Method and apparatus for estimating terminal voltage of battery, method and apparatus for computing open circuit voltage of battery, and method and apparatus for computing battery capacity
First Claim
1. A method for estimating a terminal voltage of a battery comprising the steps of:
- periodically measuring a terminal voltage and a discharge current of a battery that supplies an electric power to loads in a vehicle;
calculating a voltage-current characteristic expressing a correlation between the terminal voltage and the discharge current; and
estimating an estimated voltage that is an estimated terminal voltage of the battery in a constant load discharging state thereof from the voltage-current characteristic, wherein when the battery carries out a constant load discharge with a current value large enough to cancel a charge-side polarization arisen in the battery at least just before the discharge, the voltage-current characteristic including an influence of a polarization is calculated from the terminal voltage and the discharge current of the battery, which are periodically measured while the discharge current of the constant load discharge decreases from the maximum current value, the voltage-current characteristic including the influence of the polarization is shifted in the direction of a voltage coordinate axis so that a voltage value at a reference current value lower than the maximum current value in the voltage-current characteristic including the influence of the polarization agrees with a reference voltage value at the reference current value in the voltage-current characteristic, which does not include the influence of the polarization but depends only on a pure resistance component of the battery, and a voltage value corresponding to a predetermined imaginary current value in the voltage-current characteristic including the influence of the polarization shifted in the direction of the voltage coordinate axis is estimated as a value of the estimated voltage.
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Abstract
A method and an apparatus for computing a charging state of a battery without being affected by an influence of polarization are provided. First computing means computes a voltage-current characteristic including the influence of the polarization during an decrease of a discharge current of the battery on the basis of a terminal voltage and discharge current measured while the battery carries out a constant load discharge with a current value large enough to cancel a charge-side polarization arisen in the battery at least just before the discharge. A second computing means shifts the voltage-current characteristic to a specific extent in the direction of a voltage coordinate axis. A residual voltage drop value in advance stored by storing means is added to a present estimated voltage value estimated by estimating means on the basis of the shifted voltage-current characteristic, thereby a present open circuit voltage of the battery is computed.
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Citations
20 Claims
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1. A method for estimating a terminal voltage of a battery comprising the steps of:
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periodically measuring a terminal voltage and a discharge current of a battery that supplies an electric power to loads in a vehicle;
calculating a voltage-current characteristic expressing a correlation between the terminal voltage and the discharge current; and
estimating an estimated voltage that is an estimated terminal voltage of the battery in a constant load discharging state thereof from the voltage-current characteristic, wherein when the battery carries out a constant load discharge with a current value large enough to cancel a charge-side polarization arisen in the battery at least just before the discharge, the voltage-current characteristic including an influence of a polarization is calculated from the terminal voltage and the discharge current of the battery, which are periodically measured while the discharge current of the constant load discharge decreases from the maximum current value, the voltage-current characteristic including the influence of the polarization is shifted in the direction of a voltage coordinate axis so that a voltage value at a reference current value lower than the maximum current value in the voltage-current characteristic including the influence of the polarization agrees with a reference voltage value at the reference current value in the voltage-current characteristic, which does not include the influence of the polarization but depends only on a pure resistance component of the battery, and a voltage value corresponding to a predetermined imaginary current value in the voltage-current characteristic including the influence of the polarization shifted in the direction of the voltage coordinate axis is estimated as a value of the estimated voltage. - View Dependent Claims (2, 3)
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4. A method for computing an open circuit voltage of a battery comprising the steps of:
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periodically measuring a terminal voltage and a discharge current of a battery that supplies an electric power to loads in a vehicle;
calculating a voltage-current characteristic expressing a correlation between the terminal voltage and the discharge current;
estimating an estimated voltage that is an estimated terminal voltage of the battery in a constant load discharging state thereof from the voltage-current characteristic; and
computing an open circuit voltage of the battery corresponding to a terminal voltage of the battery in an equilibrium state thereof on the basis of the estimated voltage, wherein when the battery carries out a constant load discharge with a current value large enough to cancel a charge-side polarization arisen in the battery at least just before the discharge, the voltage-current characteristic including an influence of a polarization is calculated from the terminal voltage and the discharge current of the battery, which are periodically measured while the discharge current of the constant load discharge decreases from the maximum current value, the voltage-current characteristic including the influence of the polarization is shifted in the direction of a voltage coordinate axis so that a voltage value at a reference current value lower than the maximum current value in the voltage-current characteristic including the influence of the polarization agrees with a reference voltage value at the reference current value in the voltage-current characteristic, which does not include the influence of the polarization but depends only on a pure resistance component of the battery, a difference value between the open circuit voltage value at the current being zero in the voltage-current characteristic not including the influence of the polarization and the estimated voltage value estimated on the basis of the voltage-current characteristic including the influence of the polarization shifted in the direction of the voltage coordinate axis is in advance calculated as a residual voltage drop value due to an influence of a residual polarization upon a completion of the discharge of the battery, thereafter, whenever the battery carries out a constant load discharge with a current value large enough to cancel a charge-side polarization arisen in the battery at least just before the discharge, the voltage-current characteristic including the influence of the polarization is newly calculated from the terminal voltage and the discharge current of the battery periodically measured during the constant load discharge, the newly calculated voltage-current characteristic including the influence of the polarization is shifted in the direction of a voltage coordinate axis so that a voltage value at the reference current value in the newly calculated voltage-current characteristic including the influence of the polarization agrees with the reference voltage value in the voltage-current characteristic not including the influence of the polarization when the voltage-current characteristic including the influence of the polarization is newly calculated, a present estimated voltage is estimated on the basis of the newly calculated voltage-current characteristic including the influence of the polarization shifted in the direction of the voltage coordinate axis, and a present open circuit voltage is computed by adding the residual voltage drop value to the present estimated voltage value. - View Dependent Claims (5, 6, 7, 8, 9, 10)
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11. An apparatus for estimating a terminal voltage of a battery executing the steps of:
- periodically measuring a terminal voltage and a discharge current of a battery that supplies an electric power to loads in a vehicle;
calculating a voltage-current characteristic expressing a correlation between the terminal voltage and the discharge current; and
estimating an estimated voltage that is an estimated terminal voltage of the battery in a constant load discharging state thereof from the voltage-current characteristic,the apparatus comprising;
first computing means for computing a voltage-current characteristic including an influence of a polarization from a terminal voltage and a discharge current of the battery periodically measured after the discharge current of the battery starts decreasing from a maximum current value, in a constant load discharge that the battery carries out with a current value large enough to cancel a charge-side polarization arisen in the battery at least just before the discharge, second computing means for computing a voltage-current characteristic including an influence of a polarization shifted in the direction of a voltage coordinate axis so that a voltage value at a reference current value lower than the maximum current value in the voltage-current characteristic including the influence of the polarization computed by the first computing means agrees with a reference voltage value at the reference current value in the voltage-current characteristic, which does not include the influence of the polarization but depends only on a pure resistance component of the battery, when the first computing means computes the voltage-current characteristic including the influence of the polarization, and estimating means for estimating a voltage value corresponding to a predetermined imaginary current value in the voltage-current characteristic including the influence of the polarization shifted in the direction of the voltage coordinate axis computed by the second computing means is estimated as a present value of the estimated voltage of the battery. - View Dependent Claims (12, 13, 15, 16, 17, 18, 19, 20)
- periodically measuring a terminal voltage and a discharge current of a battery that supplies an electric power to loads in a vehicle;
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14. An apparatus for computing an open circuit voltage of a battery executing the steps of:
- periodically measuring a terminal voltage and a discharge current of a battery that supplies an electric power to loads in a vehicle;
calculating a voltage-current characteristic expressing a correlation between the terminal voltage and the discharge current;
estimating an estimated voltage that is an estimated terminal voltage of the battery in a constant load discharging state thereof from the voltage-current characteristic; and
computing an open circuit voltage of the battery corresponding to a terminal voltage of the battery in an equilibrium state thereof on the basis of the estimated voltage,the apparatus comprising;
storing means for storing a residual voltage drop value due to a residual polarization upon a completion of the discharge when the battery carries out a constant load discharge with a current value large enough to cancel a charge-side polarization arisen in the battery at least just before the discharge;
first computing means for computing the voltage-current characteristic including an influence of a polarization from the periodically measured terminal voltage and discharge current of the battery after the discharge current of the battery starts decreasing from a maximum current value, during the constant load discharge that the battery carries out with a current value large enough to cancel a charge-side polarization arisen in the battery at least just before the discharge;
second computing means for computing a voltage-current characteristic including the influence of the polarization shifted in the direction of a voltage coordinate axis so that a voltage value at a reference current value lower than the maximum current value in the voltage-current characteristic including the influence of the polarization, which is computed by the first computing means, agrees with a reference voltage value at the reference current value in the voltage-current characteristic, which does not include the influence of the polarization but depends only on a pure resistance component of the battery, when the first computing means computes the voltage-current characteristic including the influence of the polarization; and
estimating means for estimating a present estimated voltage of the battery on the basis of the voltage-current characteristic including the influence of the polarization shifted in the direction of a voltage coordinate axis computed by the second computing means, wherein the storing means in advance stores a difference value between a value of the estimated voltage in advance estimated on the basis of an in advance computed voltage-current characteristic including the influence of the polarization sifted in the direction of a voltage coordinate axis, which is obtained by shifting the in advance computed voltage-current characteristic including the influence of the polarization in the direction of the voltage coordinate axis, so that a voltage value at the reference current value in the in advance computed voltage-current characteristic including the influence of the polarization agrees with the reference voltage value in the in advance computed voltage-current characteristic not including the influence of the polarization and a value of the open circuit voltage at the current being zero in the in advance computed voltage-current characteristic not including the influence of the polarization, and a present open circuit voltage is computed by adding the residual voltage drop value in advance stored by the storing means to the present estimated voltage value estimated by the estimating means.
- periodically measuring a terminal voltage and a discharge current of a battery that supplies an electric power to loads in a vehicle;
Specification