Patent ID: 9641013
Date: 2017-05-02
CPC Classifications: H02J,Y02T

Claim:
1. A method of balancing rack voltages of a battery pack configured to have a structure in which a plurality of racks is connected in series or in parallel to each other, and a plurality of unit modules is connected in series to each other in each of the racks, the rack voltage balancing method comprising: (a) a voltage measurement step of measuring voltages of the racks; (b) an sorting step of sorting the racks in ascending powers based on the voltage values of the racks; (c) a comparison step of comparing a difference between a maximum voltage value and a minimum voltage value with a set voltage; (d) a charging count step of comparing the voltage values of the racks with a reference voltage to increase a charging count when the voltage values is less than the reference voltage and a discharging count step of comparing the voltage values of the racks with the reference voltage to increase a discharging count when the voltage values is greater than the reference voltage; and (e) a charging step of charging the racks if the charging count is greater than the discharging count and a discharging step of discharging the racks if the discharging count is greater than or equal to the charging count, wherein in a case in which, at step (c), the difference between the maximum voltage value and the minimum voltage value is lower than the set voltage, the racks are charged with the maximum voltage value without steps (d) and (e), and in a case in which, at step (c), the difference between the maximum voltage value and the minimum voltage value is higher than the set voltage, steps (d) and (e) are carried out.