In dual active bridge (DAB) converters, the external series inductor is often placed on the high-voltage side to reduce its losses, but in this configuration, the transformer magnetizing inductance is excited by the reflected voltage of the low-voltage port. This configuration can lead to higher transformer core losses for the DAB converter. However, in a split inductor configuration, the magnetizing current is supplied by both the high and low voltage side bridges, reducing the volt-seconds across the magnetizing inductance and therefore reducing the core losses. In this work, an analytical expression for transformer magnetization voltage is presented, and a reduction in transformer core loss using a split inductance configuration is calculated. An 11 kW, 775 V/450 V prototype is implemented, and both magnetic configurations are experimentally compared under identical volume and thermal conditions for a wide power range at 450 V. Total converter loss reduction and worst-case transformer core temperature reduction up to 9.6% and 18.3℃, respectively, are achieved under steady-state thermal conditions.
