Steady-State Modeling of a Dual-Active Bridge AC–DC Converter Considering Circuit Nonidealities and Intracycle Transient Effects

摘要

Steady-state operation of dual active bridge (DAB) ac-dc converters can show a high dependence on the circuit nonidealities and on the transient nature of the consistently changing phase-shifts necessary to achieve ac-dc operation. These aspects are not fully captured using traditional modeling approaches derived from dc-dc DAB converter analyses. To address these issues, this article presents a unified modeling approach comprising of hybrid frequency and time-domain analyses that encompass the transient nature of the ac-dc converter while providing the advantages of steady-state frequency-domain analysis. The limitations of conventional modeling approaches are quantified and addressed. Additionally, a comprehensive analysis of modeling error trends with converter parameters is presented, which demonstrates the effectiveness of the proposed method over conventional methods. Finally, using the proposed modeling approach, a numerical optimization routine is proposed to find the optimal-conduction-loss modulation trajectory. The effectiveness of the method is verified by experimental testing on a 1 kW, 230-28 V fully GaN-based single-phase DAB ac-dc converter.