Variable Frequency Drive Selection-Single Phase

[WMagill66]

I need some advice on selecting a VFD for my application. I'm building a "Test Rig" to compare 2 different UPS systems. I want to be able to adjust the input frequency (and voltage) of the UPS's. My input to the VFD (or other device) is 120VAC 60Hz and I need a 120V output (1HP or 8 Amps). I want to be able to adjust the frequency from approx. 55Hz to 65Hz while monitoring the UPS outputs with a scope. I also want to put a non-linear load on the UPS outputs. VFD's with single phase output are not standard. Can you give me some direction for the best product? Am I thinking along the right path with a VFD?

Thank you very much.
Walter

 

[GoldDigger]

I think that the pulsed output of a VFD, even with a normal load reactor or filter will be far enough from a sinusoidal wave form that your tests will not be valid. If you need high power, perhaps a VFD controlled motor generator would be practical. Otherwise a variable frequency input to a 3-channel power amplifier might work.

 

[WMagill66]

I only need 8-10 Amp max at 120V. If a VFD is not the right product do you know what I would need? What else could I use to adjust the freq between 55Hz and 65Hz on a 120VAC circuit? Would you recommend a single phase 120VAC motor with a separate motor control to adjust the freq?

 

[zbang]

I only need 8-10 Amp max at 120V. If a VFD is not the right product do you know what I would need? What else could I use to adjust the freq between 55Hz and 65Hz on a 120VAC circuit?

Chroma makes high-power AC supplies that can do all this, but they're not exactly cheap. Might be able to rent one, though.

 

[Barbqranch]

I would be tempted to get a function generator and a 1500 or 2000 W amplifier on eBay, then you might need a transformer to get the voltage right. Possibly a big fire ball, but for $300 or so, it might well work.

 

[GoldDigger]

I would be tempted to get a function generator and a 1500 or 2000 W amplifier on eBay, then you might need a transformer to get the voltage right. Possibly a big fire ball, but for $300 or so, it might well work.

Make sure that you are looking at the continuous power output rating of the amplifier. The nominal rating of an amplifier is often peak power for a limited time.
A commercial PA amplifier will often have a 70 volt line output, which will get you closer to the voltage range you need.
And you may be able to wire two such amps up in series to get more power.

 

[iceworm]

... I'm building a "Test Rig" to compare 2 different UPS systems. I want to be able to adjust the input frequency (and voltage) of the UPS's....

I only need 8-10 Amp max at ...

WM -
You have some interesting suggestions, but no one really knows what you are trying to do
To give any creditable help, we need some specs. Your profile says applications engineer, military grade power supplies and UPSs. So:
Is this job related?
A science fair project?
An enduring piece of test equipment?
A one shot test?
Do the results have to be repeatable?

Within 1%?
Within 10%?​

How close to a sine does the wave form have to be?

Crest factor?
THD?
Eyeball close?​

What kind of compliance do you need? Does close does the waveform have to hold from no-load to full-load?
What does the budget look like? $C, $K, $10K?

Money is on one side of the equation - every thing else on the other.

Although if this is for work, can't have the customer - or the management - looking at two monkeys, one football, and snarl of wire.

Choices

ice

 

[Jraef]

Without addressing what it might be you are attempting to do (because others already raised good points), there is at least one supplier of VFDs that can deliver single phase in and single phase out. It is a UK company called Invertek, who sells their products in the US under brand label to a company called Bardac and another one called Anacon. There are a couple of other very small companies out there as well, but their products are designed for cheap things like bathroom fart fans and such (for the HVAC industry because of the need for air balancing).
Hoffman Controls (not related to the enclosure company) and Control Resources.

The Invertek drives are fairly decent industrial products. Not cheap though.