Deciphering multiphase interleaved PWM converters with coupled inductors

Relevant video
A primer to: Multiphase Buck Converters

Error correction: on slide
and not the one above.

[ats]

Interesting video. I've seen this done with a toroidal coupled inductor with out of phase components, and the main benefit was touted to be the improved performance of the magnetics because of the lack of DC bias. That seemed like a reasonable explanation but would be interested in hearing your thoughts...

[petegaslondon]

Hi Prof nice to see you back (ah you've been quite prolific, i just didnt subscribe - lets fix that)
interesting - I thought that the inverse coupling being better was kinda obvious, but didnt expect the rise in circulating current - interesting set of tradeoffs :)

Also, pretty relevant now everybodys squeezing more power phases into high performance PC motherboards!

[RaedMohsen]

Great video.
I tried to duplicate the simuation model of the two phase coupled inductor buck and I always have an average difference between the current of the two coupled inductors. In other words, they are not sharing equally. Yours seem to be sharing nicely.
I am not sure if there is something that I missed in the simulation.

[solenskinerable]

thanks for the video! correct me if im wrong, but i think the lack of dc bias would allow the use of powder cores with a very high permeability per turn for their size, as long as the linkage is v high - while uncoupled or loosely coupled cores would have to use a larger distributed air gap to not lose permeability by the ampereturns of dc flux. ltspice doesnt seem able to couple inductors with nonlinear flux expressions, but maybe it could be done with dependant current sources? 🤔

[SR-mldn]

Thanks for the video. No one can explain it so intuitive as prof. Ben-yaakov. All most every buck converter circuits I've seen utilize the load is on "0 V". Is it possible to operate with symmetrical supply voltage and push-pull configuration so the load is kind of floating. I was thinking of a use case where the rail supply is under +/- 50 V measured to ground and measured over the load it will be 100 V max. For safety reasons where people could some how touch only one of the output at the time and therefore exposed to max 50 V.

[benm]

Professor, thank you for another great video!
I'm not sure I follow the takeaway that opposite polarity is preferred. If low output ripple is a desirable trait, what is the cost of same-polarity coupling? Size to reduce copper losses? Would either approach be preferable to reduce AC core losses?

[AhmedAli-opng]

Professor i really like your intuitive way of teaching. I also want to enter the realm of power electronics. But i am not sure how do i go with it. Like how do i realize which field of power electronics will be the topic of research in next decade. I am clueless at the moment. I would really like if you could give a generic input for enthusiastic newbies in this field.

[pietroferlita]

Prof. I think the model of the coupled inductors, used as in slide 11, is wrong. You can clearly see that the self-inductances on each side leaving the other open are not L. Same if you want to compute the mutual inductance, you don't get kL. The correct one is with L in place of L/k² and k:1 instead of k²:1

[chaiyonglim]

Hi professor, can you comment what is the benefits of using coupled inductors for multiphase buck? most published papers claimed it is good for power density (size), able to use smaller L and C, better transient performance. But as you showed ripple current is actually higher and we would need larger L and Cout to have the same inductor current ripple per phase and output capacitor rms current compared to non-coupled inductors case?

[madaboy]

Hello, thank you for the very good explanation. Could you please tell me what are the values of {L} and {R} used in the simulation?

[isacdaimary]

Thank you Professor, But at 05:31, I see two variables Ksimpe and K: which is confusing for me. Can you please look into this or just share the LTspice simulation file?

[AhmedAli-opng]

What is the difference between coupled inductor and transformer? Both have windings around the same core so what makes them different?

[azharajiel]

thanks so much for this explain, I want to design more mutual inductors for multi convrtetrs in one core in planar inductor to reduce the size of pcb. can I make that? and How, please?

[justpaulo]

I think the relevant video you mention at 5:40 is this one:

I actually have difficulty in understanding the mathematical transformation of the coupled inductor to the particular model you are using.

[LydellAaron]

Are you familiar with the dynamics associated with synthetic inductors made from op amps? These synthetic inductors do not have magnetic cores. Interested in using these in a project and came across your lectures.

[rahulpj]

Sir, In the video 5:49 how L/K^2 is coming actually it is Lm = KL.