Electrochemical impedance spectroscopy in battery management systems
First Claim
1. A method of determining a State of Health (SoH) and/or State of Charge (SoC) of a rechargeable battery during charging and discharging of said battery, the method comprising the steps of:
- (a) generating a first excitation signal that is a continuously varying harmonic signal having a first frequency within a first selected frequency range;
(b) generating a second excitation signal that is a single frequency constant signal having a second frequency within a second selected frequency range that comprises frequencies that are higher than the frequencies in the first selected frequency range;
(c) applying said first and second excitation signals to said rechargeable battery;
(d) measuring a first response signal for said first excitation signal and a second response signal for said second excitation signal;
(e) calculating an Electrochemical Impedance (El) from the ratio between the first and second excitation signals and their respective first and second response signals; and
(f) determining at least one of the SoH and the SoC of the rechargeable battery by performing at least one of (i) a comparison of the calculated El to a circuit model for the battery, and (ii) a direct evaluation of characteristics of the EL.
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Abstract
The invention pertains to a method of determining the State of Health (SoH) and/or State of Charge (SoC) of a rechargeable battery during use of said battery, the method comprising the steps of: generating a first excitation signal within a first selected frequency range, generating a second excitation signal within a second selected frequency range, applying said first and second excitation signals on said rechargeable battery, measuring the response signal for each of said two excitation signals, and then calculate the Electrochemical Impedance (El) as the ratio between the excitation signals and respective response signals, and then determine the SoH and/or SoC of the rechargeable battery by comparing the calculated El to a circuit model for the battery and/or determining the SoH and/or SoC of the rechargeable battery by directly evaluating characteristics of the El. The invention also pertains to a battery management system configured for executing the steps of the method according to the invention.
22 Citations
16 Claims
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1. A method of determining a State of Health (SoH) and/or State of Charge (SoC) of a rechargeable battery during charging and discharging of said battery, the method comprising the steps of:
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(a) generating a first excitation signal that is a continuously varying harmonic signal having a first frequency within a first selected frequency range; (b) generating a second excitation signal that is a single frequency constant signal having a second frequency within a second selected frequency range that comprises frequencies that are higher than the frequencies in the first selected frequency range; (c) applying said first and second excitation signals to said rechargeable battery; (d) measuring a first response signal for said first excitation signal and a second response signal for said second excitation signal; (e) calculating an Electrochemical Impedance (El) from the ratio between the first and second excitation signals and their respective first and second response signals; and (f) determining at least one of the SoH and the SoC of the rechargeable battery by performing at least one of (i) a comparison of the calculated El to a circuit model for the battery, and (ii) a direct evaluation of characteristics of the EL. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification