Abstract: A parameter estimation device using a filter includes a preprocessing computing circuit, a state estimating circuit and a state-of-charge estimating circuit. A low-pass filter of the preprocessing computing circuit transfers the voltage preprocessing value and the current preprocessing value from inputted discharge-and-charge current value and terminal voltage value, respectively. The state estimating circuit estimates parameters of a state equation of a battery equivalent model based on the battery equivalent model containing a resistance and a capacitor from the voltage preprocessing value and the current preprocessing value inputted. The state-of-charge estimating circuit estimates the state of charge from state quantity obtained. The time constant varies in such a way that the higher the temperature and the state of charge becomes the smaller the time constant becomes.

Abstract: A parameter estimation device using a filter has a preprocessing computing means 6, a state estimating means 7 and a state-of-charge estimating means 9. A low-pass filter 61 of the preprocessing computing means 6 transfers voltage preprocessing value Vp and current preprocessing value Ip from inputted discharge-and-charge current value I and terminal voltage value V, respectively. The state estimating means 7 estimates parameters of a state equation of a battery equivalent model 7A based on the battery equivalent model 7A containing a resistance and a capacitor from the voltage preprocessing value and the current preprocessing value inputted from the means 6. The state-of-charge estimating means 9 estimates the state of charge from state quantity obtained by the means 7. The time constant varies in such a way that the higher the temperature and the state of charge SoC becomes the smaller the time constant becomes.