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Method for estimating a quantity of a state of a battery

  • US 9,170,304 B2
  • Filed: 04/09/2009
  • Issued: 10/27/2015
  • Est. Priority Date: 04/11/2008
  • Status: Active Grant
First Claim
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1. A battery state detecting method for estimating at least a quantity of a state of a battery, at least a state of charge (SOC) and a state of health (SOH),whereinthe method comprises the steps of:

  • generating reference data associated with a reference relaxation function Fref(t), wherein the reference relaxation function Fref(t) approximates a variation of voltage Δ

    V(t) obtained by measuring values of an open circuit voltage (OCV) of the battery in a standard state of the battery during a predetermined cycle, and wherein the predetermined cycle is associated with a period from a time of completion of discharge or charge of the battery to a time when a measured value of the OCV substantially becomes constant;

    forming a relaxation function Fn(t) that approximates the variation voltage Δ

    V(t) based on a sum of at least a first relaxation function for a first reaction speed of the battery associated with an ion reaction and a second relaxation function for a second reaction speed of the battery associated with an electrolytic reaction; and

    estimating the quantity of the state of the battery after the completion of the charge or the discharge based on the relaxation function Fn (t) and the reference data associated with the reference relaxation function Fref(t), wherein the first relaxation function and the second relaxation function are optimized by dividing the variation voltage Δ

    V(t), which is approximated from the measured values of the OCV, into components corresponding to at least the first reaction speed and the second reaction speed, and SOCref and SOHiref are the SOC and an i-th SOH per reaction speed in the standard state of the battery, respectively, SOCn and SOHin are the SOC and a different i-th SOH per reaction speed after the completion of an n-th charge or discharge, respectively, g(T) is a function associated with dependency on temperature T, fin (t) is an i-th relaxation function per reaction speed fi(t) included in the relaxation function Fn(t), and firef(t) is an i-th reference relaxation function per reaction speed fi(t) included in the reference relaxation function Fref(t), andwherein the relaxation function per reaction speed fin (t) after the completion of the n-th charge or discharge is expressed as;


    fin(t)=fref(t)*(SOCn/SOCref)*(SOHin/SOHiref)*g(T).

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