Find Maximum Torque Envelope for Motor

To generate calibration tables using torque percent as an input, calculate an intermediate set of values to create a 1-D lookup table based on the torque envelope and run an optimization.

For this example, to calculate the intermediate set of values, set up functions for:

  • Current magnitude, Is

  • Torque model, TrqModel

    CAGE can only optimize models, so a torque model is required.

Note

If you want to use torque as a table input instead of torque percent, set up only the function for Is, and skip the remaining steps for finding the maximum torque envelope for the motor.

  1. In the CAGE Browser toolbar, use New Function Model wizard to create these functions:

    • Is = sqrt(Id^2 + Iq^2)

    • TrqModel = Trq

    Click the New Function Model icon New function model icon.

    Enter the formula Is = sqrt(Id^2 + Iq^2).

    Function model wizard dialog

    From the Available Inputs, assign to the Model Input. The inputs Id and Iq are automatically assigned to the Id and Iq models.

    Function model wizard dialog

  2. In the Cage Browser, verify that the function models for Is and TrqModel have these descriptions:

    • Is — sqrt(Id^2 + Iq^2)

    • TrqModel — Trq

    Models dialog with Vs selected

Create 1-D Lookup Table from Model

Create a table with all the optimization points. For this example, the table is the torque envelope as a function of motor speed, n.

  1. In the CAGE Browser, select File > New > 1D Lookup Table.

  2. In the Create Lookup Table dialog box, set Name to TrqEnvelope and Units to Nm.

  3. From Rows (Y) input select motor speed, n.

  4. Select Use operating points for breakpoints to use operating points for breakpoints.

  5. Click OK.

Create 1D Lookup Table

Run Optimization on Torque Envelope

For this example, run an optimization with these specifications:

  • Current magnitude, Is, less than or equal to 615 A

  • Voltage magnitude Vs, less than or equal to 222.8 V

  1. In the CAGE Browser, click Optimization.

    CAGE Browser Optimization button.

  2. The Optimization Quick Start dialog box opens to guide you through the optimization setup. Click Next.

    Optimization Quick Start dialog box welcome page.

  3. In the Optimization Quick Start dialog box on the Objectives tab:

    • From the Model list, select TrqModel.

    • From the Goal list, select Maximize.

    The variable Trq is automatically selected to optimize. Click Next.

    Create optimization from model dialog with TrqModel model selected on the objectives tab.

  4. In the Optimization Quick Start dialog box on the Constraints tab, add the optimization constraint for the current magnitude, Is <= 615, and voltage magnitude, Vs <= 222.8. Select the variable Id to optimize in addition to Trq. Then, click Next.

    Create optimization from model dialog with constraints defined on the constraints tab.

  5. In the Optimization Quick Start dialog box on the Operating Points tab:

    • From the Operating points list select Breakpoints and TrqEnvelope(n).

    • Under Optimize operating points, select Point: optimize each operating point separately.

    Click Apply. Then, click Close.

    Create optimization from model dialog with operating points defined on the operating points tab.

  6. In the CAGE Browser, carefully verify the Objectives and Constraints.

    Cage browser with TrqModel and Is_Boundary selected

  7. In the CAGE Browser, click Run.

Fill Lookup Tables

Fill the torque envelope table.

  1. In the CAGE Browser, select Solution > Fill Lookup Tables

  2. In the Lookup Table Filling Optimization Results Wizard dialog box, click Next to fill the TrqEnvelope(n_norm) lookup table.

    Lookup Table Fill Wizard

  3. In the next view of the table filling wizard, select TrqModel from the optimization results to fill the TrqEnvelope table. Click Finish.

    Lookup Table Fill Wizard select optimization results

  4. Review the results for TrqEnvelope. The results are similar to the results shown here.

    TrqEnvelope versus n normal plot

  5. Select File > Save Project. Save the gs_example.cag file to the work folder.

Create Function Model for Torque Grid

Using the optimized TrqEnvelope table set up the torque grid function model TrqGrid.

  1. In the CAGE Browser toolbar, use the New Function Model wizard to create the function TrqGrid = TrqPercent/100*TrqEnvelope.

    Note

    If you want to use torque as a table input instead of torque percent, you can skip creating a function model for TrqGrid.

    Function Model Wizard TrqGrid definition

  2. In the CAGE Browser, right-click the model Iq and select Edit Inputs. Update the Assigned Input for the Model Input Trq to use TrqGrid. Leave Duplicate models selected to create Iq_TrqGrid, Is_TrqGrid, and Vs_TrqGrid.

    Edit inputs for Iq

    Click OK.

    Click Yes to change the inputs for the models.

  3. In the CAGE Browser, verify that the TrqGrid function models have these descriptions:

    • TrqGrid — n, TrqPercent

    • Is_TrqGrid — Id, n, TrqPercent

    • Iq_TrqGrid — Id, n, TrqPercent

    Edit models dialog