Comparison and selection of magnetic materials for coupled inductor used in interleaved three-level multi-phase DC-DC converters

The coupled inductor can reduce the large inductor current ripple in the interleaved multiphase three-level converter, while keeping the benefits of interleaving. The design of coupled inductor is different from conventional two-level converters. This paper analyzes the flux in a new structure of the coupled inductor for three-level converter, and proposes a detailed design method to select proper core material, like amorphous or nano-crystalline, to achieve the minimum volume or weight. The choice isn´t only related to frequency, but also the converter´s voltage and current specifications. Amorphous and nano-crystalline materials are compared, and the material selection guideline is given at the end of this paper.