Multisampling Control of LCL-type Grid-connected Inverter with an Improved Repetitive Filter

Multisampling control provides an attractive way to reduce the control delays in LCL filter based grid-connected inverters, and thereby the bandwidth and stability margin will be improved. However, high frequency switching harmonics (SHs) are introduced in the control loop, which will lead to low frequency aliased harmonics in the grid current. Hence, filtering the multisampled high frequency SHs is necessary. Traditional repetitive filter is a potential candidate to eliminate the noisy signals, but it only makes sense for parts of the SHs. In this paper, an improved repetitive filter is proposed to remove all the sampled SHs and keep the advantage of phase boost at the same time. Finally, a single-loop control with the inverter current feedback is employed, and the effectiveness of the proposed method is verified through the simulation results.