Method of and apparatus for measuring battery capacity by impedance spectrum analysis
First Claim
1. A method of measuring battery capacity by measurement and analysis of impedance spectrum, which is to measure a characteristic impedance spectrum of primary and secondary batteries and determine the battery capacity the method comprising the steps of:
- (1) measuring the characteristic impedance spectrum of a battery in a predetermined frequency region;
(2) determining one or more parameter from the measured impedance spectrum;
(3) monitoring in advance the correlation between the determined model parameter and the battery capacity measured by a real-time discharge technique; and
(4) determining the battery capacity from the characteristic impedance spectrum of a battery having an unknown capacity based on the monitored correlation.
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Abstract
Provided with a method of measuring battery capacity by impedance spectrum analysis, which is to measure a characteristic impedance spectrum of primary and secondary batteries and determine the battery capacity the method including the steps of: (1) measuring the characteristic impedance spectrum of a battery in a predetermined frequency region; (2) determining a parameter from the measured impedance spectrum; (3) monitoring in advance the correlation between the determined parameter and the battery capacity measured by a real-time discharge technique; and (4) determining the battery capacity from the characteristic impedance spectrum of a battery having an unknown capacity based on the monitored correlation.
50 Citations
11 Claims
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1. A method of measuring battery capacity by measurement and analysis of impedance spectrum, which is to measure a characteristic impedance spectrum of primary and secondary batteries and determine the battery capacity the method comprising the steps of:
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(1) measuring the characteristic impedance spectrum of a battery in a predetermined frequency region;
(2) determining one or more parameter from the measured impedance spectrum;
(3) monitoring in advance the correlation between the determined model parameter and the battery capacity measured by a real-time discharge technique; and
(4) determining the battery capacity from the characteristic impedance spectrum of a battery having an unknown capacity based on the monitored correlation. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for measuring battery capacity by impedance spectrum analysis, the apparatus comprising:
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a battery connector unit having a battery connected thereto;
a measurement unit for applying an input current corresponding to a digital input signal composed of a superposition of predefined finite multiple frequencies to both terminals of the battery via the battery connector unit, and converting input current and output voltage applied to both terminals of the battery into a digital signal continuously; and
a central control unit for storing the digital signal output from the measurement unit, converting the digital signal to a complex digital impedance expressed by a function of frequency by performing a Fourier transform, and fitting the complex impedance to a predefined model parameter or a plural of model parameters. - View Dependent Claims (8, 9, 10, 11)
a digital signal memory device for storing the digital input signal composed of a superposition of predefined finite multiple frequencies;
a constant current source for applying an input current corresponding to the digital input signal memorized in the digital signal memory device in advance to both terminals of the battery via the battery connector unit; and
an analog/digital converter for converting the input current and output voltage applied to both terminals of the battery to a digital signal continuously and inputting the digital signal to the central control unit.
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10. The apparatus as claimed in claim 7, wherein the central control unit comprises:
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a central processing unit for performing a measurement of the battery capacity;
a memory device for storing and outputting the digital signal of the input current and output voltage applied to both terminals of the battery from the plural meter units;
an I/O unit for outputting a predetermined control signal to the plural meter units and inputtung a predetermined measured signal from the plural meter units under the control of the central processing unit;
a Fourier transformer for Fourier transforming the measured value of the plural measurement units into a complex impedance expressed by a function of frequency under the control of the central processing unit; and
an impedance function fitting unit for converting the complex impedance Fourier transformed at the Fourier transformer into a predefined model parameter or a plural of model parameters.
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11. The apparatus as claimed in claim 8, wherein the measurement unit comprises:
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a digital signal memory device for storing the digital input signal composed of a superposition of predefined finite multiple frequencies;
a constant current source for applying an input current corresponding to the digital input signal memorized in the digital signal memory device in advance to both terminals of the battery via the battery connector unit; and
an analog/digital converter for converting the input current and output voltage applied to both terminals of the battery to a digital signal continuously and inputting the digital signal to the central control unit.
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Specification