Simulation-Based Analysis of Passive Balancing for Parallel Lithium-Ion Cells

The cell balancing in electric vehicles delivers the maximum energy into or out of the cell during charging or discharging. The proposed system simulates the passive cell balancing of a three-cell lithium-ion battery system by developing a Simulink model using the soc parameter. The initial State of Charge of the cells is 22%, 25%, and 27%. Voltage and current sensors monitor the state of each cell while a calibrated current source controls the rate of balancing depending on the SOC difference. To remove generated heat, convection heat transfer is employed to reduce thermal accumulation in resistors and nearby cells. SOC convergence is achieved where the balancing current decreases as the SOC levels approach an optimal level. This method is thus well suited for applications in which cost and low power consumption are desirable, and consistent performance.