Research Achievements - Original paper -
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Evaluation of Common-Mode Noise in GNSS-Based Synchronized Parallel-Connected Power Converters with Phase Shift Control
Shotaro Takahashi, Ryosuke Kanbayashi
IEEJ Journal of Industry Applications ( IEEJ ) 14 ( 4 ) 2025.07 [Refereed]
Research paper (journal) Domestic Co-author
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Passive Cancellation of Input and Output Common-Mode Noise in Three-Phase PWM Inverter-Fed Motor Drive Systems
Shotaro Takahashi, Ryosuke Kanbayashi
IEEJ Journal of Industry Applications ( IEEJ ) 14 ( 3 ) 2025.05 [Refereed]
Research paper (journal) Domestic Co-author
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Shotaro Takahashi
Applied Sciences ( MDPI ) 14 ( 3 ) 2024.01 [Refereed]
Research paper (journal) Single author
This article proposes a simulation model of single-phase common-mode inductors to evaluate the small-signal characteristic of common-mode inductors when the stray capacitance cancellation method is applied. From the estimated stray capacitance of common-mode inductors, the value of the cancellation capacitors is determined and implemented into the model. Thus, the proposed model can simulate the small-signal characteristic of common-mode inductors with the capacitance cancellation method at the design stage. To validate the proposed model, a comparison between measured and simulated attenuation characteristics of fabricated single-phase common-mode inductors is performed. The comparison result clarifies that the high-frequency attenuation improvement of the capacitance cancellation method is limited for manganese–zinc ferrite-based common-mode inductors due to the steep change of the complex permeability.
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Shotaro Takahashi
IEEE Access ( IEEE ) 11 134485 - 134494 2023.12 [Refereed]
Research paper (journal) Single author
This article presents a circuit simulation-based design method for common-mode (CM) transformer-less hybrid EMI filters (HEFs) to obtain the required CM current attenuation. First, a simulation-based design method of the HEF, including the passive filtering components, is presented. The prototype HEF is implemented in a DC-fed three-phase motor drive system to validate the design method and evaluate the HEF’s performance. The measured results validate the presented design method and show that the HEF can increase the CM current attenuation of a passive EMI filter (PEF) up to 8.2 dB in the frequency range from 100 kHz to 1.4 MHz. Furthermore, the measured result clarifies that implementing a voltage-sensing parallel-compensating active feedback circuit can reduce the volume of the CMI used in a PEF designed to achieve the same attenuation of the HEF by about 75 %.
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Experimental Study of Radiated Emission Due to Secondary Common-Mode Current in Buck Converters
Shotaro Takahashi
Applied Sciences ( MDPI AG ) 13 ( 21 ) 11735 - 11735 2023.10 [Refereed]
Research paper (journal) Single author
High switching frequency and fast switching speed of wide bandgap power semiconductor device-based power converters may increase radiated emissions more than conventional silicon-power device-based power converters. Based on the background, this article experimentally investigates radiated emission sources in buck converters. The experimental system constructed in this article has two common-mode noise paths, the primary common-mode and the secondary common-mode. First, this article outlines that a secondary common-mode voltage source is caused by a primary common-mode current and an imbalance of power supply side impedances, and the secondary common-mode current path acts as a monopole antenna. The common-mode currents and the radiated emissions are measured in an anechoic chamber when the common-mode inductor for each mode is connected. The measurement results show that the primary common-mode current generates the secondary common-mode noise, and the secondary common-mode noise is the dominant source of radiated emission in the experimental system.
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Shotaro Takahashi
IEEE Access ( Institute of Electrical and Electronics Engineers (IEEE) ) 10 123068 - 123079 2022.11 [Refereed]
Research paper (journal) Single author
Due to their high permeability and high effective permittivity, manganese zinc (MnZn) ferrites exhibit magnetic resonance depending on the core dimension. Once magnetic resonance occurs, the relative permeability of MnZn ferrites decreases drastically in the high-frequency (HF) range. The decrease in the relative permeability can influence the HF noise reduction performance of common-mode inductors (CMIs). Based on the above, this study experimentally investigates the impact of the dimensional effect of MnZn ferrites on the small-signal characteristics of CMIs. First, the CM small-signal characteristics of CMIs with different core dimensions indicated that the dimensional effect of MnZn ferrites decreases the CM impedances of the CMIs in the HF range. Two types of core division (air gap insertion and core lamination) were applied to the core to mitigate the dimensional effect on the CM impedances of the CMIs. The influence of the core divisions on the complex permeabilities and the small-signal characteristics of the CMIs were evaluated based on the experimental results. The measurement results clarified that core lamination might be the appropriate option in EMI filtering applications because it can mitigate the dimensional effect and increase the CM impedance of CMIs in the HF range without increasing the number of turns.
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Attenuation Characteristics of the Input/Output Coupling Passive EMI Filter on Conducted Emission in Motor Drive Systems
Shotaro Takahashi, Sari Maekawa
IEEJ Journal of Industry Applications ( IEEJ ) 11 ( 5 ) 2022.05 [Refereed]
Research paper (journal)
The authors propose an input/output coupling passive electromagnetic interference filter (PEF) for motor drive systems. The input/output coupling PEF uses magnetic coupling and integrates the common-mode inductors connected to the input and output sides of an inverter into a single magnetic component. Hence, this study investigates the attenuation characteristics of the input/output coupling PEF on conducted emission in motor drive systems. The measured results show that the input/output coupling PEF increases the attenuation of conducted emission compared to conventional PEFs over a broad range of frequencies.
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Wideband Small-Signal Model of Common-Mode Inductors Based on Stray Capacitance Estimation Method
Shotaro Takahashi, Sari Maekawa
IEEJ Journal of Industry Applications ( IEEJ ) 11 ( 3 ) 2022.03 [Refereed]
Research paper (journal) Domestic Co-author
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Takahashi Shotaro, Wada Keiji, Ayano Hideki, Ogasawara Satoshi, Shimizu Toshihisa
IEEJ Journal of Industry Applications ( 一般社団法人 電気学会 ) 11 ( 1 ) 7 - 19 2022.01 [Refereed] [Invited]
Research paper (journal) Domestic Co-author
<p>The switching frequency of power converters is continuing to increase with the demand for their increased power density. Therefore, the frequency band of the electromagnetic interference (EMI) generated by power converters ranges from several kilohertz to 100MHz or more, thereby increasing the importance of EMI countermeasures in power converters. In addition, with the practical applications of smart grids and microgrids and the introduction of 5G technology, cases wherein power converters and information communication devices are placed in close proximity are continuing to increase. Thus, in societies wherein power converters and information communication devices are highly integrated, it is necessary to ensure electromagnetic compatibility based on a different concept. This paper presents a review on modeling and suppression techniques for the EMI generated by power converters and discusses future prospects in this field.</p>
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Shotaro Takahashi, Keiji Wada
IEEJ Transactions on Industry Applications ( IEEJ ) 142 ( 1 ) 33 - 40 2022.01 [Refereed]
Research paper (journal) Domestic Co-author
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Experimental Evaluation of the Relationship between Dimensional Dependencies of MnZn Ferrites and Filter Inductor Impedances
Shotaro Takahashi, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Michio Tamate
Electrical Engineering in Japan (Wiley Online Library) 214 ( 2 ) 1 - 10 2021.06 [Refereed]
Research paper (journal) Domestic Co-author
This study investigates the relationship between filter inductor impedance and dimensional resonance of MnZn ferrite. Experimental results clarify that multiple factors affect inductor impedance resonances. These can be classified into three factors: the inherent characteristics of a magnetic material, self-resonance due to winding stray capacitance, and winding that acts as a distributed constant line. Next, based on the measurement results, the dimensional dependencies of complex permeabilities (dimensional resonance) and the influence of dimensional resonance on inductor impedance are discussed in detail. Finally, this study verifies that the influence of dimensional resonance on complex permeability can be mitigated, and filter inductor impedance can be increased in the high frequency range by core lamination. All experiments are performed using off-the-shelf magnetic core products.
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Method for Improving Frequency Characteristic of Common-Mode Inductors Based on Gapped Ferrite Cores
Shotaro Takahashi, Keiji Wada
The IEICE Transactions on Communications (Japanese Edition) J104-B ( 6 ) 442 - 452 2021.06 [Refereed]
Research paper (journal) Domestic Co-author
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Circuit Simulation Model of Single-Phase Common-Mode Inductors Based on the Permeance-Capacitance Analogy
Shotaro Takahashi, Satoshi Ogasawara
IEEJ Transactions on Industry Applications 140 ( 12 ) 911 - 919 2020.12 [Refereed]
Research paper (journal)
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Experimental evaluation of the relationship between dimensional dependencies of MnZn ferrites and filter inductor impedances
Shotaro Takahashi, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Michio Tamate
IEEJ Transactions on Industry Applications 140 ( 6 ) 433 - 441 2020.06 [Refereed]
Research paper (journal)
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A simple technique for estimating the winding stray capacitance of high-frequency three-phase common-mode inductors
Shotaro Takahashi, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Michio Tamate
IEEJ Transactions on Industry Applications 139 ( 3 ) 339 - 347 2019.03 [Refereed]
Research paper (journal)
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Common-Mode Voltage Attenuation of an Active Common-Mode Filter in a Motor Drive System Fed by a PWM Inverter
S. Takahashi, S. Ogasawara, M. Takemoto, K. Orikawa, M. Tamate
IEEE Transactions on Industry Applications ( IEEE ) 55 ( 3 ) 2721 - 2730 2019.01 [Refereed]
Research paper (journal)
The switching speeds of next-generation power semiconductor devices, such as those made of silicon carbide and gallium nitride are roughly ten times those of conventional devices (e.g., silicon insulated-gate bipolar transistors). This increases the frequency range of the electromagnetic noise accompanying the switching operations of pulsewidth modulated (PWM) converters and worsens the influence of radiated noise. The authors have previously proposed an active common-mode filter (ACF) that reduces the radiated noise from the power cables connected to a PWM converter and evaluated its effect in reducing radiated noise by using a function generator as a common-mode (CM) noise source. In this paper, the ACF is applied to a motor drive system fed by a three-phase PWM inverter, and the attenuation characteristics of the CM voltage are evaluated. To avoid saturating the ACF, the combination of an active common-noise canceller and the ACF is discussed. The experimental results show that the system constructed in this paper can suppress the CM voltage produced by the PWM inverter over a wide frequency range from 100 to 100 MHz.
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Proposal of an active common-mode filter capable of reducing radiated EMI from power cables
Shotaro Takahashi, Satoshi Ogasawara, Masatsugu Takemoto, Koji Orikawa, Michio Tamate
IEEJ Transactions on Industry Applications 137 ( 8 ) 639 - 646 2017.08 [Refereed]
Research paper (journal)