Charging rate estimating method, charging rate estimating unit and battery system
First Claim
1. The method for calculating charged rate of a secondary battery which supplies electric power to loads, comprising the steps of:
- measuring voltages of the secondary battery within predetermined period of time after termination of charge or discharge to obtain a plural measured voltages along time axis;
sequentially calculating the plural measured voltages to determine coefficients of a quadric or more exponential damping function which approximates time characteristic of an open circuit voltage of the secondary battery;
calculating a convergent value of the open circuit voltage of the secondary battery based on at least the coefficients determined; and
calculating the charged rate based on the convergent value of the open circuit voltage.
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Abstract
The method for calculating charged rate of a secondary battery is intended to calculate charged rate of a secondary battery which supplies electric power to loads, and comprises the step to measure voltage of the secondary battery more than once in a predetermined period of time after termination of charge or discharge, the step to determine the coefficients of a quadric or more exponential damping function which approximates the time characteristic of the open circuit voltage of the secondary battery by recursive calculation with the plural measured voltage values, and the step to calculate a convergent value of the open circuit voltage of the secondary battery from at least the exponential damping function with the coefficients determined above. Therefore, precise charged rate of the secondary battery can be calculated from the precise convergent value of the open circuit voltage
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Citations
17 Claims
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1. The method for calculating charged rate of a secondary battery which supplies electric power to loads, comprising the steps of:
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measuring voltages of the secondary battery within predetermined period of time after termination of charge or discharge to obtain a plural measured voltages along time axis;
sequentially calculating the plural measured voltages to determine coefficients of a quadric or more exponential damping function which approximates time characteristic of an open circuit voltage of the secondary battery;
calculating a convergent value of the open circuit voltage of the secondary battery based on at least the coefficients determined; and
calculating the charged rate based on the convergent value of the open circuit voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 17)
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8. An apparatus of calculating charged rate of a secondary battery, which calculates the charged rate of the secondary battery to supply at least a load with electrical power, comprising:
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a voltage sensor to measure voltage of the secondary battery;
a control part to execute and control the computing process for calculation of the charged rate; and
a storage part to store the voltage value output from the voltage sensor and the datum required for the computing process on the control part;
wherein the control part receives the output from the voltage sensor once or more within a predetermined period of time after termination of charge or discharge, stores the more than one voltage measurement value into the storage part, recursively calculates with the more than one voltage measurement value to be read from the storage part, determines the coefficients of a quadric or more exponential damping function to approximate the time characteristic of the open circuit voltage of the secondary battery, calculates a convergent value of the open circuit voltage based on the determined coefficients, and executes to calculating the charged rate from the convergent value. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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Specification