The three-phase dual active bridge plays a pivotal role in the power transfer, owing to its higher-power density with respect to single phase variant. However, it suffers from a low efficiency during operation at light load conditions due to loss of soft device switching. By dividing the phase secondary winding into two, unevenly, the efficiency can be improved by ensuring soft switching at low load conditions with appropriate phase shift angles between the primary and secondary voltages. Thus, this paper provides a detailed mathematical analysis for three phase transformers, which shows the effect of phase secondary windings partitioning on the phase shift angles of induced voltages.