Faculty Profiles - TAKEMOTO Masatsugu

Papers - TAKEMOTO Masatsugu

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

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

2016 XXII INTERNATIONAL CONFERENCE ON ELECTRICAL MACHINES (ICEM) 272 - 278 2016

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

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 make measure against eddy current loss of Nd sintered PM in terms of cost. Therefore, general axial gap motors employing Nd sintered PM often have the unsatisfactory characteristics such as low efficiency, even though the motor produces high torque. 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 3D-FEA 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.

An Examination for Improvement of Constant Output Characteristics at High-Speed Region in a Spoke-Type IPMSM using Ferrite Permanent Magnet by Changing the Shape of Rotor Surface Reviewed

Shova Nagano, Masatsugu Takemoto, Satoshi Ogasawara

2016 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 2016

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

In recent years, interior permanent magnet synchronous motors (IPMSMs) using ferrite permanent magnet are being studied for high power density motor application, such as electric vehicles. However, the residual flux density of ferrite magnet is lower than that of rare-earth permanent magnet. Thus, in general, it is difficult for IPMSMs using ferrite magnet to maintain constant high output power in high-speed region. Accordingly, a spoke-type IPMSM using ferrite magnet with specification similar to the currently commercially available IPMSM using rare-earth magnet is examined in this research. Owing to increasing constant output power in high-speed region, analysis with 3D-FEA was conducted and the analysis results show that the constant output characteristics in high-speed region are improved by contriving the shape of the rotor surface. Moreover, experimental results of a prototype of the examined spoke-type IPMSM using ferrite magnet will be presented in this paper.

A Basic Study of a Novel Homopolar-Type Magnetic Bearing Unifying Four C-Shaped Cores for High Output and Low Loss Reviewed

Matsuzaki Tatsuya, Takemoto Masatsugu, Ogasawara Satoshi, Nishihama Kazuo, Kori Daisuke, Nagata Koichiro

IEEE TRANSACTIONS ON MAGNETICS 51 ( 11 ) 2015.11

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

A magnetic bearing (MB) can suspend a rotor shaft with noncontact, so the MB has been used for high-output and high-speed machines. In general, heteropolar-type MB structure is used, because of its simple structure and low cost. However, the heteropolartype MB structure has a problem in terms of rotor iron loss caused by an alternating magnetic field on a rotor core. On the other hand, general homopolar-type MB structure has a low rotor iron loss caused by a dc magnetic field on a rotor core. However, as the general homopolar-type MB has a complicated structure and needs a large magnet for generating the bias flux, it becomes costly. Therefore, this paper discusses a novel homopolar-type MB structure unifying four C-shaped cores for high output and low iron loss. It is shown with three-dimensional finite element analysis that the novel homopolar-type MB has lower iron loss and lower cost than the general homopolar-type MB, which is known for its low iron loss.

DOI： 10.1109/TMAG.2015.2456338

Size and weight reduction of an in-wheel axial-gap motor using ferrite permanent magnets for electric city commuters Reviewed

T. Takahashi, M. Takemoto, S. Ogasawara, W. Hino, K. Takezaki

2015 18th International Conference on Electrical Machines and Systems (ICEMS) 2015.10

Estimation of Stray Capacitance and Permittivity between Compressor Motor Windings and Stator in Operation Reviewed

TANG Yizhanyi, 小笠原悟司, 竹本真紹, 金森正樹, 石田圭一, 遠藤隆久

日本冷凍空調学会論文集 32 ( 3 ) 255 - 261 2015.9

Language：Japanese Publisher：Japan Society of Refrigerating and Air Conditioning Engineers

This paper proposes a method to estimate the stray capacitance between compressor motor windings and stator in operation, and the permittivity of refrigerant and lubricant oil mixture in this area. By applying this method, the complex experiment equipments and sensors are unnecessary. The estimation about the stray capacitance between the motor windings and stator in operation becomes possible according to the equivalent circuit of the inverter air conditioner by analyzing the high frequency leakage current of ground line. Further, the permittivity of refrigerant and lubricant oil mixture can be calculated by comparing the stray capacitance of equivalent circuit in operation with the stray capacitance of the compressor without refrigerant and lubricant oil. It is meaningful to discuss and solve the problem of EMI (electromagnetic interference) noise.

DOI： 10.11322/tjsrae.15-12_OA

Energy Efficiency of SR and IPM Generators for Hybrid Electric Vehicle Reviewed

Urase Katsuhiko, Yabu Noboru, Kiyota Kyohei, Sugimoto Hiroya, Chiba Akira, Takemoto Masatsugu, Ogasawara Satoshi, Hoshi Nobukazu

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS 51 ( 4 ) 2874 - 2883 2015.7

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

A new switched reluctance (SR) generator was designed for possible application in hybrid electric vehicles. The proposed generator was designed to be mostly competitive with the target interior permanent-magnet (IPM) generator currently used in mass-produced hybrid vehicles. The energy efficiencies of the SR and IPM generators were compared in typical driving cycles, such as US06, HWFET, and UDDS modes. We found that the energy efficiency of the SR generator was close to the IPM generator in high-speed driving cycles because the SR generator has no iron loss during the generator idling period due to the fact that it has no PM.

DOI： 10.1109/TIA.2014.2387478

Investigation of Miniaturization and Loss Reduction in a 5‐axis Active Control Type Bearingless Canned Motor Pump Utilizing Passive Magnetic Bearings Reviewed

宮本和弥, 竹本真紹, 小笠原悟司, 平櫛真男

日本AEM学会誌 23 ( 2 ) 250 - 257 2015.6

A basic study of a novel homopolar type magnetic bearing unifying four C-shaped cores for high output and low loss Reviewed

T. Matsuzaki, M. Takemoto, S. Ogasawara, K. Nishihama, D. Kori, K. Nagata

2015 IEEE Magnetics Conference (INTERMAG) 2015.5

Development of a Rare-Earth-Free SR Motor With High Torque Density for Hybrid Vehicles Reviewed

Chiba Akira, Kiyota Kyohei, Hoshi Nobukazu, Takemoto Masatsugu, Ogasawara Satoshi

IEEE TRANSACTIONS ON ENERGY CONVERSION 30 ( 1 ) 175 - 182 2015.3

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

The increased price and the limited supply of rare-earth materials have been recognized as a problem by the international clean energy community. Rare-earth permanent magnets are widely used in electrical motors in hybrid and pure electrical vehicles, which are prized for improving fuel efficiency and reducing carbon dioxide (CO2) emissions. Such motors must have characteristics of high efficiency, compactness, and high torque density, as well as a wide range of operating speeds. So far, these demands have not been achieved without the use of rare-earth permanent magnets. Here, we show that a switched reluctance motor that is competitive with rare-earth permanent-magnet motors can be designed. The developed motor contains no rare-earth permanent magnets, but rather, employs high-silicon steel with low iron loss to improve efficiency. Experiments showed that the developed motor has competitive or better efficiency, torque density, compactness, and range of operating speeds compared with a standard rare-earth permanent-magnet motor. Our results demonstrate how a rare-earth-free motor could be developed to be competitive with rare-earth permanent-magnet motors, for use as a more affordable and sustainable alternative, not only in electric and hybrid vehicles, but also in the wide variety of industrial applications.

DOI： 10.1109/TEC.2014.2343962

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

2015 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 3886 - 3894 2015

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

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 high-speed 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 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.

A Control Method for Three-Phase to High-Frequency Single-Phase Matrix Converter Based on Instantaneous Input Voltages Reviewed

Agnes Hadinata, Satoshi Ogasawara, Masatsugu Takemoto, Takashi Hyodo

2015 IEEE 2ND INTERNATIONAL FUTURE ENERGY ELECTRONICS CONFERENCE (IFEEC) 2015

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

This paper proposes a new control method for three-phase to high-frequency single-phase matrix converter (MC) based on instantaneous input voltages. Direct conversion of AC input power to AC output power by MC resulting in higher conversion efficiency, longer lifespan, and more compact size compared to the conventional method by using PWM rectifier and PWM inverter. The proposed MC can produce high frequency output equal to its power devices' switching frequency. The feature of the proposed control method is its sophisticated calculation based on instantaneous input voltages, producing unity input power factor and regulating the output voltage according to the reference value at any instant. Some simulation and experiment results are shown to prove the validity and effectiveness of the proposed method.

Examination to Make Eddy Current Loss Density Uniform in Divided Nd-Fe-B Magnets of a High Torque Density Motor with Axial-gap Structure Reviewed

Ayato Nihonyanagi, Masatsugu Takemoto, Satoshi Ogasawara, Koji Inoue

2015 IEEE 2ND INTERNATIONAL FUTURE ENERGY ELECTRONICS CONFERENCE (IFEEC) 2015

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

An axial-gap motor with Nd-Fe-B magnets was examined by three-dimensional finite element analysis (3D-FEA) in order to achieve high torque density over 66.8 Nm/L under the constraint of a maximum current density of 12 A/mm(2), and it was confirmed that the examined motor could satisfy these conditions. In this examination, suppressing eddy current loss occurring in these magnets by equally dividing a magnet constituting one pole toward radial direction was attempted. However, 3D-FEA results revealed that the eddy current loss density generated in each magnet which was equally divided was not uniform and had a large bias. So, this paper provides examination to make the eddy current loss density uniform in divided magnets by adjusting split width appropriately.

Examination of an Axial-gap Generator with Ferrite Permanent Magnets Realizing Miniaturization and High Output Power of Engine Generators Reviewed

Ayato Nihonyanagi, Masatsugu Takemoto, Satoshi Ogasawara

2015 IEEE INTERNATIONAL ELECTRIC MACHINES & DRIVES CONFERENCE (IEMDC) 300 - 307 2015

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

In general engine generators, the engine and generator are separate units connected by a mechanical coupling. This tends to increase the package size of general engine generators. In this paper, we are able to achieve miniaturization and high output power of the generator by adopting an axial-gap structure through using ferrite permanent magnets. At the same time, the package size is reduced dramatically by integrating the axial-gap generator into the engine. This paper also discusses methods for reducing the eddy current losses that occur in the windings due to the open-slot structure of the stator core and occur in the rotor support component. By using results from three-dimensional finite element analysis, we show that the eddy current loss that occurs in the windings is reduced by using appropriate methods to wind the coils with rectangular wires. In addition, the eddy current loss that occurs in the rotor support component is decreased by appropriately selecting the material and changing the shape of the component. Experimental results show that the studied structure is effective for realizing miniaturization and high output power of the generator, as well as for decreasing the package size of the engine generator.

Rotor Design of a 150kW 6,000rpm/25,000rpm High speed Induction Motor for Testing Equipment of EV/HEV traction motors Reviewed

Takafumi Nagaoka, Masatsugu Takemoto, Satoshi Ogasawara

2015 18TH INTERNATIONAL CONFERENCE ON ELECTRICAL MACHINES AND SYSTEMS (ICEMS) 163 - 168 2015

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

Recent models of hybrid vehicles and electric vehicles include traction motors with increasing capacity for rotation speed. Therefore, high-speed testing equipment suitable for use with traction motors and motor components is required in automotive research and development. Induction motors (IMs) with oil-cooling are suitable motors for testing equipment. Solutions for some drawbacks of high-speed IMs will be proposed in this paper. Also, several solutions, such as high-tension magnet steel and transitional analysis via finite element modeling, will be introduced. Test reports are shown for rotation speeds of up to 23,000 rpm.

Development of frequency-analysis equipment capable of judging propagation direction of conductive EMI Reviewed

Noriyuki Nosaka, Satoshi Ogasawara, Masatsugu Takemoto, Yoshitaka Iwaji, Kazutoshi Ogawa

2014 IEEE Energy Conversion Congress and Exposition (ECCE) 2014.9

A Novel Magnet Polarity Identification Method for Initial Position Estimation for Sensorless IPMSM Drive Reviewed

Minglei Gu, Satoshi Ogasawara, Masatsugu Takemoto

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 9 ( 4 ) 434 - 441 2014.7

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

This paper proposes a novel magnet polarity identification method for initial position estimation during startup for interior permanent magnet synchronous machine (IPMSM) drives. The rotor's initial position estimation is based on magnetic saliency and employs high-frequency (HF) components of the voltage and current that are excited by the multi space-vector pulse-width modulation (MSVPWM) pattern. However, there is a common trouble in the estimation methods based on the magnetic saliency: it is necessary to identify the magnet polarity in order to distinguish the north and south poles since the estimated position angle is a periodic function with p radians. In this paper, a novel inductance estimation method is presented and the magnet polarity is uniquely identified by the relationship between the estimated inductance and the magnetic saturation effect. Experimental results confirm the advantages of the proposed method: it is reliable, accurate, and convenient, and can be done in real time. (C) 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

DOI： 10.1002/tee.21990

Developments of Ferrite PM In-Wheel Motors with Axial-Gap Structure for Electric City Commuters Reviewed

M. Takemoto, K. Sone, S. Ogasawara, W. Hino, K. Takezaki

the EVTeC 2014 & APE Japan ( 20144075 ) 2014.5

Sensorless IPMSM position estimation based on multi SVPWM with elimination of inverter nonlinear effects Reviewed

Minglei Gu, Satoshi Ogasawara, Masatsugu Takemoto

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 9 ( 2 ) 219 - 227 2014.3

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

This paper presents a position-sensorless interior permanent magnet synchronous motor (IPMSM) control system at low and zero speed based on a multi-space-vector pulse-width modulation (MSVPWM) pattern with the elimination of nonlinear inverter effects. In conventional sensorless methods based on the MSVPWM pattern, the high-frequency (HF) components of voltage and current are used to estimate the rotor position information. However, the inverter nonlinear effects, such as forward voltage drops and deadtime, distort the HF components of the voltage and current so that an error occurs in the position estimation. Therefore, an improved position estimation scheme is developed in this paper. The compensated HF components of the voltage taking account of the inverter nonlinear effects can be used to decrease the estimation error. The proposed method can be implemented without increasing any hardware cost. Experimental results confirm the effectiveness of the proposed method. (c) 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

DOI： 10.1002/tee.21959

Basic Characteristic of A Two-Unit Outer Rotor Type Bearingless Motor with Consequent Pole Permanent Magnet Structure Reviewed

Masatsugu Takemoto

2014 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-HIROSHIMA 2014 - ECCE-ASIA) 1000 - 1005 2014

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

Bearingless motors (BelMs), that can realize shaft suspending without mechanical contacts and lubrication by electromagnetic force, have been proposed. However, in outer rotor type BelMs, one-unit structure with small shaft output alone have been developed. Therefore, this paper introduces a two-unit outer rotor type BelM with consequent-pole permanent magnet structure (CPPM) for high shaft output and the magnetic suspension characteristics of the proposed motor with experimental results. It can be verified that the proposed motor is equipped with the sufficient performance in order to make for practical use.

Examination for the Higher Efficiency in a Ferrite Permanent Magnet 10 kW In-Wheel Axial-Gap Motor with Coreless Rotor Structure Reviewed

Kodai Sone, Masatsugu Takemoto, Satoshi Ogasawara, Kenichi Takezaki, Wataru Hino

2014 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE) 5885 - 5892 2014

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

Powerful rare earth permanent magnets (PMs) are generally utilized in in-wheel PM synchronous motors for electric city commuters. However, the use of rare earth PMs has become undesirable due to high prices. An in-wheel PM synchronous motor that does not employ rare earth PMs therefore needs to be developed. We have previously proposed an in-wheel axial-gap motor that can generate high torque density and has features such as a coreless rotor structure with ferrite PMs and a reduction gearbox inside the stator. Through further research, we confirmed that suppression of eddy current loss arising in the rotor is important for attaining higher efficiency in high output motors. Accordingly, here we introduce an improved rotor with slits which can suppress eddy current loss. The results of experiments on a new prototype show that the improved rotor is effective in producing high efficiency and can satisfy the properties demanded of the in-wheel motors for electric city commuters.

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