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# 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 kst, which is equal to the ratio of the sum of pure steel lengths to the design length of the laminated core.

kst = lst / ltotal

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 kst factor:
μ1 = μ / kst.
• In non-linear case it is necessary to define the magnetization curve. Instead of material original curve B(H) the modified curve B1(H) should be used.

In the strong fields the difference between B and B1 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 H1 = 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.