Laminated cores simulation

Laminated cores 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.

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 B₁(H) should be used.

magnetization_curve_for_laminated_core

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.

Additional links on this subject:
Magnetic core from Wikipedia, the free encyclopedia