Frequency-Domain Modeling of Dual-Active-Bridge Converter Based on Harmonic Balance Approach

Abstract

The dual active bridge (DAB) converter contains both ac and dc states. Hence, state-space average modeling of DAB is intricate. In the literature, several models of DAB have been developed to reconstruct the ac state. However, full-order models provide better accuracy than reduced order models. Frequency-domain-based modeling captures the total behavior of the converter, such as generalized average modeling (GAM) or series-based solutions. However, with the consideration of more harmonics in the model, derivation of state equations and, thus, state matrices become tedious. This article proposes a harmonic state-space (HSS) modeling framework for DAB that overcomes earlier obstacles and accurately models both the ac and dc states depending on the inclusion of the number of harmonics in it. The modeling framework described here is applicable to single, dual, and triple phase-shift modulation schemes. This modeling framework presents a straight forward approach and has a definite structure, which presents flexibility and ease in deriving the input–output relationship. Both large-signal and small-signal models are derived and analyzed. This model is validated by time-domain simulation, performed on MATLAB/Simulink. Experimental investigations on a prototype of DAB also validate this model.