Design and Analysis of Resonant Network for Dual Active Bridge Converter

The power transfer characteristics of dual active bridge (DAB) converters are highly dependent on the resonant network, even under the same pulsewidth modulation (PWM) technique. This article mainly addresses the design and analysis of resonant networks for DAB converters. Unlike previous studies that typically focus on tuning predetermined resonant network structures, this study introduces a methodology for determining both the structure and specific parameters of resonant networks that fulfill the system's input-output requirements. Through theoretical analysis using a general two-port passive network model, the design degrees of freedom and their impact on the properties of resonant networks are explored. Because there are numerous candidate resonant networks, it is crucial to compare the properties of DAB converters utilizing each network. To facilitate comparison, PWM solutions that achieve soft switching and minimize root-mean-square (rms) currents for each resonant network are derived. A detailed analysis is carried out on how these PWM solutions vary with the resonant network design and how they impact the DAB converter's power transfer properties, including rms currents, reactive power, and control sensitivity. The proposed design methodology and analysis are experimentally validated with two distinct 3.5-kW DAB converters.