Modeling and Mitigation of Transformer Saturation in Dual-Active-Bridge Converter

Bi-directional dual active bridge (DAB) converter, due to non-ideal behavior and switching characteristics, a flux walking phenomenon appears in high frequency (HF) transformer and results in the transformer's saturation in transient and steady state operating conditions. The saturation effect of the HF transformer affects severely damage the DAB converter performance. This study focuses on the transformer model based analysis and mitigates the magnetizing saturation problem in the DAB converter. In this paper, a practical transformer is modelled and simulated, considering the B-H curve data of the high-frequency transformer. A control strategy is proposed to force average magnetizing current of the transformer is to zero to overcome the saturation problem of the HF transformer. The proposed concept is validated through MATLAB simulink simulation and experimental studies from 1kW laboratory prototype of Dual Active Bridge converter.