BALANCER DRIVING CONTROL OF BATTERY CELL VOLTAGE


The voltage of the battery cell has an excessively charged range and an excessively discharged range. When the voltage of the battery cell is excessively charged, or excessively discharged, the battery cell should dramatically be deteriorated. For this reason, the BMU controls the battery cell not to excessively be charged or excessively be discharged. When the drive battery is charged, the BMU should control the battery cell having the highest voltage not to be in excessively charged range. When the drive battery is discharged, the BMU should control the battery cell having the lowest voltage not to be in excessively discharged range. When the drive battery is repeatedly charged and discharged, the voltage should vary among the battery cells. If the voltage varies, some battery cells can reach the excessively charged range or the excessively discharged range faster than other battery cells. This causes the available capacity of the drive battery to decrease. For this reason, the BMU drives the balancer installed in the CMU under the specified conditions to reduce the difference in the voltage among the battery cells. This allows the available capacity of the drive battery to increase.


The difference among the cell voltages may exceed the specified value while the regular charge is performed. In such a case, the BMU should send the balancer drive enable signal and the target cell voltage to the CMU through the Bat-CAN. When receiving the signal, the CMU should drive the balancer so that the target cell voltage can be obtained.