# How to set a new B(H) curve?

The lamination B(H) curve is selected according to the material name in the material library. The material data is a .txt file "material name"J.txt in the MaterialData folder. The first column is the excitation field H in A/m starting from 0, and the first line is the value of the fundamental frequency at which the flux density B is given. Interpolation is used to calculate the effective B(H) curve at operating frequency.

For the saturation coefficient calculation, another curve B(H) can be used where B is given at very high magnetic field values using :

`Input.Simu.type_BHsat = 1; `

This curve is defined in the file "material name"satJ.txt in the same way as a normal B(H) curve (first row is the vector of frequencies).

Alternatively, one can use some analytical B(H) curve model defined for any value of excitation field. This model does not depend on the frequency, and can be activated with

`Input.Simu.type_BHsat = 2; `

The parameters of the analytical B(H) curve are then defined in the machine by

```Input.Magnetics.Bmax_BHsat = 1.5;       Input.Magnetics.mur0_BHsat = 8585;           Input.Magnetics.a_BHsat = 0.25575;            Input.Magnetics.mur1_BHsat = 21.79; ```
• Bmax_BHsat is the max flux density [T]
• mur0_BHsat is the relative permeability close to H=0
• a_BHsat is a shape parameter of the B(H) curve elbow
• mur1_BHsat is the relative permeability when H tends to infinity.

This is illustrated in the following figure:

MANATEE B(H) curve analytical

To visually fit a given B(H) curve to that specific model, a graphical user interface can be triggered with :

`Input.Simu.type_BHsat = 3; `
MANATEE B(H) curve GUI

Some post processings (e.g. plot_BH function) allow checking these input parameters.