STATE-OF-CHARGE ESTIMATION METHOD AND STATE-OF-CHARGE ESTIMATION DEVICE

摘要

Voltage-change convergence time (τ) taken from the termination of charging and discharging of a secondary battery until the convergence of change in open-circuit voltage is measured in advance for each combination of the state-of-charge of the secondary battery at a charging and discharging termination time and the temperature of the secondary battery at the charging and discharging termination time. When the charging and discharging of the secondary battery is terminated in actual use, voltage-change convergence time (τ) corresponding to the temperature and the state-of-charge based on the integrated current value at the charging and discharging termination time is selected and the selected voltage-change convergence time (τ) is applied to a voltage characteristic formula.

主权项

1. A state-of-charge estimation method for estimating a state of charge of a secondary battery by approximating a time change in an open-circuit voltage of the secondary battery after termination of charge and discharge by a voltage characteristic expression, and calculating the open-circuit voltage from the voltage characteristic expression where the secondary battery is stable,
the method comprising the steps of: measuring beforehand a voltage-change convergence time τ from termination of charge and discharge of the secondary battery until convergence of change in the open-circuit voltage, for each combination of state of charge of the secondary battery at the time of termination of charge and discharge and the temperature of the secondary battery at the time of termination of charge and discharge; and upon termination of charge and discharge of the secondary battery, selecting the voltage-change convergence time τ corresponding to the state of charge and the temperature at the time of termination of charge and discharge, and using the selected voltage-change convergence time τ in the voltage characteristic expression.