Stator magnetomotive force as a function of space (plot_smmf_space)

Post-processing documentation
Matlab commandplot_smmf_space
Module EM.pp
Description PLOT_SMMF_SPACE plots the stator magnetomotive force as a function of space
Parameters
Restrictions
See also plot_rmmf_space, plot_smmf_time, plot_smmf_cfft2, plot_smmf_surf

Result

This command plots the stator magnetomotive force (armature mmf) as a function of airgap angle, including Fourier harmonics, at a given instant defined in Input.Plot.j_t0.

Stator magnetomotive force over space
Stator magnetomotive force over space
plot_smmf_space

This allows to identify armature field main space harmonics or wavenumbers. The fundamental of wavenumber r=p (number of pole pair) is marked in red. This example shows the mmf of a 36s6p distributed winding, one can see that the largest harmonics are at Zs+/p=33 and 39 due to coil distribution in Zs slots ("stepped harmonics").

These space harmonics can be responsible for magnetic noise and vibration in electrical machines, especially in concentrated winding topologies where subharmonics can lead to low magnetic force wavenumbers.

To lower these space harmonics and reduce noise and vibration, available techniques include

  • short pitch double layer winding
  • stator skewing (linear slot inclination)
  • increase of slot number per pole per phase

In MANATEE the space harmonics of stator armature field can be artificially cancelled using Input.Simu.is_ideal_smmf = 1. For more information see How to cancel stator or rotor mmf space harmonics?.

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