A magnetic integration structure for the buck-cascaded half-bridge DC-DC converter

Existing magnetic integration methods can be classified into three kinds: the non-coupled, the coupled, and their “mixtures”. They, having different features, are appropriate for different applications. For the buck-cascaded half-bridge (duty cycle ≈ 50%) DC-DC converter, the analysis results show that the non-coupled magnetic integration methods are preferred. In this paper, a non-coupled magnetic integration structure including two inductors and one transformer is proposed for it. In the proposed structure, the limited window areas of the magnetic cores are fully utilized. With the increase of the winding cross-section areas and the heat dissipation surface area, the copper loss of the integrated magnetics can be reduced and the cooling condition of it can be improved. A quarter-brick prototype of the buck-cascaded half-bridge DC-DC converter with 48-V input and 1.5-V/60-A output is implemented and tested to verify the feasibility of the proposed magnetic integration structure. With the experimental data, the power loss of the integrated magnatics has been analyzed. Finally, some optimization proposals are offered.