# HMagn4: Coil with ferromagnetic core

Sinusoidal voltage is applied to the electric coil with ferromagnetic core.

Problem Type:
An axisymmetric problem of nonlinear AC magnetics.

Geometry:
Due to the model symmetry only the right half of the coil is presented in the model (shown by upper half of its cross-section). Therefore the circuit elements' values are defined twice less than in the real object.

Given:
Magnetic permeability of the steel core μ - nonlinear;
Conductivity of the steel core g = 10,000,000 S/m;
Magnetic permeability of the winding μ = 1;
Conductivity of the winding (copper) g = 56,000,000 S/m;
Number of turns w = 120;
Applied voltage value U = 13.33 V;
Frequency f = 50 Hz.

Problem:
Determine the electric current within the coil windings.

Solution:
Current vs time plot in the real coil has non-sinusoidal shape (see TECircuit1 example). With AC magnetics module we can estimate RMS value much faster. The drawback of this approach is that we cannot estimate the wave form.

Results:

 Problem Current (RMS value), A Current (wave form), A Transient 34.1 48.1·sin(wt + 108°) + 3.2·sin(3wt + 147°) + 1·sin(5wt + 177°) AC magnetics 35.3 49.9·sin(wt + 104°)

See the HMagn4.pbm problem in the Examples folder.