A Magnetic Integrated LCL-EMI Filter for a Single-Phase SiC-MOSFET Grid-Connected Inverter

Harmonic and electromagnetic interference (EMI) filters are the two important parts in the grid-connected inverter for the harmonic and EMI noise suppression. This article investigates the combined magnetic integration of the harmonic and EMI filters with the volume and weight reduction, which is defined as the integrated LCL-EMI filter in this article. Both common-mode (CM) and differential-mode (DM) models of the integrated inductor with EE-type magnetic core are built and analyzed. By designing the air gap of the center leg and arranging the windings properly, the distribution of magnetic flux on the magnetic branch can be controlled. As a result, harmonic inductors and a CM inductor can be effectively designed in the center leg and side leg, respectively. A symmetrical LCL filter is designed instead of the traditional asymmetrical structure with an integrated magnetic core. The current harmonic distortion analysis and EMI measurement results based on simulation and experiment results verify the effectiveness of the proposed integration method in the silicon carbide (SiC) MOSFET-based grid-connected inverter. Moreover, weight and volume comparisons between the integrated inductor and the traditional discrete inductors also reflect the superiority of the magnetic integrated LCL-EMI filter.