Battery state estimation apparatus

A battery state estimation apparatus which estimates a state of a secondary battery based on a battery model of the secondary battery, wherein

• the battery model comprises:
• a DC resistance model which expresses DC resistance of the secondary battery;
• a reaction resistance model which expresses reaction resistance of the secondary battery and is derived from a Butler-Volmer equation, and which includes a reaction resistance parameter correlated with an exchange current density;
• and
• a diffusion resistance model which is an equivalent circuit model in which a plurality of parallel connections of a resistor and a capacitor are connected in series, and expresses diffusion resistance of the secondary battery, the diffusion resistance including a common first parameter which determines a resistance value of each of the resistors and capacitance of each of the capacitors, and a common second parameter which determines the capacitance of each of the capacitors,
• the apparatus comprising:
• a DC information storage section which stores information on the DC resistance related to temperature of the secondary battery;
• a reaction information storage section which stores information on the reaction resistance parameter related to the temperature of the secondary battery;
• a diffusion information storage section which stores information on each of the first parameter and the second parameter related to the temperature of the secondary battery;
• and
• a state estimation section which calculates the DC resistance, the reaction resistance parameter, the first parameter, and the second parameter from the information stored in the DC information storage section, the reaction information storage section, and the diffusion information storage section, by using the temperature of the secondary battery as input, and estimates the state of the secondary battery based on the calculated DC resistance, reaction resistance parameter, first parameter, and second parameter.