Optimum Air Gap Selection in Powder Core Inductors

The requirements of magnetics for power electronics are high power density and low power losses, driven by the need for more compact and more efficient power converters. Metal powder materials are a common choice for high power and high frequency inductors subject to a magnetic field bias applied because of the high saturation flux density and their "distributed" air gap property that allows adopting these materials in un-gapped core configurations. Nevertheless, in certain conditions, a concentrated air gap could maximize the overall inductance factor for a given winding configuration (i.e. the number of turns). Therefore, this paper proposes a straightforward procedure to maximize the inductance factor of metal powder magnetic cores by selecting the optimum air gap length for a specified design operating point. The proposed methodology is theoretically described and then experimentally validated on an XFlux 60 core from Magnetics ® .