Explicit discrete modelling of bidirectional dual active bridge dc-dc converter using multi-time scale mixed system model

Abstract

Dual active bridge (DAB) is one of the most popular high power isolated bidirectional dc-dc converter. It offers high power density, a low number of passive components, high efficiency. It is essential to model the converter so that it can be used in applications such as solid-state transformer, micro-grids, and dc distribution systems. Moreover, modelling a system is used to design inductor, select the switches, and controller design. The advantage of the discrete-time models is that they explicitly describe state trajectories in all sub-intervals of converter operation, meaning they are capable of providing exact solutions for ac state variables. This study proposes time scaling mixed system model of the DAB. The proposed method provides explicit solutions of the large and small signal, which can be used to study the steady-state and transient nature of the converter. The experimental results validate the proposed model with high accuracy in the open and closed-loop operation.