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Coil with ferromagnetic core

QuickField simulation example

This is an example of the coil with ferromagnetic core simulation, performed with QuickField software.

Engineering question
How to find transient current in coil with ferromagnetic core?

Engineering answer
Set up an axisymmetric QuickField Transient Magnetics problem for a coil with a ferromagnetic core and evaluate transient current from computed field results.

Typical applications
ferromagnetic core coils, magnetization transient coils, nonlinear magnetic inductors

Problem Type
Axisymmetric problem of transient magnetics.

Geometry
Coil with ferromagnetic core Sinusoidal voltage is applied to the electric coil with ferromagnetic core. Core Winding C R U 120 mm Ø 40 mm Ø 50 mm Ø 100 mm

Given
Conductivity of the steel core g = 10 MS/m;
Conductivity of the winding (copper) g = 56 MS/m;
Number of turns w = 120;
Applied voltage value (amplitude) U = 10√2 V;
Frequency f = 50 Hz.
Magnetic permeability of the steel core μ - nonlinear:

Task
Determine the electric current within the coil winding.

Solution
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.
The current wave period is T = 1 / f = 0.02 sec. We choose the time step of 0.0005 second that guarantees a smooth plot. The finishing time 0.2 sec includes 10 periods and is long enough to fade out initial transient currents. To reduce the results file size only the last period is stored (starting from moment 0.18 sec).

Results
The fundamental harmonic approximation of the current in the winding is: I(t) = 51.5 · sin(t·2π/T + 108°)


Coil with ferromagnetic core