| 摘要 |
PROBLEM TO BE SOLVED: To accurately estimate residual capacity by measuring battery voltage and battery current of a secondary battery, calculating the battery voltage from an equivalent circuit model of the secondary battery including a part represented by a separated diffusion equation where a charge diffusion effect is radially equally divided into N with setting a positive electrode active material particles to be spherical, and correcting a current integrated value based on a comparing result with the measured battery voltage. SOLUTION: An equivalent circuit model of the secondary battery including a part represented by a separated diffusion equation of an equation I (where, q is charge, D is diffusion coefficient, andΔx is r/N) is created. Battery current I (k) and battery voltage V are measured, and the current is integrated to provide discharge capacity Q. A voltage change Vz is calculated with an equation III, a battery voltage Vm is calculated with an equation IV, a correction amount Qc is provided with an equation V, the discharge capacity Q is corrected, and a charge state (SOC) is calculated with an equation II. In the equations, I is battery current, E is electromotive force, Rs is resistance of collector or electrolyte, Cd1 is capacity of an electric double layer, Rt is charge movement reaction resistance, and Ts is sampling period.
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