BATTERY SYSTEM WITH FUNCTION OF PREVENTING ABNORMAL VOLTAGE AT OUTPUT STAGE AND CONTROL METHOD THEREOF

A system for preventing an abnormal voltage of a battery at an output stage includes a battery management system (BMS), which includes: a plurality of voltage sensors configured to detect first voltages of a plurality of battery cells; an automatic cut-off switch configured to cut off power applied from the plurality of battery cells according to a first control signal from the BMS; a high-voltage interlock switch connected to the automatic cut-off switch and configured to operate at a second voltage that is a preset voltage or more; an active voltage switch configured to operate at a third voltage transmitted through the automatic shut-off switch to control the relay switch; and a controller configured to, in response to detecting a voltage, which is higher than a threshold voltage, among the first voltages by the voltage sensor, provide a cut-off control signal to the relay switch.