Publication

Abstract : Electric vehicles (EVs) are clean substitutes for conventional vehicles. Battery management system (BMS) is the intelligence behind the EV battery packs. One of the key functions of BMS is cell balancing, which balances the battery cells voltages equally during charging. Most of today’s EVs are adopting a passive cell balancing scheme, which uses fixed dissipative resistors to remove the extra charge from the overcharged cell to balance the charge in all the cells equally. One of the main concerns about the passive balancer is the balancing time. The long balancing time is manageable if the vehicle is charged through conventional charging (5–6 h) system and cell imbalance is minimum. Under fast DC charging scenarios as well as maximum imbalance condition, passive balancing with a fixed resistor is not an optimum solution. Either for fresh cell or aged cell, the passive cell balancing with variable balancing resistor is used based on the balancing current requirement under slow or fast charging scenarios are implemented. The passive system with variable resistor outcome is compared using Matlab-Simscape.