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Author: search.filters.author.Nitta, Shuichi

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    A current mode analysis on ground leakage current noise generation in unbalanced and balanced switching converters
    (2010-01-01)
    Intachot, Terdsak
    ;
    Chuladaycha, Nontawat
    ;
    Prempraneerach, Yothin
    ;
    Nitta, Shuichi
    This paper presents the new switching converter model used for analyzing the generation mechanism of ringing ground leakage (GL) current, generated during the transient, at switch on/off of any switching converter. By applying the Norton model, the proposed new model of switching converter can be formulated. The ringing GL current is evaluated at the switching on/off of the unbalanced (half-bridge converter) and the balanced converter (full-bridge converter) for bidirectional D.C. motor drive used as an example. It is concluded that the measured and simulated results of the generated GL current agree well with the numerical analysis results, analyzed by the proposed new model of switching converter, in terms of the minimum or maximum peak currents and the ringing frequency. Copyright © 2010 The Institute of Electronics, Information and Communication Engineers.
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    Conductive common-mode noise reduction by system balance improvement on three phase inverter
    (2008-09-19)
    Boonpirom, Nimit
    ;
    Prempraneerach, Yothin
    ;
    Aunchaleevarapan, Kaison
    ;
    Nitta, Shuichi
    This paper aims for the conductive common-mode noise reduction by system balance improvement on three phase inverter. The main objective is to improve the system balance on three phase inverter based on passive balance and active balance for common-mode noise reduction. As a result, the common-mode current which is generated by PWM switching voltage will be cancelled in frame ground. The concept of system balance and equivalent circuit on double-switch converter for three phase inverter is proposed. Furthermore, the experimental results of three phase induction motor drive by three phase inverter, that is both of time domain measuring and spectrum of common-mode noise measuring are employed respectively.
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    A study on the system imbalance of the single-switch converter for the conductive common mode noise reduction
    (2007-01-01)
    Boonpirom, Nimit
    ;
    Prempraneerach, Yothin
    ;
    Paithoonwatanakij, Kitti
    ;
    Aunchaleevarapan, Kraison
    ;
    Nitta, Shuichi
    This paper reduces system imbalance by replacing the single-switch converter with a synchronized double-switch converter based on two active switches technique and hybrid balance technique, including active balance and passive balance for common mode noise reduction. The system balance is experimentally evaluated by the common mode rejection ratio (CMRR). Finally, examples show that the CMRR of the single-switch converter is improved from 1.67 dB to 32.04 dB when the double-converter with two active switches technique is applied and to 41.5 dB when the double-switch converter with hybrid balance technique is applied. Copyright © 2007 The Institute of Electronics, Information and Communication Engineers.
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    Conducted Emission Characteristics of an Active Snubber Boost Converter
    (2003-09-01)
    Tantisukarom, Chaiya
    ;
    Khanngern, Werachet
    ;
    Nitta, Shuichi
    In this paper, the conducted emission characteristics of an active snubber boost converter with proposed timing diagram are investigated and compared with its conventional boost converter. It is illustrated theoretically and experimentally that the soft switching technique can reduce the high switching dv/dt and di/dt rate, as well as the conducted emission noise spectra generated from the hard-switched counterpart effectively. The presented active snubber boost converter shows the line to ground and the neutral to ground conducted emission spectra significantly be improved at high frequency range over the hard-switched operation. © 2003, The Institute of Electrical Engineers of Japan. All rights reserved.
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    Novel method for predicting PCB configurations for near-field and far-field radiated EMI using a neural network
    (2003-01-01)
    Aunchaleevarapan, Kraison
    ;
    Paithoonwatanakij, Kitti
    ;
    Khan-Ngern, Werachet
    ;
    Nitta, Shuichi
    The Neural Network (NN) is applied to recognize basic PCB configurations using its magnetic near-field spectra and radiated far-field emission. The learning process is accomplished by using the computed spectra of the radiated field from PCBs having different configurations. The anomaly is detected through the monitoring of the spectra's amplitude frequency by injecting a voltage pulse at the PCB configuration. The trained NN is then applied to the identification of PCB layouts from radiated emission measurements. The trained NN can identify all of those PCB configurations from the magnetic near-field spectra and the radiated far-field EMI. Moreover, the calculated results of the NN are compared with the actual far-field measurements and other models for evaluation. Finally, the NN used for predicting far-field emission from their magnetic near-field measurement is proposed. Experiments show that the NN can predict the far-field spectra from the magnetic near-field spectra.