Given:
Core type: E19/8/5-3C81 (by Ferroxcube)
Magnetic permeability of MnZn ferrite μ=2700
Primary winding:
Number of turns - 80
Waveform - periodic rectangular wave
Frequency - 20 kHz
Voltage magnitude - 40 V

Task:
Calculate core loss.

Solution:
According to Dartmouth university report^{1} published by Dr. Sullivan and Dr. Harris for rectangular waves it is possible to use Steinmetz-like equation (referred as equation (8) in this report): P_{v}[W/m^{3}] = max(k_{1}·f^{α1}·B^{β1}, k_{2}·f^{α2}·B^{β2}),
with material-dependent parameters, which for the E-core E19/8/5-3C81 from Ferroxcube are: k_{1} = 18.02, α1 = 1.23, β1 = 2.45 k_{2} = 0.000350, α2 = 2.10, β2 = 2.33.

Following this approach, to estimate the losses at a square wave excitation, we need to run Transient Magnetic analysis with a square wave source, and at the moment when the fluxes are at their maximums integrate the volume losses across the parts of our interest.
This may be easily implemented using Microsoft Excel and QuickField.

Results: Magnetic flux density distribution at t = 2.5 ms (maximal values).