Assessing the quantity of energy in a motor vehicle battery

Patent metadata

Field	Value
Publication number	US-2016377684-A1
Application number	US-201415102382-A
Country	US
Kind code	A1
Filing date	Dec 2, 2014
Priority date	Dec 12, 2013
Publication date	Dec 29, 2016
Grant date	—

Abstract

A method for evaluating a quantity of energy at constant power of a battery includes determining a value of a capacity parameter for the battery, constructing a table of values for a parameter of voltage across terminals of the battery as a function of a value of a current parameter, for N values of a state of charge parameter, determining a value of an internal resistance parameter for the battery, providing a table of values of an open-circuit voltage parameter, estimating a value of the state of charge parameter at an initial time, and estimating a quantity of energy parameter between a final and initial states of charge using a function whose variable is the state of charge parameter and whose parameters are said value of the capacity parameter for the battery, said value of the internal resistance parameter, and said value of the open-circuit voltage parameter.

First claim

1 - 10 . (canceled)

11 . A method for evaluating a quantity of energy at constant power of a battery of an automobile vehicle, said quantity of energy corresponding to a extractible quantity of energy or to a quantity of energy to be accumulated, said method comprising:
(a) determining a value of a capacity parameter for the battery; (b) constructing, during a charge phase of the battery, a table of values for a parameter of voltage across terminals of the battery as a function of a value of a current parameter for N values of a state of charge parameter; (c) determining a value of an internal resistance parameter for the battery as a function of a state of charge parameter for said battery based on the table constructed at the step (b); (d) providing a table of values of an open-circuit voltage parameter for the battery as a function of the state of charge parameter for the battery; (e) estimating a value of the state of charge parameter for the battery at an initial time, corresponding to an initial state of charge of the battery; and (f) estimating by calculation a value of a quantity of energy parameter between a final state of charge and said initial state of charge using a function whose variable is the state of charge parameter and whose parameters are said value of the capacity parameter for the battery, said value of the internal resistance parameter and said value of the open-circuit voltage parameter.

12 . The method as claimed in claim 11 , in which the function used in the step (f) for estimating the quantity of energy is written:
f ( z )= Uoc ( z )+√{square root over (Δ( z ))}  (2),
in which: Δ(z) is a term taking into account the energy losses, being a function of the value of the state of charge parameter, Uoc(z) represents the open-circuit voltage parameter as a function of the value of the state of charge parameter, and the value of the quantity of energy parameter is obtained by integration of said function between the value of the state of charge parameter in the initial state and the value of the state of charge parameter in the final state, said value of the final state of charge parameter being the solution of the equation:

U
final

=

Uoc


(

z
f

)

+

R


(

z
f

)



P

U
final

(
1
)

in which:
U final represents the parameter of voltage across the terminals of the battery in the final state of charge,
R(z f ) represents the internal resistance parameter of the battery in the final state of charge,
Uoc(z f ) represents the open-circuit voltage parameter as a function of the value of the final state of charge parameter, and
P is the constant value of the power parameter.

13 . The method as claimed in claim 12 , in which the function is approximated by a polynomial of order n less than or equal to N-1 and said value of quantity of energy parameter is expressed by:

E
P

≈

Q
2



(

r


(

z
f

)

-

r


(

z
0

)

)

.

(
3
)

in which:
r(z) is the integral of said polynomial of order n, and
Q represents the capacity parameter.

14 . The method as claimed in claim 11 , in which the steps (a) and (b) are iterated over a lifetime of the battery, independently of each other and of the steps (e) and (f) of said method.

15 . The method as claimed in claim H, in which the step (e) for estimating the value of the initial state of charge parameter comprises, at the initial time:
(i) measuring the value of the parameter of voltage across the terminals of the battery and the value of the parameter of current flowing in the battery when said value of the current parameter is stable for a predetermined period of time during a discharge phase of the battery, and (ii) deducing from the measuring the value of the initial state of charge parameter based on the table constructed at the step (b).

16 . The method as claimed in claim 15 , in which the step e comprises the following additional steps:
(iii) estimating a second value of the initial state of charge parameter by another prediction method, (iv) comparing the first value of the initial state of charge parameter determined at the step (ii) with the second value of the initial state of charge parameter determined at the step (iii), and (v) using the value of the initial state of charge parameter determined at the step (ii) if the difference from the comparing is less than a predetermined value, otherwise, using the second value of the initial state of charge parameter determined at the step (iii).

17 . The method as claimed in claim 11 , further comprising, after the step (f), the following additional step:
(g) determining a new value of the initial sta

Assignees

• Renault Sa

Inventors

• Leirens Sylvain
• Lallich Sylvain

Classifications

• G01R31/3651 Primary

  Physics · mapped topic

• G01R31/007

  using microprocessors or computers · CPC title

• B60L11/1861

  Operations & Transport · mapped topic

• G01R31/3662

  Physics · mapped topic

• G01R31/3675

  Physics · mapped topic