PFC Switched-Mode Power Supply

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Has anyone out there ever tried Active PFC'ing the front end of their Switched-Mode Power Supply?

Brief mentions were made on another Power Supply Design thread (5000W SMPSU), and it was suggested that with the mention of PFC'ing, a new thread should be started.

OK, so, any takers? :eek:

Steve
 
Steve, continuing this topic, here's another combined solution from Fairchild - PFC and converter - all-in-one already synchronized - FAN4803 chip. I tried to attach pdf application note but, unfortunately, it's exceeding maximum attachment size.
I'm in particular interested how to make a PFC for a single SMPS supplied from 3-phase mains, didn't find such information yet. Can anyone share experience about 3-phase power factor corrector principles?
 
Synch'ed PFC and PWM

Alme,

Thanks for the link. I seem to remember Mico-Linear had the same thing a few years back, but they couldn't make it sell. A PFC synchonized to a doudle-ended PWM (Like an SG3525 or MC33025), all in one chip, all with totem-pole outputs. Pretty cool. :cannotbe:

As for 3-Phase PFC, I, to would like to see something like this, as I recall, 3-Phase power already has a high power factor (something like 0.8), so PFCing that shoul be rather easy, I think. :xeye:

OK, after I looked at it, I see that the ZVS is used to reduce losses even further, and improve things a little bit. However, it is NOT a PWM synch'ed to the ZVS PFC.

The chip I was referring to was a constant-frequency PFC, synch'ed to a dual-output PWM, and wasgood for at least a couple of kW.

Steve
 
3-Phase PF

Not too certain. It would seem that if the cap were very big (say, more than 1-2uF), then this would seem to defeat the purpose of the PFC in the first place.

I know that a small cap is used right off the rectifier bridge to remove some of the high-frequency component, but that's it. The 120Hz haversines are what is supposed to be fed into the PFC stage.

Perhaps with a 3-phase (depending on the type- either 120-208V wye or 250V delta) there are three single-phase bridges, each with its own PFC, and then combine the three at the outputs. I'm just guessing here, but I will do a Google search and see if anyone makes a 3-Phase PFC Controller.

The PFC-PWM Chip I referred to in my last post was MicroLinear's ML4826 PFC and dual PWM Controller chip. However, it would seem that MicroLinear has divested itself of its power control line od producxts and is soley on the GHz thing. I was lucky, however to get a schematic and datasheet from their book. :)

I guess I will have to stick to using ON's MC33262 PFC chip and ON's MC33025 @Mhz doudle-ended PWM chip. I mean, they're not bad, in act, they're both very good chips, but I just would like something with the PFC and the PWM all in one chip, synchronized. :bawling: The '33262 is critical conduction, not constant frequency.
 
3-Phase PFC

I just did a Google search for 3-Phase PFC, and came up with this link-

http://www.technologydynamicsinc.com/galvanically.php

and it's downloadable into PDF format, too. I read it, and basically, it's like I thought- three 1-Phase PFCs OR'ed together at their outputs. Works with 115V Delta systems. This is peculiar, beacuse I don't know where anyone uses 3Ph Delta at 115V per phase. :confused: I do know that in the US, it's either 120/208V wye with neutral, or 240V Delta with no neutral. Hmmmm..... :scratch:
 
Thanks for the link, Steve. I find this information confirming my ideas about 3-phase PF correction. Still it's not quite clear how they sum DC outputs into single capacitor - this looks somehow strange like connecting voltage sources in parallel.

Seems to me that I already mentioned MC34262 chip in '5000W SMPSU' thread :) I tried to calculate chokes for 'critical conduction' and 'constant frequency' PFCs and got that choke volume is visibly smaller for fixed frequency operation. The advantage of '34262 is simplicity and not that strict flyback diode requirements; disadvantages are floating EMI spectrum and impossibility to synchronize with other subsystems.

okay, waiting for other guys to join this discussion :)
 
DC -DC DC-AC SMPS SUPER POWER

THIS HOLA IS MY TO THINK FOR 3 PHASES I FOR SYMMETRICAL, THESE ARE MY DESIGNS. YOU THEMSELVES THINK. WITH SG3525Y IRFZ44H
 

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My PFC Front End

I have noww figured out (with a little help from folks here) how to shrink the size of pic files to get under the 102kB size limit. Later today I will post pic(s) of my MC33262-based 180W PFC Front end. Note the series-connected output caps, as this provides a convenient midpoint for a half-bridge DC-DC converter to be connected to.

Steve
 
Steve, sorry for not answering till now, I've been busy with work.
So assuming that you use such high-voltage components, your PFC output voltage is about 400V, am I right? (390uF caps in series? :bigeyes: )
can you post its schematic please?

By the way I begin to think that PFC issue is too far from audio guys focus since there's no others' contributions to the topic :) That's maybe true; I have interest in it because I've been both audio and power electronics engineer in my practice.
 
PFC Output

Alme,

I set the output voltage for about +390V, and the two 390uF caps are each 250WVDC, and, yes, they are in series. The schematic I used was from the old Motorola data book for their discrete semiconductors. This was a 180W universal input PFC for the MC33262. Basically, this is the extended temperature range version of the MC34262. Here is the link:

http://www.onsemi.com/pub/Collateral/MC34262-D.PDF

Instead of the one 220uf Output cap, I substituted 2-390uF Caps for the half-bridge centertap, and their almost double value over the original 220uF is because since they are in series, their effective value is halved. And for the MTP8N50E. I substituted the now-discontinued MTW20N50E N-Channel MOSFET. The input rectifiers are MUR 8100's. The input rectifiers need to be ultra-fast types because now, high-frequency pulses are being drawn off the AC line.

Steve
 
Steve, in your pointed pdf they say that it's one of advantages of critical-conduction mode - flyback diode actually shouldn't be ultrafast type there (rather cheap 250ns standard recovery type will fit). On the contrary, fixed-frequency PFC needs diode as fast as possible (25-35-50ns type) because it switches full current at the moment of going into reverse bias.
So what is the intention of your PFC? What you supply thru it?
 
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