A 80-kW Isolated DC–DC Converter for Railway Applications

This paper provides an analysis of a three-phase dual active bridge (DAB) topology used as high-power-density dc-dc converter for railway applications. The three-phase DAB is analyzed concerning the current intervals, the output power, and softswitching region, including the impact of zero-voltage switching capacitors. Furthermore, two measures are proposed to achieve soft-switching in the entire operating range, being auxiliary inductors and a straightforward switching strategy called the burst mode. Optimal component values are calculated to minimize losses in the complete operating range and to assess which measure is best suited. A prototype with the specifications acquired from the application has been built, yielding an efficiency of 95.6% at a nominal output power of 80 kW.