AC/AC Converter Design

[MrBananas]

I am trying to generate 1000Hz, 3-phase, 36Volt RMS, 200W total power system from 60Hz single phase line.

Motor-generator or commercial solution not practical (expense). We would like this power supply to operate over the range from 60Hz-1000Hz, so transformer designs are probably out as well.

One solution I had considered was to rectify & filter the 120VAC 60Hz, use a buck converter to reduce the voltage to +-50(ish)V supplies, then use 3 inverters and filters to generate the 3 phases at 36V RMS.

Anybody have any suggestions/comments? Thanks in advance...

 

[CarlPugh]

It is not as easy to build a three phase source as it would appear. And in addition the variable frequency further complicates everything.
The first question is. Are you building only one of these, are will it be a production item?
The approach will be different depending on how many you plan to build.
+50(ish)V power supplies seems kinda low. Peak to peak Ac voltage is 2X36X2^0.5=102 volt.

 

[itsmoked]

No CarlPugh, 50V is correct...

One suggestion would be to get an AC drive and HACK the dickens out of it... All the semiconductors would have the screwy drive systems, current and voltage ratings, and heat sinking you'd need already. Plus the three phasidness covered.

 

[MrBananas]

This would be a one-time build item, and will serve as a laboratory power supply. That's why we need the large frequency range of operation.

Thanks for the AC drive suggestion itsmoked. Unfortunately we don't use a lot of motors so we don't have any AC drives laying around.

I'm still considering the idea I had before, except I'm now looking at SEPIC converters rather than buck, as they are a little easier to control (since the FET is ref'd to ground rather than floating).

Still open to suggestions if anyone has them...thanks...

 

[BrianR]

You can purchase benchtop power supplies that offer variable voltage variable frequency output that covers the range you want. We bought a 1KVA 10-1000Hz, 0-240VRMS unit a few years ago but I cannot recall the manufacturer. A Google search would probably help.

Otherwise I would use a variable frequency motor speed controller, which will give 3-phase out and follow it with a transformer to 36V. Transformers using ferrite or audio grade core material will operate over this frequency range.

 

[itsmoked]

MrBananas I would still use an AC drive.. You are talking about the smallest species in existance! A new one will cost less than half your parts costs. Buy a new one and hack it. If you can find one with the turn up ratio you need then use BrianR's suggestion.. You'd have one weeks sooner.

 

[MacRae]

If you are going to hack it, do a web search on surplus units. There are many surplus traders dealing with them and the prices can be very reasonable.

 

[itsmoked]

New ones only cost 200 bucks.............