Multi-simulation: stator slot skewing effect at no-load, variable-speed

Tutorial summary
Project name tuto_BPMSM_06
Machine name machine_BPMSM_A
Source project tuto_BPMSM_05
Description Sensitivity study on stator skew angle

In this example the no-load project tuto_BPMSM_05_test is copied pasted in a new project named tuto_BPMSM_06_test to find the optimal stator skew angle with respect to acoustic noise at no-load, variable speed.

The single input variable to be varied is the stator skew angle rate, expressed in stator slot pitch, given by

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

The skew rate is evenly varied from 0.8 to 1.2 stator slot pitch with 21 different values using

Input.Simu.types_var=[0]; %continuous variable
Input.Simu.types_val=[0]; % Value defined by interval
Input.Simu.type_sampling=[0]; % linspace sampling
Input.Simu.bds_contvar={[0.8 1.2]}; %Values between 0.8 and 1.2
Input.Simu.Nval_contvar=[21]; % 21 values
180. Setup of skew_rates variation
Setup of skew_rates variation

The output variable that is tracked during the sensitivity analysis is the maximum sound power level calculated from N0_min to N0_max rpm:

Input.Simu.names_resp={'LwrA_max'};
180. Workflow group (Sensitivity tab)
Workflow group (Sensitivity tab)

The default skew shape is linear, it is defined by the machine parameter

Input.Geometry.type_skew_geoS=0;

Finally the electromagnetic skewed model based on 7 slices is activated using

180. Numerical group (Magnetics tab)
Numerical group (Magnetics tab)
Input.Simu.type_skew = 2;          
Input.Simu.Nskew_slices = 7;

A the end of the calculation, the noise as a function of the skew rate can be plot using plot_MS_all_resp_var

Evolution of LwrA as a function of skew_rates
Evolution of LwrA as a function of skew_rates

One can see that the maximum noise at variable speed no-load, which is dominated by a zero-th wavenumber, is minimized close to one stator slot pitch.

The optimal skew angle depends on the type of the force wave responsible for noise and depends on the load condition, so the optimal skew rate is not always one slot pitch.

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