A Comprehensive Optimization Strategy of DAB Converter With Minimal Current Stress and Full Soft Switching in the Whole Operating Range

Dual active bridge (DAB) converter has been widely used in electric vehicles (EVs) with the advantages of its simple structure and high performance. Traditional optimization strategies based on triple phase shift (TPS) of DAB cannot optimize both soft switching and current stress. To overcome this challenge, a comprehensive optimization strategy based on TPS (TPS-CO) adapted to the whole operating range is proposed in this article. The power range, current stress, and soft-switching features for TPS are detailed, and the mathematical model of TPS-CO is established. Accordingly, the optimal path method for seeking the minimal current stress in zero voltage switching (ZVS) region over full-power range is proposed. Therein, it solves the problem of zero current switching (ZCS) operation of TPS at light loads and significantly extends the ZVS range. The proposed strategy is implemented through closed-loop control. Finally, experimental results on a 1.6-kW laboratory prototype demonstrate the significant efficiency advantages of the proposed TPS-CO strategy of the DAB converter with widely varying voltage ratios and full-power range compared with the conventional strategies, and the peak efficiency can be promoted up to 2% at light loads as reported in the experimental statistics.