Arbitrary order generalized state-space averaging model of dual active bridge converters

Generalized average modeling (GAM) can model the inductor current of dual active bridge (DAB) converters, which violates small-signal conditions. However, GAM provides inaccurate results of the inductor current and output voltage because it only considers dc and first harmonic components, thus limiting the applications in dynamic control and harmonic analysis. This study proposes an arbitrary order generalized state-space averaging model (AO-GSSAM) for DAB converters that considers arbitrary order harmonics. The arbitrary order small-signal model and phase-shift-ratio-to-output-voltage gains of the AO-GSSAM are derived for further controller design. AO-GSSAM can also work in acceleration mode (AM) to reduce time while maintaining acceptable accuracy. Simulations and hardware experiments show that the inductor current and output voltage ripples of the AO-GSSAM are in good agreement with the detailed switching model. The various harmonic characteristics of the inductor currents and voltage ripples can be acquired arbitrarily. Moreover, the balance of accuracy and speed can be achieved by optimizing the harmonic levels of practical application requirements. The proposed AO-GSSAM for DAB converters can be extended to the state-of-the-art topologies of other dc-dc converters.