Design of LCL-Filter for Grid-Connected Buck-Boost Inverter Based on Unfolding Circuit

In this paper a determining of LCL-filter for grid-connected buck-boost inverter based on unfolding circuit is presented. The main idea is reducing the amplitude of high-switching harmonic, which introduces a significant part to the grid current spectrum. This leads to reduce the THD value of the output current. A suitable ratio of inductances of LCL-filter can provide a necessary accuracy of the energy. The simulation results are presented as a verification of the design of LCL-filter. The closed-loop control system based on the proportional-resonant controller is used to check theoretical statements.