Seamless Mode Transfer Control Strategy of Two-stage Energy Storage Converter under Time-sharing Operation Mode

The technology of energy storage has attracted more and more attention, where the two-stage energy storage converter is flexible and can be utilized to realize power quality improvement in grid-connected mode and provide emergency power supply in off-grid mode. Under the most of existing control strategies, the battery must keep working in both modes to balance the power flow, leading to battery life reduction. To solve above-mentioned problem, a timesharing operation mode is proposed in this paper. However, it is difficult for converter to achieve a seamless transfer between grid-connected and off-grid mode, because both the front-stage DC/DC converter and the battery are in a standby state. Therefore, an improved mode transfer strategy under time-sharing operation mode is further proposed to solve this issue. Finally, a prototype of the energy storage converter is developed, and the effectiveness of the control strategy is verified by simulation and experiment results.