Abstract:
Direct current electric springs (DCES), as a new way to solve the power quality problem caused by the uncertainty of the output of photovoltaic and wind power integrated into the DC microgrid, has the advantages of flexible configuration and small size. This paper proposed an extended-phase-shift (EPS) control strategy for DCES with parallel topology based on the triple active bridge (TAB). Compared with single-phase-shifting (SPS) control strategy, EPS can reduce the backflow power on the power supply side, increase the zero-voltage switching (ZVS) interval, reduce the current stress of the switching device, and reduce the photovoltaic power supply capacity and other advantages. Based on the EPS control, the ZVS of all the switching devices in the larger fluctuation range of the power supply side voltage of the DCES with parallel topology was realized, and the backflow power optimization control strategy was proposed. Finally, the correctness and effectiveness of the proposed EPS control strategy were verified.