Saturable Ferrite Core Inductors in LCL Filters of Three-Phase Voltage Source Inverters

Abstract:
This article presents a filter inductance design methodology for saturable ferrite inductors with stepped air gaps in three-phase LCL filters. The analysis shows that allowing saturation of the filter inductor enables the choice of smaller cores or reduces the inductors winding resistance. This results in higher power density or efficiency. The paper contains a design methodology for stepped air-gap inductors based on a reluctance model including fringing flux effects. The findings are verified by means of field simulation and time domain simulation.