Sensitivity study on stator skew at full-load

The project tuto_SPMSM_03 can be copied / pasted and renamed as tuto_SPMSM_06_test to define a sensitivity study on stator skew at partial load with imposed sinusoidal current.

The multi-slice skew modeling is activated with 5 slices with:

Input.Simu.type_skew = 1;
Input.Simu.Nskew_slices = 5;

The sensitivity analysis is activated:

Input.Simu.type_sensitivity = 1;

The design variable skew_rates (stator skew rate in stator slot pitch) is selected

Input.Simu.names_var={'skew_rates';};

As we want a continuous variable evenly taken in an interval as an input, one puts

Input.Simu.types_var=[0]; % Continuous values
Input.Simu.types_val=[0]; % Value in an interval

To make the skew rate in stator slot pitch vary between 0 and 2, the boundaries are defined as :

Input.Simu.bds_contvar={[0 2]};

To generate 20 different skew rate one defines

Input.Simu.Nval_contvar=[20];

The 20 values will be defined as a linespace of this interval:

Input.Simu.type_sampling = 0;

To look at the cogging torque, torque ripple and the maximum sound power level at variable speed (synthesized sonogram) one should specify

Input.Simu.names_resp={'TemM_rip';'Tcog_rip';'LwrA_max'};

With the GUI, all these parameters are set in Workflow Sensitivity/Optimization.

Once the calculation is finished, once can look at the results using plot_MS_all_resp_var.

Cogging torque as a function of the stator skew rate
Cogging torque as a function of the stator skew rate
Maximum sound power level at variable speed as a function of the stator skew rate
Maximum sound power level at variable speed as a function of the stator skew rate

As we have defined 3 response variables we can also visualize the cloud of points in 3D using plot_MS_resp3D.

One can see in particular that acoustic noise globally increase with torque ripple, but this is because the acoustic noise is dominated by the breathing mode of the machine (excitation wavenumber r=0), this is not true in general.

Acoustic noise as a function of Torque ripple
Acoustic noise as a function of Torque ripple

In this particular case a stator slot pitch skew reduces significantly the noise but it is not the optimal angle for torque ripple reduction.

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