A control strategy for paralleled bi-directional DC-DC converters used in energy storage systems

摘要

According to the control requirements of modular power used in energy storage systems, a parallel control strategy for bi-directional DC-DC converter is proposed and applied to the bi-directional DC-DC converter combined by current-fed half bridge and voltage-fed half bridge. While converters operate in parallel, the master-slave control based on digital communications can solve the problem of unequal current distribution caused by different parasitic parameters between parallel modules, and the strategy is with strong anti-interference ability. When running, each slave module will modify the reference of its own internal current loop by comparing its bus side current with the master module's bus side current via its current-sharing loop, so that the current sharing at the DC bus side can be achieved. Meanwhile, with the auto-master-selected strategy, a new master module will arise immediately when the former master module fails, which solves the problem of system failure when master module breaks down with traditional master-salve control. The simulation and experimental results prove the validity of the parallel control strategy.