The development of distributed energy resources brings significant advantages to bipolar DC microgrids.Due to load asymmetry，voltage imbalance may occur between the positive and negative poles of a bipolar DC microgrid.Voltage balancers have therefore been introduced and are generally classified into centralized and distributed configurations.A centralized voltage balancer cannot address voltage imbalance caused by long-distance power lines or terminal loads，while a distributed voltage balancer increases system cost due to the construction of additional facilities.To overcome these drawbacks，energy storage systems can be integrated into bipolar DC microgrids.However，this approach requires separate installation at each voltage pole.In this paper，a voltage balancing method is proposed that integrates the functions of a bidirectional converter and a voltage balancer into a single energy storage system.By controlling the charging and discharging of the energy storage battery，the proposed system is able to store and supply power while simultaneously mitigating the voltage imbalance between the positive and negative poles.Meanwhile，the number of power conversion stages is effectively reduced，thus improving the operational reliability of the bipolar DC microgrid.The effectiveness of the proposed method is verified through simulation studies and experiments conducted on a 4 kW rated laboratory prototype.