Discrete time modeling of output disturbances in the dual active bridge converter

The small-signal modeling of dual active bridge (DAB) converter dynamics in discrete time is a useful analysis tool due to the ability to incorporate behavior during zero-voltage switching (ZVS) intervals explicitly, and is advantageous for the direct design of digital compensators. While the control-to-output transfer function has been modeled previously, accurate models of the output impedance of the DAB converter which account for the converter behavior during switching intervals have not been proposed. A discrete time model of the DAB output impedance is developed and tested against experimental results for a 1 MHz, 50-to-4 V, 10 W DAB converter. The model is then extended to the analysis of load current step changes asynchronous to the discrete time sampling instances.