A Switched-Capacitor Multilevel Inverter for grid-connected PV systems with MPPT ability and reduced components

摘要

One of the important applications of power electronic converters is in low power Renewable Energy Generation Systems (REGS). In this paper a new application for single phase grid connected switched capacitor multilevel inverter in REGS has been proposed. According to control strategy and Seri-parallel switching of semiconductors, it has controllable output voltage amplitude with low total harmonic distortion in compare with similar topologies, and it does not have any complicated algorithm for balancing the capacitors voltage, respectively. In this study, a powerful method for maximum power point tracking (MPPT) under mismatching condition and grid-connected PV principles, based on 5-level inverter extracted from proposed general Switched Capacitor Multilevel Inverter (SCMLI) topology, is recommended. In this case, due to boost inherent capability of proposed SCMLI, the conventional dc/dc converter which usually used in the PV modules array to reinforce the input dc voltage has been removed. Hereby proposed MPPT strategy can track the maximum power of PV module directly on the basis of changing the provided phase difference between the inverter voltage and grid. In the rest of the paper, various simulation results by PSCAD/EMTDC software are presented to show the effectiveness of the proposed technique.