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

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Original poster: "Daniel McCauley" <dhmccauley@xxxxxxxxxxxxxxxxxxxxxxxxxx>

Lookin' good!  So when do we get to see some actual sparks ! ! ! !

Dan



> 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
>
>
>
>
>