An Improved DC Bias Elimination Strategy with Extended Phase Shift Control for Dual-Active-Bridge DC-DC

The minimum current stress model based on Dual active bridge (DAB) DC-DC converter is adopted, which is the independent variable of power transmission. In this paper, the phenomenon of dc bias caused by the sudden change of transmission power is analyzed, and the improvement scheme based on extended-phase-shift control method is proposed. Through changing the corresponding phase shift duty ratio and switch sequence, this method can eliminate the dc bias phenomenon in half a switching cycle and reach the steady state quickly. In the end, the proposed scheme is verified and compared with the traditional method through simulation experiment based on Matlab2017a/Simulink platform. Simulation results show that the transient current improvement scheme for the change of transmission power can obtain faster dynamic response speed, and has less losses, which improves the transmission efficiency.