Charged state estimating device and charged state estimating method of secondary battery
First Claim
1. A device for estimating a charged state of a secondary battery provided with a detector capable of detecting an input/output current, an output voltage and a battery temperature, comprising:
- a characteristic storing means for storing a characteristic relation between an open circuit voltage and a remaining capacity of said secondary battery;
a stable state determining means for determining whether said secondary battery operates in a stable state in which said input/output current is maintained not higher than a limit current set in accordance with said battery temperature for at least a voltage stabilizing period set in accordance with said battery temperature, wherein said limit current increases as said battery temperature increases; and
a first charged state estimating means for estimating the remaining capacity of said secondary battery based on the characteristic relation stored in said characteristic storing means, regarding said output voltage as said open circuit voltage, when said secondary battery is determined to be operating in said stable state.
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Abstract
When a battery current is not larger than a limit current set depending on the battery temperature and is flowing continuously for a predetermined time set depending on the battery temperature or longer, a decision is made that a secondary battery is in stable state. When the secondary battery is in stabilized state, the battery voltage is considered to be equal to the open circuit voltage and SOC estimation is performed based on the open circuit voltage-SOC characteristics. When the product of the internal resistance of the secondary battery and the limit current is made substantially constant (constant voltage) by setting the limit current in association with temperature dependence of the internal resistance, estimation error can be kept within a predetermined range in the stabilized state even if SOC estimation is performed while the battery voltage is assumed as the open circuit voltage. Consequently, SOC can be estimated with high precision within a predetermined error by a simple and reliable system under stabilized state.
42 Citations
12 Claims
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1. A device for estimating a charged state of a secondary battery provided with a detector capable of detecting an input/output current, an output voltage and a battery temperature, comprising:
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a characteristic storing means for storing a characteristic relation between an open circuit voltage and a remaining capacity of said secondary battery; a stable state determining means for determining whether said secondary battery operates in a stable state in which said input/output current is maintained not higher than a limit current set in accordance with said battery temperature for at least a voltage stabilizing period set in accordance with said battery temperature, wherein said limit current increases as said battery temperature increases; and a first charged state estimating means for estimating the remaining capacity of said secondary battery based on the characteristic relation stored in said characteristic storing means, regarding said output voltage as said open circuit voltage, when said secondary battery is determined to be operating in said stable state. - View Dependent Claims (2, 3, 4, 5, 6, 11)
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7. A method of estimating a charged state of a secondary battery provided with a detector capable of detecting an input/output current, an output voltage and a battery temperature, comprising:
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a stable state determining step of determining whether said secondary battery operates in a stable state in which said input/output current is maintained not higher than a limit current set in accordance with said battery temperature for at least a voltage stabilizing period set in accordance with said battery temperature, wherein said limit current increases as said battery temperature increases; and a first charged state estimating step of estimating the remaining capacity of said secondary battery based on a characteristic relation between an open circuit voltage and a remaining capacity of said secondary battery, regarding said output voltage as the open circuit voltage of said secondary battery, when said secondary battery is determined to be operating in the stable state. - View Dependent Claims (8, 9, 10, 12)
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Specification