Generalized projective method

Introduction

This chapter discusses the use of the Generalized projective method to create force collections in the Import / Export data context : this kind of collection allows to compute forces on a generic mesh (i.e., a set of points) with the aim to be exported towards OptiStruct to setup a NVH analysis of electrical devices, such as rotating machines. This method and then the collection created may be seen as an extension of the simplified projective method dedicated to rotating machines which overcome its limitations.

Description of the approach

This approach is based on two data supports defined by the user: one for the data collect and secondly a set of supports to compute and integrate the magnetic pressure to be exported. The support to collect the data must be imported with the help of the data supports as it is shown in (b) part of Figure 1. The set of supports to compute and integrate the magnetic pressure can be defined by an extruded compound path, a 2D grid as shown in (a) part of Figure 1 or an extruded geometric line in an air region. All the components of the magnetic pressure are computed with the Maxwell tensor approach and can be integrated with all available methods on the set of supports; finally, they are projected on the support for the data collect.

Figure 1. Axial flux motor in Flux 3D: (a) the support to compute and integrate magnetic pressure created from a 2D annular grid, (b) the support to collect the data imported from OptiStruct

Note: To have accurate results, the computation support (the grid on the figure above) must have a fine discretization.

Creation of this collection

This type of collection especially dedicated to electrical rotating machines is available in all Flux modules (2D, 3D and Skew) for static and transient magnetic applications. Its creation is made via the following steps:

In the data tree, select the menu Forces data collection
In the dedicated GUI for Forces data collection, select Generalized projective method
In the Definition tab:
1. Choose an imported data support to collect the data
2. Choose a list of data supports to compute and integrate the magnetic pressure
In the Advanced tab, the user can decompose the computed forces in radial and tangential components. To this aim, he is invited to:
1. Select the rotation axis (X, Y or Z expressed in XYZ1 coordinate system)
2. Choose a pivot point by its coordinates and a coordinate system
Choose the collection interval:
- Collect for all the steps of the scenario
- Collect only for the current step
- Collect for a specified interval
Click OK
Right click on the forces data collection just created in the data tree and run the command Collect data

Note: In advanced mode, more integration options are available, see this page.

Note: As a next step, forces can be visualized with the Data visualizers and / or exported towards OptiStruct with the Data export.

Example

In this example, the aim is to compute the global force on each tooth of the 3D axial flux machine described in Figure 1 after solving a scenario in Flux.

To this aim, a support to collect the data is imported from OptiStruct which is the same as part (b) of Figure 1; . On the computation support which is also the same as part (a) of Figure 1; on this support, forces are computed with the Generalized projective method described before.

Once the data collection is correctly defined, the data must be collected with a right click and the command Collect data on the forces data collection; forces can now be visualized with the Data visualizers as shown in the figure below:

Figure 2. Visualization of global forces per tooth for a 3D axial flux machine: (a) the forces normal to the collect support, (b) the forces tangential to the collect support.