Battery control apparatus, electric vehicle, and computer-readable medium storing a program that causes a computer to execute processing for estimating a state of charge of a secondary battery

Abstract

The present invention can speedily and accurately estimate an SOC of a secondary battery immediately after a charge/discharge operation resumes. A determination unit determines whether a dormant period is longer than a predetermined time in response to an initiation of power supply from a secondary battery to a motor generator. The dormant period is equivalent to the duration from a previous stop of power supply to a present initiation of power supply. If the dormant period is longer than the predetermined time, a state-of-charge estimating unit sets an initial SOC based on a peak battery voltage drop ΔVs and a peak discharge current Is, wherein the peak battery voltage drop ΔVs represents a difference between a battery voltage Vo measured before initiating power supply and a lowest battery voltage Vs measured after initiating power supply and the peak discharge current Is represents a maximum current value measured after initiating power supply. The state-of-charge estimating unit estimates a state of charge of the secondary batterybased on the initial SOC as a value effective immediately after initiating power supply.