Diagnosis of energy storage systems during operation

Patent metadata

Field	Value
Publication number	US-2021181257-A1
Application number	US-202017117936-A
Country	US
Kind code	A1
Filing date	Dec 10, 2020
Priority date	Dec 11, 2019
Publication date	Jun 17, 2021
Grant date	—

Abstract

A method for determining an open circuit voltage of an electrochemical device, including: a. collecting measurement data of the device, the measurements i. including at least the current It and the voltage Ut at the terminals of the device, ii. being time-stamped, and iii. being acquired during an uninterrupted and operational functional period of the device; b. calculating, for a plurality of times t, iv. a corrected intensity by applying a correction function to the measured intensity It, and v. an instantaneous charge based on a time series of the corrected intensity so as to obtain, for each time t, a set of collected and calculated data; c. grouping the data sets into ranges of instantaneous charge values based on the charge value of each set; and d. separately for each group, calculating an open circuit voltage of the device.

First claim

1 . A method for determining an open circuit voltage of an electrochemical device, implemented by computer means, comprising:
a. collecting measurement data of the device, said measurements
i. including at least the current I t and the voltage U t at the terminals of the device,
ii. being time-stamped, and
iii. being acquired during an uninterrupted and operational functional period of the device;
b. calculating, for a plurality of times t,
iv. a corrected intensity I cor,t by applying a correction function to the measured intensity I t , and
v. an instantaneous charge Q t based on a time series of the corrected intensity I cor so as to obtain, for each time t, a set of collected and calculated data I t , U t , I cor,t , Q t ;
c. grouping the data sets into ranges of instantaneous charge values based on said charge value of each set; d. separately for each group, calculating an open circuit voltage of the device.

2 . The method according to claim 1 , further comprising, after calculating the open circuit voltages:
e. calculating a state of health of the device according to the following formula:

S

O

H

=

Q

1
→
2

,

ag



é

Q

1
→
2

,

ini

t

[

Math
.


7

]

where Q 1→2,agé corresponds to the charge difference Q between two data sets corresponding to two open circuit voltages COV 1 and COV 2 and where Q 1→2,init corresponds to the charge Q exchanged between the two open circuit voltages COV 1 and COV 2 in an initial state of the device for which the state of health is considered to be maximal.

3 . The method according to claim 1 , further comprising, after calculating the open circuit voltages:
f. subjecting the calculated open circuit voltages to an incremental capacity analysis so as to obtain a curve of characteristic patterns; g. comparing the obtained curve to reference curves corresponding to various states of health in order to identify the corresponding state of health.

4 . The method according to claim 1 , wherein the calculation step is carried out iteratively at each time t and wherein the calculation of the instantaneous charge Q t based on a time series of the corrected intensity I cor is implemented according to the following formula:
Q ( t )= Q ( t=t 0 )+∫ t 0 t I corr (τ) dτ   [Math. 3]

where Q(t=t 0 ) is a charge level relative to the initial charge level.

5 . The method according to claim 4 , wherein the calculation step further comprises:
vi. calculating a state of charge according to the following formula:

SOC
i

=

SOC

i
-
1

+

∫

i
-
1

i



α


(

I
i

)


d

t

Q

m



ax

,
i

=

SOC

i
-
1

+

∫

i
-
1

i



I

c

o

r

r


d

t

Q

Assignees

• Electricite De France

Inventors

• Lancel Gilles
• Brun Emeric

Classifications

• G01R31/54

  Testing for continuity · CPC title

• G01R31/392

  Determining battery ageing or deterioration, e.g. state of health · CPC title

• G01R31/3842 Primary

  combining voltage and current measurements · CPC title

• G01R31/3648 Primary

  comprising digital calculation means, e.g. for performing an algorithm · CPC title

• G01R31/3828

  using current integration · CPC title