Using variable frequency drive as a 3-phase converter

[spiffitz]

We have a power supply (**broken link removed**) that needs 3-phase power. The only converter we have is a VFD (**broken link removed**). Is it a viable solution to power the Cosel with the Hitachi set to 60hz?

What's another economical, easier way of doing this? We're kind of on a close deadline and the Cosel by itself already took a month of waiting.

 

[Diver300]

It seems very strange that a power supply at only 1500W has a 3 phase input.

I would not want to run it from a variable speed drive. They are designed for highly inductive loads and they often have a lot of fast voltage changes which could cause problems with the power supply.

As the first thing in the power supply is a rectifier, have you tried running it on single phase at 240 V? It might be OK. Problems could arise if the smoothing capacitor isn't large enough or the "open phase" detector (see the data sheet) stops it running.

You could even run it from DC. The input stage of a variable speed drive is a rectifier and smoothing capacitor so you could just use that much of the drive and connect the DC link to the input of the power supply.

It doesn't seem particularly useful to have a DC link voltage in the variable speed drive and a DC level in the power supply, and to join them by converting to 60 Hz and immediately converting back to DC.

 

[Ubergeek63]

buy a big bridge and a big cap and run it off the resulting high voltage rail after defeating the open phase circuit if you need to.

You should not just plug it in since it will not have a big enough cap internally since it was meant for 3 phase. Single phase needs a big cap to hold up the supply rail when the AC line is low. 3 phase does not need any hold up, only noise filtering since once rectified the voltage never goes below 70% of max.

The other possibility is that it actually has a 3 phase transformer in it, but I do not think they would bother at that low a load. You should open it up to make sure. If it does you will need to take it out.