Re: Recent s.s.t.c work

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "K. C. Herrick" <kchdlh@xxxxxxx>

For the record, a photo of the present state of work, 
<http://hot-streamer.com/temp/KCH_TCH3.jpg>http://hot-streamer.com/temp/KCH_TCH3.jpg. 
Ref. also -KCH_TCH1 & -2.

Per Steve Conner's comment & my belated realization, I've relocated 
my toroidal current-transformer to one end of the primary LC--the 
capacitor end, as most convenient.  It's inside the bucket at top 
center & has100 turns.  The blue/white twisted pair will lead from 
that to the 2nd, 1:1, transformer on the l.v. circuit board.

I've cut the copper sheet-stock connection between the pairs of 
electrolytic capacitors and installed a 100 mV/50 A current shunt, 
visible at the center of the image.  That's for monitoring IGBT 
common-mode current if any (and negligible, I hope!). It's 
electrically at mains-common so differential probes should not see 
too much common-mode voltage to scope-ground.

I have installed the replacement pair of (used) IGBT bricks, recently 
received, & have added, for their protection,  2 uF/800 V capacitors 
across the electrolytics (just visible behind & below the current 
shunt) and strings of breakover diodes directly across the bricks, 
visible above the copper-braid interconnecting straps.

The "-"-side current shunt for sensing over-current remains the same, 
at the upper left.

I've modified the circuits on the l.v. board and what remains now is 
to put that board back in place & re-start the debugging procedures, 
paying more attention this time to common-mode current and proper 
feedback operation.  I'll start out with no h.v., no connections to 
the IGBTs and substitution from a sig-gen of the feedback signal from 
the 100T toroid, hoping to get most of the l.v. circuits operating as 
designed prior to connecting up the IGBTs.

But first, likely a spot of loafing.  I've found that, in retirement, 
I tend to loaf more and work less.

KCH