Research on grid-connected interleaved inverter with L filter

Grid-connected inverter is one of the key techniques of renewable energy generation. High-order filter like LCL filter is normally used as a standard interface to the grid to provide the proper attenuation of switching frequency harmonics. However the resonant of LCL filter limits the improvement of both steady state and dynamic performance of grid-connected inverter. In this paper, a new solution of grid-connected inverter with multi-interleaved techniques is investigated, where a simple L filter is employed in each interleaved unit instead of LCL filter. Analytical study and parameters´ design of this solution is presented. It can be founded that the total size of passive filter of this type of interleaved grid-connected inverter is almost the half of that of traditional LCL filter based grid-connected inverter. Additionally, the mathematic model of this L-filter based interleaved (LFI) grid-connected inverter is deduced. Although the control structure of the proposed topology is very complex, the control algorithm is comparative simple thanks to the simple equivalent mathematic model. Simulations and experiments are finally conducted to verify the presented method has improved steady state and dynamic performance.