Performance evaluation of a three-phase dual active bridge DC-DC converter with different transformer winding configurations

This paper investigates the impact of three transformer winding configurations, i.e. the Y-Y, the Y-Delta, and the Delta-Delta configuration, on the performance of a three-phase dual active bridge (DAB) dc–dc converter. For each configuration, equations for the phase currents, power flow, and zero voltage switching (ZVS) boundaries are derived for all possible switching modes of the three-phase DAB. Thereafter, a comparison is made of the stress on the switches, the transformer and the filter capacitors for the selected winding configurations. The comparison reveals that the Y-Y and Delta-Delta configuration perform equally regarding above aspects, with the only difference of a lower winding current for the Delta-Delta configuration. The Y-Delta configuration shows a constant commutation current for phase-shifts from zero to 30 degrees. Therefore, this configuration features a wider ZVS region for low output powers. Overall, the Y-Delta configuration performs best for power levels between 50 and 80%, regarding the stress on the switches, the transformer, and the filter capacitors. The theoretical analysis is supported with measurements obtained from a high-power experimental setup.