Optimal design of GaN and PCB-winding Based Transformer-Inductor-Integrated Magnetics for CLL resonant converter

Abstract

A transformer-inductor-integrated magnetic structure with PCB-winding is presented for a GaN-based CLL resonant converter. In comparison with a conventional LLC resonant converter, the resonant inductor of the CLL resonant converter is placed on the secondary side of the transformer to eliminate the circulating current-related losses. Core losses of both the transformer and the resonant inductor are reduced by sharing a common magnetic plate between them. To suppress the common-mode noise induced by the PCB-winding, part of the primary windings are used as shielding layers, and a symmetrical PCB winding structure is implemented for a 10:2 turns ratio transformer. A 700kHz 400V/48V CLL converter is designed and tested to verify the effectiveness of the integrated magnetics.