In order to increase the input and output voltage range of the energy storage system, this paper will conduct in-depth research on the modulation strategy of the bidirectional DC/DC module of the energy storage system. In this paper, the LLC resonant converter with bidirectional operation is used as the connection port between the battery and the DC bus in the energy storage system. The working principle of this topology and the commonly used modulation strategies are briefly described, and then the hybrid modulation strategy is analyzed in detail, which can ensure the normal operation of the DC bus voltage in the range of 310V to 380V. The correctness and effectiveness of the strategy are verified by experiments.

Energy storage system; Bidirectional LLC resonant converter; Hybrid modulation strategy