Small-signal Model for Dual-active-bridge Converter Considering Total Elimination of Reactive Current

Abstract

Emerging technologies such as electric vehicles, sol-id-state transformers, and DC transformers are implemented using the closed-loop bi-directional dual-active-bridge (DAB) converter. In this context, it is necessary to have average models that provide an efficient way of tuning the proportional integral (PI) compensator parameters for large- and small-signal applications. We present a novel small-signal model (SSM) for DAB converter with a single closed-loop PI controller and the total elimination of reactive current $(I_{Q}=0)$. The method applies a modulation technique for $I_{Q}=0$ and introduces a composite function in the controller while reducing the original nonlinear switching model, which allows to decrease the order of the transfer function and analyze the closed-loop operation. The proposed SSM is analyzed using different response time, load, and DC voltage changes. The simulation and experimental results demonstrate the ease of implementation and effectiveness of the proposed model with respect to other SSM techniques.

Keywords

• Small-signal model (SSM)
• dual-active-bridge (DAB) converter
• reactive current elimination
• proportional integral (PI) control