Magnetic Integration of the LCL Filter in Grid-connected Inverters

LCL filter is widely used in grid-connected inverters due to its outstanding performance of attenuating the switching frequency current harmonics.An LCL filter has two individual inductors.Numbers of magnetic cores are required,and large volume has to be reserved for these two inductors.In order to reduce the core size,this paper proposed a decoupled magnetic integration method to combine the two discrete inductors together.However,the reluctance of the common core can hardly be zero,which leads to the coupling between the two inductors of an LCL filter.As a consequence,the attenuating ability of the LCL filter at high frequency would be weakened.In order to reduce the coupling coefficient to a satisfactory range,the suitable height and magnetic material of the common core are selected.Experimental results from both single-phase and three-phase grid-connected inverters validate the effectiveness of the proposed magnetic integration method.