Modeling, Analysis and Design of a Magnetically Integrated LCL Filter for Grid-Tied Inverters

LCL-type filters are widely used in grid-connected inverter systems due to their good capability of harmonic suppression. But in traditional design, the components of LCL-filters are placed discretely, which would waste some volume and is adverse to the compact design of the inverter. For addressing this issue, in this work, to reduce the volume occupied by the inductors of LCL-filters, we proposed a magnetic integration method of the two inductors, which finished the magnetic integrated design on one EE-type core. By designing air-gaps in both the side-legs of the EE-type core, the magnetic decoupling effect between the two windings is mitigated to a low span. Then, the influence of magnetic integration on the ability of harmonic depression is modeled and analyzed and the feasibility and superiority of the magnetic integration method proposed in this paper are verified by simulation.