In article ,
Ignoramus12834 wrote:

On Sat, 26 Nov 2005 21:57:00 GMT, John Husvar wrote:
In article ,
Ignoramus29530 wrote:

On Fri, 25 Nov 2005 19:21:37 -0500, legg wrote:
On Fri, 25 Nov 2005 20:59:12 GMT, Ignoramus29530
wrote:

I believe the most effective method of inverting after a large
inductance is to short the current flow during the change of phase.

This is most simply achieved by turning all the bridge switches on; by
enforcing a drive overlap on the phase switch drive circuit.

That's exactly what I am doing, yes.

There will be an overshoot of voltage as the arc has to be
re-established on each switching cycle, but there is no need to absorb
energy or clamp this voltage, until the load is removed completely.
When this happens, you'd best short the output and turn off the
source.

Well, that's square wave output, and supposedly, the arc would not
have enough time to extinguish during about 5 uS when the bridge is
shorted. At least that is my home.

The overshoot is somewhat acceptable, but I would like it lower for
safety considerations. The spec for my manual says that highest
voltage is 150v, and I would like to keep all voltage below that, so
that I do not damage the welder..

i

Well, following this thread throughout, it's clear you've been having a
lot of fun, Igor. Good on ya and congrats on getting it working under
load!

Thanks John... It definitely was fun, although now I begin to question
the cost vs. benefit issue. Just how often would I weld aluminum, is
not clear. But once I started, I could not stop. And it was very
educational and not too expensive, although the little electronic
and electrical trinkets cost a lot more than expected.

By the way, do you live here?

http://members.cox.net/transam57/lights.wmv

I will try to find a computer that can play this...

i

Should work with Windows Media Player. It's apparently what happens when
an EE has too much idle time.