Transient Model and Elimination Method for DC Bias Current in Dual Active Bridge Converter

This paper derives the time-domain (TD) expression of the transient DC bias current in the dual active bridge (DAB) based on the Fourier series, and reveals the relationships between the transient DC bias current and the change of phase-shift angles. Then, the DC bias elimination (DCBE) scheme is proposed. The transient model and the DCBE method proposed in this paper are applicable for the sudden changes of phase-shift angles in all the modulation methods. The DCBE proposed in this paper is easy to be implemented, which can guarantee the DAB to diminish the transient process within half of a switching cycle. Therefore, it can ensure the safety and reliability of the DAB and improve its dynamic performance. Experimental results verify the superiority of DCBE proposed in this paper.