Analysis and Design of a Flyback; Part 20, Transformer design C

In this video lecture, I review the design procedure in more detail in how to select the wire based on the wire's current carring capabilities. I also show how to calculate the DC and AC power losses in the transformer and show how to optimize the design by using a spreadsheet based on the equations that I present. Questions and comments can be sent to [e-mail]

[@cdlopez29]

Hello Robert, let me congratulate you for your excellent videos, which contain invaluable information about the design of flyback converters, thank you very much and I wish you a good life

[@RobertBolanos]

Thank you Cristian for the words. You made my day!

[@anandparalkar]

Dear Robert, Could you please consider doing the following in the next set of videos: 1. Relating temperature rise and power loss of the transformer. 2. **Actual measurement of temperature rise.** 3. How to set the permissible temperature rise of the transformer. (Material limitations and ambient considerations.) 4. Is there a way to *measure* core loss and wire loss separately. One gets greedy after being fed....you know. :) Regards, Anand

[@anandparalkar]

....neat optimization...didn't realize that the Excel you have shown can be used for this type of optimization.

[@imranhussain399]

Hi Sir, you are great in making complex concepts easy. I need your favor. I am a junior research engineer. I am trying to develop a flyback converter just for understanding purposes. Our goal is something different. Flyback have following specs: Np=30T, Ns=2500T, fs=34kHz, D=47%, Vin=20V, RL=1Meg. Leakage Inductance Llk=200 uH. The Core is UU Core of MnZn Material having Effective Core area of Ae=191mm^2. Both primary and Secondary Windings are wound on separate legs. Primary Winding is of Single Copper Conductor of AWG=25. The issue which I am facing is that during ON Time (Ton), the inductor current doesn't increase linearly rather it oscillates and it seems that there are sinusoidal oscillations which are superimposed on the linearly Increasing Inductor Current. Due to this reason Output Voltage is much smaller in amplitude than the theoretical one. can you Plz explain the reason and Phenomenon which causes inductor current Oscillating. and also how can we solve that problem. Any helpful Information will be Appreciated. A Rough Sketch of Primary Inductor Current during Ton is attached herewith . drive.google.com/file/d/1HHPh5b1vHrkywzdQzuXvkwrtDxF-Ipu2/view?usp=sharing

[@RobertBolanos]

Hi Imran, If you have a schematic and a parts list, please send to [e-mail] Also, what is the inductance of the primary open circuit, and the inductance of the secondary open circuit. Then take the short circuit inductance measurement of both the primary and secondary. Also, do you have a output capacitor and what is its value? I also need the Vinput operating rangne. Vout, Iout. Robert Bolanos

[@RobertBolanos]

You got it Anand, will add temperature rise calculation.

[@pepitoczw]

Excelente video!!! A question I have tried to follow the Rdc equation (15:17 and 23:42) and I can see that there is a factor in the multiplication = *2.4, why? This value does not correspond to the one in the excel sheet provided by you... is it an adjustment factor? thank you very much for your reply.

[@Telectronics]

Wow superb video Mr. Bolanos ! I have watched a lot of your videos and learned a lot from you thank you for your time and effort ! I still have a question though If I have a unknown core is it possible to make the graph of kW/m^3 in relation to the flux in tesla by myself like you have shown in the datasheet video 19 I guess it was ? The flux I get from my turns calculation but how to measure kW/m^3 ? If I know kW/m^3 I can then calculate core loss in W like you said.

[@DeepSingh-wo1tt]

Sir in TV flyback there are 8-10 rings of windings, How those are different from this type of flybacks? I want design calculation for tv flybacks

[@pziler6895]

Hello, can you add RCD Snubber circuit calculation ?

[@UsmanKhan-cj2bc]

Sir I have selected EE55/55/21 core (TDK) as it was available at my place, the problem is that there is no info about mean length turn in data sheet. Is there anyway to calculate MLT ??

[@rmeshpresh879]

Hello sir, you didn't explain "% of height (50%)" in video. can you explain it in comment?

[@rakeshrohira4605]

Dear Robert :- I have been thru your previous videos...and I have almost made an excel sheet exact identical to yours. IN your previous video the current in primary works out to a differnet value 3.76 Amps. Basis of calculation is Ipeak*D^0.5...however in this video...the valu of current drops to 2.17 amps...which I am not able to figure out how it changed. Could you please confirm which value of current is correct ? Thanks & Regards -Rakesh

[@RobertBolanos]

Hi Rakesh, email me at [e-mail] and I will send you my SPICE file along with an updated Excell Flyback Script. Robert

[@bogdan546]

Hello Robert, The Excel spreadsheet can be put here ?

[@RobertBolanos]

Send email to [e-mail]

[@karastom2304]

Thanks so much Robert, please can you explain how we calculate the gap for the forward transformer?

[@RobertBolanos]

The forward transformer does not have a gap. However, the flyback does has a gap. You can calculate the gap. However, the gap is found empirically by winding the bobbin and then you grind the center part of the core and you reassemble and measure with a LCR meter. You repeat this process until you get the required inductance. kzbin.info/www/bejne/o4iTZIGnq72YsJo Watch the first 13 minutes of the video. Hope this clarifies your question.

[@karastom2304]

Thanks so much ,you are very helpful

[@karastom2304]

Hi Robert ,what will happen if he forward has gap,is this energy will increase loses and saturate the transformer and can damage MOSFET?

[@RobertBolanos]

The flyback has a gap and because you want a specific inductance in the primary. A forward, you do not design for a specific inductance. However, by putting a small gap will not hurt your forward transformer. What it does it make the B versus H plot wider which means that it desensitizes the changes in the inductance. Typically, a ungapped core will have a +/-20 tolerance, by putting a gap, you can reduce the change to 5*/- percent change. Hope this makes sense.

[@karastom2304]

Thanks so much

[@chintukota757]

vo=n(d/1-d)*vin this is for ccm?.sir what abt dcm please dcm caluclation

[@RobertBolanos]

All the calculations are for a discontinuous conduction mode flyback

[@anandparalkar]

What is 'x' in Dowell's equation? Is it the length of the wire?

[@RobertBolanos]

it is the diameter of the wire

[@anandparalkar]

....thanks Robert.

[@boopathimanikandan1497]

Can u please share me the excel spreadsheet?

[@RobertBolanos]

Please send me your email to [e-mail]

[@chintukota757]

12v input 12v output 0.6A can i use these equations

[@RobertBolanos]

Yes it will work for a discontinuous flyback. If you email me at [e-mail], I can send you the excel spreadsheet

[@chintukota757]

[e-mail]

[@chintukota757]

please send auxlury winding equations also

[@nutankumar683]

can provide whole process in pdf formet

[@RobertBolanos]

If you email me at [e-mail], I can send you my notes, spice files and excel spreadsheet for the flyback.

[@pepitoczw]

Hello Robert, The Excel spreadsheet can be put here ?

[@RobertBolanos]

Contact me at [e-mail]

[@RobertBolanos]

Send me you email and I will send