Calibrate Powertrain Blockset and Simscape Battery Blocks

Since R2023a

If your model contains battery blocks from Powertrain Blockset™ or Simscape™ Battery™, you can use the CAGE browser to calibrate the block lookup tables with experimental data. You can calibrate these blocks:

• Battery (Table-Based) (Simscape Battery)

• Battery Equivalent Circuit (Simscape Battery)

• Equivalent Circuit Battery (Powertrain Blockset)

• Estimation Equivalent Circuit Battery (Powertrain Blockset)

The CAGE browser optimizes the lookup tables for blocks with up to three RC circuits. In the Battery (Table-Based) block, specify the number of equivalent RC circuits with the Charge dynamics parameter. In the Powertrain Blockset blocks, set the number of RC series pairs values with the Number of series RC pairs parameter.

Note

You cannot optimize Battery (Table-Based) blocks that model aging, thermal, and fade characteristics. Set:

• Fade characteristic to Disabled.

• Internal resistance calendar aging to Disabled.

• Capacity calendar aging to Disabled.

• Thermal port to Omit.

After calibrating the block, you can save the adjusted lookup tables to a MAT file, view validation plots in the CAGE browser, or export the data to the Simulation Data Inspector.

Import the Block and Data Set

To calibrate a battery block:

1. Open the CAGE Browser. In MATLAB^®, in the Apps tab, in the Apps section, click MBC Optimization.

2. Click Feature Filling and select the model that contains the block. The model must contain one of the supported blocks from Powertrain Blockset or Simscape Battery. If your model contains more than one supported block, the browser shows a list of the supported blocks. Select one of the blocks and click OK.

   

3. In the Select Folder to Open window, select the folder that contains the data set. The data must be in a MAT file.

Calibrate the Block

After selecting the block and the dataset, the Import window opens. The window displays the location of the model, the block type, and the number of RC circuits that CAGE detects in the block.

You can specify these properties:

• Data sample time — The sample time to use during calibration. Set this value to 0 to match the sample time to the imported data set.

• Charging current — The direction that the charging current flows. You can select positive or negative.

• Use measured SOC — Whether to use the measured state of charge (SOC) if the data set contains that information. Otherwise, CAGE uses the battery capacity and the current to calculate the SOC.

• Feature inputs and output signals — The CAGE variables and the associated variables in the data set. CAGE maps the CAGE variables to the corresponding data names. If you select an Equivalent Circuit Battery block or a Battery (Table-Based) block with the Temperature dependent tables property enabled, the window also displays the Temperature parameter and a variable to calibrate.

• Lookup tables – The lookup tables that CAGE adjusts. CAGE automatically selects the bounds for the lookup tables. To set the initial value for the lookup table to a constant value, adjust the value in the Mean Value column.

For example, this window displays the options available for a Battery (Table-Based) block with three RC circuits and no temperature dependency.

Battery (Table-Based) blocks have a direct specification for the time constant, tau. For Powertrain Blockset blocks, CAGE infers tau from the series resistance and capacitance.

After specifying the properties, click OK to start calibration.

Blocks Used for Calibration

To calibrate the block, you must define strategies in CAGE that use blocks in the cgeqlib library. See Block Support. When defining strategies for battery blocks, CAGE uses blocks in the Battery Systems sublibrary to represent common components found in battery equivalent circuits. Like other blocks in the cgeqlib library, you can use these blocks to create custom strategies.

CAGE Project Templates for Battery Block Calibration

To define the starting strategies and lookup tables for battery block calibration, CAGE loads template projects that contains prebuilt strategies. In these projects, each strategy models a mathematical section of a battery by using CAGE-supported blocks, and the strategies together model the whole battery. To model batteries, the templates derive their strategies from Simulink^® models that use CAGE-supported blocks. Although you do not use these Simulink models directly, you can open and view them to learn about the design.

CAGE uses these template projects:

CAGE Project	Corresponding Simulink Model	Description
mbcBatterySOC_counter.cag	BatteryEstimSOC_counter.slx	A project used for calibrating battery blocks that do not have temperature dependency or current directionality effects. This project is used when performing a feature fill from the Battery (Table-Based) (Simscape Battery) block.
mbcBatterySOC_dir_counter.cag	BatteryEstimSOC_dir_counter.slx	A project used for calibrating battery blocks that do not have temperature dependency, but do have current directionality effects. This project is used when performing a feature fill from the Battery (Table-Based) (Simscape Battery) block.
mbcBatterySOCT_counter.cag	BatteryEstimSOCT_counter.slx	A project used for calibrating battery blocks that have temperature dependency, but do not have current directionality effects. This project is used when performing a feature fill from the Battery (Table-Based) (Simscape Battery) block with temperature dependency enabled.
mbcBatterySOCT_dir_counter.cag	BatteryEstimSOCT_dir_counter.slx	A project used for calibrating battery blocks that have temperature dependency and current directionality effects. This project is used when performing a feature fill from the Battery (Table-Based) (Simscape Battery) block with temperature dependency enabled.
mbcBatterySOCT_ECB.cag	BatteryEstimSOCT_ECB.slx	A project used for calibrating battery blocks that have an equivalent circuit model with hysteresis and a constant temperature thermal model. This project is used when performing a feature fill from the Battery Equivalent Circuit (Simscape Battery) with temperature dependency enabled.
mbcBatterySOCT_ECBdir.cag	BatteryEstimSOCT_ECBdir.slx	A project used for calibrating battery blocks that have an equivalent circuit model with hysteresis, current directionality, and a constant temperature thermal model. This project is used when performing a feature fill from the Battery Equivalent Circuit (Simscape Battery) with temperature dependency and current directionality enabled.
mbcBatterySOCT_ECB_PTBS.cag	BatteryEstimSOCT_ECB_PTBS.slx	A project used for calibrating battery blocks that have an equivalent circuit model with hysteresis, current directionality, and a constant temperature thermal model. This project is used when performing a feature fill from the Equivalent Circuit Battery (Powertrain Blockset) with temperature dependency enabled.
mbcBatterySOCT_ECBdir_PTBS.cag	BatteryEstimSOCT_ECBdir_PTBS.slx	A project used for calibrating battery blocks that have an equivalent circuit model with hysteresis, current directionality, and a constant temperature thermal model. This project is used when performing a feature fill from the Equivalent Circuit Battery (Powertrain Blockset) with temperature dependency and current directionality enabled.
Not available	BatteryEstimSOCT_dir_counter_power_hyst.slx	Example simulink model that demonstrates an entropic heating and a thermal model.
mbcBatterySOCTI_ECB.cag	BatteryEstimSOCTI_ECB.slx	A project used for calibrating battery blocks that have an equivalent circuit model with hysteresis and a constant temperature thermal model. This project is used when performing a feature fill from the Battery Equivalent Circuit (Simscape Battery) with temperature dependency and current dependency enabled. R0, R1, R2, R3, Tau1, Tau2, and Tau3 are 3-D lookup tables.

Each template CAGE project supports feature filling for battery blocks that contain up to three RC circuits. CAGE automatically selects the template and adjusts the strategies based on the number of RC circuits, measured SOC, and temperature dependency you specify for your block. For example, if you enable Use measured SOC in the Import window, CAGE does not use the SOC Counter block in the strategies.

You can find the template projects and corresponding Simulink models in the toolbox/mbc/mbctraining folder.

View Calibration Progress

You can view the lookup table calibration progress in the Lookup Table Preview tab in the CAGE browser. To change the preview while the model calibrates, select the lookup table from the Lookup Table Display option.

As the model fits the data to the model, the Fill Progress window displays the residuals and the root-mean-square deviation (RSME) associated with the fit. You can end calibration manually by clicking Accept. CAGE runs a maximum of 300 iterations.

Inspect Results

CAGE generates validation plots you can use to inspect the fit of your parameters. Open the Validation tab to view the results. You can select the type of plot and the data.

For more information, see Validate Feature and Export Lookup Tables.

Export Results

CAGE adjusts the parameters of the block in the Simulink model after it estimates the parameters. If you run feature fills again on the block, CAGE overwrites the parameters. You can export these results for later use in a separate file. See Import and Export Calibrations. CAGE stores the updated parameters in the same location they were originally defined, such as a base workspace, model workspace, or data dictionary.

You can also export the data to the Simulation Data Inspector for additional visualization options. In the Validation tab, click Export To SDI. The export includes the modeled voltage, reference voltage, residuals, relative residuals, and current.