well, on those things, thers so many paramenters like slip compensation, counter-EMF compensation, DC injection.. all that good stuff.. they're SCR finals as well, which i place alot of faith in..

as far as inductance i can always add a cap or 2 in there to adjust P.F. and bring the voltage and current more in phase, electrically..
shouldn't be that bad.. as far as adjustability, it is infinite being that the core is whats moving and creating a flux variance, instead of, like you said, just tapping various winds on the secondary like they do now..
and i'll follow the 125% rule when sizing it.. i have a few bigass SCRs laying around from some vector drives i worked on that ran 150HP centrifugal pumps in a paper mill. i can always switch SCR units since the PWM boards in vector drives and VFDs are practiacally the same. i think they're just straghforward 3ph ones with no freewhee diode.. no that that actually matters in this application..

counter EMF should only occur on power down and.. well, now that i think about it, theres probably gonna be a good amount on stopping the welding process. i can counter that with an R-C array and some (bigass) snubber diodes i think..

you're bringing up good points tho.. keep doing that..lol

it makes me think.

damn good point as well, 5-0, might hafta look those up.. i know they exist, but no one wants to come off them. i know someone with a gas-powered weder, and theres a freq box on it, but he won't just sell that.. i originally was going to do THAT about 2 years ago..lol.. plus, i get bragging rights if it works, and i learn something..

no education is had in just buying something!! lol :D

JUst move up here and you can use our chit..lol. :-)

Cool idea though...

In the future check out govliquidation.com , and search for any equipment you are looking for. At work I buy a lot of our instruments from there and I have seen lots of welders on there. But don't buy up all of the scopes. meters, or signal generators...I need to buy some of those :-)

You could just jack up your fiddy, and drive a 10 KW generator into the VFD, then just throttle the fiddy to get the variable AC output. A Fiddyrator so to speak. I hope you have an O-Scope when you start powering that thing up to watch the sign waves, your gonna need it!

lol.. got a tektronix at the warehouse, and got about 10 DMM's laying around!!!!

thanks for those sites, Rick and 5-0.. good stuff..

White, another idea! You could drive a 10 hp motor with the VFD, and let that motor spin another motor. Just excite the third phase of the driven motor with capacitors and you isolate your VFD from all the bad stuff. Speeding up or slowing down the driver end, will also vary the frequency............just a mad scientist idea you know! I have seen three phase power derived this way from a single phase source. It has been around for years! Do you follow me?
Oh, I forgot that your after a square wave,,,,,,,,,,Oh Well!

i got ya man!! my welders 1ph, so i could use a transformer to technically tie 2 phases together to create a higher output freq, but in all actuality, i'm going for simplicity.. lol

got a point (again) tho.. but
i'm going t use an M-G set on my perpetual motion thing whenever i get around to that..lol

i've been working on that one for lik half my life, since i've always been a geek and been doing this crap since i was about 5.

i think i've figured out perpetual (endless) motion, and if i can make it efficient enough to carry a parasitic load, either electrically or mechanically, i would have just invented clean, endless electrical power that could fit in your basement.

i'd be stupid rich, then i could fly everyone on here to the bahamas and we'd all go ridin and get something to eat.

mmmmm...chicken

double chicken for you, since i'm drooling over that site now.

you get an atta-boy.

NICE!!!!!!

It is a good site to get cheap stuff, most of our test equip came from there. You can buy a lot of random stuff there too.