BATTERY MANAGEMENT SYSTEM, BATTERY PACK, ELECTRIC VEHICLE, AND BATTERY MANAGEMENT METHOD

A battery management system, including: a current measuring unit measuring a cell current (CC) flowing through battery cells (BCs) in series, a voltage measuring unit measuring a cell voltage of each BC, and a control unit to: classify the BCs into at least one group based on a state of charge (SOC) of each BC estimated in a previous cycle (PCY), estimate an average polarization voltage of a current cycle (CCY) of each group, based on an average SOC of the PCY, a first CC of each group, and a second CC of each group, using a first Kalman filter, the first CC being measured in the PCY, and the second CC being measured in the CCY, estimate the SOC of the CCY of each BC, based on the first CC, the second CC, and the average polarization voltage of the CCY of each group, using a second Kalman filter.