PCB integrated transformer composed with ferrite mosaics for LLC resonant converter

A mosaic structured core composed with ferrite mosaics for passive embedded substrate is described in this paper. The ferrite mosaic structured core is finished after cutting, laminating and assembling the ferrite mosaics which consist of a supporting plate and ferrite units with small size stuck on it. This structure is applied to a transformer design for 48 V to 12 V, 500 W LLC resonant bus converter with efficiency up to 97%. Analysis is conducted to show this structure working well and finite element analysis (FEA) is executed for simulation of the power losses in the new structure core. Experiment results show that gap control is a big challenge to mosaic structured transformers.