How to choose the electromagnetic model?

MANATEE offers several possibilities to calculate the airgap flux distribution and the resulting electromagnetic quantities (e.g. back emf, magnetic stress, magnetic losses in magnets and laminations). The choice of the model depends on the modeling assumptions, required accuracy and calculation time. Three main models are available:

  • permeance / magnetomotive force (mmf) models (also called Winding Function Model)
  • subdomain models
  • FEA models (using the automated coupling with FEMM or importing the flux from another software)

The following table summarizes the advantages and drawbacks of each model:

MANATEE electromagnetic model comparison

The permeance / winding function model (WFM) has the advantage to take into account phase current time harmonics due to PWM within a very short computation time. Time harmonics can also be efficiently modeled in subdomain models (SDM) using field reconstruction methods. They can be included in finite element method (FEM) but it makes variable speed calculations much slower.

Another advantage of WFM is to take into account static and dynamic eccentricities and uneven airgap shape. All the models can account for stator and rotor skewing.

However, subdomain models are preferred for the vibroacoustic simulation of electric machines because the tangential component of the flux density can play an important role in the estimation of radial harmonic magnetic forces. It also directly influences tangential harmonic magnetic forces that can affect radial vibrations of the yoke and resulting noise.

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