Abstract: In order to speed up the process of "carbon neutrality" and "peak carbon dioxide emissions"，fossil

energy has been gradually replaced by renewable energy，and renewable energy will become the main power

generation mode in the future. The combination of energy storage system and bidirectional converter become the core component to maintain the voltage stability of microgrid，and realize peak shaving and valley filling. In view of this background，the dual active bridge（DAB）converter with strong energy bidirectional regulation capability was

studied. The working process of the DAB converter in a specific working mode was analyzed in detail by using triple

phase shift control. This working mode is suitable for light load conditions and has the capability of bidirectional

energy transmission. The corresponding mathematical models of current stress，a current stress optimization strategy which is based on triple phase shift control was proposed. The current stress was taken as the optimization objective，and the soft switching range and mode boundary were taken as the constraints，and the optimal phase shift combination was obtained. The optimal control strategy can reduce the current stress of the converter and improve the performance of the converter under the condition of ensuring the soft-switching operation. Finally，the correctness of the theoretical analysis was verified by experimental tests.

      Key words: dual active bridge（DAB）converter；triple phase shif（t TPS）control；soft switching；optimal control