Improved Modulation for Dual Active Bridge Based Three-Phase Single-Stage AC-DC Converter

The DAB based three-phase isolated single-stage (DAB-3P1S) AC-DC converter has the advantages of wide voltage conversion range, high efficiency and high power density. However, it suffers from the AC side current distortion with the conventional modulation strategies. In this paper, an improved space vector phase-shifted modulation for the DAB-3P1S ACDC converter is proposed to decouple the high frequency transformer (HFT) primary side current and realize the precise calculation of the phase shifts to eliminate the AC side current distortion. Furthermore, taking the minimization of the RMS value of the HFT primary side current as the constraint, the exact relationships between the desired AC side current and the three phase shifts are determined to realize the precise control of instantaneous AC side current and the efficiency improvement. Detailed experimental results validate the correctness of the theoretical analysis and the feasibility of the proposed modulation strategy.