Method for determining power limit of battery, and battery management system

Patent metadata

Field	Value
Publication number	US-11366169-B2
Application number	US-201916616682-A
Country	US
Kind code	B2
Filing date	Jan 10, 2019
Priority date	Feb 1, 2018
Publication date	Jun 21, 2022
Grant date	Jun 21, 2022

Abstract

Disclosed is a method and a battery management system for periodically determining at least one of charge power limit and discharge power limit of a battery. The method according to an embodiment of the present disclosure includes predicting the terminal voltage and the net resistance of the battery after a predefined time from the current time using an equivalent circuit model for the battery, and determining the charge power limit or the discharge power limit of the battery from the predicted terminal voltage and net resistance.

First claim

What is claimed is:

1. A method for determining a power limit of a battery using an equivalent circuit model for the battery, the equivalent circuit model including a first resistor, a second resistor connected in series to the first resistor, and a capacitor connected in parallel to the second resistor, the method comprising:
measuring a terminal voltage and a current of the battery;
estimating a resistance of the first resistor, a resistance of the second resistor, and a polarization voltage of the battery;
predicting a terminal voltage of the battery after a predefined time by inputting the resistance of the second resistor, the measured terminal voltage, the measured current, and the polarization voltage into a given Equation 1;
predicting a net resistance of the battery after the predefined time by inputting the resistance of the first resistor and the resistance of the second resistor into a given Equation 2;
determining a charge current limit to be equal to a sum of (i) the measured current and (ii) a difference between a given maximum charge voltage and the predicted terminal voltage divided by the predicted net resistance;
determining a charge voltage limit to be equal to a sum of (i) the measured terminal voltage and (ii) a difference between the charge current limit and the measured current multiplied by the resistance of the first resistor;
determining a charge power limit of the battery to be equal to the charge current limit multiplied by the charge voltage limit; and
limiting one or both of a charge voltage and a charge power of the battery based on the determined charge voltage limit and the determined charge power limit.

2. The method according to claim 1 , further comprising:
determining a discharge current limit based on the measured current, the predicted terminal voltage, the predicted net resistance, and a given minimum discharge voltage;
determining a discharge voltage limit based on the predicted terminal voltage, the measured current, the discharge current limit, and the net resistance; and
determining a discharge power limit of the battery based on the discharge current limit and the discharge voltage limit.

3. The method according to claim 1 , wherein the given Equation 1 is as follows:

V
pred

⁡

(
n
)

=

V
⁡

(
n
)

+

{

1
-

exp

-

T
hard

τ

}

⁢

{

R

2
⁢

_
⁢
est

⁡

(
n
)

⁢

I
⁡

(
n
)

-

V
pola

⁡

(
n
)

}

,

〈Equation  1〉

where:
V(n) is the measured terminal voltage,
R 2_est (n) is the estimated resistance of the second resistor,
I(n) is the measured current,
V pola (n) is the polarization voltage,
τ is a preset time constant of the second resistor and the capacitor,
T hard is the predefined time, and
V pred (n) is the predicted terminal voltage.

4. The method according to claim 1 , wherein the given Equation 2 is as follows:

R
net

⁡

(
n
)

=

R

1
⁢

_
⁢
est

⁡

(
n
)

+

{

1
-

exp

Assignees

• Lg Chemical Ltd
• Lg Energy Solution Ltd

Inventors

• Ahn Hyoung Jun

Classifications

• H02J7/80

  including monitoring or indicating arrangements · CPC title

• H02J7/61

  against overcharge · CPC title

• H02J7/63

  against overdischarge · CPC title

• H01M10/48

  Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569) · CPC title

• H01M50/569

  Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals (battery terminal connectors with integrated measuring arrangements G01R31/364) · CPC title