US 12,248,027 B2
Method for determining the value of a parameter related to the state of health of an electrochemical cell in a battery, system for electronic management of a battery, and corresponding battery
Sebastien Laurent, Merignac (FR); Nathalie Legrand, Burges (FR); Sebastien Benjamin, Leognan (FR); and Cedric Gousset, Bordeaux (FR)
Assigned to SAFT, Levallois-Perret (FR)
Appl. No. 17/787,022
Filed by SAFT, Levallois-Perret (FR)
PCT Filed Dec. 17, 2020, PCT No. PCT/EP2020/086888
§ 371(c)(1), (2) Date Jun. 17, 2022,
PCT Pub. No. WO2021/123063, PCT Pub. Date Jun. 24, 2021.
Claims priority of application No. 1915283 (FR), filed on Dec. 20, 2019.
Prior Publication US 2023/0032837 A1, Feb. 2, 2023
Int. Cl. G01R 31/392 (2019.01); G01R 31/367 (2019.01); G01R 31/3842 (2019.01); G01R 31/389 (2019.01); H02J 7/00 (2006.01)
CPC G01R 31/392 (2019.01) [G01R 31/367 (2019.01); G01R 31/3842 (2019.01); G01R 31/389 (2019.01); H02J 7/0048 (2020.01)] 10 Claims
OG exemplary drawing
 
1. A method for determining, without use of current pulses, a resistance, R, of at least one electrochemical cell of a battery, the resistance R reflecting a state of health, SOH, of the electrochemical cell, the electrochemical cell being of an LiFePO4 type or an LiMnFePO4 type exhibiting a value of open circuit voltage, OCV, which for the LiFePO4 type or an LiMnFePO4 type of the electrochemical cell, is constant regardless of a degree of ageing of the electrochemical cell and consequently of the state of health, SOH, over a unique region of interest [SOCmin, SOCmax] of state of charge, SOC, having a lower bound SOCmin and an upper bound SOCmax and being comprised in an interval [44%, 60%], which is from 44% to 60% inclusive, of SOC of the at least one electrochemical cell, the method comprising the steps of:
initially providing a table associating values for the state of charge, SOC, with values for the open circuit voltage, OCV, of said at least one electrochemical cell, each value, of the values, for the state of charge, SOC, being associated with a value for an electric charge, Ah,
determining, in a first determination step, a value of electric capacity, C, of the at least one electrochemical cell,
determining in a second determination step a value, of the values, for the state of charge, SOC, of the electrochemical cell, expressed as a percentage of a maximum state of charge from at least one of:
a relation SOC=1−Ah/C, where Ah is the electric charge of the at least one electrochemical cell expressed in Ampere-hour under discharge of said electrochemical cell, and
a relation SOC=Ah/C, where Ah is electric charge of the at least one electrochemical cell expressed in Ampere-hour under charge of said electrochemical cell,
implementing a verification step comprising determining:
whether the determined value for the state of charge, SOC, falls within said unique region of interest ([SOCmin, SOCmax]) comprised in the interval [44%, 60%] of SOC, and
repeating, as long as a result of said verification step is not positive, the first determination step, the second determination step, and the verification step; and
calculating a value of the resistance, R, using a relation R=(U−OCV)/I, where U and I are respective voltage and current values at the terminals of the at least one electrochemical cell, and, in the relation, the OCV is a constant value of the open circuit voltage, OCV, over the region of interest [SOCmin, SOCmax], taken from said table associating values for the state of charge, SOC, with the values for the open circuit voltage, OCV.