Using Powder Materials to Replace Air-Gaps for Fringing Flux Reduction

Abstract:
Amorphous or nanocrystalline gapped cores as well as powder cores are both popular in industrial power choke design. Both show different advantages and drawbacks, depending on their function within a circuit. In this paper we present a design-approach, combining both core-materials for choke design. The drawbacks of air gapped solutions are shown and compared to a solution, where the air gap is replaced by a distributed gap using a piece of powder material. We illustrate the much higher fringing flux of an air gapped structure and related losses. The design procedure of an inductor using a powdered material instead of an air-gap and the different saturation behavior of both solutions are shown.