A Symmetrical Modular CUK-SEPIC Based Converter for Photovoltaic Applications

This paper presents a novel symmetrical modular CUK/SEPIC inverter (MCSI) for grid-tied Photovoltaic (PV) applications. The MSCI is a single stage of series-connected of submodules (SMs), which are based on an isolated CUK/SEPIC power converter. The proposed topology is featured with modularity, galvanically isolation, and an independent maximum power point tracking (MPPT) functionalities on different input ports. Employed SMs are distinguished by their capability to deliver high voltage gain and a stable continuous current with minimal ripple at the input and output. Therefore, the filtering capacitance can be reduced, especially on the input side, which improves its suitability for PV systems. This work employs a new modulation approach that functions without introducing a DC offset, hence decreasing voltage stress on switches and minimising conduction losses. Moreover, the MSCI's operation principles and its corresponding control strategy have been discussed. The performance of the proposed MSCI is validated by computer simulations and a scaled-down experiments.