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Two stage conversion systems (TSCSs) normally use either boost converter or high gain dc-dc converter along with dc-ac inverter in order to transfer power from low input voltage dc source to high voltage ac load. When these TSCSs operate at extremely low input voltages, the boost converter has to operate at extremely high duty ratios. This in turn results in more losses and reverse recovery problems. Usage of high gain dc-dc converter results in more number of components, increase in control complexity and decrease in reliability. Single-stage conversion systems (SSCSs) are formed by merging both dc-dc and dc-ac conversion processes. These SSCSs have advantages like low loss, more compactness and less reverse recovery problems. In this study, a high gain coupled inductor-based single-phase SSCS is presented. This SSCS topology has many desirable features such as high gain, less switching losses, free from leakage inductance adverse effects and compact. Principle of operation, steady-state analysis and design of the proposed topology are described in detail. MATLAB simulation results of the proposed topology and experimental results using DSP28335-based experimental setup are presented to validate the proposed scheme.

Single-stage DC-AC converter systems (SSCSs) are developed by merging both DC-DC and DC-AC conversion processes. These SSCS transfer power from photovoltaics (PV) to loads/grid in one stage. In this study, a PV-based grid tied single-stage DC-AC converter system (GTSS) for low-voltage PV systems is presented. Generally, when SSCSs are connected to the grid, grid voltage template is used to generate reference current which is to be tracked. In doing so, the GTSS delivers power to the grid at a power factor other than unity. A suitable control scheme is implemented in this study to control active and reactive powers' flow from the GTSS to the grid while continuously operating PV at maximum power point. The proposed control scheme of GTSS has attributes such as less complexity and requires simple proportional integral controller. Modelling of control loops in the proposed control scheme is mentioned. A detailed MATLAB/SIMULINK-based simulation and experimental studies are conducted to validate the proposed control scheme.

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