A Novel Three Dimensional (3D) Winding Structure for Planar Transformers

This paper presents a novel 3D planar transformer winding structure. The proposed winding structure achieves low AC resistance without multiple interleaving between primary and secondary windings. The parasitic capacitance between primary and secondary windings are significantly reduced by the proposed structure. The 3D finite element analysis (FEA) has proven effective current sharing between all paralleled traces. The proposed 3D winding structure is applied to a 3.2 kW 500 kHz LLC resonant converter and >98% efficiency is demonstrated.