Method and system for monitoring state of lead acid battery
First Claim
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1. A method of monitoring a state of a battery, comprising:
- determining a threshold value of an internal impedance of the battery;
preparing an expression indicating a correlation between a residual capacity of the battery and an internal impedance of the battery when the internal impedance is greater than the threshold value;
measuring the internal impedance of the battery;
determining an initial value of the residual capacity of the battery when the measured internal impedance is less than or equal to the threshold value; and
monitoring a value of the residual capacity with the expression when the measured internal impedance is greater than the threshold value.
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Abstract
In order to monitor a state of a battery, a threshold value of an internal impedance of the battery is first determined. It is prepared an approximate expression indicating a correlation between a residual capacity of the battery and an internal impedance of the battery which is greater than the threshold value. The internal impedance of the battery is then measured. When the measured internal impedance is the threshold value or less, the residual capacity is determined as an initial value. When the measured internal impedance is greater than the threshold value, the residual capacity is monitored with the approximate expression.
8 Citations
40 Claims
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1. A method of monitoring a state of a battery, comprising:
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determining a threshold value of an internal impedance of the battery;
preparing an expression indicating a correlation between a residual capacity of the battery and an internal impedance of the battery when the internal impedance is greater than the threshold value;
measuring the internal impedance of the battery;
determining an initial value of the residual capacity of the battery when the measured internal impedance is less than or equal to the threshold value; and
monitoring a value of the residual capacity with the expression when the measured internal impedance is greater than the threshold value. - View Dependent Claims (13, 14, 15, 16)
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2. A system of monitoring a state of a battery, comprising:
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a storage for storing a predetermined expression for calculating a correlation between a residual capacity of the battery and an internal impedance of the battery when the internal impedance of the battery is greater than a predetermined threshold value;
an instrument for measuring the internal impedance of the battery; and
a monitor for monitoring the residual capacity of the battery with the predetermined expression when the measured internal impedance is greater than the threshold value, and determining an initial value of the residual capacity of the battery when the measured internal impedance is less than or equal to the threshold value. - View Dependent Claims (17, 18, 19, 20)
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3. A method of monitoring a state of a battery, comprising:
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measuring an internal impedance of the battery each time a first time period is elapsed;
storing the measured internal impedance as time-serial impedance data;
monitoring a residual capacity of the battery;
gathering the time-serial impedance data during a second time period prior to a time point at which the monitored residual capacity is less than or equal to a threshold value;
obtaining an expression for calculating a correlation between the internal impedance and the residual capacity based on the gathered time-serial impedance data; and
predicting a residual lifetime of the battery based on the obtained expression. - View Dependent Claims (4, 21, 22, 23, 24)
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5. A method of monitoring a state of a battery, comprising:
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measuring an internal impedance of the battery each time a first time period is elapsed;
storing the measured internal impedance as time-serial impedance data;
obtaining an average value of the time-serial impedance data each time a second time period is elapsed;
comparing an average value of a certain second time period and a preceding second time period to obtain a changing rate of the average value; and
generating an alarm when the obtained changing rate is greater than or equal to a predetermined value. - View Dependent Claims (25, 26, 27, 28)
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6. A method of monitoring a state of a battery, comprising:
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measuring an internal impedance of the battery each time a first time period is elapsed;
storing the measured internal impedance as time-serial impedance data;
obtaining an average value of the time-serial impedance data each time a second time period is elapsed;
obtaining an expression indicating a correlation between the average value and an elapsed time in the second time period, based on the time-serial impedance data each time the second time period is elapsed;
predicting a time point at which a changing rate of the average value compared to at least one of a preceding average value is greater than or equal to a predetermined value, based on the expression; and
displaying the predicted time point as a residual lifetime of the battery. - View Dependent Claims (29, 30, 31, 32)
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7. A system of monitoring a state of a battery, comprising:
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an instrument for measuring an internal impedance of the battery each time a first time period is elapsed;
a storage for storing the measured internal impedance as time-serial impedance data;
a monitor for monitoring a residual capacity of the battery; and
a calculator for gathering the time-serial impedance data during a second time period prior to a time point at which the monitored residual capacity is less than or equal to a threshold value;
obtaining an expression indicating a correlation between the internal impedance and the residual capacity based on the gathered time-serial impedance data; and
predicting a residual lifetime of a battery based on the obtained expression. - View Dependent Claims (8, 33, 34, 35, 36)
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9. A system of monitoring a state of a battery, comprising:
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an instrument for measuring an internal impedance of the battery each time a first time period is elapsed;
a storage for storing the measured internal impedance as time-serial impedance data;
a calculator for obtaining an average value of the time-serial impedance data each time a second time period is elapsed;
a comparator for comparing an average value of a certain second time period and a preceding second time period to obtain a changing rate of the average value; and
an alarm for generating an alarm when the obtained changing rate is greater than or equal to a predetermined value. - View Dependent Claims (37, 38, 39, 40)
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10. A system of monitoring a state of a battery, comprising:
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an instrument for measuring an internal impedance of the battery each time a first time period is elapsed;
a storage for storing the measured internal impedance as time-serial impedance data;
a calculator for obtaining an average value of the time-serial impedance data each time a second time period is elapsed;
obtaining an expression indicating a correlation between the average value and an elapsed time in the second time period, based on the time-serial impedance data each time the second time period is elapsed; and
predicting a time point at which a changing rate of the average value is greater than or equal to a predetermined value, based on the expression; and
a display for displaying the predicted time point as a residual lifetime of the battery.
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11. A method of measuring an internal impedance of a battery, comprising:
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measuring an internal impedance and a temperature of the battery at the same time;
storing the measured internal impedance and the measured temperature as time-serial impedance data and time-serial temperature data;
obtaining a correction coefficient based on a correlation between the time-serial impedance data and the time-serial temperature data during a predetermined time period; and
correcting the measured internal impedance with the correction coefficient as a value at a reference temperature.
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12. A system for measuring an internal impedance of a battery, comprising:
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an instrument for measuring an internal impedance and a temperature of the battery at the same time;
a storage for storing the measured internal impedance and the measured temperature as time-serial impedance data and time-serial temperature data;
a calculator for obtaining a correction coefficient based on a correlation between the time-serial impedance data and the time-serial temperature data during a predetermined time period; and
a corrector for correcting the measured internal impedance with the correction coefficient as a value at a reference temperature.
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Specification