If anyone can afford to view this, please may it be requested to provide here some summarisation of the findings?Bridgeless boost PFC converter has high efficiency by eliminating the input diode bridge. However, Common Mode (CM) conducted EMI becomes a great issue.
Thankyou very much indeed Easy Peasy, that looks like the actual research paper itself. Very Much appreciated.....shows that these IEEEResearch paper things are perhaps a bit of a money-grabber scam(?)From the paper author:
Thanks, it would be great to see the schem BOM, Layout, cooling, Heatsinks, etc etc for these, not that we would be able to. Eg, what measures did they use to pass Conducted EMC?, particularly pertaining to common mode EMC.....(and of course Radiated EMC, because poor common mode performance leads to poor Radiated EMC performance)........and did they "self-approve" for EMC?.....we know that big companies can do this....can fail EMC and still ship...without worry....big Lawyers!there are squillions of Telecom grade rectifiers out there - 1-3kW, that use the so called Bridge-less approach in one form or another - all meet class B for EMC
Thanks, it would be great to see the schem BOM, Layout, cooling, Heatsinks, etc etc for these, not that we would be able to. Eg, what measures did they use to pass Conducted EMC?, particularly pertaining to common mode EMC.....(and of course Radiated EMC, because poor common mode performance leads to poor Radiated EMC performance)........and did they "self-approve" for EMC?.....we know that big companies can do this....can fail EMC and still ship...without worry....big Lawyers!
One wouldlnt be considered subversive in suspecting that the Bridgeless PSUs likely fail Radiated & possibly conducted EMC , but luckily dont interfere with the comms equipment that they are supplying.
A small start-up, with no lawyers, might struggle to put out a Bridgeless PFC design.
....I mean, one would wonder if they used the bifilar wound coupled Boost inductor(s) method?....as in paper of post #7 above....and if they did, did they have that in first prototype?......a big rich company can of course afford to do a non-coupled design first, check it out, send it for pre-approvals, then re-do it if it fails badly.......a small company cant afford this kind of repitition. They have to get it right first time.
AYK, the "engineer in the street" cannot simply afford to put together a Bridgeless prototype and test if for conducted and Radiated EMC......and in truth, there is no accurate way to calculate what kind of EMC scan trace a particular power supply will produce....(ref common mode and radiated EMC) ......so without this...most poor companies wont be able to risk embarking on a Bridgeless PFC design....because Bridgeless is potentially going to fail them on conducted and Radiated.....they just cant pre-calculate this......realistically its impossible to do so...and the paper in #7 shows the far-out methods which need to be done to pass EMC with Bridgeless,,,,,extra expense.........i mean seriously, two boost PFC inductors wound bifilar on the same core....... Who is going to do a PSU which may end up needing the expense of that?....when they could do a "normal" boost PFC that only needs the one inductor.
Thanks, you bring very good points to the table......AYK, common mode problem spike frequencies of SMPS's are not really calculable. I used to work for an EE that did the PSUs for British military...they described picking common mode EMC components for a power supply, as like "shovelling currents into a cake mix"If you know what frequencies your generating you can make a reasonable stab at a fitst pass CM filter design
.........I think you may have hit the nail on the head here.....ie...if youre going to go bridgeless PFC....maybe make sure you have a well sealed and gasketted metal enclosure, which is very well earthed.......(which it wont likely be, as most earth cables have high inductance in reference to the frequencies concerned.)If you have a earthed box and your conducted emissions are controlled then theres little else left to radiate.
.....AYK, with a bridgeless PFC...your "first stab" might have to involve a Bridgeless PFC with coupled Boost inductors, (as in post #7 above) wound bifilar on the same core....And your boss will be getting worried about the cost that might get racked up in producing this Bridgeless PFC based SMPS and getting it through EMC approvals.you can make a reasonable stab at a fitst pass CM filter design also.
Thanks, please do bring forward titles of those that cover the Bridgeless PFC fully including getting it through EMC.....though i have to confess, i have violated my Electronics book spending limit years ago.........few seem to be less than £100 nowTheres some great power conversion books that cover these topics in reasonable detail
....Though such a statement is in disagreement with the paper of #7 above......#7 claims that the simple addition of those two things does NOT solve the common mode EMC issue.{QUOTE___] These two modifications eliminate the common-mode noise problem of the bridgeless-boost PFC [----UNQUOTE].....and speaks of the addition of a second boost inductor, and 2 diodes.
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