Efficient Integrated Transformer-Inductor With High PCB Utilization and Optimized Core

This article addresses the challenges associated with the high winding and core loss in the integrated transformer-inductor (ITL). To overcome these challenges, we propose an improved winding design of the ITL by utilizing idle shielding layers for inductor integration within the matrix transformer. This method offers full printed circuit board utilization, where all the layers are consumed as winding, significantly reducing the winding loss of the ITL. Moreover, we propose an improved core structure of the ITL that offers better flux distribution of the leakage flux within the magnetic core. This method reduces the core loss by more than 50% compared to the conventional core structure. We demonstrate the effectiveness of our proposed concepts by presenting the ITL design used in a high-efficiency high-power-density 3-kW 400-V-to-48-V LLC module. The proposed converter achieves a peak efficiency of 98.7% and a power density of 1500 W/in(3).