Cell balancing control for serially connected lithium-ion batteries

In this paper, modified bidirectional Cûk converters are utilized as the equalizing circuits for battery cell balancing, and they are designed to be operated in discontinuous inductor conduction mode (DICM). A topology model of the serially connected battery pack with cell equalizers is developed here. Based on this topology model, an optimal balancing method is proposed to regulate the equalizing currents with coordinately controlling all converters. Simulation results indicate that the difference between the cells' state of charge (SOC) could converge to an acceptable range in a relatively short time under the optimal equalizing control.