Design of a Fully Integrated EMI Filter for a Single-Phase Grid-Connected Inverter

EMI filter is an essential part of the inverter system due to the high operative switching frequency of power switch tube. The optimization of electromagnetic interference (EMI) filter design has a far-reaching impact on the coming industrial application area. Based on the Silicon carbide (SiC) MOSFET single-phase inverter, this article investigates a full integration strategy with the UU-type ferrite core and flexible multi-layer foil (FMLF) applied. The FMLF contains electrical-, dielectric- and insulation layers. With the ingenious design of the FMLF windings, the inductance and capacitance can be integrated into the same unit. Based on the special design with double dielectric layer embedded, a novel full integration structure comes into being, with the common-mode (CM) and differential-mode (DM) capacitance designed following with the CM and DM inductance. The magnetic simulation has been conducted for analyzing the structure and ensuring that the core will not reach saturation under full load. A SiC MOSFET single-phase inverter has been designed as the experiment platform, and the conducted EMI noise measurement results have verified the feasibility and validity of the proposed fully integrated structure.