Power Electronics and Applications (EPE'14-ECCE Europe), 2014 16th European Conference on, 26-28 August 2014 Lappeenranta This paper presents the design of a three phase dual active bridge (DAB) topology as high-power-density dc-dc converter for railway applications. The three-phase DAB is analyzed concerning the current intervals, the output power and soft-switching region, including the effect of zero-voltage switching (ZVS) capacitors. Furthermore, two methods are discussed, aiming to extend the soft-switching region, since no-load conditions in the entire operating range are required. A prototype design is made, in which optimal component values are calculated, to minimize losses. Finally, a prototype is built with the required specifications, resulting in an efficiency of 95:6% at 80kW of output power.