Convert current 2D magnetic application to Skew

Introduction

A Flux 2D project may be converted to a Flux Skew project. This conversion is useful for rotating electrical machine designers who start their analysis with an unskewed 2D simulation for the sake of simplicity, and who decide later to consider the effect of skewing.

This chapter explains how to perform this kind of conversion and discusses the conditions under which such a conversion is available. The conversion rules and the limitations are also covered.

Available conversions

Table 1 shows the available conversions to Flux Skew:

Table 1. Available module conversions between 2D and Skew
Flux Skew applications	Rotating Machine in Magneto Static	Rotating Induction Machine in Steady State AC Magnetic	Rotating Machine in Transient Magnetic
Flux 2D applications	Rotating Machine in Magneto Static	Rotating Induction Machine in Steady State AC Magnetic	Rotating Machine in Transient Magnetic
Magneto Static		-	-
Steady State AC Magnetic	-		-
Transient Magnetic	-	-

How to convert the current application

Conversions to Flux Skew are available while in pre-processing and after defining a first application in Flux 2D.

To perform such a conversion in Flux 2D project:

Click on the menu Application;
Choose Convert current application;
Finally, select the option to Skew module.
Note: The remaining options in the Convert current application menu perform common application conversions in the Flux 2D project. These conversions are presented in this dedicated page:Convert current application (in a given Flux module).

At this point, a dialog box appears and prompts the user to provide additional information required to complete the conversion:

In the Save converted project as field, provide a name for the converted project.
Note: The name for the converted project must not be the same as the name of the initial 2D project.
Select from the Open Flux Skew after conversion drop down menu if the converted project will open automatically after the conversion process or not (i.e., choose between options yes or no).

Important: After completing a conversion, it is recommended to:

Verify in the Flux 2D's project console output for a summary of the actions that were automatically performed and so identify the entities that eventually have been deactivated or modified (refer to sections Conversion rules and Limitations). In that way, the user can make the necessary modifications in the generated Skew project to recreate or redefine the involved entities.
In the resulting Skew project:
- Review the definition of regions, materials and circuits;
- Execute the Check physics and the Check circuit commands (available in the Physics menu while in pre-processing) for making the required changes to fix possible warnings and errors;
- Open the Edit current application dialog box to define the skewing topology (Flux Skew). In fact, by default the following options are set:
  - Skewed mechanical set: Rotating
  - Skewing type: Continuous
  - Topology description: Simple (homogeneous layers)
  - Length unit and axial length: equal to the "Length unit" and the "Depth of the domain" set in the original 2D project, respectively
  - Rotation angle (degrees): 0
  - Number of layers along the axial length: 1

Note:

In case of a conversion from a Magneto Static or a Steady State AC Magnetic application to Skew module, in the 2D's project console output, it may appear a warning saying that: "The demagnetization option of MATERIAL is not compatible with Flux Skew. This option was disabled in the converted project.", even if demagnetization is not available in Magneto Static and in Steady State AC Magnetic applications.

This message is displayed when the 2D project was previously converted from a Transient Magnetic application (where this option was activated) to a Magneto Static or a Steady State AC Magnetic application and then to Skew module. Moreover, it can be triggered from a python file that has been exported from a 2D Transient Magnetic application describing such a material, and then used in Skew module (Conversion rules).

Conversion rules

The following rules are observed while converting from Flux 2D to Flux Skew:

A project must be saved, before the command to Skew module can be used.
To be convertible, the Flux 2D project must contain two mechanical set entities: one of type Rotation around one axis and the other of type Fixed (Mechanical set: definition (structure)).
Regions with current density are not supported in Skew module. The default option Air or vacuum region is then selected in the Type for region field in case such regions existed in the original 2D project (Transient Magnetic volume (3D) / face (2D) region).
Certain features become deactivated in the converted Flux Skew project:
- The option Taking into account demagnetization during solving process (Magnet (unidirectional): demagnetization curve (HcB, HcJ and Br)) of magnet materials of type Nonlinear magnet described by HcB, HcJ and Br module.
- The Mechanical Stress dependence (B(Stress) magneto-mechanical model: dependency between B(H) constitutive law and mechanical stress) option in Laminated magnetic non conducting regions.
- The Detailed description (considers proximity and skin effects) (Coil Conductor region with losses and detailed geometrical description) option for the evaluation of Joule losses in Coil conductor regions.

Limitations

The following limitations exist when converting a project from Flux 2D to Flux Skew:

It is not possible to convert from Flux 2D to Flux Skew and also change the application at the same time. If this is required, an application conversion must also be performed in Flux Skew after the module conversion is completed.
The conversion of axisymmetric Flux 2D projects is forbidden.
The following entities cannot be converted and are deleted in the resulting Flux Skew project:
- Point regions
- Line regions
- Symmetries
- Sensors
- Scenarios
- Paths
- Grids