Virtual Resistance Control for an Active Battery Management System

A virtual resistance control scheme is proposed for an active state-of-charge (SOC) balancing system within a behind-the-meter-storage (BTMS) battery pack. The proposed control enables the balancing system converters to simultaneously track a reference current while also regulating a shared 12 V bus. This enables the system to balance the cell SOCs while supporting auxiliary system loads on the 12 V bus. The advantage of the virtual resistance technique lies in its robustness to the actual resistances of the system. Without virtual resistance, the reference current tracking and 12 V bus load sharing among the converters would be dictated by the varying resistances between each converter and the 12 V bus, which are unequal and difficult to measure accurately. However, by applying the virtual resistance technique, these differences are negated such that the expected reference current tracking and equal load sharing are achieved.