Re: 3phase PFC

Terry Given wrote:
Jamie Morken wrote:
legg wrote:

On Fri, 09 May 2008 00:55:21 GMT, Jamie Morken <jmorken@xxxxxxx>
wrote:


Here is the ltspice circuit so far:

"http://www.rocketresearch.org/new/3phase%20PFC/3phaseltspice test.zip"

Are there any 3phase PFC controller IC's out there?


- All the controller outputs were labeled for ph1 - effectively
shorted together

- All modulator references had the same phase angle. (After
correction, your model will not work with alt solver, so you'll have
to switch back to the normal solver.)

- There was no current feedback. This chip expects to see
negative-going current sensing signals on the Mout pin of less than
1V1 peak.

- Once running, you have to load it to get current waveforms.

- Don't expect to see attempted regulation prior to the 6.5mSec
timestamp, as the inrush and overshoot doesn't clear prior to that
time, even with a 1KW load. Also don't expect 60Hz performance at
600Hz.

The asc file is reworked (and still needs much more attention to run
properly as a simulation) at:

http://www.magma.ca/~legg/TVS/1249-3phase-2.zip

With simulations that take as long to run as this one does,
doublechecking your work, your ideas and your aims becomes important,
prior to pressing the GUI's 'run' button. Make sure you've got plenty
of drive space. The raw files mount up at the rate of about 150Meg per
millisecond of active converter runtime.I'm always surprised that they
run at all.

The Vienna rectifier is about the most expensive,complicated and lossy
version of PFC correction that a body could have picked.


LOL. too true. Im sure they could have added a few more diodes if they had tried just a little bit harder

Thank you for modifying the sim to work! :)

What circuits would be better than the vienna rectifier for 3phase
PFC? I found two other ones:

http://www.rocketresearch.org/new/3phase%20PFC/3%20phase%20PFC%20stage.png

http://www.rocketresearch.org/new/3phase%20PFC/3%20phase%20PFC%20stage2.jpg


I would like to generate +220V and -220V rails, and use them to generate
splitphase 120VAC sine waves using halfbridges and two LC filters. What
would be the best 3phase PFC circuit to generate these two rails, or if
not using 3phase PFC, could a boost circuit off the 3phase 6diode
rectifier generate a positive and negative rail?

cheers,
Jamie

It sure can. use a pair of boost converters, with a half-bridge as the switches, the center-tap of which becomes 0V. So its:


---nnnnnn---+--->|-----+--- V+
| |
3ph X [Cbig]
BR | |
+--0V------+
| |
X [Cbig]
| |
---nnnnnn---+---|<-----+--- V-


X is typically an IGBT half-bridge, but can be FETs etc.

Hi Terry,

Thanks for the dual rail boost! ;)


the same trick used to make a single-phase boost PFC (force current to follow envelope of full-wave rectified line voltage) also works for three-phase systems; the 6-diode bridge automagically "unfolds" the current waveform.

Is this an alternate circuit to the vienna rectifier for 3phase PFC?
Do you have a schematic of it?

Here's an ltspice sim from Larry Carroll on the ltspice yahoo
group, it implements 3phase PFC with one cycle PFC control!

"http://www.rocketresearch.org/new/3phase%20PFC/lbcarroll backup.zip"

cheers,
Jamie









Cheers
Terry
.

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