STATE ESTIMATING DEVICE FOR SECONDARY BATTERY

摘要

A diffusion estimating unit (100) estimates a lithium concentration distribution in an active substance in accordance with such a diffusion equation in an active substance as is expressed by polar coordinates. A release voltage estimating unit (110) determines a release voltage (U(?)) in accordance with a local SOC (?) based on such a lithium concentration in an active substance boundary as is estimated by the diffusion estimating unit (100). A current estimating unit (120) estimates a battery current density (I(t)) in accordance with the voltage-current relation model formula simplified from the electrochemical reaction equation, by using a battery voltage (V(t)) measured by a voltage sensor, the estimated release voltage (U(?)), and the battery parameter value set by a battery parameter value setting unit (130). A boundary condition setting unit (140) sets the boundary conditions sequentially at the active substance boundary face of the diffusion equation of the diffusion estimating unit (100), on the basis of the estimated battery current density (I(t)). As a result, the internal state based on the electrochemical reaction can be dynamically estimated to perform the state estimation of the secondary battery using the battery model having a lightened calculation load.