A hybrid AC/DC microgrid structure is designed

and the role of the energy storage converter in this microgrid is analyzed. The switchings between grid-connected and island modes are the focus of attention. For problems in the transition between different working conditions

the seamless switching control strategy is proposed for the energy storage converter

including the compensation algorithm for the transient process during grid-connected mode transition to the island mode

and the pre-synchronization method for the transient process during the island mode transition to the grid-connected mode. Use of the control method proposed makes it possible to achieve seamless switching between the two working conditions above

and the converter output voltage and current are smooth and impact-free during the switching of operating modes. The validity and reliability of the method proposed are verified by simulation and experimental results.This work is supported by National High Technology Research and Development Program of China(863 Program)(No. 2012AA051201).