Understanding Core Loss Measurement

In summary, the conversation discusses a search for a method to measure core loss in RF transformers and inductors, specifically focusing on a PhD thesis that introduces a practical method in Chapter 3. However, there are issues with understanding equation 3.1, specifically why Pcore depends on capital Ipp instead of lower-case ipp and why it also depends on the duty cycle D. After further investigation and help from outside sources, it is discovered that there is a typo in equation 3.1 and that the dependency on D is due to higher harmonic amplitudes contributing to higher core loss.
  • #1
reson8r
6
2
Hello folks,

I'm looking for a way to measure core loss in RF transformers and inductors. I found a PhD thesis here:
https://vtechworks.lib.vt.edu/bitstream/handle/10919/19296/Mu_M_D_2013.pdf
which looks like just the ticket, but I'm having trouble understanding key parts. I've tried contacting the author with no success.

Chapter 3 introduces a good practical method, but I'm stumped at eqn 3.1 (pg 66).
  • Why does Pcore depend on capital Ipp and not lower-case ipp? Capital Ipp results from the magnetizing inductance (Lm in fig 3.1), but lower-case ipp is the current step due to core loss.
  • Why does Pcore depend on duty cycle D? Driving fig 3.1 with a rectangular wave would result in a rectangular voltage across Rcore, so the power loss in Rcore shouldn't depend on D at all.
  • Not only do I not understand why D is in there, I don't see how its use in eqn 3.1 is derived.
In short, I pretty much don't get eqn 3.1 at all! If anyone can help, I would greatly appreciate it. Then perhaps eqn 3.2 will start making sense...

Gerrit
 
  • #3
I've gotten to the bottom of this, with some help from elsewhere. There is indeed a typo in eqn 3.1 -- Ipp should be ipp. And page 23 of the paper does touch on core loss dependency on D. Duty cycles away from 50% contain higher harmonic amplitudes, which contribute to higher core loss. That makes sense!
 

Related to Understanding Core Loss Measurement

1. What is core loss measurement?

Core loss measurement is a process used to determine the amount of energy that is lost in the core of a magnetic material when it is subjected to an alternating magnetic field. This measurement is important for understanding the efficiency and performance of magnetic components such as transformers, motors, and inductors.

2. How is core loss measured?

Core loss is typically measured using a specialized instrument called a core loss tester. This instrument applies an alternating magnetic field to the core and measures the resulting energy loss. The core loss is then calculated by subtracting the energy put into the core from the energy that is recovered.

3. What factors affect core loss?

Several factors can affect core loss, including the type of magnetic material, the frequency of the alternating magnetic field, and the temperature of the core. Additionally, the geometry and design of the core can also have an impact on the level of core loss.

4. Why is understanding core loss important?

Core loss is an important factor in the design and performance of magnetic components. By accurately measuring and understanding core loss, engineers can improve the efficiency and reliability of these components. This can lead to cost savings and improved performance in various applications.

5. Can core loss be reduced?

Yes, core loss can be reduced through various methods such as using high-quality magnetic materials, optimizing the design of the core, and controlling the operating temperature. By reducing core loss, the overall performance and efficiency of magnetic components can be improved.

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