Invertor required

[scooterist007]

Very few actually make 380V. The HY ones DO NOT make 380V, they are listed as 220V and 380V input but do not upconvert. The Egogo (spelling) ones do but cost more. This seems to cheap for it to do the same ..... need true RMS meter and then see if it does, but dont be surprised if it does not.

Ok I did a search and the company your talking about is ecogoo, that's the only company that makes them, all the usual manufacturers ie Mitsubishi, Allen Bradley, Siemens etc do not make one, I don't see how they can make a true 220 single phase to 380 three phase, the only way I can see it happening is by converting it to DC and then chopping it to make the three phases and inverting it back to AC which would then be 220v three phase, then they would have to up the voltage to 380v, the only way to do that is generate the 220 supply, so that would mean using transformers, now some of the vfd's are saying they are for 20 odd kw, now to get that amount of power from a original 220v single phase supply they would have to use a big transformer! And the vfd's I see for sale are not that big, so I resort back to my original post that you can't get a 220v single phase to 380v three phase vfd that is a true accurate one

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[Voicecoil]

All these VFD's will be rectifying the AC input to DC, and then doing stuff with that to make the 3 phase O/P. For low power (and low cost) you can use a capacitor/diode voltage doubler on the input to generate ~650V DC, alternatively for larger power you can use a switchmode Power factor Corrector (PFC) stage to do the same and also keep you legal for harmonic currents. This will need just one (or a few) small decent inductors, if the switching frequency is high it's quite possible to get 3 KW through a couple of cores maybe 35 or 40mm across, larger powers pro-rata, so you don't need massive transformers.

[Neale]

I use an "inverter" that works on the voltage-doubler principle - it was a bit of a bodge by a now-out-of-business company who grafted a voltage-doubler to the front of what is quite a nice ABB 380V VFD but it does mean single-phase 240V in and 400V or so 3-phase output. It works fine until you put a heavy load on it when the effectively half-mains frequency input means that the DC voltage sags too much between cycles and the VFD trips. I've been kicking around the idea of finding a 3KW 240-415V transformer and go back to the original ABB VFD input arrangement - and a cheap transformer has not found its way to my workshop yet - or try one of those Ecogoo 240-380V boxes (I linked to this company in an earlier post on this thread). They seem to deliver a lot of performance for the price, if they work as well as they claim...

My lathe has a mechanical variable-speed mechanism so I have no experience with dual-speed motors and VFDs. In fact, I run the VFD at 50Hz output, with a switch that drops this to 25Hz for a quick low-speed option.

[Voicecoil]

I use an "inverter" that works on the voltage-doubler principle - it was a bit of a bodge by a now-out-of-business company who grafted a voltage-doubler to the front of what is quite a nice ABB 380V VFD but it does mean single-phase 240V in and 400V or so 3-phase output. It works fine until you put a heavy load on it when the effectively half-mains frequency input means that the DC voltage sags too much between cycles and the VFD trips.

Sounds like they missed a trick and only used a half wave voltage doubler and/or got the capacitor sizes too small. The full wave voltage doubler circuit works pretty well if you do the sums for the output power and choose the right size caps, but it does have twice the component count of the simple circuit.