| 摘要 |
In the present invention, a circuit selection unit (13) turns switches (S1, S2) on and off so that the resistance of a charge and discharge circuit (17) changes at least once while an electric storage device starts to be charged in a state where the voltage of the electric storage device (2) is the upper limit voltage, whereupon the voltage reaches the lower limit voltage. An amount of electricity estimation unit (14) computes the amount of electricity by integrating over time the current during the time period from the discharge-start time point to an arbitrarily determined time point, and computes the relationship between the amount of electricity and the voltage of the electric storage device (2). An internal resistance estimation unit (15) computes the internal resistance on the basis of the voltage and current of the electric storage device (2) at points in time where the resistance is different. An electric energy estimation unit (16) computes the relationship between the amount of electricity and the open voltage on the basis of the relationship between the amount of electricity and the voltage, and the current and internal resistance of the electric storage device (2). When the electric storage device (2) is charged and discharged, the electric energy estimation unit (16) estimates the electric energy of the electric storage device (2) on the basis of the relationship between the amount of electricity and the open voltage, the internal resistance, and the charge and discharge current. |
