METHOD FOR IN SITU BATTERY DIAGNOSTIC BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY
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Abstract
The invention is a method for estimating the internal state of a system for the electrochemical storage of electrical energy, such as a battery. For various internal states of batteries of the same type as a battery being analysed, impedance measurements are carried out by adding an electrical signal to the current passing through the batteries. Then, an RC circuit is used to model the impedances. Next, a relationship is calibrated between the SoC (and/or the SoH) and the parameters of the RC circuit using multivariate statistical analysis. A measurement of the impedance of the battery under analysis is carried out which is modeled using the RC circuit. Finally, the relationship of the equivalent electric circuit defined for the battery being analysed is used to estimate the internal state of that battery.
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Citations
48 Claims
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1-14. -14. (canceled)
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15. A method for estimating an internal state of a first electrochemical system for storage of electrical energy in which at least one property relating to the internal state of the first electrochemical system is estimated from an electrical measurement obtained from impedance spectroscopy, comprising:
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measuring the at least one property relating to internal states of at least one second electrochemical system of a type identical to the first electrochemical system and performing an electrical measurement of the at least one property of the second electrochemical system at multiple frequencies using impedance spectroscopy; defining an equivalent electrical circuit comprising at least one parameter for modeling electrical responses of the second electrochemical system; calibrating a relationship between the at least one property and the at least one parameter by performing a statistical analysis of values of the at least one property and values of the at least one parameter; determining an electrical response of the first electrochemical system at multiple frequencies by determining the at least one parameter such that an electrical response of the equivalent electrical circuit is equivalent to the electrical response of the first electrochemical system; and estimating the internal state of the first electrochemical system by calculating the at least one property by use of the relationship. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A system for estimating an internal state of first electrochemical system for storage of electrical energy, comprising:
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a sensor including means for measuring electrical impedance of the first electrochemical system by use of impedance spectroscopy; a memory for storing a representation of an equivalent electrical circuit of at least one second electrochemical system for storage of electrical energy of a type identical to the first electrochemical system and a relationship between at least one property relating to an internal state of the first electrochemical system and at least one parameter of the equivalent electrical circuit with the relationship being calibrated from measurements of internal states of the at least one second electrochemical system of a type identical to the first electrochemical system; means for defining parameters of the first equivalent electrical circuit for modeling an electrical response of the first electrochemical system for storage of energy; and means for calculating the at least one property relating to the internal state of the first electrochemical system using the relationship. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48)
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Specification