Comparative study of three transformer concepts for high current dual active bridge converters

Abstract:
Three different transformer designs of the high current DC-DC converter (12 V/ 360 V, 1 kW, 25 kHz) with dual active bridge (DAB) topology are evaluated and compared in this paper, from either electrical or thermal point of view. Three transformers are: planar transformer with 30 turns of PCB tracks and two interleaved copper foils attached on the PCB, barrel transformer with 30 turns Litz wire and copper foils and planar transformer with copper foils and Litz wire as low and high voltage windings, respectively. Experiments show that the planar transformer with copper foil and Litz wire has the highest potential to fit in the final converter design. A thermal management concept is proposed on this transformer and results shows that the prototype DAB converter with this planar transformer achieves 93 % efficiency at 1 kW output power.