ElectronicBits#22 - HF Power Inductor Design

The presentation describes an intuitive procedure for designing high frequency air gaped power inductors and distributed gap inductors.
Error correction: In slide 3-4 H=nI/l (l is missing)

[@jamesjohnston9319]

Just started a new job and needed to brush up on DC-DC converter design, so this course is an absoloute Godsend, many thanks prof!

[@brandonfreese3005]

Currently struggling with my Power Electronics course. You are saving my life prof, thank you!!!!!!!!!!!

[@sambenyaakov]

Happy to help!😊Thanks for comment.

[@sudhanshutelrandhe5857]

Best video covering practical aspects of Inductor design. Thank you Prof. Sam.

[@sambenyaakov]

Thanks😊

[@RicardoPenders]

Thanks to your videos I now have a lot less interference going back into the mains when I use my monster ZVS driver, for me it's now easier to know where the signals go and how I can isolate different frequencies, especially the high frequencies with high power from going back to the the line voltage or mains.

[@sambenyaakov]

Thanks for sharing

[@damiend1221]

Very practical! Thank you for this lecture and the others!

[@sambenyaakov]

Thanks

[@kimhawkk9544]

Thank you so much Prof. Sam!

[@sambenyaakov]

Thanks

[@SemtexEngineer]

One minor error skipped through at 24:02, for the RMS value of I the 1/T term is inside the square root. Excellent video! Thank you for sharing it!

[@sambenyaakov]

Thank you for the correction. You have a keen eye. Sorry for the slip up. I could have said that I did it on purpose to see who would catch. But I did not :-)

[@swh19]

Your lectures are always enjoyable to me!!!

[@sambenyaakov]

Thanks. Comments like yours keep me going.

[@sambenyaakov]

Hi, I think I saw a comment fofyour regarding an equation in minute 20.06 of video (to divide by 2?). I can't locate the comment. Please rephrase as I do not understand the reason why you think that a correction is needed.

[@swh19]

Hi Professor, that's fine now. I've just figured that out. Thanks for the reply.

[@faidularcs]

JeffH always we are students feeling hungry for every details explaining knowledge which, got like SIR SAM BEN YAKOOV Thankyou

[@babylonfive]

Great stuff.

[@VasanthBattula]

Respected professor Is HF transformer and HF inductor are same?

[@boubalex5846]

you are awesome, really thank you

[@sambenyaakov]

😊👍

[@saadthabit5694]

well done Mr. Ben Yaakov

[@sambenyaakov]

Thanks for comment.

[@johnconrad5487]

thanks for sharing the video

[@SuperSharonpaul]

Thank you so much for the lecture professor! can you please tell why the number of turns and the Window area depends on the RMS current, while the cross sectional area depends on the peak current in 20:29

[@sambenyaakov]

Rms determices the cross section of wire and area of wires and time n is the area you need in window which we what to fill. Ae is bound by the constraint Ipk L= n Ae Bmax

[@ankitkherodiya2961]

Awesome Lectures. Great work. Can you upload some lectures on pcb design & layout consideration for SMPS? Thanks

[@sambenyaakov]

Will try.

[@popovlist]

Hi professor, thanks a lot for the lecture. Question here, how do we take into account an offset with delta B when looking into selecting an inductor? For example I got a simulation of the flux density in a power inductor, but apart from the carrier frequency expected variation, there is a notable offset due mains frequency. So do I take that into account or look only into the ripple caused by the high frequency?

[@sambenyaakov]

Losses area a function of Bac but you need tp make sure that Bpk does not approach the saturation of the ferrite.

[@popovlist]

@@sambenyaakov many thanks

[@Stelios.Posantzis]

Prof. Ben-Yaakov, is there a core losses calculation part? Also, how come there is no copper losses equivalent? Combining the core size calculation with the copper losses (and possibly the core losses too) one could create a (probably) quite nice optimization problem.

[@sambenyaakov]

Thanks. These are left for homework😊Given the Delta(B), the frequency, the magnetic materiel chosen, the diameter of the wire and the mean winding length the losses can be calculated.

[@alibahrami1991]

Very useful material. at 34:45, it is mentioned 1 Amp/m=79.5 Oe. I think it should be reversed, I mean "1 Oe=79.5 A/m" is the correct relationship.

[@sambenyaakov]

You are of course correct. Thanks for pointing out the typo.

[@shishirtrivedi3668]

It was a very informative video. Actually, I have been working on inductor design and after selecting a ferrite toroidal core (x1.5Ap required), I have observed that it is saturating due to very low Bsat (0.2T) of the core, I assume. After watching the video, I plan on introducing a small air gap in toroid ring core as I have a lot of area unutilized. Any thoughts on this?

[@sambenyaakov]

Yes, you need a gap if there is a need to store energy. See other more recent related videos in my channel.

[@ashokchakravarthi87]

Hello Professor, is there any alternate way for selecting distributed core size without seeing manufacturers LI^2 curves.

[@sambenyaakov]

The LI^2 are really not a design tool but rather a pointer to the approximate core you need. You can use the AP approach to locate core.

[@pabloq3411]

Hi Professor. Why didn't you talk about skin effect? Is it already considered in some part and I did not realize? Thanks.

[@sambenyaakov]

There is that much you can put in one video kzbin.info/www/bejne/ioG2k6iLhK2bi8k

[@VasanthBattula]

Excellent sir

[@sambenyaakov]

Thanks. I am happy that the video caters to the young :-)

[@umakanthbojanapalli3240]

Valuable information sir

[@sambenyaakov]

Thanks

[@TheSecrecyOfFrequency]

Is the Core Size Selection Chart Software at 44:09 publically available? I can't seem to find it.

[@sambenyaakov]

As far as I remeber this is from Magnetics catalog. Copy the screen😊

[@TheSecrecyOfFrequency]

@@sambenyaakov Thankyou. I had already found their site but everything seems to be in PDF form only now. But at least with your confirmation of it, I can ask them if its still around. Thanks.

[@naveenmukundan2234]

Thanks for the video Prof! It was very enlightning. I have a question regarding distributed gap core. When you say the core has u= 125 does it mean that effective u is 125 or does it mean the effective mean is u0*125 (1.256e-6*125 = 0.157e-3)? Can you please clarify.

[@sambenyaakov]

Hi, thanks for comment. 125 is reative mu. For actual permeability you need to multiply by nu0.

[@HL65536]

Do the maximum stored energy and/or core losses change with introducing an air gap into a ferrite core?

[@sambenyaakov]

See kzbin.info/www/bejne/jKS1pJp6f7KGp9k&feature=share

[@dezektronics3052]

Thank you Professor for continuous sharing of inspirational ideas. By the way, I'm just curious, in 6:07, you define "H" as "H=nl". However, is "H" suppose to be H=nI/L, where H is the magnetising force in ampere-turns per meter (At/m)? .

[@sambenyaakov]

Yes, correct. I have put a note on that at the description section. Thanks

[@karastom2304]

Hi Dr Sam, thanks so much , as usual you are amazing , your lectures are very helpful . i have question about the Ac ,i do not see in the equations the effect of frequency on Ac, like when frequency is high we should be able to use smaller Ac , and also what is the effect of the topology (forward, flyback,half bridge, full bridge on the Ac. Thanks so much Dr Sam

[@sambenyaakov]

Hi Karas, This video is a very basic tutorial. Additonal issues are covered in the new kzbin.info/www/bejne/qF7LfGWFj9VoepI

[@shivannagovindappa5672]

Frequency decides the value of Inductance,Higher the frequency lower the L as you need to store power for shorter time and less LI

[@javieralejandromelian3579]

Dear Sam, did you design/construct laminated gno iron core ac inductors?

[@sambenyaakov]

Not really I am working on high switching frequency systems

[@karastom2304]

Thanks Dr Sam, very good explanation In resonance circuit we have to pick inductor with high Q, is this means that inductance will be stable and not vary when Q is high? and how we can figure required value that we need it?

[@sambenyaakov]

in power electronics we talk about series resistance and not Q High Q basically means low Rs. In power electronics some changes in inductance are tolerated because the systems usually works in closed loop.

[@karastom2304]

@@sambenyaakov thanks Dr Sam But there are some materials that have high Q And resistance depending on wires , so Q related to materials not to wires? Is that right

[@sambenyaakov]

@@karastom2304 Sure you are correct, core losses account. But still, in RF circuits of low power we worry about Q, in power electronics we talk about losses.

[@siamak1246]

Dr. Yaakov, could you tell me a company that make toroidal distributed air gap core (8:44). I need this type for my project. Thanks

[@sambenyaakov]

Magnetics

[@siamak1246]

Many thanks

[@idk2412]

Hello Professor, again, amazing videos can't thank you enough for everything! I've recently become aware of the difference between small signal permeability and average permeability, where Uavg=B/H and Usmall_sig=dB/dH. I've always just used Uavg (Ur and/or Ue). I'm still figuring out which applications use which, but it seems generally we use Uavg within HF power inductor design. Is that correct? The reason I bring this up is that n=(L*Ipk)/(Ae*Bmax) is now a bit confusing to me notation-wise since when I think of Ipk I think of the DC component + half the ripple component. So, when using that formula shouldn't we just be using the peak average current, not including half of the ac component?

[@sambenyaakov]

Thanks. Have you seen doi.org/10.36227/techrxiv.14975082.v1

[@idk2412]

@@sambenyaakov Thanks, I have not read that before, it was a great read on permeabilities. I'm still not sure if the paper addresses my last question about the DC component + half the ripple. Or if it does, I clearly didn't pick it up :)

[@catalin3407]

At 32:20 , mu0 (magnetic permeability of free space) is 4*Pi*10^(-7), but in the video they show it is "-8". Can you explain why is this, please?

[@sambenyaakov]

Units. l is in cm and A in cm^2

[@catalin3407]

Yes, I saw that. It did not make sense because I did not see the "dot" in front of the "4". So it is actually 0.4*Pi*10^(-8) H/cm, which by the way I think you have a typo at 32:26

[@sambenyaakov]

You are correct. I guess I also did not see the dot and didn't ponder about the value. Thanks.

[@jimidjoriginal9295]

Hello professor, this was a very nice lecture but i can't seem to understand the RMS value at 23:30. First of all I have seen the comments below and i know that 1/T should be inside the square root, i suppose that the integral limits should be at a given period of time (0 to T for example) but i am not sure about the equivalent equation of inductor current (IL). I used LTSpice in order to simulate the situation on a buck converter during DCM and CCM operation but i can't seem to find the right value of RMS current through the inductor with calculations, the value differs completely from the calculated value of LTspice. Last thing i want to mention is that i have seen the generic corresponding formula of a periodic signal over time from Wikipedia (Definition - Equation 2), should the f(t) (corresponding inductor current - IL) be replaced with the typical equation of V = L*di/dt or something else? Thank you.

[@sambenyaakov]

Sorry too involved, I cano't go into it.

[@pavanp611]

Can you pls guide me to arrive at core cross section Area if only secondary voltage and primary current of 30A rms is available .

[@sambenyaakov]

How about turns ratio and frequency?

[@pavanp611]

Sam Ben-Yaakov sir, frequency is 50hz and the power drawn is 10mW from the CT. Turns ratio I have to arrive . I dint have turn ratio too

[@pavanp611]

Sir can u take up a session on how to arrive at cross sectional area and no of turns, if we draw power from CT.

[@nachiketadeshmukh8444]

Sir, Why is it that the cores with discrete air gap have a sharp saturation, whereas powder iron cores with distributed air gap have a soft saturation? Can you please justify physically?

[@sambenyaakov]

Good question. I am not sure, perhps has to do with the nature of the ferromagnetic powder?

[@chitrasingh9200]

Did you write any book for SMPS or power electronics

[@sambenyaakov]

no, papers and videos.

[@eralp2726]

Dear Professor, Can I get slides for my academic study?

[@sambenyaakov]

Sorry, these are not available.

[@UsmanKhan-cj2bc]

Sir how to calculate MLT if not available in data sheet ??

[@sambenyaakov]

Look at cross section drawing. find the approximate radius of the mid winding R and the 2*Pi*R

[@appassets]

Where can I get a copy of these slides?

[@sambenyaakov]

Hold on, I may be able to dig them for you.

[@VasanthBattula]

At 9.44 it is called fringing effect

[@sambenyaakov]

Thanks.

[@VasanthBattula]

Respected professor may I know the status of my application

[@faidularcs]

Dear sir please do a video of HF TOROIDAL inductor design with details Thankyou

[@sambenyaakov]

see kzbin.info/www/bejne/bH7MaYR6eZxkrKc

[@nachiketadeshmukh8444]

Sir, Please add a note - n * I = mmf (manetomotive force) mmf/length = H

[@sambenyaakov]

No one escapes errors: "manetomotive"???😊

[@nachiketadeshmukh8444]

@@sambenyaakov Indeed. :D