Spectrogram - U, f, N

1. Positioning and objective

The aim of the test “Mechanics – NVH – Spectrogram – U-f-N” is to perform NVH analysis on the machine when operating at a set of targeted working points defined with the following inputs values U, f, N (Line-Line voltage, Power supply frequency, Speed).

This test is available only in the beta mode. It means that all the computation process and results are not entirely qualified yet. However, this gives users, the capability to use and to evaluate this new feature by themselves.

“Working point – Sine wave – Motor – U, f, N” Illustration

This test give data allowing NVH prediction in early electromagnetic and design stage.

The modal analysis of the stator mechanical structure, the sound power level spectrogram per engine order versus speed and the resulting overall weighted sound power level versus speed are computed and displayed.

These results allow to see if there are any problems linked with NVH over the considered speed range.

And finally, this test helps to answer the following question:

Could the machine have any risks in connection with NVH? Yes / No.

The following table helps to classify the test “Mechanics – NVH – Spectrogram – U-f-N”.

Family Mechanics
Package NVH
Convention #
Test Spectrogram - U - f - N
Positioning of the test “Mechanics – NVH – Spectrogram – U-f-N”

2. User inputs

The three main user input parameters are the supplied Line-Line voltage, the power supply frequency, and the speed (or the slip). In addition, temperatures of winding and squirrel cage must be set.

3. Main outputs

Test results are illustrated with data, graphs, and tables.

  1. Curves to give an overview of the electromagnetic behavior of the machine versus speed

    • Power
    • Mechanical torque
    • Line current
    • Control angle
    • Magnet temperature
  2. Graphs, curves, and maps to illustrate NVH analysis results

    • Modal analysis
    • Radiation efficiency
    • Sound power level spectrogram in speed-engine order area
    • Sound power level spectrogram in speed-frequency area
    • Overall weighted sound power level versus speed