Design of Flyback magnetics: The Ap approach

A direct, non-iterative procedure for the design of the magnetic element of the Flyback converter - the coupled inductor which is sometime referred to as the "flyback transformer".
Please see the background material at:
ElectroicBits#9 HF Transformer Design
• ElectroicBits#9 HF Tra...
and
ElectronicBits#22 - HF Power Inductor Design
• ElectronicBits#22 - H...

[@sadunnakipoglu9471]

Greetings to you and thank you, I appreciate your effort. Regards from Turkey.

[@sambenyaakov]

👍🙏

[@Robert-un3cf]

This channel is an amazing resource. Really grateful you're sharing your knowledge. :)

[@sambenyaakov]

Thanks

[@naveensoni5150]

Hello Sir I found your video interesting, for my thesis work, can you also elaborate that, what if blackback transformer using in old CRT TV with 220 V Ac supply having flyback connected to its Picture Tube with breakage wire passing a connection to a metal net *(same as speaker net) will give current to this as well. it will give shock from a far distance, may be because of the magnetic field, but up to what distance?

[@CNLohr]

It would be extremely helpful if there was an example with a specific amount of power, and a real core selection specifically including units. It's difficult to follow because information specified from core manufacturers and other aspects of the design are not necessarily in units that these equations help with directly.

[@sambenyaakov]

Thanks, good point. Perhaps in the future. See other magnetics related videos in my KZbin channel.

[@CNLohr]

@@sambenyaakov Oh, I'm going through them :) Thank you for putting all these together!

[@Chrls5]

WOW, ok so, i went and tested out this theory, and i got pretty good results. i used the equations to reverse engineer a core, so i took these core equations and created a virtual core, this virtual core has a toroid shape with the Ae kept the same, so the mass had to be equated , then went and wound 10 turns, and measured the inductance and kept the value on a note, then i added 10 more turns and i measured the inductance, then from the Delta, i created a difference equation, which i used to estimate, if this was a toroid core, the permeability in both virtual and real, applying the toroid core inductance equation, then went back to the real core with the parameters extracted from the virtual one, and i got an estimated error, from the calculations to the real deal of about 10% , so really accurate model, so maybe this 10% amounts to the losses not being considered, i designed a fly-back power supply, 2 outputs, 12V@3A each, with a final efficiency of 82%, way more than i expected !! Thanks for sharing!!

[@sambenyaakov]

Thanks for note and for sharing your experience. Interesting.

[@sudhanshutelrandhe5857]

Thank you sir

[@sambenyaakov]

😊

[@pratapkuruva9072]

Hi sir, In the flyback transformer design we see kge method and aeraproduct method, which one we should follow

[@sambenyaakov]

I don't know about kge, is it ripe? I am for the Ap approach. Have you seen kzbin.info/www/bejne/j2G6iJ1ombSSnpo ?

[@stepsvideos]

Thank you very much for your videos. I just found your channel today. I am not understanding why the flyback needs an air gap. My first thought is that you could store a lot more energy in the core, but this of course must be incorrect.

[@sambenyaakov]

Thanks for comment.The energy is in fact stored in the air gap because the H is much higher there (magnetic flux density is the same in gap and core). See kzbin.info/www/bejne/bH7MaYR6eZxkrKc

[@stepsvideos]

Excellent, thanks again.

[@TheAfricanEngineer]

Brilliant content, your videos are very informative. Would you follow the same design procedure for an LLC converter's "Transformer" since it also has to store energy?

[@sambenyaakov]

Indeed. See kzbin.info/www/bejne/g2SydoBsodOZiKc

[@krakamak]

May I ask you, when you do the explanation of saturation limits, why the integral boundaries have magnetic flux density dimension, when the integral itself time based? With this integral form for me it becomes a bit messy, although I know that dI/dt = Ipk/(D*T) and dB/dt = Bmax/(D*T), so by multiplying both sides with (D*T) we get the expected form.

[@sambenyaakov]

Indeed the multiplication is assumed

[@sereza1981]

Hi Sam Ben-Yaakov! Again thank you for your lectures. I have question about demension of Bmax: is it in Weber per m2(Tesla)? Thank you!

[@sambenyaakov]

Indeed. Thanks.

[@piyushmen]

In a flyback converter, if it is in CCM, then there is a DC current in the transformer. does that limit the maximum deltaB that we can get without hitting the Bsat limit. Also, if one decides to use interleaving, so that the maximum MMF in the core reduces, does that impact the deltaB somehow and how does that affect the design?

[@sambenyaakov]

DeltaB that affects losses is a function of the AC component. Saturation is a function of total instantaneous current.

[@ashishjha9961]

hi sir, your video is great. I have one question, as we see here by incresing number of turns we can reduce magnetic flux density (B) of the core to prevent saturation, but we also know that by Ampere’s law, the magnetic field inside a solenoid is given by BL=µIN which shows B is propotional to number of turns. Please clearify this confusion of mine that by incresing number of turns we reduce flux density(B) or increase it ? Thankss.

[@sambenyaakov]

Excellent question which, I think, many are wondering about. Increasing the number of turns will decrease B in cases that the larger n REDUCES the current. For example a transformer. If you increase the number of turns of a transformer, the magnetization inductance will and the magnetization current current will decrease. This will reduce B. If you increase the number of turns in Flyback then for same power Iav will be the same while Delta(I) will decrease. So Delta(B) will decrease. The bottom line: increase in n decreases Delta(B) due to AC voltages but increases B due to DC current. I hope explanation is clear enough.

[@sambenyaakov]

Welcome to join www.linkedin.com/groups/13606756

[@PlayboyHZ]

Is the design of a flyback transformer the same as for a coupled inductor in a two phase buck converter?

[@sambenyaakov]

Pretty much the same

[@muhammadbilalrafique6080]

Thank you, Sir, for this informative video. Sir, I need your help with the CCM Flyback Transformer question. How Can I contact you?

[@sambenyaakov]

You can write to [e-mail]

[@punyashreepattanayak2560]

Hello Sir, Your video is really very helpful. But I have some doubts. I am designing a 120W flyback converter. What will happen, if I will use a continuous core as used for high frequency transformers?

[@sambenyaakov]

I guess you mean CCM. No problem.

[@NNNILabs]

+PUNYASHREE PATTANAYAK Maybe you mean no air gap in the core. If you do use one for the flyback topology, you will be wasting a lot of energy as the transformer saturates at low currents. The inductance will also increase, and a lower operating frequency is needed.

[@sambenyaakov]

Correct. If no air gap is indeed meant. The core will stature. Energy can be stored (as required in the flyback converter operation) only in gaped cores.

[@ashishkashyap2917]

If we start with AP then how can we find L value before knowing the Ae??

[@sambenyaakov]

I don't follow. L is a starting point, found from the circuit requirements.

[@Mr2718281828459]

Why does transformer require a core?

[@sambenyaakov]

To increase magnetization impedance

[@vickys1460]

Sir what will be the unit of AP calculated from given formula? m4 or mm4

[@sambenyaakov]

Vicky S m4

[@sambenyaakov]

m4

[@vickys1460]

Thank you sir