IEEJ Transactions on Industry Applications
Online ISSN : 1348-8163
Print ISSN : 0913-6339
ISSN-L : 0913-6339
Volume 139, Issue 7
Displaying 1-24 of 24 articles from this issue
Paper
  • Keita Furukawa, Keisuke Kusaka, Jun-ichi Itoh
    2019 Volume 139 Issue 7 Pages 612-623
    Published: July 01, 2019
    Released on J-STAGE: July 01, 2019
    JOURNAL RESTRICTED ACCESS

    This paper proposes a novel method of improving the overall coupling coefficient of a wireless power transfer system by using a four-winding transformer of which two pairs of windings each are connected in parallel in the primary side and secondary side. By weakening the coupling coefficients kc between the parallel windings, the overall magnetic coupling between the primary side and secondary side of the transformer is improved. In order to confirm the validity of the proposed method, a conventional high-kc four-winding transmission coil and the proposed low-kc four-winding transmission coil are experimentally assessed. Then, the coils are introduced into a non-resonant inductive power transfer system utilizing a dual active bridge converter in order to confirm the correction of the input power factor. As a result, the overall magnetic coupling of the proposed four-winding coils was found to be improved by 17% compared with the overall magnetic coupling of the conventional coil. Moreover, the input power factor for the entire load is corrected with the proposed four-winding coil. Therefore, a low kc is effective in improving the overall magnetic coupling.

    Download PDF (4062K)
  • Atsushi Matsumoto, Makoto Ozaki, Masaru Hasegawa
    2019 Volume 139 Issue 7 Pages 624-630
    Published: July 01, 2019
    Released on J-STAGE: July 01, 2019
    JOURNAL RESTRICTED ACCESS

    This paper proposes a new estimation method for the position and current phase of maximum torque per ampere (MTPA) operations at low-speed based on the “Ld model”, which is a robust mathematical model designed to address magnetic saturation in interior permanent magnet synchronous motors (IPMSMs). In general, sensorless control techniques based on high frequency signal injection can guarantee reasonable torque control performance even at zero speed. The motor parameter variation of most method is robust. However, the MTPA control in those methods requires q-axis inductance that significantly varies owing to magnetic saturation. Therefore, a parameter mismatch may occur that decreases motor efficiency and reduces operation range. As mentioned above, this paper proposes a new position sensorless MTPA control method based on the Ld model.

    Download PDF (1020K)
  • Takanobu Ohno, Nobukazu Hoshi
    2019 Volume 139 Issue 7 Pages 631-636
    Published: July 01, 2019
    Released on J-STAGE: July 01, 2019
    JOURNAL RESTRICTED ACCESS

    A triple active bridge (TAB) DC/DC converter is a multi-port converter that has flexible power flow controls. A TAB converter is capable of bi-directional power transmission, electrical isolation and wide voltage range operation, which are applicable to various equipment. Owing to these characteristics, it has gained popularity as a power converter for an advanced power grid. However, the TAB faces an obstacle in the design of the controller by the nature of 2-input 2-output interference system. As a partial solution to this interference, a novel local decoupling compensator is proposed. To realize stable operation at a wide operating range, it is necessary to estimate the distribution of the interference and the performance of the decoupling compensator in the entire operation range. In this paper, the properties of the interference are measured by conducting experiments on the prototype TAB converter using the interference measurement method, and the effective range of the local decoupling compensator is indicated. Consequently, the validity of the controller design is clarified over a wide operation range.

    Download PDF (6692K)
  • Masamichi Inoue, Shinji Doki
    2019 Volume 139 Issue 7 Pages 637-644
    Published: July 01, 2019
    Released on J-STAGE: July 01, 2019
    JOURNAL RESTRICTED ACCESS

    This paper describes a new discrete-time PMSM model for the discrete design of current vector control systems. The discrete design of current control system minimizes the discretization error and improves the current control performance at the sampling point. The conventional PMSM model discretization method presumes that park transformation runs continuously. When the sampling frequency is considerably lower than the fundamental electric frequency, this assumption is invalid and the control performance will degrade due to modeling error. In this paper, the authors propose a method of PMSM model discretization considering discrete-time park transformation and design an additional cross-coupling compensator for the proposed model. The experimetntation results demonstrate the effectiveness of the proposed model.

    Download PDF (3497K)
  • Shumpei Hayashi, Hiroshi Hashimoto, Takashi Tokuyama, Takuya Matsumoto ...
    2019 Volume 139 Issue 7 Pages 645-651
    Published: July 01, 2019
    Released on J-STAGE: July 01, 2019
    JOURNAL RESTRICTED ACCESS

    In a linear motor which is used in various industrial applications, improvement of thrust density to minimize instrument size is desired. This paper presents a structure to increase the magnetic flux generated from a permanent magnet by three-dimensionally configuring magnetic poles. We constructed an analytical model of a cylindrical-type linear motor with the developed magnetic pole structure and compared the general SPM (Surface Permanent Magnet) structure with the permanent magnet quantity. As a result, the magnetic flux linkage of the developed model increased to about twice that of the comparison model. For this reason, it was confirmed by analyzing that the thrust increases to about twice that of the comparison model by increasing the air gap magnetic flux density without increasing the surface contributing to the generation of the force and the volume of the electric motor.

    Download PDF (1981K)
  • Yuki Hasegawa, Seiya Hiroki, Kuniyuki Motojima
    2019 Volume 139 Issue 7 Pages 652-656
    Published: July 01, 2019
    Released on J-STAGE: July 01, 2019
    JOURNAL RESTRICTED ACCESS

    In large-scale factories or power plants metal tube clogging sometimes leads to serious accidents. However, metal tube testing for the detection of foreign objects requires a long testing time and considerable effort. Therefore, we proposed an original inspection method of a single metallic tube using electromagnetic wave reflection in the tube. However, for branched tubes, it is difficult to estimate the position of the clog by electromagnetic wave reflection. To evaluate the position of clog in the branched tubes, we proposed a new detection method using the group delay time in electromagnetic waves. The group delay time in electromagnetic waves is slightly affected by the bifurcation area. To verify the new method, the group delay time characteristics were measured in the branched tubes. The position of clog could be easily detected by the proposed method.

    Download PDF (1937K)
  • Ryo Haneda, Hirofumi Akagi
    2019 Volume 139 Issue 7 Pages 657-664
    Published: July 01, 2019
    Released on J-STAGE: July 01, 2019
    JOURNAL RESTRICTED ACCESS

    This paper describes the 750-V, 100-kW, 20-kHz bidirectional isolated dual-active-bridge (DAB) dc-dc converter using the latest 1.2-kV, 400-A SiC-MOSFET 4-in-1 modules integrated with SBDs. It focuses on power conversion efficiency and transient characteristics. This dc-dc converter is characterized by being capable of an appropriate switchover between continuous operation and intermittent operation for the purpose of efficiency improvement. The intermittent operation achieves more efficient power conversion for partial loads than does the continuous operation. However, the intermittent operation may cause different upper and lower peak currents in the converter, thus resulting in an increase in the amount of switching loss. This paper introduces an advanced control method for the intermittent operation, which improves the efficiency. Experimental results reveal that the advanced method improves the efficiency from 98.4% in the previous method to 98.6% at 22kW. The efficiency in continuous operation at 100kW is 98.3% in the case of using the previous four 2-in-1 modules without SBD, while it is improved to 98.9% in the case of using the two 4-in-1 modules. Experimental transient characteristics show that no dc magnetic-flux bias occurs even during switchover between continuous and intermittent operation when power reversal from -100kW to 100kW occurs within a time interval of 1ms. Finally, it is verified that the dc-dc converter is capable of providing fast power-reversing performance from -100kW to 100kW within a time interval as short as 25µs.

    Download PDF (3010K)
  • Kenta Konishi, Tadashi Fukami, Masato Koyama, Hiroshi Mitsuda, Masaki ...
    2019 Volume 139 Issue 7 Pages 665-672
    Published: July 01, 2019
    Released on J-STAGE: July 01, 2019
    JOURNAL RESTRICTED ACCESS

    In this paper, the effects of magnetic saturation and d-q axis cross-coupling on the torque characteristics of an electromagnet-assisted ferrite magnet motor (EMaFM) are investigated through finite element analysis (FEA) and experiments. The EMaFM is a new type of motor, which is a combination of a surface permanent magnet synchronous motor (SPMSM) and a flux-modulating synchronous motor (FMSM). A 1.5-kW prototype machine is used for this investigation, and its inductance and torque characteristics are analyzed on the basis of a mathematical model that includes the mutual inductance between the d-axis and q-axis windings. The results show that the FMSM part is more easily affected by the magnetic saturation and d-q axis cross-coupling compared with the SPMSM part.

    Download PDF (2528K)
  • Ryo Kuwana, Daisuke Shinma, Atsushi Fushimi, Hideki Hanami, Isao Hara, ...
    2019 Volume 139 Issue 7 Pages 673-680
    Published: July 01, 2019
    Released on J-STAGE: July 01, 2019
    JOURNAL RESTRICTED ACCESS

    In nuclear power plants, hydrogen accumulation inside the pressure transmitter causes sensor drift. By analyzing the drift factors, we found that the factors contributing to drift were radiolysis of silicone oil as well as hydrogen permeation. We proposed a drift suppression method using palladium, which is a hydrogen occluding material. The effects of suppressing drift were evaluated through hydrogen absorption experiments of palladium (Pd) in the silicone oil. The experimental results in an environment equivalent to 10 years of an actual plant indicated that the amount of drift in the pressure transmitter without Pd was +8.64kPa. Our method using Pd for the pressure transmitter showed that the amount of drift was below the detection limit (+0.01kPa).

    Download PDF (2133K)
News Letter
 
feedback
Top