Terry's DRSSTC - Controller - Happy Day!! :-))

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Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi All,

Oh happy day today!!

The long thought out messy DRSSTC controller circuit seems to be working 
perfectly in today's "first" bench test!!!

http://drsstc.com/~terrell/schematics/Controller.gif

This circuit takes all the RUN, PULSE IN, FAULT, etc. signals and turns 
them into digital pulses that go to the gate drive card.  I made it on a 
proto-board for now since it would have been an expensive 4-layer board 
otherwise and I wanted it to be versatile.

http://drsstc.com/~terrell/pictures/ControllerTest-Controller.JPG

I wired it all up in bed last night.  Shockingly, I did not may any wiring 
errors even with the help of a little Canadinan Mist to steady my nerves :o))

So I hooked it up to a few toys:

http://drsstc.com/~terrell/pictures/ControllerTest-SetUp.JPG

The first look was at the dead time circuit using the 1N4148 diodes, 1K 
resistors, and 1000pF caps.  These are the gate drive output signals with a 
100kHz `8 amp input to the CT:

http://drsstc.com/~terrell/pictures/ControllerTest-1000pFDeadTime.gif

Yeah!!  1uS dead time and it could be a LOT longer!!  But great for the max 
deadtime in my case.  If I simply remove the caps I get:

http://drsstc.com/~terrell/pictures/ControllerTest-0pFDeadTime.gif

http://drsstc.com/~terrell/pictures/ControllerTest-0pFDeadTime-01.gif

164nS!  smaller than is practical...  So I seem to have the dead times 
under total control!!!!

Here is the CT input signal vs. the gate drive output:

http://drsstc.com/~terrell/pictures/ControllerTest-Input-Output.gif

Can't get much better than that ;-))

So I got out the Pearson 411 and set the scope input on 50 ohms and all 
that good stuff to look at the total I(Lp) to gate drive delay:

http://drsstc.com/~terrell/pictures/ControllerTest-Input-Output-Real.gif

Looks like about 200nS.  That actually gets better at higher currents!  The 
"cheap" CT seems to have a little delay and I ordered up some better 
ones.  However, this is certainly in the "good enough" range now!!

So for this weekend, everything on my project's todo list worked 
perfectly!!!  So I will stop for now before I go busting something ;-))

Cheers,

	Terry