fitecmToHppcTest

Estimate parameters of battery equivalent circuit model from HPPCTest object

Since R2025a

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Syntax

equivalentCircuitModel = fitecmToHppcTest(myFitECM,myHppcTest)

Description

equivalentCircuitModel = fitecmToHppcTest(myFitECM,myHppcTest) estimates the parameters of a battery equivalent circuit model (ECM) for a sequence of constant current pulses inside an HPPCTest object, myHppcTest, and returns an ECM object with the estimated parameters. The function retrieves the ECM object to fit the pulse data in from the FitEquivalentCircuitModel object, myFitECM.

example

Examples

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This example shows how to fit a series of hybrid pulse power characterization (HPPC) profiles inside an ECM by using the fitting method of a FitEquivalentCircuitModel object.

Note

This workflow is not recommended. To fit HPPC data inside an ECM, use the fitECM function instead.

Import the package required to use the FitEquivalentCircuitModel object and its methods.

import simscape.battery.parameters.*;

Open the DownloadBatteryData example and load the required HPPC data obtained for a BAK 2.9 Ah battery cell at 25 °C. This data consists of a table with three columns. The columns of the table refer to time, voltage, and current values, respectively.

openExample("simscapebattery/DownloadBatteryDataExample")
load("testDataBAKcells/hppcDataBAKcell25degC.mat")

Store the HPPC data inside an HPPCTest object by using the hppcTest function. The HPPC data is a table, so you must also specify each column name by using the TimeVariable, VoltageVariable, and CurrentVariable arguments. These names must match the names of the columns in the hppcData table.

hppcExp = hppcTest(hppcData,...
    TimeVariable="time (s)",...
    VoltageVariable="voltage (V)",...
    CurrentVariable="current (A)");

Analyze the TestSummary property of the hppcExp object. There are 18 identified profiles inside the loaded HPPC data.

hppcExp.TestSummary
18×13 table

    PulseID    Directionality      SOC          HPPCData         PulseDuration    PseudoOCV_V    MaximumVoltage    MinimumVoltage    Current_A    C_rate    PulseStartIndex    PulseEndIndex    Temperature_degC
    _______    ______________    _______    _________________    _____________    ___________    ______________    ______________    _________    ______    _______________    _____________    ________________

       1        "Discharge"            1    {701×6 timetable}         30            4.1745           4.1745            3.7846         -6.1869     1.8976           354              1055               25       
       2        "Discharge"      0.90376    {701×6 timetable}         30            4.0837           4.0837            3.7479          -6.187     1.8977          2702              3403               25       
       3        "Discharge"      0.80754    {702×6 timetable}         30            4.0132           4.0132            3.6652         -6.1867     1.8975          5049              5751               25       
       4        "Discharge"      0.71133    {701×6 timetable}         30            3.9226           3.9226            3.5775         -6.1868     1.8976          7398              8099               25       
       5        "Discharge"      0.61512    {701×6 timetable}         30             3.846            3.846            3.4942         -6.1868     1.8976          9746             10447               25       
       6        "Discharge"      0.51891    {701×6 timetable}         30            3.7353           3.7353            3.4001         -6.1871     1.8977         12094             12795               25       
       7        "Discharge"       0.4227    {701×6 timetable}         30              3.65             3.65            3.3236         -6.1867     1.8975         14442             15143               25       
       8        "Discharge"      0.32649    {701×6 timetable}         30            3.6015           3.6015            3.2652         -6.1869     1.8976         16790             17491               25       
       9        "Discharge"      0.23028    {701×6 timetable}         30            3.5507           3.5507            3.1931         -6.1869     1.8976         19138             19839               25       
      10        "Charge"         0.98415    {502×6 timetable}         10            4.1158           4.3889            4.1158          4.6393      1.423          1055              1557               25       
      11        "Charge"         0.88793    {502×6 timetable}         10             4.057           4.3001             4.057          4.6406     1.4233          3403              3905               25       
      12        "Charge"         0.79172    {502×6 timetable}         10            3.9674           4.2113            3.9674          4.6394      1.423          5751              6253               25       
      13        "Charge"         0.69551    {502×6 timetable}         10            3.8751           4.1175            3.8751          4.6396      1.423          8099              8601               25       
      14        "Charge"          0.5993    {502×6 timetable}         10            3.7905           4.0355            3.7905          4.6396      1.423         10447             10949               25       
      15        "Charge"         0.50309    {502×6 timetable}         10            3.6936           3.9339            3.6936          4.6405     1.4233         12795             13297               25       
      16        "Charge"         0.40688    {502×6 timetable}         10            3.6224           3.8602            3.6224          4.6396      1.423         15143             15645               25       
      17        "Charge"         0.31066    {502×6 timetable}         10            3.5695           3.8109            3.5695          4.6397     1.4231         17491             17993               25       
      18        "Charge"         0.21445    {502×6 timetable}         10            3.5098           3.7597            3.5098          4.6397     1.4231         19839             20341               25

Fit the entire HPPC data to an equivalent circuit model by using the fitecmToHppcTest method of a FitEquivalentCircuitModel object. The fitecmToHppcTest function fits the HPPC data to the ECM object specified in the ECM property of the FitEquivalentCircuitModel object. 

myFitEcmObject = FitEquivalentCircuitModel;
equivalentCircModel = fitecmToHppcTest(myFitEcmObject,hppcExp)
equivalentCircModel = 

  ECM with properties:

                          NumRCPairs: 2
                       NumParameters: 5
                       ParameterList: ["R0"    "R1"    "C1"    "R2"    "C2"]
                    CircuitImpedance: "R0 + 1/(i*w*C1+1/R1) + 1/(i*w*C2+1/R2)"
                     ParameterValues: [0.0442 0.0112 1.2079e+03 0.0140 7.4513e+03]
                ModelParameterTables: [1×1 struct]
            ResistanceSOCBreakpoints: [0 0.1000 0.2000 0.3000 0.4000 0.5000 0.6000 0.7000 0.8000 0.9000 1] (1)
    ResistanceTemperatureBreakpoints: [278 293 313] (K)
        ResistanceCurrentBreakpoints: 1 (A)

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The fitecmToHppcTest method returns an ECM object with estimated fitted parameters from all the identified profiles inside the HPPCTest object.

Input Arguments

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Fit equivalent circuit model, specified as a FitEquivalentCircuitModel object. This object contains the data that the fitecm function requires to estimate the parameters of the battery ECM, including the ECM, fitting method, and fitting options.

Sequence of constant current pulses stored inside a hybrid pulse power characterization (HPPC) test container, specified as an HPPCTest object.

Output Arguments

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Equivalent circuit model with estimated parameters, returned as an ECM object.

Version History

Introduced in R2025a

See Also

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