Challenges of the parallel connection of Dual Active Bridge converters

This work investigates the challenges associated with implementing Dual Active Bridge (DAB) converters in parallel applications with high demand loads. The research begins with a review of the state-of-the-art DAB converter; highlighting its advantages over other isolated bidirectional converters, modulation technique, modeling, and the voltage loop employed to its operation. Subsequently, a detailed analysis of DAB components designs, and sizing is conducted, focusing on critical aspects such as transformer ratio, inductance, and output ca pacitance. A simulation-based study examines the factors contributing to undesirable behavior in DAB converters, with particular emphasis on design considerations and the impact of dead time. Given the computational demand of High-fidelity simulations for switched power con verters, this work explores existing methods to reduce lengthy simulation times while keeping sufficient dynamic behavior fidelity. A novel approach combining two existing simulation types is proposed to address this issue. The primary challenges that arise when paralleling two DAB converter are investigated. Key factors as sensor errors, cable impedance mismatch, circulating current in the converters, and oscillations induced by dead time behavior are analyzed. As the contribution of this works, control techniques such as droop control and an inner current loop are proposed to mitigate these undesirable problems, enhancing system robustness

https://orcid.org/0000-0002-1889-1353