US 7,352,156 B2Granted

State-of-charge estimating device of secondary battery

AssigneeNissan Motor Co., Ltd.

InventorsHiroyuki Ashizawa, Hideo Nakamura, Hisafumi Asai

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Abstract

A state-of-charge (SOC) estimating device and method for a secondary battery that estimates the SOC of the battery with high precision when variation takes place in the parameters of the battery model, even if the input current is constant. A first SOC estimating part estimates the open-circuit voltage by estimating the battery parameters en bloc using an adaptive digital filter computing treatment from the measurement values of the current and the terminal voltage and computes a first estimated SOC of the secondary battery from the open-circuit voltage and a predetermined relationship between the open-circuit voltage and the SOC. A second SOC estimating part computes a second estimated SOC by means of current-integration. State-of-charge estimated value-selecting part selects the second SOC value as when the current is constant and otherwise selects the first SOC value.

Claims27

Dependent claims

A state-of-charge estimating device for estimating a state-of-charge of a secondary battery connected to a load, comprising:

a current detecting device for detecting a current I of the secondary battery;
a terminal voltage detecting device for detecting a terminal voltage V of the secondary battery;
and
a controller receiving input from the current detecting device and the terminal voltage detecting device, the controller including:
an open-circuit voltage estimating part operable to perform an adaptive digital filter computing treatment to estimate at least one battery parameter in a battery model
V
=
B
⁡
(
s
)
A
⁡
(
s
)
·
I
+
1
A
⁡
(
s
)
·
V
O
en bloc based on the current I and terminal voltage V of the secondary battery and the battery model
V
=
B
⁡
(
s
)
A
⁡
(
s
)
·
I
+
1
A
⁡
(
s
)
·
V
O
and to estimate an estimated open-circuit voltage VO of the secondary battery, wherein A(s) and B(s) are polynomials of Laplace operator s;
a first state-of-charge estimating part operable to estimate a first state-of-charge value based on the estimated open-circuit voltage VO of the secondary battery and a previously derived relationship between an open-circuit voltage and a state-of-charge of the secondary battery;
a second state-of-charge estimating part operable to estimate a second state-of-charge value using a method capable of estimating the state-of-charge even if the current I is constant while one or more of the at least one battery parameter varies;
and
a state-of-charge estimated value-selecting part operable to switch from the first state-of-charge value to the second state-of-charge value as the state-of-charge when the current I is constant and otherwise to select the first state-of-charge value as the state-of-charge.

56 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/487,882Filed 16 Jul 2006
Priority: JP 2005-20806819 Jul 2005
Published: US 2007/0029973 A18 Feb 2007
Granted: 1 Apr 2008
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01R 31/3828
Arrangements for monitoring battery or accumulator variables, e.g. SoC: using current integration
G01R 31/367
Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of…
G01R 31/374
Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of…
G01R
Measuring electric variables