Tutorial summary | |
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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

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'};`

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

`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

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**.