A Soft-Switching Control Method for Dual Active Bridge Converter Over the Full Power and Wide Voltage Regulation Range

The dual active bridge (DAB) has been widely adopted in isolated dc-dc conversion applications due to its capability for bidirectional power transfer. Among the various control strategies for DAB converters, the triple-phase-shift (TPS) control is recognized for its effectiveness. In this article, a soft-switching control method based on TPS control is proposed, which is advantageous for enhancing the efficiency of the DAB converter over the full power and wide voltage regulation range. First, the twelve operating modes of the DAB converter are categorized. And then an innovative methodology is introduced, wherein the DAB converter is equivalently transformed into a four-switch buck-boost (FSBB) converter by decomposing the midpoint voltage waveforms on both the primary and secondary sides. On the basis of the equivalent circuit, a hybrid phase-shift control method based on the soft switching is proposed, which delineates the DAB converter into six operating modes. To secure smooth and seamless transitions between these modes, a unified uni-variate control method is presented, which is simple and readily implementable. Ultimately, a 2.5 kW prototype is constructed, and the correctness and effective-ness of the proposed method are validated via the experimental results.