AnLLCLPower Filter for Single‐Phase Grid‐Connected Inverter

This chapter presents a novel topology of higher-order power filter, named as LLCL filter, for single-phase grid-connected voltage-source inverter. A small inductor is inserted in the branch loop of the capacitor in the traditional LCL filter to form a series resonant circuit at the switching frequency. In particular, it can attenuate the switching frequency current ripple component better than the LCL filter thereby reducing the total inductance and volume. In addition, the parametric design criteria for the proposed LLCL filter are also discussed. Experiments on the conventional LCL filter and the proposed LLCL filter are carried out on a 1.8 kW single-phase grid-connected inverter prototype. Results are compared, analyzed and discussed, and evaluated accordingly.