estimateBatteryEISParameters
Estimate initial parameters for electrochemical-impedance-spectroscopy fractional-order model
Since R2025a
Description
The estimateBatteryEISParameters function estimates the initial parameters for a specific electrochemical-impedance-spectroscopy (EIS) fractional-order model.
The estimateBatteryEISParameters function calculates the parameters based on a-priori fit of several lithium-ion batteries and provides an approximation of the order of magnitude of the parameters only. The calculation of the parameter initial estimate depends on the battery capacity, temperature, and remaining capacity.
An EISModel object models the fractional-order model that this function
uses to estimate the initial parameters. The CircuitTopology property of
this EISModel object is equal to
"R0+L1+(R1,CPE1)+(R2,CPE2)+CPE3". This value models an
EISModel object with this 2-ZARC circuit topology:
These initial parameters estimates serve as an approximated initial guess for optimization-based fitting strategies of EIS parameters. The values that this function returns are only an approximation and they are not the final parameter values or representative of any system. As a result, expect great deviations between the simulated and the actual physical behavior of a battery system. To ensure the requisite accuracy, validate the simulated behavior against experimental data and refine the parameter values and models.
initialParameters = estimateBatteryEISParameters(Name=Value)"R0+L1+(R1,CPE1)+(R2,CPE2)+CPE3" circuit topology from the
battery capacity, temperature, and remaining capacity.
Examples
This example shows how to estimate the parameters of an EIS model based on an initial parameter recommendation.
Open the DownloadBatteryEISData example and load the required
electrochemical impedance spectroscopy (EIS) data. This data has been generated from a
battery with a nominal capacity of 30/1000 A*Hr at a temperature of
25 degree Celsius. This data consists of a
500-by-3 matrix of doubles. The columns of the
matrix refer to the frequency, real impedance, and imaginary impedance values,
respectively.
openExample("simscapebattery/DownloadBatteryEISDataExample") load("generatedEISData.mat")
Fit the EIS data to a fractional-order equivalent circuit model. To fit the data and
create an EISModel object, use the fitEISModel
function.
eisfom = fitEISModel(eisData);
Analyze how the function performed the fit on the frequency model by using the
plot function. This plot shows the simulated data against the
measured data, where the X-axis represents the real part of the
impedance and the Y-axis represents the imaginary part of the
impedance.
plot(eisfom,Parent=figure,DisplayMode="Nyquist")
Now get a recommendation of the initial parameters of the EIS model by using the
estimateBatteryEISParameters
function.
initParameters = estimateBatteryEISParameters("BatteryCapacity",simscape.Value(25/1000,"A*hr"));
initParameters =
0.8262 0.0000 7.6919 0.6339 0.0410 1.1282 1.0000 0.0085 0.6877 6.4704Create another EISModel object and assign it the initial parameters
you
estimated.
eisfom = eisModel(ParameterValues=initParameters)
eisfomtest =
EISModel with properties:
CircuitTopology: "R0+L1+(R1,CPE1)+(R2,CPE2)+CPE3"
NumParameters: 10
ParameterList: ["R0" "L1" "R1" "CPE1n" "CPE1Q" "R2" "CPE2n" "CPE2Q" "CPE3n" "CPE3Q"]
ParameterValues: [0.8262 1.0000e-06 7.6919 0.6339 0.0410 1.1282 1 0.0085 0.6877 6.4704]
CircuitImpedance: "((((R0 + (i*w*L1)) + ((R1 * (1/(((i*w)^CPE1n)*CPE1Q))) / (R1 + (1/(((i*w)^CPE1n)*CPE1Q))))) + ((R2 * (1/(((i*w)^CPE2n)*CPE2Q))) / (R2 + (1/(((i*w)^CPE2n)*CPE2Q))))) + (1/(((i*w)^CPE3n)*CPE3Q)))"
ParameterList: ["R0" "L1" "R1" "CPE1n" "CPE1Q" "R2" "CPE2n" "CPE2Q" "CPE3n" "CPE3Q"]
Show all propertiesFit the EIS model based on the initial parameters you estimated.
eisfom = fitEISModel(eisData,EISFOM=eisfom);
Analyze the accuracy of the fit. Notice how the fit is more accurate for the model with the estimated initial parameters.
plot(eisfom,Parent=figure,DisplayMode="Nyquist")
Name-Value Arguments
Output Arguments
Version History
Introduced in R2025a
