How to calculate magnetic forces per tooth?


This article shows how to use MANATEE fast NVH simulation softwarae of e-motors to calculate the time waveforms of lumped magnetic forces for each stator tooth and at each skew slice.


MANATEE includes a projection tool which calculates equivalent magnetic forces and bending moments at stator tooth tips either based on the knowledge of nodal magnetic force (Virtual Work Principle after a finite element calculation such as FEMM) or based on the knowledge of the airgap flux distribution.

The forces in [N] are stored in matrices Output.Mechanics.XFTeeth_rad (radial forces) and Output.Mechanics.XFTeeth_tan (tangential forces). The reference frame is the polar frame so negative radial forces mean that the stator tooth is pulled towards the airgap (for an outer stator machine). The force is given per tooth for each skew slice.

The matrices XFTeeth have size is [Nt_totc,Zsc,Nskew_slices] where Zsc is the stator slot number divided by the number of spatial symmetries (Output.Geometry.npera), Nt_totc the total number of timesteps after application of symmetries and Nskew_slices is the number of skew slices (in case of skew modeling).

Scripting implementation

The calculation of lumped magnetic tooth forces can be activated with Input.Simu.is_comp_toothforces= 1;

GUI implementation


Plot commands

The associated plot commands are plot_Fteeth_machine_fft2 (extraction of a specific force wavenumber and frequency projected on stator teeth), plot_Fteeth_machine_fft (extraction of a specific force frequency projected on stator teeth) and plot_Fteeth_machine_time (visualization of forces per tooth at a specific time).

Validation cases

Associated validation cases are SM_005, SM_007 and SM_008.

Read more