Yazar "Abe, Hiroto" seçeneğine göre listele

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    Design of a non-thermal food processing system utilizing wire discharge of dual electrodes in underwater
    (International Journal of Innovative Computing, Information and Control, 2018) Eguchi, Kei; Jaiwanglok, Anurak; Julsereewong, Amphawan; Abe, Hiroto; Oota, Ichirou
    To provide nutritious and fresh processed foods, non-thermal food processing technologies have been developed in recent years. Among others, a non-thermal food processing method utilizing underwater shockwaves has cost-effectiveness. In this method, the design of a high voltage multiplier and its discharging method are key factors for processing target foods effectively. This paper proposes a non-thermal food processing system utilizing wire discharge of dual electrodes in underwater. Unlike conventional non-thermal food processing systems, the proposed system has two pairs of electrodes with thin metal wires. Owing to the electric discharge using thin metal wires, the energy to generate underwater shockwaves can be decreased. For this reason, by only one electric discharge, both sides of the target food are crushed by the proposed technique. The experiments using a laboratory prototype clarified that the proposed method can soften the whole flesh of the target food effectively. Furthermore, by assuming a four-terminal model, an equivalent model of the high voltage multiplier was analyzed theoretically. Concerning the series-connected voltage multiplier, the design conditions were derived to estimate the characteristics such as output voltage and power efficiency.
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    Development of a simple direct switched-capacitor ac-ac converter using cascade connection
    (International Journal of Innovative Computing, Information and Control, 2018) Eguchi, Kei; Abe, Hiroto; Ishibashi, Takaaki; Sasaki, Hirofumi
    In this paper, we propose a simple direct AC-AC converter with cascade connection by using switched-capacitor (SC) techniques. The proposed AC-AC converter is synthesized with n (= 1, 2, . . ., N) converter blocks, where each converter block realizing 1/2× step-down conversion consists of only two capacitors and four switches. Unlike conventional SC converters, power conversion of the proposed converter is achieved without a flying capacitor. Hence, the proposed converter can reduce circuit size from the conventional converters. Furthermore, high conversion ratio is realized by connecting these converter blocks in series. In other words, multiple conversion is performed by cascade topology. To evaluate the effectiveness of the proposed converter, we conducted simulation program with integrated circuit emphasis (SPICE) simulations and theoretical analysis concerning power efficiency and input power factor. The evaluation demonstrated that the proposed converter can achieve better performance than the conventional converter using a flying capacitor
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    The development of a step-down switched-capacitor inverter without flying capacitors and full-bridge circuits
    (Elsevier, 2020) Eguchi, Kei; Abe, Hiroto; Ishibashi, Takaaki
    Recently, an inductor-less inverter attracts many researchers’ attention, because the inductor-less design can provide not only small size but also small electromagnetic interference (EMI). In this paper, we propose a novel step-down switched-capacitor (SC) inverter without flying capacitors. Unlike traditional single-phase inverters, the proposed single-phase inverter has the advantages, namely, inductor-less design, downsizing by omitting flying capacitors, no full-bridge circuit, and symmetrical topology. To achieve these features, the proposed SC inverter changes the connection order of series-connected capacitors alternately. By offering a simple circuit configuration, the proposed inverter can achieve not only small EMI but also small size and high power efficiency. Furthermore, by using pulse width modulation (PWM), the proposed inverter generates a sinusoidal output without flying capacitors and full-bridge circuits. The effectiveness of the proposed inverter is justified by comparing the proposed inverter with an existing single-phase SC inverter. The simulation program with integrated circuit emphasis (SPICE) simulations demonstrate that the proposed inverter outperforms the existing SC inverter in the points of power efficiency and component counts. Concretely, about 94% power efficiency can be achieved when the output power is 2kW. Furthermore, the proposed inverter can reduce two flying capacitors from the existing SC inverter.
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    Reduction of inrush current in a shockwave non-thermal food processing system using an exponential clock pulse generator
    (MDPI, 2020) Eguchi, Kei; Asadı, Farzin; Shibata, Akira; Abe, Hiroto; Oota, Ichirou
    Recently, shockwave food processing is drawing much attention as a low-cost non-thermal food process technique. In shockwave non-thermal food processing, underwater shockwaves are generated by a high voltage generator. Therefore, high inrush currents and high voltage stress on circuit components significantly reduce the reliability and life expectancy of the circuit. However, to the best of our knowledge, stress reduction techniques and their experimental verification have not been studied yet in the shockwave non-thermal food processing system. In this paper, we propose a stress reduction technique for the shockwave non-thermal food processing system and investigate the effectiveness of the proposed technique experimentally. To achieve high reliability and life expectancy, a new high voltage multiplier with an exponential clock pulse generator is proposed for the shockwave non-thermal food processing system. By slowing down the rate at which the capacitors charge in the high voltage multiplier, the exponential clock pulse generator significantly reduces the inrush current. Furthermore, to perform shockwave non-thermal food processing continuously at a lower voltage level, we present a new electrode with a reset mechanism for wire electric discharge (WED), where a square-shaped metal wire swings on a hinge in the proposed electrode. The proposed electrode enables not only shockwave generation at a lower voltage level but also continuous non-thermal food processing, because the square-shaped metal wire is not melted in the WED process. To confirm the validity of the proposed techniques, some experiments are performed regarding the laboratory prototype of the shockwave non-thermal food processing system. In the performed experiments, reduction of inrush currents and effective food processing are confirmed.