240VAC single phase to 650VDC voltage doubler / boost converter.
240VAC single phase to 650VDC voltage doubler / boost converter.
(OP)
I'm looking for a way to supply roughly 75A, 650VDC (to a VFD DC Bus) from a 240VAC single phase source, without a transformer. I'm doing it with a transformer now, the problem is the size and weight (>500 lbs) for the machine OEM, as it is for the transportation industry and everything heavy means money. I've though of a voltage doubler circuit on the rectifier side, but I can't find a resource using Google and the couple of VFD suppliers I knew of that used to do it no longer do, indicating there may have been a problem with the concept. I get thousands of hits on circuit designs, not suppliers. I also thought of rectifying the AC to DC, then using a boost converter on the DC side, still no hits on suppliers with anything that big or at that voltage. I'm no longer in a place to be able to have my own company make this, or rather if I were to convince someone to take it on, I will be retired by the time it's released.
Any ideas? I'm looking for someone who already makes it, or close enough to it who would be willing to modify.
Any ideas? I'm looking for someone who already makes it, or close enough to it who would be willing to modify.
"Will work for (the memory of) salami"





RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
Perhaps a transformer-based circuit that operates on a frequency higher than 60hz could work. Higher frequency transformers can be much smaller and much more power dense than those that run at line frequency. Have you considered a 400hz power system, like are used on aircraft?
SceneryDriver
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
But, I think that a combination of several series connected standard switchers (cheap) can produce the voltage needed. The problem may be that the outputs have to work at elevated insulation levels. But, if you find something that can do this, then your need for current can probably be met if you parallel several Groups os series connected switchers.
There may be an optimum configuration, but I doubt very much if can beat a standard transformer. A compromise could be to use an autotransformer (not very good if you need to rise voltage around 100%, but still) and then use a doubler Circuit. Either way, it looks gloomy.
I use a cascade rectifier for voltage tests, but that one can only deliver around 50 mA and is already quite HUGE.
Can't the motor be wound for a lower voltage? Tell the customer about the problem with PWM in old motor windings and that the motor probably needs rewinding anyhow. Worth a try, I think.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
Sorenson makes DC supplies up to 130kW. They have a couple of series that exceed 50kW and several that don't but are parallel-able.
Sorenson (Now Ametek)
If you're talking a quantity instead of one or two you will likely get very good attention.
Keith Cress
kcress - http://www.flaminsystems.com
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
It looks like you need 50 KVA or more of capacity.
A 5 KVA, 60 Hz transformer will handle 50 KVA at 600 Hz. You may want to strip the windings and rewind the transformer with fewer turns of heavier wire.
At higher frequencies the transformer gets proportionally smaller.
If i was going to attempt to use a VFD to power a small three phase transformer bank one of the first people I would ask for help is jraef!
How about three 3 KVA transformers at 300 Hz?
Bill
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"Why not the best?"
Jimmy Carter
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
Keith, Sorenson/Ametek is looking like almost exactly what I wanted! Nothing they have exactly fits the bill, but they appear to be someone I can talk to about it, and yes, it's an OEM, so there are quantities involved. But the one thing they have that's close weighs in at 2150lbs, so obviously they are heavily magnetic in that design. Still, like I said, someone to talk to tomorrow. PLS (as Gunnar refers to them) for you!
"Will work for (the memory of) salami"
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
Ironically, we use Schaefer for EMC filters and sine wave filters all the time, but I'm embarrassed to say I've never looked at their entire product line. I tend to pigeon-hole suppliers into niches that fit what I know of them already. I suppose I'm a marketing department's worst nightmare in that regard.
"Will work for (the memory of) salami"
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
Something is nagging at me here... Something about "free lunch"...
"Will work for (the memory of) salami"
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
" But the one thing they have that's close weighs in at 2150lbs,"
It may just be a light lunch. Grin.
Bill
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"Why not the best?"
Jimmy Carter
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
why 500#? Is that just a round number thrown out? My guess is a 230->460 iso xfmr should weigh in around 350#?
the same as auto should weigh same as a 25kva iso or maybe 250#? alum might shave another 10-15% Cu windings (a bit more steel but net weight loss)... alum encl to reduce nema 1 weight or no encl and put in your customer's oem cabinet? optimize for 150C or higher temp rise (can use 220C insulation)? I would think a good custom xfmr mfgr could shave weight down to about 200# as auto? since you say there are more than 1 pc a lot of custom xfmr designers would put an hour into seeing how light they could make it....
anyone make a dc bus pump up unit like Siemens that does not necessarily use a xfmr (just a choke that weighs a lot less)? I can't think of a mfgr off top of my head but maybe some googling on whatever words siemens uses for their dc bus pumping scheme? I hear there is no real limit to how high you can pump the dc and with high currents....
www.KilroyWasHere<dot>com
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
Not sure how useful this will be, but...
Is there any truth in the assumption that an electronic device that can do one thing will weigh approximately the same as an electronic device that can do the opposite?
Transformerless grid-tie inverters are on the market that can regulate input voltage up to 600VDC and "sell" it to the grid at 240VAC single-phase (but at your power level more likely 3-phase at higher voltage). I quickly looked up one from ABB sized about 100 kW (I think that's the range you are looking for) then found its weight: 550 pounds.
You may be pushing a rope.
STF
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
Don't ask price :)
Best solution is DC/DC boost converter. I'm sure there are many other much cheaper solution than that (ok, not so small weight).
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
www.KilroyWasHere<dot>com
RE: 240VAC single phase to 650VDC voltage doubler / boost converter.
OK ... But would they not create the right voltage (plus a margin) if they were in series, not parallel?
True, it would be more weight for the power supplies, but that eliminates the transformer weight, doesn't it?