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Laminated cores simulation

# Laminated cores simulation

Laminated cores or laminations are used in the electrotechnical devices of almost any type. The goal of lamination is to decrease the eddy current and losses by splitting the ferromagnetic material into smaller sections, insulated from each other electrically. Due to lamination the amount of the flux conductive media (pure steel) is somewhat less then total width of laminated core. It is taken into account by use of lamination factor *k*_{st}, which is equal to the ratio of the sum of pure steel lengths to the design length of the laminated core.

*k*_{st} = *l*_{st} / *l*_{total}

Electromagnetic simulations of the device or equipment, which has laminated parts, may be performed using special approach, allowing replacement of the layered materials in the laminations by homogenous media with specially adjusted magnetic properties. Finite element mesh density in the laminations may be decreased, which leads to decrease of the computer resource requirements, and considerably increases the speed of simulation of the device with laminations.

- In the linear problem involving laminated core you can simply reduce the magnetic permeability of the core by
*k*_{st} factor:

*μ1* = *μ* / *k*_{st}.
- In non-linear case it is necessary to define the magnetization curve. Instead of material original curve
*B(H)* the modified curve *B*_{1}(H) should be used.

In the strong fields the difference between *B* and *B*_{1} becomes significant. For example, the induction *B* = 1.3 T corresponds to magnetizing force *H* = 550 A/m (steel 2211). Taking into account lamination the actual induction is

*B1* = 1.3/0.93 = 1.4 T.

This induction corresponds to the magnetizing force *H*_{1} = 1000 A/m, i.e. inductions difference 7% leads to magnetizing force difference more than 80%. It is obvious that this difference will grow with saturation.