Patent ID: 8063611
Filing Date: 2011-11-22
Classification: B60L,G01R,H01M,H02J,Y02E,Y02T

Abstract:
1. An electric storage device comprising: an electricity storing section for storing electric power; an electric current sensing section for sensing an electric current flowing through the electricity storing section; a DC blocking capacitor coupled to a positive electrode of the electricity storing section; a resistor coupled in series with the DC blocking capacitor and coupled to a negative electrode of the electricity storing section; an ON/OFF circuit coupled in parallel with the resistor such that first and second terminals of the ON/OFF circuit are connected to respective first and second terminals of the resistor; a peak voltage holding circuit; a peak current holding circuit coupled to the electric current sensing section; and a controller for controlling the peak voltage holding circuit, the peak current holding circuit, and the electric current sensing section, wherein the ON/OFF circuit is controlled, based on a condition where a direction of an electric current flowing from the positive electrode to the negative electrode of the electricity storing section is a positive direction, such that the ON/OFF circuit is turned on when the electric current flows in a negative direction or a voltage at a junction point between the DC blocking capacitor and the resistor is negative, and such that the ON/OFF circuit is turned off when the electric current flows in the positive direction or a voltage at the junction point between the DC blocking capacitor and the resistor is positive, and wherein an internal resistor of the electricity storing section is found based on a peak voltage resulting from the control and held by the peak voltage holding circuit as well as a peak current resulting from the control and held by the peak current holding circuit.