Three-Phase DAB Converter with Reconfigurable Transformer Connection Strategy

This study focuses on a three-phase DAB converter connected to a
$3\phi$
network, utilizing PS modulation. The
$3\phi$
network comprises a three-phase transformer along with an auxiliary inductor. The options considered are named YY,
$\mathbf{iDY}$
, and
$\mathbf{oDY}$
Analytical equations are derived and validated through simulations for all connections. Observations reveal that mod-ifying the transformer connection leads to variations in the ZVS regions, thereby altering the optimal operational region for achieving maximum efficiency. It is demonstrated that the
$\mathbf{iDY}$
connection has higher efficiency at high voltages, while the other two options have higher efficiency at lower output voltages. Taking this into consideration, the possibility of simultaneously operating with two distinct
$3\phi$
networks is analyzed. Depending on the converter operating point, a specific
$3\phi$
network is employed. Two pairs of
$3\phi$
network are studied: Pair 1, consisting of
$\mathbf{iDY}$
and YY, and Pair 2, consisting of
$\mathbf{oDY}$
and YY. Each project involves a different value of the auxiliary inductor. Both pairs show improvements in efficiency when compared with a conventional approach that uses a single connection for the entire operating range. Therefore, for projects with wide voltage variations at the output or input, reconfigurable transformer connections can offer significant advantages.