Faculty Profiles - DOKI, Shinji

Presentations -

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A Current Harmonic Minimum PWM for Three-Level Converters Aiming at the Low-Frequency Fluctuation Minimum of Neutral-Point Potential International conference

Guan Bo, Doki Shinji

IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS 2019.5

High-performance V/f control of PMSM using state feedback control based on n-t coordinate system

Matsuki Yosuke, Doki Shinji

ELECTRICAL ENGINEERING IN JAPAN 2019.3

Optimal Two Degrees-of-Freedom Based Neutral Point Potential Control for Three-Level Neutral Point Clamped Converters International conference

Guan Bo, Doki Shinji

JOURNAL OF POWER ELECTRONICS 2019.1

Efficiency Improvement of Motor Drive System by using a GaN Three Phase Inverter International conference

Nakayama, Y; Kanazawa, Y; Kondo, F; Inoue, M; Ohta, K; Doki, S; Shiozaki, K

2019 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT) 2019 Proceedings of the IEEE International Conference on Industrial Technology

Event date： 2019

Language：English Presentation type：Oral presentation (general)

This paper shows the effectiveness for employing the GaN-FET inverter for operating the traction motor of a compact Electric Vehicle. Utilizing GaN-FET inverter can not only reduce the conduction loss, but also reduce the switching loss. Therefore GaN-FET inverter can operate motors in higher switching frequency compared with Si-IGBT inverters. It is effective to increase the switching frequency of the inverter to improve the motor efficiency because harmonic iron losses can be reduced dramatically by increasing the switching frequency, but the inverter loss becomes relatively large when the switching frequency is set too high. Therefore, optimized switching frequency should be obtained to maximize the total efficiency of the motor drive system. Experiments are carried out to compare efficiencies of motor drive system with Si-IGBT/GaN-FET inverter in several switching frequencies. Optimization of the switching frequency for maximizing the total efficiency is demonstrated to make effective use of the GaN-FET inverter in the motor drive system.

DOI： 10.1109/ICIT.2019.8755018

Scopus

Analysis and Evaluation of Current Control System of PMSM with Time-Delay to Improve Parallelization for Implementation on Multi-core Precessors International conference

Kim, J; Seiya, K; Edahiro, M; Doki, S

2019 22ND INTERNATIONAL CONFERENCE ON ELECTRICAL MACHINES AND SYSTEMS (ICEMS 2019) 2019

Control System Based on Contact Force Distribution for Wearable Robot with Tactile Sensor International conference

Ito, D; Funabora, Y; Doki, S; Doki, K

2019 IEEE/SICE INTERNATIONAL SYMPOSIUM ON SYSTEM INTEGRATION (SII) 2019 Proceedings of the 2019 IEEE/SICE International Symposium on System Integration, SII 2019

Event date： 2019

Language：English Presentation type：Oral presentation (general)

To improve safety of wearable assist robots, the authors verified the control system based on contact force distribution with an actual robot. Because wearable assist robots contact a user and apply force directly, ensuring safety of the user is most important. In order to improve safety from the aspect of control, the contact force distribution feedback control system has been researched. The system controls contact force between a user and a robot directly. Although the system validated in principal with a simple robot model on simulation, validation with an actual robot has not done yet. In this paper, the authors describe validation of the control system based on contact force distribution with an actual robot. It is evaluated on experiments used the actual robot for arm in comparison with the conventional control system based on joint torque.

DOI： 10.1109/sii.2019.8700383

Scopus

Comparison of Two Types of Extended Electromotive Force Models in Middle / High Speed Ranges Position Sensorless Control International conference

Ohta, K; Nimura, T; Doki, S

2019 21ST EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE '19 ECCE EUROPE) 2019

Quantification of Contributing Degree to Braking Operation of Driver based on the Hidden Markov Model International conference

Hashimoto, K; Miyosawa, T; Yamada, T; Tsuchiya, T; Doki, K; Doki, S

2019 IEEE 28TH INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS (ISIE) 2019

Position Sensorless Control of Synchronous Reluctance Motors at Low-Speeds International conference

Hatanaka, T; Kato, S; Tomita, M; Hasegawa, M; Doki, S; Kato, S

2019 IEEE 4TH INTERNATIONAL FUTURE ENERGY ELECTRONICS CONFERENCE (IFEEC) 2019 2019 IEEE 4th International Future Energy Electronics Conference, IFEEC 2019

Event date： 2019

Language：English Presentation type：Oral presentation (general)

Synchronous reluctance motors (SynRMs) have attracted much attention because they do not require magnets. Position sensorless control of SynRMs at low speeds is necessary, and several methods have been proposed in this regard. A new position sensorless control method for SynRMs operating in the very low-speed region is proposed. This approach superimposes a high-frequency current with a small and constant amplitude and a constant frequency to the torque current for driving the SynRMs, by using a high-frequency current control system. It has been shown that robust position sensorless control against inductance variations can be realized using this proposed method. In the position sensorless control method based on a superimposing signal, the current should be small. Therefore, in this paper, the capability of the presented approach to achieve a minimum constant amplitude of the high-frequency current is investigated. The experimental results indicate that the proposed method is a feasible one as position sensorless control of SynRMs in very-low speed region even if the superimposed current has a minimum constant amplitude.

DOI： 10.1109/ifeec47410.2019.9014679

Scopus

Position Sensorless Control of IPMSM in Overall Speed Range by Extended EMF International conference

Nimura, T; Doki, S

2019 21ST EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE '19 ECCE EUROPE) 2019

Markerless Measurement System of Body Surface Deformation for Structure Determination of Wearable Robot International conference

Honda, S; Funabora, Y; Doki, S; Doki, K

2019 IEEE/SICE INTERNATIONAL SYMPOSIUM ON SYSTEM INTEGRATION (SII) 2019 Proceedings of the 2019 IEEE/SICE International Symposium on System Integration, SII 2019

Event date： 2019

Language：English Presentation type：Oral presentation (general)

The authors aim to realize a wearable robot that supports the motion of entire torso. The first task to realize the robot is to determine its structure suitable for motion support. Focusing on the body surface where the robot makes direct contact, we examine the robot structure that can follow the deformation of the body surface. In order to clarify the robot structure, it is necessary to measure the deformation of the body surface. However, with the existing measurement method of body surface deformation using markers, the robot structure can not be clarified. Hence, we have studied a new system to measure the deformation of the body surface without using any markers. In this system, the body surface shape is obtained as time-series point cloud data. After that, the body surface (point cloud data) is divided into multiple local areas, and the time-series correspondence of each local area is clarified. Finally, the deformation is measured by tracking each local area. In this paper, the details of the system are described, and the measurement accuracy of the system is discussed. Furthermore, we quantitatively clarify how the body surface of the torso deforms at the time of forward bending by using the system.

DOI： 10.1109/sii.2019.8700351

Scopus

Sensor Fail-Safe of PMSM Current Control System By Utilizing Current And Position State Estimation Techniques International conference

Hori, S; Doki, S

2019 22ND INTERNATIONAL CONFERENCE ON ELECTRICAL MACHINES AND SYSTEMS (ICEMS 2019) 2019

Pole Assignment of Full-Order Flux Observer to Realize Both MTPA Control and Position Sensorless Control of IPMSM International conference

Kato, S; Hatanaka, T; Tomita, M; Matsumoto, A; Hasegawa, M; Doki, S

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

Analysis and Evaluation of Current Control System of PMSM with Time-Delay to Improve Parallelization for Implementation on Multi-core Precessors International conference

Kim, J; Seiya, K; Edahiro, M; Doki, S

2019 22ND INTERNATIONAL CONFERENCE ON ELECTRICAL MACHINES AND SYSTEMS (ICEMS 2019) 2019

A Robust Neutral Point Potential Control for Single Phase Three Level Rectifier based on The Multiple Degree of Freedom International conference

Guan, B; Doki, S

2018 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT) 2018 Proceedings of the IEEE International Conference on Industrial Technology

Event date： 2018

Language：English Presentation type：Oral presentation (general)

For single phase three level neutral point clamped (TL-NPC) rectifier, if the two DC-link capacitors are linked to two different loads respectively or a TL-NPC inverter, the neutral point potential (NPP) problem would be serious. It is rarely discussed at present, although some NPP control methods based on zero-sequence voltage injection have been raised, which does not deal with the asymmetrical loads in DC-side. Actually, if one phase voltage reaches to the maximum, the other one will go to the minimum. At this operation condition, the NPP control ability is limited, since there are few zero sequence voltage to choose. In this paper, a robust NPP control based on multiple degree of freedom (DOF) is proposed. Not only the zero sequence voltage, another two DOF are defined and utilized to control the NPP. As a result, the NPP control ability can be remarkably enhanced to deal with the NPP problem under some strong asymmetrical loads. The comparisons on the control domain of neutral point current for the traditional NPP control and proposed way are done firstly. Then, the simulation results are also given to verify the correctness and feasibility of proposed method.

DOI： 10.1109/ICIT.2018.8352247

Scopus

Analysis of an Application of the Extended Electromotive Force Model Based Position Sensorless Control on the Wound-Field Synchronous Motor with Dual-Three Phases in Standstill/Low Speed Region International conference

Wang, S; Imai, K; Doki, S

IECON 2018 - 44TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY 2018

EEMFs Excited by Signal Injection for Position Sensorless Control of PMSMs and Their Performance Comparison by Using Imaginary Electromotive Force International conference

Nimura, T; Kondo, S; Doki, S; Tomita, M

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) 2018

Position Sensorless Control for Wound-Field Synchronous Motor with Double Three-phase Wound Stator Using Extended Electromotive Force Model International conference

Imai, K; Doki, S; Fujii, K; Jung, S

2018 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT) 2018 Proceedings of the IEEE International Conference on Industrial Technology

Event date： 2018

Language：English Presentation type：Oral presentation (general)

In this paper, a position sensorless control method for the Wound-Field Synchronous Motor with Double Three-phase wound stator(D-WFSM) in middle or high speed driving is proposed. Extended electromotive force observer used commonly for PMSMs is selected for the target motor's position sensorless control method. However, the method is mainly used for motors with single-set stator and that for motors with two-set stator has not been applied. This is the first time to apply the position sensorless method based on extended electromotive force into WFSMs and two-set motors. Therefore, in this paper, a new extended electromotive force model for two-set motors is proposed. Then, the effectiveness of the proposed method is verified through experiments.

DOI： 10.1109/ICIT.2018.8352226

Scopus

Maximum Torque Control Reference Frame Based on a Torque Map for IPMSMs with Large Inductance Variation International conference

Ohta, K; Ohnuma, T; Doki, S

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) 2018

Majority Rule Sensor Fusion System with Particle Filter for Robust Robot Localization International conference

Ohashi, N; Funabora, Y; Doki, S; Doki, K

2018 IEEE/ASME INTERNATIONAL CONFERENCE ON ADVANCED INTELLIGENT MECHATRONICS (AIM) 2018

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Presentations -