Design of Fully Decoupled Planar Magnetic Integrated Three‐Phase Harmonic Filter for the Grid‐Connected Inverter System

ABSTRACT The three‐phase inverter is a crucial power conversion device in renewable energy generation systems, but its output current contains numerous harmonics. These harmonics necessitate the use of harmonic filters to meet grid connection standards. Compared to L or LC filters, the LCL filter is widely used as a third‐order filter due to its higher noise attenuation rate. However, the LCL filter's multiple inductors result in a larger volume and weight, which hinders the improvement of the system's power density. Magnetic integration technology effectively reduces the filter's volume and weight, but the coupling between inductors can impact the high‐frequency noise attenuation ability. This article proposes a planar magnetic integration scheme that achieves decoupling of inverter side and grid side inductors, with a low coupling coefficient between both inverter side inductors and grid side inductors. Compared to traditional filters, the proposed magnetic integrated LCL filter is lighter and more compact, thereby enhancing system power density. The harmonic suppression effect of the designed magnetic integrated LCL filter is validated through simulations and experiments. Even under asymmetric load conditions, the proposed filter demonstrates good harmonic suppression performance.