Abstract: Dual active bridge（DAB） converter is an ideal high-power bidirectional DC/DC converter and a key equipment for bidirectional energy transmission between energy router system and energy storage units. In order to achieve the soft switching of converter and to improve the working conditions of switching device and power transmission efficiency, this paper analyzes the operation principle of triple phase shift（TPS） modulation for DAB converter. By analyzing the switching modes and opearation waveforms of DAB converter under TPS modulation method, the condition of soft switching of converter is obtained. By combining with the existing optimization control algorithm of inductor current RMS, a modulation strategy for implementing soft switching of all devices in full power range is proposed. Finally, a prototype of DAB is built, and the experimental results verify the validity of the theoretical analysis and the effectiveness of proposed modulation scheme.