# Power Ferrite Core Loss model use of Kdc (Maxwell Core Loss With DC Bias)

**1**

Hello Ansys Community.

I intend to reproduce inductor core losses of experimental results using Maxwell transient simulation. I have obtained the core losses using the B-H loop method (a.k.a. Two-wire method). The experiment was performed using a boost converter, so variations of current ripple, DC Bias and frequency could be made.

To achieve this, I setup the following Maxwell project:

- A Maxwell Circuit simulation simulates the Boost Converter. The circuit is excited with the values of electrical measurements. The inductor of the circuit is assigned as an external winding (Maxwell 2D);

- In Maxwell 2D I set the excitation to be the external circuit.

- To characterize the material, I used experimentally measured B-H curve to set the relative permeability.

- Core loss data (BP Curve) was set using manufacturer provided curves for two frequencies, 10kHz and 20kHz, for which the best fit is the
**Power Ferrite**core loss model. The Steinmetz parameters obtained by Maxwell matched the manufacturer provided ones well. My measurements are in 10kHz.

The project reproduces reality very well: the output voltage matches the measurements, and so does the RMS and ripple current in the inductor. The problem is in core losses with DC Bias.

As far as I understand, the core loss curves provided by the manufacturer are measured given a sinusoidal excitation, and so should be the curves we provide Maxwell with. I believe that maxwell works out the whole non-sinusoidal excitation part by itself.

The manual isn't very informative on DC-DC converter simulation, and the nature of the inductor waveforms (Nonsinusoidal + DC Bias) isn't easily covered by models. This is where the guessing starts.

1. I *assume* that the *B *in the *BP *curve we provide Maxwell with is actually the Peak value of *B*. Given the DC Bias of my scenario, I *guessed* that Maxwell understands it as: Bpk = ΔB/2. Am I correct? At least this is what matches manufacturer data. I could not find information about this on the manual.

2. In the user manual, on Section "Assigning Materials 9-39", the equation through which the term **Kdc** affects the **Electrical Steel **core loss model is presented, but I haven't been able to find anything about the **Power Ferrite** core loss model. In fact, I couldn't even find the equation for Power Ferrite core loss model, but I have *guessed* that it is: Pv = Cm * f^x * B^y.

So how does the **Kdc **term comes into play here? I have been trying to *guess* how it works by trial and error, mainly assuming that it works exactly like it does for the **Electrical Steel **core loss model, as a simple multiplier inside the **Cdc** term, which would then multiply the **Pv** equation.** Can I have confirmation on this?**

3. Also, I am aware that the program has an automated way of determining **Kdc** if I just leave it at zero, but then the results don't agree with experimental data. I have also tested and confirmed that if I put in a very small value for **Kdc**, say, 1E-10, the results agree with experimental data for low DC Bias. It does act different that just leaving it at zero, which led me to believe that the use of **Kdc **for the** Power Ferrite **core loss model would be similar to the **Electrical Steel** core loss model.

4. My approach to determine the weight of DC Bias on material core loss is fitting the experimental results, but then again, without confirmation of how **Kdc** affects the **Pv** equation for **Power** **Ferrite**, it is difficult to work it out.

The main question here then is:

**How is the "Power Ferrite" core loss model affected by Kdc? **

## Comments

3MemberHere are some pictures that wouldn't fit the main post.

9MemberHello @pbolsi ,

How did you manage to find Kdc?

Regards.