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 0 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.