Description |
function Ploss = core_loss(t,B,Kfe,a,b)
Written by: Yoash Levron, January 2013.
This function evaluates losses in a magnetic cores for an arbitrary flux waveform. It employs the iGSE method, as described in:
"K. Venkatachalam, C.R. Sullivan, C.R. ,
T. Abdallah, H. Tacca, Accurate Prediction of ferrite core loss with nonsinusoidal waveforms using only Steinmetz parameters"
Accuracy of predicted power loss:
For a sinusoidal waveform, the iGSE
results in power loss equal to the "regular" Steinmetz model. For a nonsinusoidal waveform the iGSE method is much more accurate, because it includes high-order harmonics.
Experiments show that the accuracy of the
iGSE depends on the number points when
the derivative dB/dt is infinite. This occurs on "voltage jumps" of the voltage applied to the magnetic device. (switching points in a typical switching power supply). Therefore, for a smooth B(t) signal, accuracy of power loss is good, on the order of 10%, in comparison to experimantal measurements. The iGSE method assumes a magnetic flux with zero DC bias. This is another source of possible inaccuracy.
The input parameters are only the Steinmetz model parameters of the magnetic material. These are the "usual" parameter which are given by the manufacturer for sinusoidal excitations.
The steinmetz equation is:
Ploss = Kfe * f^a * (Bptp/2)^b
where:
Ploss - [W/cm^3] average power loss per volume
Kfe - [W/cm^3] core loss coefficient
f - [Hz] excitation frequency
a - frequency exponent (constant)
Bptp - [T] peak-to-peak flux density.
b - density flux exponent (constant)
function inputs:
t - [sec] time signal vector.
B - [T] magnetic flux density vector
B(t) is the magnetic flux vs. time.
Kfe, a, b - the material's steinmetz Parameters.
The function returns Ploss - the average power loss per volume. |