Result interpretation : Graphical Output (Variable speed)

The variable speed vibroacoustic simulation of the SPMSM has been set-up in the project tuto_SPMSM_01. This article details the main graphical post processing available in command line once a variable speed simulation is completed.

All the variable speed graphical post processing start with plot_VS, they can be accessed with by using the Matlab auto-completion or in the post_processing documentation.

The variable speed average radial acceleration can be displayed as a spectrogram with plot_VS_Ar_spectrogram

Radial acceleration spectrogram
Radial acceleration spectrogram

If you are not familiar with this graph you can refer to our detailed article on what is a spectrogram?. One can see that significant vibration occurs at 5000 and 6500 rpm.

The overall SPL (sound pressure level) can be displayed with plot_VS_ASPL_overall

Overall sound pressure level
Overall sound pressure level

The red line corresponds to the speed above which the spectrum is complete up to specified maximum frequency Input.Simu.freq_max_spec.

To further understand where resonances come from, one can plot the sonagram (variable speed noise spectrum) with plot_VS_ASPL_sonagram

Variable speed noise spectrum
Variable speed noise spectrum

The contribution of the structural modes to the acoustic noise level can also be checked with (plot_VS_ASWL_modal_cont) :

Contribution of the structural modes to the acoustic noise level
Contribution of the structural modes to the acoustic noise level

The following resonances occur (fs is the fundamental electrical frequency and fR is the rotation mechanical frequency):

  • mode (0,0) (breathing mode) of the stack is excited at 2*6235 rpm by an harmonic force at 36fs=LCM(Zs,2p)fR
  • mode (0,0) (breathing mode) of the stack is excited at 6235 rpm by an harmonic force at 72fs=2LCM(Zs,2p)fR
  • mode (4,0) of the stack is excited at 11010 rpm by an harmonic force at 16fs=LCM(Zs,2p)fR-2fs
  • mode (4,0) of the stack is excited at 8795 rpm by an harmonic force at 20fs=LCM(Zs,2p)fR+2fs
  • mode (4,0) of the stack is excited at 5180 rpm by an harmonic force at 34fs=2LCM(Zs,2p)fR-2fs
  • mode (4,0) of the stack is excited at 4628 rpm by an harmonic force at 38fs=2LCM(Zs,2p)fR+2fs
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