著者

Shuhei Shimmyo Katsutoku Takeuchi Norio Takahashi Makoto Matsushita Kouhei Ohnishi

出版者

The Institute of Electrical Engineers of Japan

雑誌

IEEJ Journal of Industry Applications (ISSN:21871094)

巻号頁・発行日

vol.5, no.2, pp.69-77, 2016-03-01 (Released:2016-03-01)

参考文献数

18

被引用文献数

4 7

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This paper discusses the suppression of torque ripple using multi-level inverters in motor drives. Because it is possible to improve the output waveforms using multi-level inverters, it is also possible to improve the control performance of motors. In this paper, the multi-level inverters achieve precise motion control, and a theoretical distortion index for multi-level motor drives that takes the control sensitivity into account is proposed. By calculating the distortion index, the optimal equivalent carrier frequency that can minimize torque ripple can be obtained. The validity of the proposed method is confirmed by our experimental results.

著者

Katsutoku Takeuchi Makoto Matsushita Yuichi Tsuboi Naoyuki Amemiya

出版者

The Institute of Electrical Engineers of Japan

雑誌

IEEJ Journal of Industry Applications (ISSN:21871094)

巻号頁・発行日

vol.10, no.5, pp.577-588, 2021-09-01 (Released:2021-09-01)

参考文献数

20

被引用文献数

1

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To perform finite element analysis (FEA) for estimating the characteristics of synchronous machines (SMs), a current condition corresponding to an operating point is necessary as an analysis input. Accurate identification for the current condition is a difficult problem because it is strongly susceptible to magnetic saturation, e.g., the cross-coupling saturation between d- and q-axes. Especially in a wound-field SM, its flexibility makes the identification more complicated; in other words, three independent variables, such as the amplitude and phase of armature current and amplitude of field current, have to be identified for SMs, whereas two variables are required for a permanent magnet SM or synchronous reluctance machine. Thus, numerous researchers have studied construction of the identification method. This paper proposes a novel identification method for the current condition of wound-field SMs using saturation functions defined by the flux maps. It is demonstrated that the proposed method can correctly identify a large number of current conditions in a short computation time. In addition, the influences of magnetic saturation on the characteristics of the SM were investigated by comparing the identification results obtained by the linear and nonlinear FEA. It is revealed that the magnetic saturation drastically affects the current condition and must be considered in the identification methodology.

著者

Anfernee Goon Yuhao Wu Makoto Matsushita Katsuro Inoue

雑誌

ソフトウェアエンジニアリングシンポジウム2016論文集

巻号頁・発行日

vol.2016, pp.255-256, 2016-08-24

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A code clone is a fragment of code which is duplicated throughout the source code of a project and have been shown to make a project less maintainable because all code clones will share potential bugs and problems. This study analyzes the code clone ratios over the entire development lifetime of Git, a widely used open-source project written in C/C++ to understand development habits and the changing maintainability of the software. The study utilizes bash scripting in conjunction with CCFinderX and GitHub to automate the detection of clones across development history. The results showed very stable ratios across development history, with the code clone ratios only fluctuating greatly during the beginning of development mostly, which can imply design choices not being concrete during the beginning of development as well as considerably more functionality being added at the beginning of development relative to the rest of the development cycle. Overall, the clone ratios over the development of Git has given some insight on the different aspects of the development process such as refactoring and how Git handles such aspects. Developers should be able to improve on their approach to development and increase their software’s maintainability by looking at code clone ratios over the version evolution of their own projects.