Method and device for estimating open circuit voltage of battery
First Claim
1. A method of estimating an open circuit voltage of a battery for supplying electric power to a load, comprising the steps of:
- measuring and collecting a terminal voltage of the battery in an open circuit state in a specific cycle after completion of a charge or discharge of the battery;
computing a voltage value, to which a power approximation expression asymptotically approaches, as an assumed open circuit voltage of each time period from the collected terminal voltage, wherein the power approximation expression has an exponent of −
0.5 or about −
0.5 and is determined on the basis of the terminal voltage of each time period of a plurality of predetermined time periods; and
estimating the assumed open circuit voltage of a time period, in which its difference from the assumed open circuit voltage of a neighboring time period becomes minimum, as an open circuit voltage.
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Accused Products
Abstract
Measuring device measures a terminal voltage of the battery in an open circuit state in a specific cycle after completion of a charge or discharge of the battery and collecting device collects the measured terminal voltage. Computing device computes a voltage value, to which a power approximation expression asymptotically approaches, as an assumed open circuit voltage of each time period from the collected terminal voltage, wherein the power approximation expression has an exponent of −0.5 or about −0.5 and is determined on the basis of the terminal voltage of each time period of a plurality of predetermined time periods. The assumed open circuit voltage of a time period, in which its difference from the assumed open circuit voltage of a neighboring time period becomes minimum, is estimated as an open circuit voltage.
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Citations
16 Claims
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1. A method of estimating an open circuit voltage of a battery for supplying electric power to a load, comprising the steps of:
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measuring and collecting a terminal voltage of the battery in an open circuit state in a specific cycle after completion of a charge or discharge of the battery;
computing a voltage value, to which a power approximation expression asymptotically approaches, as an assumed open circuit voltage of each time period from the collected terminal voltage, wherein the power approximation expression has an exponent of −
0.5 or about −
0.5 and is determined on the basis of the terminal voltage of each time period of a plurality of predetermined time periods; and
estimating the assumed open circuit voltage of a time period, in which its difference from the assumed open circuit voltage of a neighboring time period becomes minimum, as an open circuit voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of estimating an open circuit voltage of a battery for supplying electric power to a load, comprising the steps of:
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measuring and collecting a terminal voltage of the battery in an open circuit state in a specific cycle after completion of a charge of the battery;
computing a voltage value, to which a power approximation expression asymptotically approaches, as an assumed open circuit voltage of each time period from the collected terminal voltage, wherein the power approximation expression has an exponent of −
0.5 or about −
0.5 and is determined on the basis of the terminal voltage of each time period of a plurality of predetermined time periods; and
estimating the assumed open circuit voltage of a time period, in which its difference from the assumed open circuit voltage of a neighboring time period becomes minimum, as an open circuit voltage, wherein on the basis of a difference value between the terminal voltage in an open circuit state for each time period and an assumed open circuit voltage, a predetermined power approximation expression having a negative exponent is determined, and the determination of the power approximation expression is carried out repeatedly by updating the assumed open circuit voltage until the exponent of the determined power approximation expression becomes −
0.5 or about −
0.5, thereby computing a voltage value to which the power approximation expression asymptotically approaches.- View Dependent Claims (9, 10, 11)
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12. A method of estimating an open circuit voltage of a battery for supplying electric power to a load, comprising the steps of:
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measuring and collecting a terminal voltage of the battery in an open circuit state in a specific cycle after completion of a discharge of the battery;
computing a voltage value, to which a power approximation expression asymptotically approaches, as an assumed open circuit voltage of each time period from the collected terminal voltage, wherein the power approximation expression has an exponent of −
0.5 or about −
0.5 and is determined on the basis of the terminal voltage of each time period of a plurality of predetermined time periods; and
estimating the assumed open circuit voltage of a time period, in which its difference from the assumed open circuit voltage of a neighboring time period becomes minimum, as an open circuit voltage, wherein on the basis of an absolute value of a value obtained by subtracting the assumed open circuit voltage from the terminal voltage in an open circuit state for each time period and on the basis of a difference value between the terminal voltage in an open circuit state for each time period and an assumed open circuit voltage, a predetermined power approximation expression having a negative exponent is determined, and the determination of the power approximation expression is carried out repeatedly by updating the assumed open circuit voltage until the exponent of the determined power approximation expression becomes −
0.5 or about −
0.5, thereby computing a voltage value to which the power approximation expression asymptotically approaches.- View Dependent Claims (13, 14, 15)
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16. A device for estimating an open circuit voltage of a battery for supplying electric power to a load, comprising:
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measuring means for measuring a terminal voltage of the battery in an open circuit state in a specific cycle after completion of a charge or discharge of the battery;
collecting means for collecting the terminal voltage of the battery in an open circuit state, which is measured by the measuring means; and
computing means for computing a voltage value, to which a power approximation expression asymptotically approaches, as an assumed open circuit voltage of each time period from the terminal voltage collected by the collecting means, wherein the power approximation expression has an exponent of −
0.5 or about −
0.5 and is determined on the basis of the terminal voltage of each time period of a plurality of predetermined time periods,wherein the assumed open circuit voltage of a time period, in which its difference from the assumed open circuit voltage of a neighboring time period becomes minimum, is estimated as an open circuit voltage.
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Specification