Patent ID: 6664795
Filing Date: 2003-12-16
Classification: B60K,B60L,B60W,H02J,Y02T

Abstract:
A system for detecting remaining charge of an electric double layer capacitor, comprising:a current-voltage sensor which generates an output indicative of a terminal voltage across terminals of the capacitor and an output indicative of charge/discharge current charged into and discharged from the capacitor; an electronic control unit which inputs the outputs of the current-voltage sensor indicative of the terminal voltage and charge/discharge current and calculates a remaining charge of the capacitor based on a mathematical model having the remaining charge of the capacitor as a state variable, wherein the electronic control unit comprises: remaining charge calculating means for inputting the detected terminal voltage and charge/discharge current to a state equation constituting the mathematical model and for calculating the remaining charge of the capacitor; estimated terminal voltage calculating means for calculating a voltage drop across the capacitor based on the detected charge/discharge current and an internal resistance of the capacitor and for subtracting the calculated voltage drop from the calculated remaining charge to obtain an estimated terminal voltage of the capacitor; and remaining charge correcting means for calculating a product obtained by multiplying a difference between the detected terminal voltage and the estimated terminal voltage by a gain of an observer obtained from the state equation that estimates the state variable, and for correcting the remaining charge based on the calculated product.