Dual-Active Bridge (DAB) converters play a critical role in many applications, such as in DC microgrids, where the nonlinear characteristics of the high-frequency transformer interact in a complex manner with other parts of the converter. To further improve the accuracy of modeling and simulation, these nonlinear characteristics are incorporated into the simulation. In this paper, a novel method is proposed to directly extract data from hysteresis loop images to obtain key parameters for the Preisach model. This method is highly applicable to various core materials. The accuracy and effectiveness of the model are validated through experimental results obtained from a DAB prototype. Ultimately, the model eliminates the need for traditional core test data and can be seamlessly integrated into circuit models to accurately predict operational waveforms in critical saturation regions.