Variable-speed open circuit vibro-acoustic simulation with permeance / mmf model (FEA calculation for rotor mmf)

Tutorial summary
Project name tuto_IPMSM_02
Machine name machine_IPMSM_A
Source project tuto_IPMSM_01
Description This project aims at improving the calculation of the rotor mmf by using the automated call to the non linear magnetostatic model of FEMM.

The project tuto_IPMSM_01_test is copied/pasted (or loaded and saved with the GUI) in a new project tuto_IPMSM_02 will the following change:

120. Electromagnetic group (Method panel)
Electromagnetic group (Method panel)
Input.Simu.type_rmmf_model =  2;

The call to FEMM is very short and does not significantly change the overall computing time. The FEMM model is temporarily saved and should look like this:

FEMM model
FEMM model

The spatial flux distribution has a bit changed with non linear magnetostatics, it can be checked with (plot_B_space) :

Airgap total flux density over space
Airgap total flux density over space

The noise as a function of speed is now given by (plot_VS_ASWL_modal_cont) :

Structural mode contribution to A-weighted SWL
Structural mode contribution to A-weighted SWL

One can see that two main resonance occur with the breathing mode of the stack, respectively close to 3000 and 6000 rpm.

The frequency of the vibration waves responsible for the noise can be found looking at the spectrograms or using the order tracking analysis with (plot_VS_ASWL_order_analysis) :

Order analysis [dBA re. 1pW]
Order analysis [dBA re. 1pW]

The two force wave responsible for the two resonances have frequencies of 12fs and 24fs.

These conclusions show that at no-load up to 6500 rpm, the Prius electrical machine acoustic noise shows two resonances at 12th and 24th the electrical frequency with the breathing mode of the stack. This is in full agreement with the conclusions of this FEA work:

Conclusion of "Electromagnetic and vibrational characteristic of IPM over full torque-speed range"
Conclusion of "Electromagnetic and vibrational characteristic of IPM over full torque-speed range"

Running a full electromagnetic and structural finite element model at variable speed requires several hours of calculation, while MANATEE only takes a few seconds to obtain the same conclusions.

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