJ Transactions on Industry Applications 136 ( 2 ) 100 - 109 2016

Language：Japanese Publisher：Institute of Electrical Engineers of Japan

In the analysis of switched reluctance motors (SRMs), the analytical error of 2D FEA caused by the magnetic flux change in the direction of the axis, which is not considered in 2D FEA, is a serious problem. In this paper, a novel method for making a 2D-FEA model of an SRM, which can equivalently consider the influence of the threedimensional effect, is proposed. A 2D-FEA model of an SRM can be easily made by adjusting only the shape of two regions in a rotor by employing the proposed method. The optimum values of two parameters, defined in this paper for adjusting the shapes of the rotor with the proposed method, are easily extrapolated. A comparison of the experimental results with 2D FEA using the proposed method confirms that the proposed method is effective in considering the three-dimensional effect.

DOI： 10.1541/ieejias.136.100

Examination to Enhance Efficiency of V-shaped IPMSM Using Concentrated Winding Structure at High Speed and High Torque Area Reviewed

Ayato Nihonyanagi, Masatsugu Takemoto, Satoshi Ogasawara, Naohiko Aoki, Kwansu Lee

2016 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 2016

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

IPMSMs used for industrial applications generally require high efficiency operation in a certain operating point or area in addition to constant torque operation. In this research, the examined motor demands high efficiency operation at high speed and high torque area. In this case, the current phase angle is small and it is difficult to use reluctance torque effectively. Furthermore, concentrated winding structure has been adopted to cut manufacturing cost and to use limited space effectively. In general, IPMSMs using concentrated winding structure have a difficulty of generating reluctance torque from the perspective of getting q-axis armature reaction magnetic flux. In this paper, to enhance the efficiency of V-shaped IPMSM using concentrated winding structure at high speed and high torque area, the rotor structures which effectively use permanent magnet torque have been examined. Analysis result of 2D-FEA shows that the examined rotor structure, which arranges disproportional gap and large flux barrier on the q-axis magnetic flux path, can enhance the efficiency at high speed and high torque by suppressing the q-axis magnetic flux and by concentrating the field magnetic flux of PMs on the d-axis.

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