Analysis and Design of a Flyback; Transformer Design A, Part 18

In this video lecture, I give a design procedure in how to select the core, the material, the number of turns, and how to size the wire to fit all the primary winding in one layer. Questions and comments can be sent to [e-mail]

[@backpacknrideoff3211]

absolutely amazinnglecture, I am very confident now with transformer design,thank you so much

[@anandparalkar]

Robert, thanks so much for taking the time to put this video together. It really helps newbie designers like myself to get started quickly.

[@RobertBolanos]

Hi Anand, I hope you and the family are doing well. Give my regards to you mother, father, and brother for me. I remember them from our trip to Austin. Best regards, Robert

[@anandparalkar]

....sure.....need to catch-up on the latest two videos...

[@anandparalkar]

That's a really neat Excel. Will take away a lot of sweat work when going through a design.

[@karastom2304]

Thanks so much you are very smart engineer

[@eternalskychuang4469]

Thanks for Robert share It help me so mush

[@harin188]

thanks a lot sir ur video is very usefull

[@RobertBolanos]

Satyavijay, good catch, it should be duty^2. I will make a annotation on the video in the next day or so. Thank you

[@satd2024]

Thanks for another great video. The formula for primary inductance at starting shows only Duty but in the example (at 23.20 min) it shows Duty square (Duty ^2) in the formula. Somewhat confused about formula please clarify.

[@-dazz-]

Señor Bolanos, si las visitas a su canal se disparan en los próximos días, soy yo viendo sus videos una y otra vez, porque son buenísimos pero yo soy un poco lento. XD. Muchísimas gracias por compartir sus conocimientos de manera tan clara y exhaustiva

[@RobertBolanos]

dazz , muchas gracias por tu mensaje. Con todo respecto, Roberto Bolanos

[@RobertBolanos]

dazz mandane mensaje a [e-mail] y yo te mando mid notas y files para similar.

[@-dazz-]

@@RobertBolanos Muchas gracias de nuevo. Sus notas seguro me servirían de referencia, y para simulación yo uso LTSpice pero supongo que podré adaptar los circuitos. Le escribo ese mail en breve. Canales como el suyo deberían tener mucha más divulgación, pero lamentablemente el algoritmo de Google parece promocionar el clickbait y la basura sensacionalista por encima de la calidad del contenido. En fin, feliz año nuevo a usted y los suyos!

[@satd2024]

Sir, Many books / articles uses different-different formula for calculating number of primary turns. If we plug-in our data in those different formulas answers will be different for every formula. Some are including waveform coefficient as well as duty ratio others omit one of it or both. How to decide which formula should we use?

[@nurulamin5056]

give the list of core size selection

[@srinivasssd7545]

Robert , I have a doubt regarding topology constant value ??? What is the exact value we should use ???.I have found some other value Kt= 0.00033 for flyback which one I should follow please suggest sir..

[@chintukota757]

how primary inductance equation came sir?

[@Ramkumar-le4me]

please send the all the datasheet and excel sheet which you have refeered in this video

[@friendman2001]

I am going through your lessons and enjoying them. Are the lessons and the switching power supplies A to Z book to be used as a reference good enough for power supply design?

[@RobertBolanos]

Yes, that is a very good book. I have that book!

[@chintukota757]

in Lm duty*duty or only duty cycle

[@peeyushchauhan2189]

Sir at instant 25:00 u have solved the Ap formula but the result should be 419.322 cm4 where he term .0.042cm4 has come..can you explain . might be i am missing some thing.

[@Ramkumar-le4me]

You have selected EFD 20 core you have selected in design example. but in the datasheet max wattage is less than 24 how you select EFD20.Please calrify

[@RobertBolanos]

Chintu, it should be Lm*Duty*Duty. Robert

[@titeman9374]

Alright I appreciate your reply why I talk about arranging all your videos together for easy access because right now I can not see your video on tutorial 10,13,15,16,21, and some others .Thanks

[@RobertBolanos]

Let me see if I can fix that. It is very good feedback. If you are having trouble, then other people are having trouble as well. Robert

[@RobertBolanos]

Hi Tite Man, I think I fixed it. Please check it out. Thank you so much for the feedback. I think this is much better. You should be able to play them in the correct sequence. Robert Bolanos

[@titeman9374]

Please can you send me your core chart

[@quangcuon6683]

Hi sir, at 19:50 I think the current input Iin RMS = Ipeak*squareroot(Duty/3). Correct me pls! 🙂

[@RobertBolanos]

Hi Cuon, nice catch! You are correct!

[@quangcuon6683]

@@RobertBolanos Love that you confirmed 😍

[@vickys3555]

Sir in some books it is mentioned that air gap is necessary in case of flyback transformer design and for that AL value is also important, but you have designed transformer by different method and didn't mentioned air gap. So please clear my doubt. Thank you

[@RobertBolanos]

Vicky, That is so true. We need an airgap. So you use a core that has higher AL that will exceed the designed inductance. For example, if you watch video 6, I wound the transformer ungapped and then grinded the center core to get the designed design inductance. There is a formula to calculate the gap. However, some people use sheet of paper inserted into the gap to simulate a gap. I prefer to start grinding and measure the inductance until I get the desired inductance. That was a great question. RB

[@harikrishna1256]

Even I have this doubt Do you have any document where I can design a Flyback trafo?

[@TheGovindtrm]

Sir, is it really required to calculate inductance.. Seems, no where we are using it. Can you please explain..

[@RobertBolanos]

Yes, it is necessary to calculate the primary inductance. The amount of inductance determines what mode of current conduction you are operating. This video discussion is for a simple design using discontinuous conduction mode (DCM) and using a current mode PWM. Using these two properties allows you to design a simple compensation where you don't have to worry about the RHPZ and the subharmonic oscillation and thus you don't need to use slope conpensation. Hope this make sense.

[@karastom2304]

Hi Robert is .16T for any level of power?

[@RobertBolanos]

When calculating the AP of the core, use 0.16T. But when you are calculating the Nturn, then use B from 0.16T to 80% of the materials Bsaturation. In my example, my Bsaturation is 0.370T. So my my example, I can use a B from 0.16T to 0.293T. However, as B goes up, Nturns goes down, and Pcore_losss go up. So there are many compromisise. I will be doing another video tonight review this information and then cover the subject of skin effects and proximity losses.

[@karastom2304]

Thanks so much

[@titeman9374]

Please send me your excel calculator

[@RobertBolanos]

Send me your email address.

[@rakeshrohira4605]

Can you send me the excel calculator also at my Email [e-mail]. Thanks

[@RobertBolanos]

Satyavijay, good catch, it should be duty^2. I will make a annotation on the video in the next day or so. Thank you.