Re: Solid-state status

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Kennan C Herrick by way of Terry Fritz <twftesla-at-uswest-dot-net>" <kcha1-at-juno-dot-com>

Marco-

Yes, and thanks for the reminder.  I'd thought of that but I decided I
wanted the gate drive--to 6 MOSFETs in parallel--to be more closely
referred, electrically, to the common source-bus (which I have now made
more "common" with jumper wires).  In order to do that, it turns out I
have to use 2 driving transformers per 12 MOSFETs instead of 1.  That
requires the semi-major circuit scramble I referred to and that, in turn,
means I likely will not need to use a tw. pair, as such, since my drive
ends up much closer to the MOSFETs.  But Murphy still lurks, of course.

By the way, I downloaded, then unzipped using PK, the file you reference
and it came out as a Word Pad document which seems not to be right. 
Should I do something different?

KCH

On Mon, 18 Dec 2000 07:58:13 -0700 "Tesla list" <tesla-at-pupman-dot-com>
writes:
> Original poster: "Marco Denicolai by way of Terry Fritz 
> <twftesla-at-uswest-dot-net>" <Marco.Denicolai-at-tellabs.fi>
> 
> Hi.
> 
> I guess you are aware of the "trick" of using twisted pairs to drive 
> the MOSFET
> gates, using a different return conductor for the load current. 
> Twisted
> pair has
> got very low inductance. You can implement the same trick also on a 
> 2-layer PCB
> board.
> 
> Then there is the paper I wrote about IGBT faults and solutions at
> 
> http://www.saunalahti.fi/dncmrc/slrconv.zip
> 
> Regards
> 
> 
> 
> 
> 
> "Tesla list" <tesla-at-pupman-dot-com> on 17.12.2000 07:03:35
> 
> To:   tesla-at-pupman-dot-com
> cc:    (bcc: Marco Denicolai/MARTIS)
> Subject:  Solid-state status
> 
> 
> 
> Original poster: "Kennan C Herrick by way of Terry Fritz 
> <twftesla-at-uswest-dot-net>"
> <kcha1-at-juno-dot-com>
> 
> Holiday madness being upon us, my T.c. work has slowed.  But some 
> may
> have interest in the current problem:  Turns out my gate-drive lines 
> are
> too long.  Some ringing but the more serious problem is Miller 
> current at
> MOSFET turn-off, causing turning on again of those that are supposed 
> to
> be going off, by virtue of the voltage drop in the too-long lines.  
> Such
> turn-on is a major no-no, of course, so I am having to re-do my
> gate-driving scheme.  It will take some semi-major scrambling-around 
> of
> circuits, cutting of p.c.-board traces, adding jumpers, etc.  
> Dog-work,
> like much of the previous toil leading up to the present design.
> 
> But basically, my "current-loop" scheme works and--as soon as we 
> clear
> this season's frenetic activities, I'll get to that dog work & 
> advise.
> No offense to dogs.
> 
> KCH