A High Frequency CLLLC Bi-directional Series Resonant Converter DAB Using an Integrated PCB Winding Transformer

A unique integrated printed circuit board winding transformer has been proposed in this paper to be used in a high efficiency, high power density capacitor-inductor-inductor-inductor-capacitor series resonant dual active bridge converter (CLLLC-SRes-DAB) and key design considerations for CLLLC-SRes-DAB are addressed. Winding structure, core arrangement of the series inductor and transformer, and the shape of heatsink are carefully designed in order to minimize core volume, transformer intra-winding capacitance (C
TX
), and eddy current losses caused by fringing flux near air gaps. A 6.6kW CLLLC-SRes-DAB prototype with a 500kHz series resonant frequency has been built to evaluate the performance of the proposed transformer. 98% peak efficiency is achieved in this 6.6kW CLLLC-SRes-DAB design.