Complex FFT of radial Maxwell force (plot_Fr_cfft2)

Post-processing documentation
Matlab commandplot_Fr_cfft2
Module EM.pp
Description PLOT_FR_CFFT2 plots the complex 2D Fourier transform of the airgap radial magnetic force per unit area
Parameters
Restrictions
See also plot_Fr_fft2, plot_Fr_fft2_stem, plot_Ft_cfft2

Result

This MANATEE software post processing plots the 2D complex Fourier Transform of radial magnetic pressure as a 3d stem plot in dB scale:

Maxwell tensor main lines and stator natural frequencies
Maxwell tensor main lines and stator natural frequencies
plot_Fr_cfft2

Negative wavenumbers and frequencies account for the different propagation direction of force waves. The largest force harmonics should occur at r=2p (twice the number of pole pairs), f=2fs (twice the fundamental electrical frequency), and at r=0 f=0 (static force). Note that only the lowest force wavenumbers are important in magnetic noise and vibration process.

The reference level of the pressure dB scale can be tuned in

Input.Plot.PM0ref

For further plot options (e.g. change axis) see How to change plot options.

This type of graph is very useful to identify which are the main harmonic forces responsible for magnetic noise and vibration of electrical machines. When a large force harmonic is close from a natural frequency, large vibration and noise is expected.

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