Matlab command | plot_smmf_space |
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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*.

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?.