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Method and apparatus for online determination of battery state of charge and state of health

  • US 9,157,966 B2
  • Filed: 11/25/2011
  • Issued: 10/13/2015
  • Est. Priority Date: 11/25/2011
  • Status: Active Grant
First Claim
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1. A system for determining on-line battery'"'"'s state of charge, the system comprising:

  • a measurement section having a voltage sensor, a current sensor and a temperature sensor, the measurement section adapted to take on-line measurements from the battery;

    a computer having a battery dynamic model stored in a non-volatile memory, the battery dynamic model including various values of parameters Rs, Cst, Rst, Clt and Rlt determined at various temperatures, terminal voltages and currents while the battery is off line, the parameters being elements of a battery model that includes;

    a resistance Rs in series with a first and a second RC branch;

    the first RC branch representing a polarization phenomenon for short time just after keeping the battery in rest;

    the first RC branch including a capacitor Cst connected in parallel with a resistor Rst;

    the second RC branch representing the polarization phenomenon for long time just after keeping the battery in rest;

    the second RC branch including a capacitor Clt connected in parallel with a resistor Rlt;

    a computer having a processor adapted to receive the on-line measurements from the measurement section and to calculate an open circuit voltage online, using an equation
    VOC=VBAT

    V
    R

    V
    P where VBAT

    Battery terminal voltage, Δ

    VR

    Voltage drop due to battery resistance, and Δ

    VP

    Voltage drop due to polarization phenomenon;

    wherein Δ

    VP is computed using an equation

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