Uneven airgap vibro-acoustic effects with permeance / mmf model

The non-circularity of stator and rotor laminations can be due to segmentation effects, welding effects, manufacturing tolerances, deflections due to weight and thermal expansion forces, etc. The non-circularity of the laminations modulate the magnetic forces and therefore significantly change the vibration and acoustic behaviour of the machine. These effects can be studied in MANATEE using the permeance / mmf model.

To study the effect of a periodic change of the lamination shape (“flower-shape”), a new project is set-up in tuto_test_SCIM_18 by copy/paste tuto_test_SCIM_01 with the following changes:

Input.Simu.type_stator_shape = 1;
Input.Simu.Nsegs =  6;
Input.Simu.deflection_rates=0.2;

In the GUI, these parameters are available simulation GUI in the Fault group.

This indicates that a 6 segment or 6 weldings stator is considered with +/- 20% deflection from the nominal airgap.

Result interpretations

The model is run as usually using in the Matlab command line

>> run_MANATEE('tuto_test_SCIM_18');

The shape of the airgap can be checked with the command plot_airgap_shape

Stator shape
Stator shape

A display amplification factor is used to plot the non-circularities in the structure Plot, you can change it by directly specifying >> Input.Plot.disp_ampfactor=100

The influence on the variable speed sound power level can be checked using the sonogram (plot_VS_ASPL_sonagram):

Sonogram with uneven airgap
Sonogram with uneven airgap

One can see that the acoustic noise spectrum is much richer than in the case of the ideal machine of tuto_test_SCIM_01:

90. Variable speed noise spectrum
Variable speed noise spectrum
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