Yazar "Fujisaki, Haruka" seçeneğine göre listele

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    A cross-connected charge pump for energy harvesting applications
    (International Journal of Innovative Computing, Information and Control, 2019) Do, Wanglok; Fujisaki, Haruka; Eguchi, Kei
    Energy harvesting is a process of capturing, storing and converting external energy from ambient energy. The energy harvesting systems commonly use a switchedmode power supply (SMPS) to convert energy harvested from the ambient energy. Therefore, the power converter is an essential component in terms of developing efficient energy harvesting systems. Among SMPS, inductor-less converter can be a solution. This paper suggests a new topology of charge pumps by cross-connecting two of them for efficient energy harvesting systems. With the cross-connected structure, the new topology transfers a stepped-up output to the output capacitor and load in all operation periods. This operation way can improve the power efficiency of the proposed charge pump and also decrease the internal resistance and the output capacitor’s capacitance of it. The performance of the proposed charge pump is verified by comparing with two conventional charge pumps, which is based on simulation program with the integrated circuit emphasis (SPICE) simulations and theoretical analysis. Moreover, we demonstrated the feasibility of the proposed one through the experimental circuit built on a breadboard. The proposed charge pump helps develop efficient energy harvesting systems.
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    Design of a cross-connected charge pump for energy harvesting systems
    (IOP Publishing, 2017) Eguchi, Kei; Fujisaki, Haruka; Oota, Ichirou
    For energy harvesting systems, a novel charge pump with cross-connected structure is proposed in this paper. Owing to the cross-connected structure, the proposed charge pump can offer the output voltage to the output load at every phase. Furthermore, the proposed charge pump can reduce the number of circuit stages from the conventional charge pump. For above-mentioned reasons, the proposed charge pump can realize not only smaller internal resistance but also smaller output capacitance than the conventional charge pump. The theoretical analysis and simulation program with integrated circuit emphasis (SPICE) simulation demonstrate that the proposed charge pump outperforms the conventional charge pump in the point of power efficiency and circuit speed.
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    A high voltage gain sc dc-dc converter based on cross-connected fibonacci-type converter
    (IEEE, 2018) Eguchi, Kei; Pongwatd, Sawai; Fujisaki, Haruka
    For energy harvesting systems, this paper presents a high voltage gain switched-capacitor (SC) converter with cross-connected topology. By cross-connecting two Fibonacci-type DC-DC converters, the proposed SC DC-DC converter provides a high stepped-up voltage which is expressed as a power of two. Unlike conventional converters, the stepped-up voltage is generated in all clock phase. Furthermore, the cross-connected structure provides the reduction of internal resistance and output capacitance. Therefore, small size and efficient energy conversion can be achieved by the proposed converter. The characteristics of the proposed converter were investigated by not only SPICE simulations but also theoretical analysis, where the proposed converter demonstrated high performance such as high voltage gain, small size, high power efficiency, and fast response speed.
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    A small dc-ac inverter by using cross-connected charge pumps
    (IJEETC, 2019) Fujisaki, Haruka; Ishibashi, Takaaki; Eguchi, Kei
    This paper introduces a Switched-Capacitor (SC) DC-AC inverter with cross-connected topology. By cross connecting two charge pump DC-DC converters, the proposed SC DC-AC inverter can achieve small size with a grounded input. Moreover, the cross-connected structure provides the reduction of internal resistance. Therefore, not only small size but also efficient energy conversion can be realized by the proposed inverter. The characteristics of the proposed inverter were investigated by theoretical analysis as well as SPICE (simulation program with integrated circuit emphasis) simulations. The proposed inverter demonstrates higher performances, such as small size and high-power efficiency, than traditional SC DC-AC converters.