220V VFD Output stepped up to 480V

Can it be done? Can you put the 230V output of a VFD into a 240/480 step up transformer? Is this a sensible way to go from 240V 1 phase to 480V three phase? Seems like this would be more expensive than a RPC. What do you guys think?

Rick

Do it the other way

220 60hz 1ph, transform to 440 60hz 1ph, feed into an oversized VFD (100%)
Output Variable voltage, variable frequency to a 440V electric motor.

You will be happy

Transformers do not like to see variable frequency. That makes then unhappy

Where can you find a 480V single phase input VFD?

Where to get a single phase 440 V VFD ? Use a three phase unit!

The DC rectification magic boxes and associated bus can make sense of just about any input. As long as the fault warnings are not offended. (low volts, high volts etc. Some VFDs will not accept a dropped leg ;-( Such units with "sophisticated fault systems" are not a good choice for this application.

Getting DC from single or multi phase input is academic, Handled internally by the VFD, but every unit is fitted with connections allowing DC input. (Well, I can't say I know about EVERY UNIT, Many do.)
In multi drive systems, a single common DC bus can supply many VFDs. After all, A VFD takes in AC, makes DC then chops up and flips over the DC to simulate AC.

A "normal" 3ph VFD must be sized to handle the increased current through only two of the three rectification diodes if so applied.
I believe this form has agreed on 100% oversize. i.e a 4hp 3ph VFD if supplied single phase to power a 2 HP motor. Actual math may come up with differing justifications, but 2:1 is easy. True, if fed with 3ph, The same VFD would be happier than a clam at high tide!

If you need a VFD unit good for up to about 4hp when supplied >380 V single phase . Let me know, there is one boxed and waiting under the work bench ;-) Like all VFDs, This unit will only output the same maximum voltage that is input. So the step up transformer should be 220-440v. No free lunch!

CalG

Where can you find a 480V single phase input VFD?

Click to expand...

EBay, eBay, eBay

Every time I look for a nice, low cost drive (on eBay) they turn out to be 480v. I just looked, and nothing 480v & cheap is listed today, so check the listings every day or two. They appear on a regular basis.

As CalG said, buy a drive that's double the size of the motor to be powered.

------------
Barry Milton

And I am offering to sell you one!

Now, what a good fellow . ;-)

Just to explain why you want to do it this way, the core and windings of a standard transformer are not designed to deal with the variable voltage, variable frequency and high harmonic content of the output of a VFD. So putting the step-up on the line side avoids the pitfalls and early demise you will suffer by putting it on the load side. They can make you a transformer to go on the load side, but you will not want to pay what it will cost.