Comparison of CCTT split-winding and EE integrated magnetics for high-power dc-dc converters

This paper investigates integrated magnetic structures for high-power dc-dc converters. A novel CCTT split-winding integrated magnetic (IM) is introduced and is compared to a conventional EE IM structure. The CCTT IM allows for a reduction in external dc inductance in comparison to the EE design. This reduced dc inductance allows for a size/volume reduction. Low-power-loss ferrite is used and this results in a very efficient design. An IM design flowchart is presented which allows for quick CCTT and EE IM designs. The flow chart incorporates fringing equations to determine the dc and ac inductance of the IM structure, thus allowing for a more accurate design. The volume vs. efficiency for both magnetic structures is compared for various values of input current ripple. 3D FEA is used to fine tune the IM designs. High-power, 80 kW, experimental results validate the CCTT IM concept and show that the magnetic component is 99.7 % efficient over the input power range.