How to use the harmonic decimation tool?

Objectives

This article shows how to use MANATEE software specialized in vibroacoustic analysis of electrical machines to perform user-defined harmonic decimation for quick e-NVH diagnosis.

Principle

The principle is to cancel a given harmonic wave, defined by its electrical frequency f and its wavenumber r (f=fs and r=p for the fundamental flux wave) and see its effect on acoustic noise and vibration. This wave can be a permeance, magnetomotive force, flux density, Maxwell stress or tooth force wave.

This tool can also be used not only on NVH levels but also on electromagnetic torque level, to assess the contribution of some specific harmonics to average torque, torque ripple and cogging torque.

GUI implementation

Inside the GUI, the harmonic decimation tool can be set using a table in Magnetics\Assumption:

Harmonic decimation tool in the GUI

By clicking on "Add row" you can add a new "remove harmonic set". For each row you can specify r and f (or leave blank for all r or all f) and select on which spectra to remove the harmonics from. In the above example:

• The first row means remove all spacial harmonics at f =100Hz from the Rotor mmf spectrum.
• The second row means remove all r=5 harmonics for all frequencies in the Permeance and radial flux spectra.
• The Third row means remove harmonic r=2, f =200Hz from Permeance and Tangential flux spectra.

These 3 lines correspond to the following code :

```Input.Simu.remove_harm_perm=[[5 NaN];[2 200.0]]; Input.Simu.remove_harm_mmfs=[]; Input.Simu.remove_harm_mmfr=[[NaN 100.0]]; Input.Simu.remove_harm_Br=[[5 NaN]];   Input.Simu.remove_harm_Bt=[[2 200.0]];  ```

Scripting implementation

To use this feature, one need to set :

```Input.Simu.remove_harm_perm=[]; Input.Simu.remove_harm_mmfs=[]; Input.Simu.remove_harm_mmfr=[]; Input.Simu.remove_harm_Br=[]; Input.Simu.remove_harm_Bt=[];   ```

The harmonic removal tool is a 5 array corresponding to (in order):

1. Permeance waves to be removed
2. Stator mmf waves to be removed
3. Rotor mmf waves to be removed
4. Radial flux density waves to be removed
5. Tangential flux density waves to be removed

Each family of waves to be removed is defined by a matrix whose first column corresponds to the wavenumbers and second column to the frequencies. The wavenumbers can be negative but the frequencies are always positive.

If one wants to remove a given space harmonic whatever its electrical frequency, this is done by specifying [r NaN]. Similary, [NaN f] removes all the waves of frequency f independently of their wavenumber.

NA

Validation cases

Use cases of this feature can be found in the tutorial section.