Info Electromagnetic transient equivalent model of dual active bridge based on the generalized branch-cutting method

Abstract

The traditional detailed model of the dual active bridge (DAB) power electronic transformer is characterized by the high dimensionality of its nodal admittance matrix and the need for a small simulation step size, which limits the speed of electromagnetic transient (EMT) simulations. To overcome these limitations, a novel EMT equivalent model based on a generalized branch-cutting method is proposed to improve the simulation efficiency of the DAB model. The DAB topology is first decomposed into two sub-networks through branch-cutting and node-tearing methods without the introduction of a one-time-step delay. Subsequently, the internal nodes of each sub-network are eliminated through network simplification, and the equivalent circuit for the port cascade module is derived. The model is then validated through simulations across various operating conditions. The results demonstrate that the model avoids the loss of accuracy associated with one-time-step delay, the relative error across different conditions remains below 1%, and the simulation acceleration ratios improve as the number of modules increases.