Multifrequency Model of Dual Active Bridge Resonant Converters With Phase-Shift Control

The dual-active-bridge (DAB) resonant converters are a cluster of efficient bidirectional dc-dc converters. It is commonly a challenge to obtain the analytic expressions of the control-to-output transfer functions especially in multi-element resonant converters. In this article, the multifrequency modeling technique is adopted to derive the general small-signal model for DAB resonant converters with various resonant tanks. The analytic expression of phase-shift-angle-to-output-voltage transfer function as well as the general control block diagram of DAB resonant converter is obtained. It is interesting to see that the models are different depending on primary side phase shift or secondary side phase shift. To have a clear picture of the differences, order reductions of the models are conducted with the example of the DAB series resonant converter. Finally, the prototype of the DAB series resonant converter is built in the lab, and the phase-shift-angle-to-output-voltage transfer function is measured, which successfully verifies the validity of the proposed model.