STATE ESTIMATING DEVICE FOR SECONDARY BATTERY

摘要

A diffusion estimation unit (100) follows a diffusion equation in an active material that is represented by a polar coordinate to estimate a distribution in concentration of lithium in the active material. An open circuit voltage estimation unit (110) obtains an open circuit voltage (U(¸)) in accordance with a local SOC(¸) based on a concentration of lithium obtained at an interface of the active material as estimated by the diffusion estimation unit (100). A current estimation unit (120) uses a battery's voltage (V(t)) measured by a voltage sensor, the estimated open circuit voltage (U(¸)), and a parameter value that is set for the battery by a battery parameter value setting unit (130), and follows a voltage-current relationship model expression simplified from an electrochemical reaction expression to estimate the battery's current density (I(t)). A boundary condition setting unit (140) sequentially sets a boundary condition for the diffusion equation of the diffusion estimation unit (100) for the active material's interface, as based on the battery's estimated current density (I(t)). Thus a battery model that allows an internal state to be estimated based on an electrochemical reaction dynamically and can also achieve an alleviated operating load can be used to estimate a state of a secondary battery.