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    Experiment of a high voltage gain switched capacitor dc-dc converter based on a cross-connected fibonacci-type converter
    (Innovative Computing, Information and Control, 2019) Rubpongse, Ratanaubol; Do, Wanglok; Eguchi, Kei
    To make an efficient converter for energy harvesting systems, a high voltage gain cross-connected switched-capacitor (SC) DC-DC converter is presented in this paper. By using a cross-connected structure based on Fibonacci-type converters, the proposed converter can realize high voltage gain, where the voltage gain is expressed as a power of two. On the other hand, unlike traditional converters, stepped-up voltage is created in every clock cycle. By using the cross-connected structure, the proposed converter can reduce the size of output capacitor and output ripple noise. Therefore, the proposed converter can be compact in size. Experimentation revealed that the proposed converter can realize a high voltage gain, fast response speed, small output ripple noise, even at a small size.
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    A step-down nesting-type ac–ac converter combined with voltage equalizers and switched-capacitor simple converters
    (Elsevier, 2019) Eguchi, Kei; Rubpongse, Ratanaubol; Shibata, Akira; Ishibashi, Takaaki
    In this paper, we present an inductor-less direct ac–ac converter with improved nesting-type topology. Unlike existing direct ac–ac converters, the proposed ac–ac converter combines a voltage equalizer and a switched-capacitor (SC) simple converter. Owing to the nesting conversion using two techniques, the proposed converter can provide a stepped-down voltage with small number of circuit components and high input power factor. To evaluate the performance of the proposed ac–ac converter, we compared the proposed ac–ac converter with existing inductor-less ac–ac converters, namely, flying capacitor type converter, symmetrical type converter, and traditional nesting-type converter, by theoretical analysis and simulation program with integrated circuit emphasis (SPICE) simulations. The SPICE simulations demonstrate that the proposed ac–ac converter outperforms existing inductor-less ac–ac? converters in the point of circuit size and input power factor, although the power efficiency of the proposed ac–ac converter is inferior to that of the symmetrical type converter. In the case of 1/4 voltage gain, the proposed ac–ac converter achieves about 82% power efficiency and 0.58 input power factor when the output power is 200 W.