List of generic advanced inputs

List of generic advanced inputs

1. Number of computations per electrical period (for transient application)

   The number of computations per electrical period “ No. comp. / elec. period ” (Number of computations per electrical period) influences the accuracy of results and the computation time.

   The default value is 50. The minimum allowed value is 13. The default value provides a good compromise between the accuracy of results and computation time.

2. Number of computed electrical periods (for transient application )

   The default value is 2. The minimum allowed value is 1 and the maximum value is 10.

3. Rotor initial position

   The computation of the test « Steady State Performance / Working Point / U-f-N » is performed by considering an initial position of the rotor. The default value is 0. The range of possible values is [-360, 360].

   Flux harmonic application (2D and SKEW) allows to compute average quantities over an electrical period for each set position for the rotor.

   Note:

   • With Flux^® Steady state AC Magnetic application (SINUS), torque ripple is wrongly estimated. In fact, the simulation is done over an electrical supply period for a fixed rotor position.

     During an electrical supply period the rotor rotates, and we also have rotor squirrel cage currents which slip from bar to bar.

     So, with Flux^® Steady state AC Magnetic application all the phenomena are not considered which is why the torque ripple torque is wrongly estimated.

   • High space harmonics impacts are not correctly considered for the same reasons described above, about the ripple torque

4. Mesh order

   To get results, Finite Element Modelling computations are performed.

   The geometry of the machine is meshed.

   Two levels of meshing can be considered: First order and second order.

   This parameter influences the accuracy of results and the computation time.

   The default level is second order mesh.

5. Airgap mesh coefficient

   The advanced user input “ Airgap mesh coefficient ” is a coefficient which adjusts the size of mesh elements inside the airgap. When you decrease the value of “ Airgap mesh coefficient ”, you reduce the size of mesh elements, thereby increasing the mesh density inside the airgap and the accuracy of results.

   The imposed Mesh Point (size of mesh elements touching points of the geometry) is described with the following parameters:

   MeshPoint = (airgap) x (airgap mesh coefficient)

   Airgap mesh coefficient is set to 1.5 by default.

   The variation range of values for this parameter is [0.05; 2].

   0.05 gives a very high mesh density and 2 gives a very coarse mesh density.

   CAUTION: Be aware, a very high mesh density does not always mean a better result quality.

   However, this always leads to a huge number of nodes in the corresponding finite element model. So, it means a need of huge numerical memory and increases the computation time considerably.