Single phase 50/60 to 3 phase 400Hz 115V

How much power?

You're looking for 230 (say 250-ish) VA. Do-able. We've done single phase 400 Hz for synchro reference/excitation using a standard audio function generator to an audio amp to a transformer. The setup used a Kenwood 5204 amp and a likely xformer from the miscellaneous heap.

but the paint-burners/car-rockers may have better ones nowadays.

A microcontroller set up as a 3-phase DDS should be do-able at 400 Hz into, say, three serial DACs with a common load line. Then three amps + transformers. Hmmm... Wye or delta?

Could be done. Could be fun!

Look for a variable frequency three phase motor drive that will run on 240 single or 208 three phase.

Here is one:

Should do just what you want.

tm

Interesting ! No problem with the DDS/Micro/ DAC/ AMP..... Would a torroid transformer work at 400Hz or would that have to be something 'special' ?

If you want to do it in hardware, here's a little 3 phase generator that'll give you what you need in deviation, since all you'll need to do is change the clock frequency to change the output frequency.

If you want to change the angles of the phases, relative to each other, you'll need additional shift register stages, and that might be better implemented in software.

We have a brutal Peavey PA amp, 400 watts RMS per channel stereo. We use it with biggish step-up transformers to make stable AC at up to

Two transformers would make an open-delta configuration. Or use the three Kenwoods and three transformers to make a proper delta or wye.

My company makes a little polyphase waveform generator

that might be used as the source. I did this one myself! Mostly.

John

Here is another variable frequency drive that is 240 single phase in and 0-240 volt ac 0 to 400 Hz three phase. Only $15 bucks. 1500 VA.

tm

You can buy inverters that operate from single phase that will generate

something for you to look at, this drive will accept single phase input of 115V and generate 3 phase out. You can also get one that accepts 115v input and generates 230 out..

In either case, you just set your min/max frequency to what you need.

Jamie

There are old military surplus 400Hz generators tat take 28VDC (if i remember correctly); perhaps some are still available and not too steeply priced. A motor - generator set is easiest way to go.

On Wed, 03 Aug 2011 19:05:50 -0500, John Fields wrote:

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-- JF

"TTman"

Any sudden start ( or stop and restart) of a 50/60 Hz drive signal will case a full inrush surge to occur - no audio amp can cope with the primary saturation current of a mains tranny of a hundred VA or more.

Only professional power amps with first class VI protection and limiting circuits would survive.

But the latter exhibit the very worst inrush surges.

Nothing is as easy at it first looks.

... Phil

=20

by=20

Actually about 400 VA, it is 3 phase. Not too bad if there is no motor load involved. For motors the start currents are easily over 10 times = the run current. You might also want a good 3 phase transformer (E-I cores only) with a tertiary harmonic suppression winding.

i/p,=20

by=20

Depends on the testing needs, variable frequency drives do not actually put out sine waves. Though that can be fixed with LC filters ($$$$)

?-)

Depends on the testing needs, variable frequency drives do not actually put out sine waves. Though that can be fixed with LC filters ($$$$)

__________++++++++++++++-------------------+++++++++++++++

The Micromaster is a PWM drive. It does put out sine wave 3 phase power and will go to 400 Hz.

LC filters are cheap and the magnetics at > 400 Hz are not that bad. Maybe some commercial line filter would work just fine.

It probably puts out cleaner power than the grid.

But for $15, how can you go wrong? Certainly cheaper than three PWM audio amps bodged together to get three phase, right?

There are models that will run on 120 volts ac also, just do a bit of searching. They are way cheaper than $15 - 30 k.

tm

"Jamie" = Maynard A. Philbrook

( Fuckwit Radio ham KA1LPA )

Especially if it is a toroidal type.

.... Phil

just get yourself a transformer, that cleans it up nicely..

Jamie

i/p,

done by

Maybe

Check it out some more, please. I claim that a typical VFD is setup to produce sinusoidal currents in the motor rather than produce sine voltages.

?-)

Check it out some more, please. I claim that a typical VFD is setup to produce sinusoidal currents in the motor rather than produce sine voltages.

?-)

Hi Joe,

I have one and it puts out a voltage sine wave into a resistive load. It uses PWM with MOSFETs running at 60 kHz into a low pass filter for each leg. Again, it is cleaner than the grid.

Could it be that the higher (many HP) units do as you say?

Regards, tm

by=20

i/p,

done=20

Maybe

=20

Hmmm. They were 25 hp and larger.