3phase-low Voltage source

[SaraJackson]

Hey all,

I am going to need a low voltage 3phase power source that I can change the voltage profile, the amplitude 0-60V and the frequency.

Note that it will be connected to an "open circuit" (no load-no current). I am studying the generated electromagnetic effect for my research.

I looked into generators, convertors, VFD but they all work with 110-450V.
Is there any way I can get at least three phase output from DC or AC for my application?

Thanks,
Sara

 

[tcmtech]

Use a VFD unit to drive three single phase Variac transformers. It will see the transformers as a load and give you the ability to vary the frequency plus the variable transformers will allow for independent voltage adjustment from there.

 

[KeepItSimpleStupid]

You missed a few critical parameters.

What's the max current per phase? (I see it's zero)
What's the frequency range?
Voltage: what units Peak to peak, RMS
Waveform: Sinusoidal or other
Phase relationship? 120 deg apart or variable?
4-quadrant or 2-quadrant power? (Has to be two quadrant)
Is distortion important?

It might be possible to generate the signals with multiple arbitrary waveform generators.
With 3 sinusoidal oscillators, you probably could generate, 3 waveform phases.
You could possibly do this with a DAQ system too.

But I can't make any suggestions until you answer the questions.

You can get ganged variacs for 3 phase applications. These might generate erros in your research.

 

[ronv]

If you own a gold mine you can google 48 volt alternator.

 

[SaraJackson]

Well, there is no current. It's an open circuit.
the Frequency range is arbitrary say 10-100Hz
Voltage : 0-60 V
Wave form: Sinusoidal, square, triangular, step
phase lag: 120

I can play around with those numbers. The main point is getting variable low 3 phase voltage out.

 

[KeepItSimpleStupid]

This might be a wierd way to generate 3 phase. A 3 phase alternator: AC Alternators About - Engineers Edge although it might be tough to control.

 

[KeepItSimpleStupid]

This could be way overkill, but it's an idea anyway: **broken link removed**

I have to register to get specs.

 

[Diver300]

This could be way overkill, but it's an idea anyway: **broken link removed**

I have to register to get specs.

That is still only 10 V pk - pk

On suggestion is a microcontroller, followed by three D to A converters, and three voltage amplifiers.

 

[KeepItSimpleStupid]

As I said. A place to start. If this thing is for 50/60 Hz and sinusoidal, then why not just use a transformer?

But if it's more funky than that, well...

 

[second286]

Could use an 80,s vehicle alternator driven by an electric motor via a pulley-tap wires off between the coils and diodes. See the net for many circuits-frequency dependent on speed of motor driving the alt. I recall a friend did a project using an older dodge alternator. If I recall correctly the output was around 70 Vac 3 phase. This output 3 phase voltage can then be reduced-see net for circuits?

 

[KeepItSimpleStupid]

Oops, no reply. Each has it's own limitations. I think it boils down to:

Generation
1. Arbitrary waveform generator (stand alone, microcontroller, PC based)
2. Multiple Sine wave generators
3. Mechanical - 3 phase generator
4. Derived from 3 phase mains supply.

Amplification/reduction
1. Transformer buck/boost, step-up, step down
2. Resistive voltage divider
3. Variac
4. High voltage OP AMP, see Apex technology (expensive)
5. Audio Amplifier (Some may work with the frequency response network removed)

Measurement
This area is open.
Phase, Voltage, waveform

Some devices may be able to generate the waveform. I think Keithley's (Keithley Instruments Inc. - A Greater Measure of Confidence) Source Meter lines can. Not sure about syncronization

 

[Reloadron]

As to a three phase sine wave with variable balanced amplitude and variable frequency years ago companies like Elgar, California Instruments and others were where you went. For mechanical solutions there was Kato motor generators. I believe California Instruments is now marketed by Amtek and still selling solid state uC controlled units. These are not cheap units, they are expensive. A classic beast was the old GE manufactures Amplydine units.

For low voltages as in 5 volt stuff there are 3 phase function generators. Again, even those are not cheap! They do offer assorted wave shapes.

Last but not least, if someone has the money there are nice A/O cards out there for those who can write software. I was not on the project but we just used some NI (National Instruments) hardware in Lab View to make a 3 phase power system. Low frequency was sub 1 Hz. Then you amplify.

There are several ways to go about it but I don't know of any cheap and easy ways to do it.

I just looked and California Instruments still exist. Go figure.

Ron