Thanks a lot for your technically informative videos and really appreciate the time you spend and willingness to share the knowledge what is the advantage of using Case-1 two single strand parallel windings arranged in a way that the flux is aiding each other on opposite half of toroidal inductor. Compared to Case-2 Winding two stands together in parallel. The same awg is selected in in both cases and both cases should fill the entire core. only one layer is used in both cases. Bothe cases carry same amount of current is each stand since they are parallel. Total inductance is also same in both cases.
Very interesting. I didn't know before that tending towards uniform spaced windings is better as would reduce the wire resistance due to proximity effects. Thanks
Good material but I waited for flux densignity distribution in this windings, it was but only for spaced winding case. That could extremly nice to show how densignity is change in case of winding distribution and how losses, inductance of inductor are changing. Once I writed on linkin case when I had problem with inductor in resonant converter (core was hot), and in this case winding distribution was problem. I change winding distribution, Q goes extremly high and transformer got damaged but problem with hot core was solved ;)
Thank you the detailed explanation of the magnetics. I have a question that I hope you can clarify. I see that there are certain benefits to keep the windings away from the airgap. In case of something like an E core used for LLC converters, the gap is usually placed only in the centre leg. In such a case, is it good idea to keep the windings away from the gap or do we accept the issues that comes with placing the winding over the gap?
Thank you Professor for another great video! This is truly unique content! If you have free minute, could you please answer such a practical question: I have a PSFB converter with series "shim" inductor in it's primary (wire is pretty thick 0.35mm @100kHz@2Arms). The problem is that inductor heats up very much, however, I noticed that the heating comes from the wire and not from the core (wire ~ 80 deg.С and core feels like 40 deg.С). Is my conclusion that this is the proximity and skin effect took place rather than core losses?
"in terms of proximity effect, the dristributed gap is the best but core losses will be very high for resonant converters" (around min 30:40). Forgive my lack of understanding but why distributed gap core is worse for resonant converters than point gapped cores? given same permeability
Because core losses are much higher in the powder core at high frequency, typical of resonant converters. See Slides 10 and 11. The comparison is for mur = 26 of the distributed core which is just about the lowest permeability you will use and this will correspond to the lowest core losses (in ferrites the permeability, obtained by a gap, does not affect losses as a function of Delta B)
@@sambenyaakov Thank you Professor. So given the same AC application and working conditions, a ferrite distributed gap core would theoretically be better than a single point gap ferrite core in terms of avoiding flux spreading (and consequence losses)? First google results: "EPCOS have created an all new distributed air gap featured in ferrite cores...The fundamental effect of having gaps of different sizes and location is to change the losses in the adjacent winding. The magnitude of this effect does depend on the fringing flux which enters the winding. The overall gap remains identical, only the location and individual size per gap are changed. .. The overall comparison between a single air gap and several smaller distributed air gaps shows that: • The average of the square of the local flux density, B² average (relevant for winding losses) decreases as the number of smaller air gaps increases. • Evenly distributed and spaced air gaps are more efficient than an uneven distribution • The best performance/ cost compromise is to use three evenly distributed air gaps. EPCOS distributed air gaps cores are realized with nonmagnetic spacers glued in between the ferrite slugs. The required priority for distributed air gaps is the AL Value."
Good thinking. I should have mentioned this in the video. Feriite distributed air gap cores are indeed the best. There are some papers on that, people have used in primarily for high power converters. The down side is the cost and that the available selection such cores is meager. I hope/wish others will read your excellent comment.
