splitting the wires, i did not do in this regard, so not even suspecting it. i won't do modelling, ever, but i learned here that even for such apparent simple circuit, measurements and some empirical approach are needed. thank you, for bringing this!
"splitting the wires" this is to explain that when measuring the impedance form input to output impedance it is like one wire. Nobody is splitting wires. What a relief that you do not do this.
Good stuff. This topic wasn't taught to me in school, and even people at work were not able to articulate the concept that well to this level of depth. Most of the testing we do is kind of like the shotgun approach where we just try a bunch of things/values and see if it gives us a lower score. I get that engineering is a lot of that due to how complex these systems get, but I'm always trying to get a better understanding even if the shotgun method gives faster results. If you do a part two, maybe mention some practical issues when measuring such as noise floor( how to reduce it)/ wire length impact(why does the standard have a minimum) / grounding plate locations/orientations/ type of wire+connectors (romex/thhn/wago)
Always a pleasure to watch your videos, interesting and very educating. Glad I got the opportunity to attend your classes in person at BGU as a student some years ago, and that I still get the chance to learn from your videos 👏
Thank u for show that cruves, i have a shot now for why this is not working well with high speed dc load. In my wiev this type common mode chokes are do better job before the diode bridge at AC side.
Dear Professor Ben-Yaakov, thank you so much for your video. Very interesting indeed. The discrepancy in the simulations with the Wurth model is 6dB in attenuation, which, I believe, might be explained with the 2x factor that is probably not accounted for in the 50 Ohm to 50 Ohm impedance matching. You have 6dB attenuation at DC in sims and 0dB in measurement. Also, it seems to me the impedance model is not correctly taking into account the inductor DCR. The measured impedance is one order of magnitude higher at DC.
For the resistive component of the impedance, it works out if you assume that each winding has a resistance of 168 mΩ. In parallel (common mode), the resistance of the choke is 84 mΩ, and in series (differential mode), it works out to 336 mΩ. I'm not sure if this is how it works in reality, but presumably it is how the LTspice model is programmed.
@@klauskragelund8883 The difference is not just in the magnitude but in shape, especially at high frequency, And, since when the datasheets show max values in plots?
Wouldn't the impedance decline be better explained by inductor having an SRF at approx 2MHz due to parasitic parallel capacitance? I calculate 8.8pF (arising from inter-winding plus winding-core-winding capacitances) which doesn't seem unreasonable given the size of the windings and core. If I understood you, you showed the permeability plots for 3F3 because it also, helpfully included the plot of imaginary permeability; the actual material used for this part could have a somewhat higher frequency characteristic before its permeability starts to decline. That aside I found it helpful and well presented explanation of the issues. The imaginary permeability component was definitely new to me.
Capacitance can indeed emulate the drop and this is how simulation models are built. But the physics is that the permeability decreases and this is the real reason for the drop in response at high frequency. On top of it there might be the resonances due to parasitic capacitances.
@@sambenyaakov Sorry, but I'm pretty sure that your explanation for this *specific* case is wrong. The Wurth part you chose has a *nanocrystalline* core which has significantly different complex permeability characteristics to conventional ferrites. In particular it has a much broader frequency range, 200kHz to 200MHz according to a Wurth presentation. Unfortunately I can't find the permeability data on Wurth's site but I found a good paper at pubmed (NIH). I can't post a link here but searching for 29360754 will easily find it. Figures 3 and 7 are particulary interesting - the first showing that u'' is almost as high as u' from low frequencies unlike ferrites which have low u'' losses at low frequencies. (This might, in part, explain the higher than expected resistance at lower frequencies). Fig 7 shows that Z continues to rise steadily well past the frequency where XL plummets due to u' falling. So the impedance curve for the Wurth CM choke you showed is almost certainly explained by the parasitic parallel capacitor dominating above 2MHz, declining at 20dB/decade. Another data point is this presentation by Wurth themselves on their CM chokes: see from 32 : 57 ruclips.net/video/yKC8Yp0E9F8/видео.html At 33 : 20 he states "..where the impedance drops due to the capacitance effect". Ok he could have got it wrong or was avoiding the complexities of permeability variance with frequency but I doubt it. Note that the part he is showing is an MnZn ferrite, not nanocrystalline. Finally why isn't the leakage inductance impedance similarly affected by the collapse in u' after 2MHz? It continues to rise linearly, well past 2MHz. This doesn't detract from the points you were making about the properties of ferrites which encouraged me to look into far more than I expected.
@sambenyaakov Sorry, but I'm pretty sure that your explanation for this *specific* case is wrong. The Wurth part you chose has a *nanocrystalline* core which has significantly different complex permeability characteristics to conventional ferrites. In particular it has a much broader frequency range, 200kHz to 200MHz according to a Wurth presentation. Unfortunately I can't find the permeability data on Wurth's site but I found a good paper at pubmed (NIH). I can't post a link here but searching for 29360754 will easily find it. Figures 3 and 7 are particulary interesting - the first showing that u'' is almost as high as u' from low frequencies unlike ferrites which have low u'' losses at low frequencies. (This might, in part, explain the higher than expected resistance at lower frequencies). Fig 7 shows that Z continues to rise steadily well past the frequency where XL plummets due to u' falling. So the impedance curve for the Wurth CM choke you showed is almost certainly explained by the parasitic parallel capacitor dominating above 2MHz, declining at 20dB/decade.
@@sambenyaakov YT suppressed my comment so I split it into two parts: Another data point is this presentation by Wurth themselves on their CM chokes: see from 32:57 ruclips.net/video/yKC8Yp0E9F8/видео.html At 33:20 he states "..where the impedance drops due to the capacitance effect". Ok he could have got it wrong or was avoiding the complexities of permeability variance with frequency but I doubt it. Finally why isn't the leakage inductance impedance similarly affected by the collapse in u' after 2MHz? It continues to rise linearly, well past 2MHz. This doesn't detract from the points you were making about the properties of ferrites which encouraged me to look into far more than I expected.
@@sambenyaakov YT make it incredibly difficult to comment - this is my third attempt splitting up my reply: @sambenyaakov Sorry, but I'm pretty sure that your explanation for this *specific* case is wrong. The Wurth part you chose has a *nanocrystalline* core which has significantly different complex permeability characteristics to conventional ferrites. In particular it has a much broader frequency range, 200kHz to 200MHz according to a Wurth presentation. Unfortunately I can't find the permeability data on Wurth's site but I found a good paper at pubmed (NIH). I can't post a link here but searching for 29360754 will easily find it. Figures 3 and 7 are particulary interesting - the first showing that u'' is almost as high as u' from low frequencies unlike ferrites which have low u'' losses at low frequencies. (This might, in part, explain the higher than expected resistance at lower frequencies).
splitting the wires, i did not do in this regard, so not even suspecting it.
i won't do modelling, ever, but i learned here that even for such apparent simple circuit, measurements and some empirical approach are needed.
thank you, for bringing this!
Thanks for comment
"splitting the wires" this is to explain that when measuring the impedance form input to output impedance it is like one wire. Nobody is splitting wires. What a relief that you do not do this.
Good stuff. This topic wasn't taught to me in school, and even people at work were not able to articulate the concept that well to this level of depth. Most of the testing we do is kind of like the shotgun approach where we just try a bunch of things/values and see if it gives us a lower score. I get that engineering is a lot of that due to how complex these systems get, but I'm always trying to get a better understanding even if the shotgun method gives faster results. If you do a part two, maybe mention some practical issues when measuring such as noise floor( how to reduce it)/ wire length impact(why does the standard have a minimum) / grounding plate locations/orientations/ type of wire+connectors (romex/thhn/wago)
Thanks fo feedback.
Always a pleasure to watch your videos, interesting and very educating. Glad I got the opportunity to attend your classes in person at BGU as a student some years ago, and that I still get the chance to learn from your videos 👏
👍😊🙏Nice to read from you. Where are you at?
Thank u for show that cruves, i have a shot now for why this is not working well with high speed dc load.
In my wiev this type common mode chokes are do better job before the diode bridge at AC side.
I am showing a DC (battery) source
very interesting, as always. thank you.
Thanks
Excellent presentation professor 🙏
Many thanks!
Dear Professor Ben-Yaakov, thank you so much for your video. Very interesting indeed. The discrepancy in the simulations with the Wurth model is 6dB in attenuation, which, I believe, might be explained with the 2x factor that is probably not accounted for in the 50 Ohm to 50 Ohm impedance matching. You have 6dB attenuation at DC in sims and 0dB in measurement. Also, it seems to me the impedance model is not correctly taking into account the inductor DCR. The measured impedance is one order of magnitude higher at DC.
Thanks for input.
Спасибо Вам! Прекрасный урок!
Thanks
For the resistive component of the impedance, it works out if you assume that each winding has a resistance of 168 mΩ. In parallel (common mode), the resistance of the choke is 84 mΩ, and in series (differential mode), it works out to 336 mΩ. I'm not sure if this is how it works in reality, but presumably it is how the LTspice model is programmed.
There is though a discrepancy between the data sheet and the LTspice model, isn't there?
@@sambenyaakov Datasheet is max value. Simulation model uses characterized data, so typical.
@@klauskragelund8883 The difference is not just in the magnitude but in shape, especially at high frequency, And, since when the datasheets show max values in plots?
👍🙏❤️
Thanks
Wouldn't the impedance decline be better explained by inductor having an SRF at approx 2MHz due to parasitic parallel capacitance? I calculate 8.8pF (arising from inter-winding plus winding-core-winding capacitances) which doesn't seem unreasonable given the size of the windings and core.
If I understood you, you showed the permeability plots for 3F3 because it also, helpfully included the plot of imaginary permeability; the actual material used for this part could have a somewhat higher frequency characteristic before its permeability starts to decline.
That aside I found it helpful and well presented explanation of the issues. The imaginary permeability component was definitely new to me.
Capacitance can indeed emulate the drop and this is how simulation models are built. But the physics is that the permeability decreases and this is the real reason for the drop in response at high frequency. On top of it there might be the resonances due to parasitic capacitances.
@@sambenyaakov Sorry, but I'm pretty sure that your explanation for this *specific* case is wrong. The Wurth part you chose has a *nanocrystalline* core which has significantly different complex permeability characteristics to conventional ferrites. In particular it has a much broader frequency range, 200kHz to 200MHz according to a Wurth presentation. Unfortunately I can't find the permeability data on Wurth's site but I found a good paper at pubmed (NIH). I can't post a link here but searching for 29360754 will easily find it. Figures 3 and 7 are particulary interesting - the first showing that u'' is almost as high as u' from low frequencies unlike ferrites which have low u'' losses at low frequencies. (This might, in part, explain the higher than expected resistance at lower frequencies).
Fig 7 shows that Z continues to rise steadily well past the frequency where XL plummets due to u' falling. So the impedance curve for the Wurth CM choke you showed is almost certainly explained by the parasitic parallel capacitor dominating above 2MHz, declining at 20dB/decade.
Another data point is this presentation by Wurth themselves on their CM chokes: see from 32 : 57 ruclips.net/video/yKC8Yp0E9F8/видео.html
At 33 : 20 he states "..where the impedance drops due to the capacitance effect". Ok he could have got it wrong or was avoiding the complexities of permeability variance with frequency but I doubt it. Note that the part he is showing is an MnZn ferrite, not nanocrystalline.
Finally why isn't the leakage inductance impedance similarly affected by the collapse in u' after 2MHz? It continues to rise linearly, well past 2MHz.
This doesn't detract from the points you were making about the properties of ferrites which encouraged me to look into far more than I expected.
@sambenyaakov Sorry, but I'm pretty sure that your explanation for this *specific* case is wrong. The Wurth part you chose has a *nanocrystalline* core which has significantly different complex permeability characteristics to conventional ferrites. In particular it has a much broader frequency range, 200kHz to 200MHz according to a Wurth presentation. Unfortunately I can't find the permeability data on Wurth's site but I found a good paper at pubmed (NIH). I can't post a link here but searching for 29360754 will easily find it. Figures 3 and 7 are particulary interesting - the first showing that u'' is almost as high as u' from low frequencies unlike ferrites which have low u'' losses at low frequencies. (This might, in part, explain the higher than expected resistance at lower frequencies).
Fig 7 shows that Z continues to rise steadily well past the frequency where XL plummets due to u' falling. So the impedance curve for the Wurth CM choke you showed is almost certainly explained by the parasitic parallel capacitor dominating above 2MHz, declining at 20dB/decade.
@@sambenyaakov YT suppressed my comment so I split it into two parts:
Another data point is this presentation by Wurth themselves on their CM chokes: see from 32:57 ruclips.net/video/yKC8Yp0E9F8/видео.html
At 33:20 he states "..where the impedance drops due to the capacitance effect". Ok he could have got it wrong or was avoiding the complexities of permeability variance with frequency but I doubt it.
Finally why isn't the leakage inductance impedance similarly affected by the collapse in u' after 2MHz? It continues to rise linearly, well past 2MHz.
This doesn't detract from the points you were making about the properties of ferrites which encouraged me to look into far more than I expected.
@@sambenyaakov YT make it incredibly difficult to comment - this is my third attempt splitting up my reply:
@sambenyaakov Sorry, but I'm pretty sure that your explanation for this *specific* case is wrong. The Wurth part you chose has a *nanocrystalline* core which has significantly different complex permeability characteristics to conventional ferrites. In particular it has a much broader frequency range, 200kHz to 200MHz according to a Wurth presentation. Unfortunately I can't find the permeability data on Wurth's site but I found a good paper at pubmed (NIH). I can't post a link here but searching for 29360754 will easily find it. Figures 3 and 7 are particulary interesting - the first showing that u'' is almost as high as u' from low frequencies unlike ferrites which have low u'' losses at low frequencies. (This might, in part, explain the higher than expected resistance at lower frequencies).
Saludos !! Para cuando un canal en español ?? Por favor !!!!!!!!
Have you tried Spanish subtitles ?
@@sambenyaakov voy a ver si existe
What is the name of the standard? Where can it be found? Thank you for the video.
There are many types and classes. The most famous CISPR25