The Characterization / Model / Maps

The Characterization / Model / Maps for characterizing the wound field synchronous machines.

Positioning and objective

The aim of the test “Characterization - Model - Motor - Maps” is to give maps along the three dimensions, If-Jd-Jq, for characterizing the 3-Phase synchronous machines with wound field.

These maps allow for predicting the behavior of the electrical rotating machine at a system level.

In this test, engineers will find a system integrator and / or control-command tool adapted to their needs and able to provide accurate maps ready to be used in system simulation software like Activate.

The performance of the machine in steady state can be deduced from the results obtained in this test in association with the drive and control mode to be considered.
Important: This new test is provided in beta mode, meaning that it is not entirely qualified. However, we make it available for testing, and we invite the users to give us their feedback and comments for improving this feature even more.

Here is an overview of the test, as shown below.
Characterization / Model / Maps – Wound field Synchronous Machines – Inner salient pole - Inner rotor (SMWF-ISP-IR) Overview

User inputs

Maps are mainly function of the following user inputs: the maximum value of the field current, the maximum value of the line current, the speed, the number of quadrants to be considered, and the rotor position dependency.

Among the standard inputs, the operating quadrants can be selected. Options allow computing and displaying 1, 2, or 4 quadrants.

This allows defining the quadrants in the Jd - Jq plane where the test will be carried out.

By default, the considered quadrants are “1st and 2nd” (i.e., the grid is defined for both negative and positive values of the current in the d axis and positive ones in the q axis). This option is chosen as the default because the Synchronous Machine with wound field heritages the characteristics of both Synchronous Machine with Permanent Magnets and Reluctance Synchronous Machines which work respectively in the second and first quadrant in the motor operating mode.

The other possible values for this input are “2nd“, “2nd and 3rd“, and “all”.
Important: The set of inputs and Flux data can be imported from a test that has already been performed in Motor Factory test environment – Performance Mapping – Efficiency maps.

Please see additional information in the section below (the import button allowing sharing the data simulated in Flux between model map and efficiency tests).

Main outputs

Different kinds of outputs are displayed like data, maps, and curves.

Here is a list of results that can be provided and displayed within the framework of this test.

Maps in the three dimensions If - Jd - Jq
  • Flux linkage
    • D-axis flux-linkage Фd
    • Q-axis flux-linkage Фq
    • Flux linkage derivative (only when the rotor position dependency is considered)
    • D-axis flux-linkage derivative with respect to the rotor position dФd/dθr
    • Q-axis flux-linkage derivative with respect to the rotor position dФq/dθr
  • Inductance
    • D-axis inductance (dynamic, cross dynamic and static)
    • Q-axis inductance (dynamic, cross dynamic and static)
  • Saliency
  • Electromagnetic torque Tem
  • Losses
    • Stator iron losses WironStator versus speed
    • Rotor iron losses WironRotor versus speed (only when the rotor position dependency is considered)
  • Total losses Wtotal versus speed

Maps in the two dimensions Jd - Jq

  • Losses
    • Joule losses WCus in stator winding
    • Power electronics losses

Curves

  • Field current flux and cross effect flux curve versus Jq
  • Joule losses WCur in rotor winding versus field current
  • Mechanical losses versus speed versus speed

Characterization / Model / Maps – Wound field Synchronous Machines – Inner salient pole - Inner rotor (SMWF-ISP-IR)

Inputs / Outputs in the test area - Illustration

Main principles of computation

One of the goals is to compute the D-axis and Q-axis flux linkage in the Jd, Jq planes at different levels of If between zero and the maximum value of If.

At each level of If, a grid of values (Jd, Jq) is considered. Finite Element modeling (Flux® software – Magnetostatic application) is then performed at every node of the grid. The corresponding flux linkage through each phase is extracted (a, b, c) through the corresponding phases (a, b, c).

D-axis flux-linkage component - d and Q-axis flux-linkage component - q are deduced according to Park’s transformation.

Next, the other outputs listed in the previous section are derived from analytical formulars.

For more details, refer to MotorFactory_2024_SMWF_ISP_IR_3PH_Test_Characterization.pdf.
Computation on a grid in Jd, Jq plane at a level of If
Note: In the examples shown in the images, negative value of Jd and positive value of Jq are considered as the 2nd quadrant is chosen as example. However, the considered quadrants can be chosen through dedicated input (e.g., user can choose all quadrants or only the 2nd, the 2nd and 3rd ones, etc.), allowing the characterization of the machine behavior for other control conditions.
Note: In case the rotor position dependency is set to “Yes”, the computation is done in the three dimensions If - Jd - Jq with an additional fourth axis corresponding to the rotor position θr. As has been stated for other types of machines, the rotor position dependency mode provides more accurate results than without rotor position dependency.

Half electrical period computation for the Characterization / Model / Maps test of synchronous machines

The user input “No. computed elec. periods” (Number of computed electrical periods only required with rotor position dependency set to “Yes”) influences the computation time of the results. A new option for this input has been added allowing the computation in a half electrical period and hence reducing the computation time by a half while maintaining the identical accuracy.

The default value of “No. computed elec. periods” is equal to 0.5. The maximum allowed value is always 1, according to the fact that computation is done to characterize steady state behavior based on magnetostatic finite element computation.
Note: The outcomes obtained at 0.5 or 1 electrical period are identical across all presented outputs, except for slight variations in rotor iron losses arising from the symmetrical assumption regarding the magnetic flux waveform on the rotor.
Note: This improvement concerns Synchronous Machines with Permanent Magnets (SMPM), Reluctance Synchronous Machine (RSM), and Synchronous Machines with wound field – Inner salient pole - Inner rotor (SMWF-ISP-IR) as well

Illustrations of results depending on the user’s inputs dealing with “No. computed elec. periods” (“0.5“ or “1”).



Electromagnetic torque in Jd - Jq area

Maximum rotor angular position with half electrical period option (1) in the drop-down menu, and maximum rotor angular position with one electrical period option (2) in the drop-down menu