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CUK pfc vs boost PFC

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biswaIITH

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Boost pfc topology and its variants are the widely used topologies as Electric vehicle battery chargeers...Does a CUK pfc have any advantages over BOOST pfcs as far as EMI/EMC is concerned????
 

https://www.edaboard.com/threads/347261/
..the above discusses it, i believe the cuk linked in the first post of that is resonant, then again i am not sure. So if it was it may have some emi/emc advantage..however, i think it is a very rare converter. (single stage isolated cuk with PFC)
 

As cuk has both continuous input and output current...but boost has discontinuous output current.....so is EMI/EMC performance better in CUK????
 

well there is a simulation of the isolated cuk PFC in that post that i linked, but in truth i dont think the current profile of the cuk is any better than the boost toward emc.
I could well be wrong, i think tesla motors are the only people in the world to have that topology (cuk PFC) working and in a volume production process and actually being sold to customers.
 

treez said:
well there is a simulation of the isolated cuk PFC in that post that i linked, but in truth i dont think the current profile of the cuk is any better than the boost toward emc.
I could well be wrong, i think tesla motors are the only people in the world to have that topology (cuk PFC) working and in a volume production process and actually being sold to customers.
Click to expand...

Well may be because of continuous output current ,the output ripple is very less....may be it has some advantages in EMI/EMC
 

to be honest, i reckon tight pcb layout, with a narrow area current loop involving the boost output diode, as well as rc snubber across the boost diode, makes emc due to the discontinuous boost diode current not a problem.
 
i actually think the Cuk PFC is actually a licenced topology, and you have to pay Tesla motors a certain fee if you incorporate it into a product. (Slobodan Cuk works for Tesla)
 

treez said:
i actually think the Cuk PFC is actually a licenced topology, and you have to pay Tesla motors a certain fee if you incorporate it into a product. (Slobodan Cuk works for Tesla)
Click to expand...
HE doesn't work for Tesla motors...Actually he formed one company name Tesla.co while he was in caltech...
 
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Both the conventional Cuk and the coupled inductor Cuk are out of patent now and suitable for PFC or a full single stage converter, benefits are any o/p voltage you want, gnd referenced drive, current limit of o/p, isolation, fully utilised transformer...
 
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    Velkarn

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I don't think you can patent a topology that is already well known and frequently used and has been prominently in the public domain since about the 1970's.
*edit*
You beat me to it E.P.
 

The new bridge-less topology from Dr Slobodan Cuk is patented - a very clever topology...
 

Yes, i hear the new cuk one is a bridgeless, isolated, PFC'd, Cuk converter....combining the bridge, pfc and downstream pwm stage , ALL into one.
I coudlnt find a decent article on it...we were sceptical that it really would be as efficient as a pfc-pwm thing.....and certainly the control circuitry would have been expensive as theres nothing off the shelf to do that with.
 

Having continuous input/output current will lower ripple current, but usually EMC/EMI issues are not due directly to ripple (in the classic sense of the triangular or trapezoidal current waveforms at the input/output). EMC is better addressed by using soft switched converters, snubbers, and shielding, and filtering. And the power inductors don't do a great job at filtering EMC.
 
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well i agree with you but may i say this valid point....the regulations are somewhat "uncorrect", and for mains smps, they do have heavy restrictions on the amount of 150khz plus ripple......so for example a bcm boost pfc operating at 160khz, say if USA mains, would not get through the regs [at least not without a lot of (not-really-needed) filtering] , but in truth, that ripple would do little harm, even if only lightly filtered. So i agree with post #14 but the regs are sometimes against this excellent sentiment...unfortunately.
 

It depends on the size of the boost inductor, for larger values the 160kHz current ripple would not cause much DM volt ripple and could be easily filtered, CM emissions would be similar to any other CCM booster...
 

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