An Equalizing Charge Control Strategy to Extend Battery Cycle Life for Electric Vehicles

In electric vehicles,battery string with many cells in series connection can provide higher voltage.But for each cell,any slight voltage difference can be amplified in the charging and discharging cycles.Unbalanced cell voltage in battery string will give rise to serious over-charging or over-discharging,and decrease the total storage capacity and the battery cycle life.Therefore,maintaining cell voltage at an equal charge/discharge level is significant for enhancing the battery cycle life.Aiming at the dissipative equalization circuits,the circuit model of battery equalization charge was studied,and an equalization charge control strategy which can not only achieves quick charge but also increases the battery cycle life was proposed.According to the proposed charge control strategy,corresponding experiments were implemented based on 72 V/ 120 AH laid-acid battery,and the experimental results show its feasibility and effectiveness.