More on transformers, leakage, turns ratio, and voltage and current transfer ratio

Important background video
• Demystifying the meani...

[@dongolahmed]

Regards Prof. Sam ... I'd like to thank you a lot for your wonderful lectures. Even though I have a PhD in Power Electronics, but I've learnt a ton of new things from your lectures 🌹

[@sambenyaakov]

Thanks Hatem for the kind words. Comments like yours keep me going.

[@SuperHal2k]

Thank you for giving us the opportunity to learn by listening to your magnificent lectures.

[@sambenyaakov]

Thanks for kind words. Comments like yours keep me going.

[@esijal]

Many thanks Professor, great summary 🙏🤞

[@sambenyaakov]

Thanks

[@bensalemn271]

Thank you professor.🙏🙏🙏

[@sambenyaakov]

🙏🙂

[@hamidk4772]

Outstanding presentation x2 (Part 1, and 2).

[@sambenyaakov]

Thanks Hamid

[@benm4784]

Thank you professor! I'm just getting into coupled inductor modeling and this is a great concise summary of points you've made in other magnetics videos. Great reference I'll be sharing

[@sambenyaakov]

👍😊

[@nilorido1201]

Tank you sam.

[@sambenyaakov]

🙏🙂

[@chiatechou7900]

Thank you 🙏

[@sambenyaakov]

Thanks

[@Stelios.Posantzis]

I can't believe I have never been pointed to this simple fact. Given that we're taught about magnetic coupling factors already in secondary school, shouldn't this rather unintuitive detail be included in the syllabus along with one or two equivalent circuits?

[@sambenyaakov]

Indeed 😊

[@Stelios.Posantzis]

@@sambenyaakov In actual fact I need to keep revisiting this as the basic understanding of transformers we have since secondary school is so ingrained that this also basic fact is all too easy to forget.

[@levnemets2148]

In some cases it is still possible to determine whether there is leakage inductance only in the primary or in the secondary too. For example, this can be seen from the waveform on the secondary winding in the LLC converter.

[@sambenyaakov]

No, you cannot. Watch the video again.

[@levnemets2148]

@@sambenyaakov Of course, applying the methods you describe, cannot show whether the leakage inductance is only in the primary winding or also in the secondary winding. But, if you simulate a LLC circuit with leakage inductance in the primary only and a circuit with leakage inductance in both the primary and secondary (total leakage inductance is the same ), you will see the difference in waveforms on the secondary.

[@sambenyaakov]

@@levnemets2148 I do not believe this is so (if you do the transformation correctly). Can you send me the simulation schematics for both cases? [e-mail]

[@davecook2428]

I had the same intuition as @levnemets as I was struggling with the concept and design of a phase shifter full bridge (PSFB) converter and didn't know if I could apply the measured leakage from the primary side of the transformer to the circuit as an addition to the needed shim inductor, or if I had to figure out the different contributions of the primary and secondary leakage inductance. It really feels like the energy in the leakage inductance on the seconday is 'stranded' over there, but when I finally had a working PSFB model in Plexim with a one to one transformer, I could distribute a total amount of leakage inductance between the two sides of the tranformer and it had the same effect on zero voltage switching (ZVS) regardless if 99% of total leakage was on the secondary side to when 99% was on the primary side. This now should mean I can just measure the leakage on the transformer primary with the secondary shorted and apply that is my starting shim inductance for ZVS. So I can make the simulator work, but I still can't feel the 'why' this is this way. I'll send pictures of the similation circuit to Ben, but unless the effects are different for a LLC vs the ZVS effects on a PSFB, I think Sam's statement holds, if otherwise, I'd also like to see a discussion of why this is different in an LLC as that 'feels' like it should be, but so far the math as Sam has explained says not. Thanks again.

[@audiokees4045]

Ben A good evening. Busy with transformer build. Have a question about measurement of the transformer, do I have to measure the inductance on the switching frequency of interest? I have a meter who works on basis of a resonance, I get when measure uH a frequency of 184 Khz. when measure in high L setting I get a measure frequency of 48 Khz and the inductance is 638 uH and 748 uH with second test. THanks in advance.

[@tamaseduard5145]

👍🙏❤

[@sambenyaakov]

😊👍🙏

[@Ian.Gostling]

Dear Sam, I wonder if you might help me with this silly question. To the best of your knowledge does the angle a secondary coil makes with the core passing through it, have any effect on the voltage induced? Thanks in advance!

[@sambenyaakov]

In general not. The induced voltage is a function of the enclosed flux. However, the geometry of the winding might affect the coupling and hence the leakage iductance.