A Dynamic Study of the Single Active Bridge Converter

In this article, a thorough study of the dynamic behavior of the single active bridge (SAB) converter is presented. The SAB converter can be considered a unidirectional version of the dual active bridge (DAB) converter, which has been extensively analyzed in recent years. However, the dynamics of the SAB converter differs from the one corresponding to the DAB converter and has not been addressed so far. The SAB converter can operate in two different conduction modes, namely discontinuous conduction mode (DCM) and continuous conduction mode (CCM). The SAB operating in DCM presents the same static and dynamic behavior as the phase-shifted controlled full bridge (PSFB) converter if the value of the inductor of the SAB is the same as the value of the output inductor of the PSFB referred to the transformer primary side. However, the dynamic behavior of the SAB converter in CCM is different and must be analyzed in detail. As a result of the analysis carried out, average small-signal linear models have been obtained for both conduction modes. These models are compared with the ones obtained for other similar converters and they have been validated with simulation and experimental results.