Method and apparatus for estimating state of charge of secondary battery
First Claim
1. A method for estimating a state of charge of a secondary battery, comprising the steps of:
- preparing a switch in a charge/discharge path of the secondary battery;
turning on the switch to connect the charge/discharge path of the secondary battery;
calculating a no-load voltage of the secondary battery when the charge/discharge path of the secondary battery is in a connected state;
turning off the switch to disconnect the charge/discharge path of the secondary battery;
measuring an open-circuit voltage of the secondary battery when the charge/discharge path of the secondary battery is in a disconnected state;
storing a polarized voltage of the secondary battery;
calculating an electromotive force of the secondary battery by subtracting the stored polarized voltage from one of the calculated no-load voltage and the measured open-circuit voltage; and
estimating the state of charge of the secondary battery based on the calculated electromotive force.
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Accused Products
Abstract
When a power switch portion 10 is in an open state and a charge/discharge path of the secondary battery 100 is in a disconnected state, an electromotive force calculation portion 109 calculates a battery electromotive force Veq by subtracting a polarized voltage Vpol stored in a polarized voltage storage portion 113 from an open-circuit voltage OCV measured by a voltage measurement portion 102. Based on the electromotive force, a state-of-charge estimation portion 110 estimates a state of charge SOC. Thus, a polarized voltage to be considered for the estimation of SOC can be limited. The state of charge (SOC) of a secondary battery can be estimated with high accuracy and quickly.
11 Citations
20 Claims
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1. A method for estimating a state of charge of a secondary battery, comprising the steps of:
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preparing a switch in a charge/discharge path of the secondary battery;
turning on the switch to connect the charge/discharge path of the secondary battery;calculating a no-load voltage of the secondary battery when the charge/discharge path of the secondary battery is in a connected state; turning off the switch to disconnect the charge/discharge path of the secondary battery; measuring an open-circuit voltage of the secondary battery when the charge/discharge path of the secondary battery is in a disconnected state; storing a polarized voltage of the secondary battery; calculating an electromotive force of the secondary battery by subtracting the stored polarized voltage from one of the calculated no-load voltage and the measured open-circuit voltage; and estimating the state of charge of the secondary battery based on the calculated electromotive force. - View Dependent Claims (3, 4, 5, 6, 7)
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2. A method for estimating a state of charge of a secondary battery, wherein the secondary battery is used in an intermediately charged state as a power source for a motor and a drive source for a load, the method comprising the steps of:
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preparing a switch in a charge/discharge path of the secondary battery; turning on the switch to connect the charge/discharge path of the secondary battery; calculating a no-load voltage of the secondary battery when the charge/discharge path of the secondary battery is in a connected state; turning off the switch to disconnect the charge/discharge path of the secondary battery; measuring an open-circuit voltage of the secondary battery when the charge/discharge path of the secondary battery is in a disconnected state; storing a polarized voltage of the secondary battery; calculating an electromotive force of the secondary battery by subtracting the stored polarized voltage from one of the calculated no-load voltage and the measured open-circuit voltage; and calculating the state of charge of the secondary battery based on the calculated electromotive force. - View Dependent Claims (15, 16, 17)
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8. An apparatus for estimating a state of charge of a secondary battery, comprising:
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a switch provided in a charge/discharge path of the secondary battery; a voltage measurement portion for turning off the switch to disconnect the charge/discharge path of the secondary battery and measuring an open circuit voltage of the secondary battery when the charge/discharge path of the secondary battery is in a disconnected state; a no-load voltage calculation portion for calculating a no-load voltage of the secondary battery when the switch is turned on and the charge/discharge path of the secondary battery is in a connected state; a polarized voltage storage portion for storing a polarized voltage of the secondary battery; an electromotive force calculation portion for calculating an electromotive force of the secondary battery by subtracting the polarized voltage stored in the polarized voltage storage portion from one of the no-load voltage calculated by the no-load voltage calculation portion and the open-circuit voltage measured by the voltage measurement portion; and a state-of-charge estimation portion for estimating the state of charge of the secondary battery based on the electromotive force from the electromotive force calculation portion. - View Dependent Claims (10, 11, 12, 13, 14)
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9. An apparatus for estimating a state of charge of a secondary battery, wherein the secondary battery is used in an intermediately charged state as a power source for a motor and a drive source for a load, the apparatus comprising:
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a switch provided in a charge/discharge path of the secondary battery; a voltage measurement portion for turning off the switch to disconnect the charge/discharge path of the secondary battery and measuring an open circuit voltage of the secondary battery when the charge/discharge path of the secondary battery is in a disconnected state; a no-load voltage calculation portion for calculating a no-load voltage of the secondary battery when the switch is turned on and the charge/discharge path of the secondary battery is in a connected state; a polarized voltage storage portion for storing a polarized voltage of the secondary battery; an electromotive force calculation portion for calculating an electromotive force of the secondary battery by subtracting the polarized voltage stored in the polarized voltage storage portion from one of the no-load voltage calculated by the no-load voltage calculation portion and the open-circuit voltage measured by the voltage measurement portion; and a state-of-charge estimation portion for estimating the state of charge of the secondary battery based on the electromotive force from the electromotive force calculation portion. - View Dependent Claims (18, 19, 20)
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Specification