Yazar "Nakashima, Daigo" seçeneğine göre listele

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    Design of a multi-input single-output step-up ac/dc converter with bipolar structure
    (Elsevier, 2020) Eguchi, Kei; Nakashima, Daigo; Shibata, Akira
    For vibration energy harvesting, we propose a multiple-input single-output (MISO) step-up ac/dc converter with bipolar structure in this paper. Unlike existing ac/dc converters for vibration energy harvesting, the proposed ac/dc converter features a bipolar MISO topology that transforms several vibration inputs to provide a step-up voltage. Furthermore, the proposed topology enables inductor-less designs. To clarify the effectiveness of the proposed converter, some computer simulations as well as breadboard-based experimental tests are performed. In the performed simulations, the voltage gain of the proposed converter with 2 modules reaches about 3.5 at 20mW and the power efficiency is about 92% at 20mW when the ac input is 3.5V at 50Hz. Furthermore, the physical feasibility of the proposed topology is proved by the breadboard-based experimental tests.
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    A Stacked cockcroft-walton high voltage multiplier for 220 V at 50 Hz inputs
    (IEEE, 2021) Eguchi, Kei; Nakashima, Daigo; Do, Wanglok
    For non-thermal food processing utilizing underwater shockwaves, this paper presents a stacked Cockcroft-Walton voltage multiplier (CWVM). By converting 220 V ac and 50 Hz inputs, the proposed multiplier generates more than 3.5 kV dc output. To generate 3.5 kV at high speed, conventional multipliers connect some voltage multipliers in series. Hence, the conventional multipliers suffer from high voltage stress on circuit components. To solve this problem, we design a novel high voltage multiplier by employing stack topology. By stacking CWVMs, the proposed multiplier can achieve high voltage gains with low voltage stress. The characteristics of the proposed multiplier are demonstrated by theoretical analysis and simulation program with integrated circuit emphasis (SPICE) simulations. The SPICE simulations demonstrated that the proposed multiplier can achieve high gains as well as high speed operation and low voltage stress.
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    A Stacked Cockcroft-Walton High Voltage Multiplier for 220 V at 50 Hz Inputs
    (Ieee, 2021) Eguchi, Kei; Nakashima, Daigo; Do, Wanglok; Asadi, Farzin
    For non-thermal food processing utilizing underwater shockwaves, this paper presents a stacked Cockcroft-Walton voltage multiplier (CWVM). By converting 220 V ac and 50 Hz inputs, the proposed multiplier generates more than 3.5 kV dc output. To generate 3.5 kV at high speed, conventional multipliers connect some voltage multipliers in series. Hence, the conventional multipliers suffer from high voltage stress on circuit components. To solve this problem, we design a novel high voltage multiplier by employing stack topology. By stacking CWVMs, the proposed multiplier can achieve high voltage gains with low voltage stress. The characteristics of the proposed multiplier are demonstrated by theoretical analysis and simulation program with integrated circuit emphasis (SPICE) simulations. The SPICE simulations demonstrated that the proposed multiplier can achieve high gains as well as high speed operation and low voltage stress.
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    Thermoelectric energy harvesting using a single inductor DC/DC converter employing a negative Dickson multiplier
    (Elsevier, 2021) Eguchi, Kei; Nakashima, Daigo; Do, Wanglok; İshibashi, Takaaki; Asadi, Farzin
    Thermoelectric energy harvesting is the concept to convert thermal energies in an electric power. For the thermoelectric energy harvesting, a single inductor dc/dc converter using a negative Dickson multiplier is presented in this research. By merging a negative Dickson multiplier into a buck-boost converter, high voltage gain, flexible output tuning, and small power loss are attained by the proposed topology. Moreover, fewer number of switch drivers and simpler switching control are achieved than conventional hybrid boost converters, because the proposed converter with a single inductor has only one transistor switch. Through theoretical analysis, a characteristic investigation is performed regarding an example of the proposed converter with 6 diodes, 6 capacitors, a MOS-switch and an inductor, where simple formulas to clarify the converter characteristics are derived by utilizing a four-port model. Furthermore, we justify the efficacy of the proposed topology by performing the comparison among hybrid dc/dc converters with a single inductor, namely, the hybrid converter using a voltage doubler and the hybrid converter using a Cockcroft–Walton multiplier. In the comparison, computer simulations using a SPICE simulator reveal that the proposed converter achieve the best performance the compared converters. Specifically, the efficiency of the proposed converter with three multiplier stages reaches about 84% when the voltage gain is 6 and the output power is 2 W. Furthermore, some experiments verify the possibility of realization by assembling the proposed converter with three multiplier stages on a printed circuit board (PCB). In laboratory tests, maximum power efficiency of 85% and the maximum voltage gain of 6.4 are measured.