Magnetic Integration Design for Input-Series Output-Parallel LLC Resonant Converter

For LLC resonant converter, the optimized design of the planar integrated structure for resonant inductors and transformers is the key point to achieve higher power density and efficiency. An ultra-thin matrix integrated structure for the power magnetic components of Input-series Output-parallel (ISOP) LLC resonant converters is investigated in this paper. Based on the theoretical calculation methods for magnetic core loss and winding loss, two transformers were integrated and designed. Furthermore, in order to further reduce the volume and loss of magnetic components, the transformer and resonant inductors are both integrated. Finally, an ISOP LLC resonant converter prototype based on the integrated magnetics was built with the high-power density of 24W/in ³ and a peak efficiency of 96%. The feasibility and effectiveness of the ultra-thin integrated structure also verified by the experimental results.