Analysis of a novel coupled inductor for LCL filter in grid-connected inverter

Because of the excellent effects for attenuating high frequency current harmonics, LCL filter is widely used in single phase and three phase systems. A LCL filter has two individual inductors which need large volume. This paper proposed a novel LCL filter with coupled inductor which can obtain the similar filtering performance as traditional LCL filter as well as the core size reduction due to the magnetic-integration. The proposed filter only need one inductor in the series main power loop which helps to reduce the volume of the magnetic by decreasing the usage of the thick windings wire conducting high current. And thus the proposed filter can effectively reduce the volume of the magnetics compared with traditional LCL filter. Theoretical analysis and implement approaches are shown in detail. The inductors of two kinds of filters for a 1.2kW inverter prototype are fabricated to verify the analysis. Experimental results validate the effectiveness of the analysis.