The effect of switching frequency on ferrite cores losses, f*Bpk and answer to riddle

[@naveenmukundan2234]

Thank you, Professor for sharing this intuitive way of looking at ferrites. I have been working on ferrites for over 25 years, yet I find your presentation very informative and purposeful. Thank you!

[@sambenyaakov]

Thanks for comment.

[@justinn771]

Hi Prof. Sam. As always your topic bring me at the end of the pesentation. Thank you.

[@sambenyaakov]

No beyond? 😊 Thanks for kind note.

[@BrijeshKumar_electrical]

Thanks Sir

[@sambenyaakov]

👍🙏

[@sandeeppinninti3087]

Thank you so much.

[@sambenyaakov]

🙏😊

[@SolidStateWorkshop]

Thanks！

[@sambenyaakov]

Thank you too!

[@preet2692]

Thank you for this very helpful video! If I may ask a question, please, wrt the equation in the slide shown in the 14 minute mark-- I've seen calculations of inductance (say in a boost converter) use the peak to peak current and ∆B value. Once the inductance has been worked out, ∆B is re calculated and divided by 2 to get the Bpk value to estimate loss from the manufacturer's graphs. Is this "divide by 2" approach applicable for inductors/ chokes as well as transformers?

[@sambenyaakov]

Yes. The Steinmetzian equation of ferrite losses is formulated for Bpk while when calculating B from Faraday law you get deltaB=2*Bpk

[@preet2692]

@@sambenyaakov Thank you very much for your response, appreciate your work!

[@ElectronicsCircuitHubECH]

Thank you so much professor. Do you have any plan to teach DC DC converter topologies ?

[@sambenyaakov]

Thans for comment, Not at this time. If I do should it be an introductory or advanced course?

[@ElectronicsCircuitHubECH]

@@sambenyaakov thanks

[@preet2692]

@@sambenyaakov an advanced course would be very helpful, professor!

[@sambenyaakov]

@@preet2692 👍🙏

[@EngineeringEssentials]

Great information sir, I was wrong about core losses. I tried an isolated SMPS with EI ferrite core rated at 100kHz. But I switched it at a frequency of 25kHz thinking that a lower switching frequency should not be a problem. The core heated up so much that it fell apart by losing glue. Your video is of great help for me professor. From your video my other conclusion is that ferrite core doesn't care whether it's a sinusoidal signal or square wave. Because higher order harmonics makes no considerable harm to the core - from a core loss perspective? Is that correct?

[@sambenyaakov]

Thank for comment and sharing your experience which seems like an experiential validation of what is said in video😊

[@PlayboyHZ]

Thank you for your videos on magnetics design, has helped me alot! I have a question that is not specific to this video, but rather about coupled inductor design. I am trying to compare the efficiency of a two phase buck converter using single inductors and coupled inductors. I am using a powder core for both design which have a flux saturation at approx 10000 gauss or 1 Tesla so for my single inductors it is not neccesary to use an air gap but for many designs of coupled inductors i have seen, they are using an air gap. Is this neccesary even though you are well below the saturation or is the air gap needed for correct functionality of the coupled inductor? Thank you in advance, Best Regards

[@sambenyaakov]

I don't follow. Powder core is a distributed gap core.

[@PlayboyHZ]

@@sambenyaakov Yes, but with a distributed airgap core, how Can I then change the coupling factor if i dont have any “physical” airgap.

[@sambenyaakov]

@@PlayboyHZ Coupling cooefficient is basically not a function of the air gap, although the air gap might affect it. See kzbin.info/www/bejne/iobJkoFqZblkj8k

[@sagarkshatriya4688]

Thank you for this knowledge sharing. I want to know about air-gap effects in flyback topology. How to counter it and it’s effects on cross regulations.

[@PlayboyHZ]

Having windings close to air gaps will cause more losses due to fringing effects. It is usually a good design to not have the windings close to the air gap(s)

[@sagarkshatriya4688]

@@PlayboyHZ we need to add some turns on primary side. Cross regulations can’t be deal even if windings are not near air gap.

[@sambenyaakov]

Counter in what respect? The gap increases leakage which affects cross regulation.

[@bobvincent5921]

Thanks. Most absorbing the effect of 3?? Materials and frequency. What about super conduction of core and winding??

[@sambenyaakov]

There is little, if any, data on ferrite losses at very low temperature.

[@sergpodolnii3962]

Hi. Could you please post a link on the mentioned video about inductors and transformers design. And a small question regarding this video. When you demonstrated B(t) with positive and negative flat tops, does it mean that the coil at these moments has DC-current through the coil, i.e. B=N*Idc/(S*A)?

[@willthecat3861]

Try seeing kzbin.info/www/bejne/aZ_JonWwhbKepLs , to start (Ap is mentioned into the video), and for flyback design, using Ap, see kzbin.info/www/bejne/j2G6iJ1ombSSnpo... finally see kzbin.info/www/bejne/j2G6iJ1ombSSnpo (Ap is mentioned near the end of the video.)

[@sergpodolnii3962]

@@willthecat3861 Thanks. Is the 3rd link correct? It duplicates the 2nd one.

[@sambenyaakov]

😊🙏

[@srijeethj3616]

Sir, can you please share the source of the F x Bmax Vs frequency graph (timestamp: 14:42)

[@sambenyaakov]

Ferroxcube has it in its catalog

[@mohalothman99]

Thanks

[@sambenyaakov]

😊🙏

[@vaks2l]

6:43 This is not correct: the loss coming from hysteresis is just one part, the other one comes from the core eddy currents, which gives Pe = k*f^2*B^2 (valid for linear materials), so the total losses are k1*f*B^2 + k2*f^2*B^2. In total, for nonlinear materials, these exponentials are given by Steinmetz coefficients alpha and beta and typically beta>alpha.

[@sambenyaakov]

Sorry but you are wrong. Ferrite material has negligible eddy current loss and the Steinmetz equation represents for the hysteresis loss.

[@vaks2l]

@@sambenyaakov I would agree to a certain extent, it is normally low due to the low electrical conductivity of ferrite materials, but still alpha>1 which indicates higher order of frequency dependance.