Apparatus For Predicting Power Parameter of Secondary Battery

Patent metadata

Field	Value
Publication number	US-2016187429-A1
Application number	US-201514979848-A
Country	US
Kind code	A1
Filing date	Dec 28, 2015
Priority date	Dec 26, 2014
Publication date	Jun 30, 2016
Grant date	—

Abstract

In an apparatus, a circuit model includes a DC resistance model, and a reaction impedance model having a nonlinear relationship between a first potential difference across a reaction resistance and a current flowing through the secondary battery. The nonlinearly relationship depends on a temperature of the secondary battery. The circuit model includes a diffusion impedance model. The apparatus predicts a future remaining voltage across the secondary battery at a future timing when a predetermined duration will have elapsed since a prediction time. The apparatus calculates a future polarization voltage across the secondary battery at the future timing. The apparatus predicts a target power parameter of the secondary battery at the future timing according to the future remaining voltage, the future polarization voltage, a first potential difference across the reaction resistance, and a second potential difference across the DC resistance model.

First claim

What is claimed is:

1 . An apparatus for predictor a target power parameter of a secondary battery, the apparatus comprising:
a first polarization voltage calculator that uses an equivalent circuit model of the secondary battery to calculate a present polarization voltage across the secondary battery at a specified prediction time, the equivalent circuit model comprising:
a DC resistance model representing a DC resistance of the secondary battery;
a reaction impedance model representing a reaction resistance of the secondary battery and having a nonlinear relationship between a first potential difference across the reaction resistance and a current flowing through the secondary battery, the nonlinearly relationship depending on a temperature of the secondary battery; and
a diffusion impedance model representing a diffusion impedance of the secondary battery and comprising at least one RC parallel circuit, the at least one RC parallel circuit comprising a diffusion resistance and a diffusion capacitance connected in parallel to each other, the DC resistance model, the reaction impedance model, and the diffusion impedance model being connected in series to each other,
the first polarization voltage calculator calculating the present polarization voltage across the secondary battery in accordance with a predetermined function defined among the present polarization voltage, the diffusion resistance, and the diffusion capacitance; a remaining voltage predictor that predicts, in accordance with a first continuous time-domain function, a future remaining voltage across the secondary battery at a future timing when a predetermined duration will have elapsed since the specified prediction time for the target power parameter, the first continuous time-domain function being defined among the diffusion resistance, the diffusion capacitance, the present polarization voltage, and the future remaining voltage; a second polarization voltage calculator that calculates, in accordance with a second continuous time-domain function, a future polarization voltage across the secondary battery at the future timing when the predetermined duration will have elapsed since the specified prediction time, the second continuous time-domain function being defined among the future polarization voltage, the diffusion resistance, and the diffusion capacitance; and a target power parameter predictor that predicts a value of the target power parameter at the future timing when the predetermined duration will have elapsed since the specified prediction time in accordance with: the future remaining voltage; the future polarization voltage; the first potential difference across the reaction resistance; and a second potential difference across the DC resistance model.

2 . The apparatus according to claim 1 , wherein the reaction impedance model is derived from a Butler-Volmer equation, and includes a reaction resistance parameter correlating with an exchange current density of the secondary battery.

3 . The apparatus according to claim 2 , wherein the reaction resistance parameter satisfies the following equation:

Δ



V

=

α
γ



T
·

sinh

-
1



(

β
·
γ
·
I

)

Where each of α and γ is a constant, β represents the reaction resistance parameter, I represents the current flowing through the secondary battery, T represents the temperature of the secondary battery, and ΔV represents the first potential difference across the reaction resistance.

4 . The apparatus according to claim 1 , wherein:
the current is a discharge current flowing through the secondary battery; the secondary battery comprises a plurality of battery cells connected in series to each other; the first polarization voltage calculator calculates, as the present polarization voltage across the secondary battery, a present polarization voltage across each of the battery cells; and the target power parameter predictor further comprises:
a first discharge terminal-voltage predictor that predicts a first terminal voltage across each of the battery cells at the future timing when a predetermined discharge duration that is the predetermined duration will have elapsed since the specified prediction time if an allowable upper limit value of the discharge current is flowing through the corresponding battery cell over the predetermined discharge duration;
a first outputtable power predictor that predicts, as the value of the target power parameter, a first value of outputtable power from the secondary battery at the future timing when the predetermined discharge duration will have elapsed since the specified prediction time according to the sum of all the first terminal voltages and the allowable upper limit value of the discharge current if a minimum value in all the first terminal voltages is equal to or more than a predetermined allowable lower limit voltage for the battery cells;
a discharge current searcher that searches for a maximum value of the discharge current required to cause the minimum value of all the first terminal voltages to be set to the allowable lower limit voltage if the minimum value in all the terminal voltages is less than the predetermined allowable lower limit voltage for the battery cells, the maximum value of the discharge current being equal to or lower than the allowable upper limit value of the discharge current;
a second discharge terminal-voltage predictor that predicts a second terminal voltage across each of the battery cells at the future timing when the predetermined discharge duration will have elapsed since the specified prediction time if the maximum value of the discharge current is flowing through the corresponding battery cell over the predetermined discharge duration; and
a second outputtable power predictor that predicts, as the value of the target power parameter, a second value of the outputtable power from the secondary battery at the future timing when the predetermined discharge duration will have elapsed since the specified prediction time according to the sum of all the second terminal voltages and the maximum value of the discharge current.

5 . The apparatus according to claim 4 , wherein the discharge current searcher is configured to search for the maximum discharge value of the discharge current within a range from zero to the allowable upper limit value of the discharge current inclusive.

6 . The apparatus according to claim 1 , wherein:
the current is a charge current flowing through the secondary battery; the secondary battery comprises a plurality of battery cells connected in series to each other; the first polarization voltage calculator calculates, as the present polarization voltage across the secondary battery, a present polarization voltage across each of the battery cells; and the target power parameter predictor further comprises:
a firs

Assignees

• Denso Corp

Inventors

• Kawai Toshiyuki
• Koike Yuuji
• Kato Keiichi

Classifications

• G01R31/396

  Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery · CPC title

• G01R31/389

  Measuring internal impedance, internal conductance or related variables · CPC title

• G01R31/367 Primary

  Software therefor, e.g. for battery testing using modelling or look-up tables · CPC title

• G01R31/3662

  Physics · mapped topic

• G01R31/3651 Primary

  Physics · mapped topic