A High Frequency Coupled Inductor with Distributed Air Gap for High Power DC-DC Converters

In coupled inductor designs, minimizing AC resistance and achieving an optimal coupling coefficient are crucial for the performance of high frequency, high power DC-DC converters. The location and length of air gaps not only influence the loss profile but also affect the coupling coefficient, directly impacting the system’s performance. This article is focused on a coupled inductor design using custom planar ferrite blocks and distributed air gaps with 3D printed bobbins for mechanical stability. The proposed design achieves over 30% reduction in AC losses by reducing fringing effects and offers the flexibility to adjust the coupling coefficient, while ensuring a cost-effective and repeatable assembly process. System level advantages of the proposed method are verified using 2D FEM simulations. Finally, experimental results for a two-phase interleaved boost converter application have been presented in this paper to validate the effectiveness of the proposed inductor design.