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The aim of this paper is to present a new topology of single-phase transformerless inverters, which can be tied to the local grid as a low-scaled ac module system. The proposed topology offers a common ground between the neutral point of the ac grid and the negative terminal of the dc supply, and can properly alleviate the concern of variable common mode voltage and leakage current problems. This promising feature is acquired by the aim of both the switched-capacitor and charge pumped circuit cells. In order to inject a tightly controlled ac current to the grid, an adaptive hysteresis current controller scheme is also presented, which can guarantee almost fixed switching frequency operation of the involved power switches. A complete theoretical analysis, comparative study, and the relevant experimental results are also given to confirm the superior performance of the proposed topology.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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A single-input double-output dc-dc isolated high step-up dc-dc converter with soft-switching feature is presented in this study. The concept is to utilise quadrupler technique to reach high voltage gain without large duty cycle. Additionally, softswitching operation for all power switches and diodes is realised to reduce overall power losses and increase power conversion efficiency over a broad range. Furthermore, the leakage inductance energy of transformer is recycled to output with an active clamp circuit. Thus, the voltage stress on main switch is reduced and a low-voltage-rated metal-oxide-semiconductor fieldeffect transistors (with low R DS on) can be used. Moreover, low input current ripple feature is helpful to lengthen life time of renewable energy power sources. Finally, the analysis is described in detail and performance of the proposed converter has been verified through experimental results.