Re: SSTC, what to build!

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

Original poster: biomed-at-miseri.winnipeg.mb.ca 


Sounds like you might be getting shoot though on your bridge.  Shoot though
where two MOSFETs are conducting on one leg of your bridge causing a short
across the supply and an over current condition of you FETS.

Try running the driver board with no load and the 100W light bulb limiting
the current to the bridge.  If it lights up at all, you've got that
problem,  bridge shoot though or a bad MOSFET.

Are you running your TL494 with pins 9 and 10 shorted together and using an
inverting and non inverting gate driver chips or pins 9 and 10 separate.
In the second case( configuration)  there is some delay added to the
signals to prevent shoot though.

Good luck,

Shaun Epp


--- Tesla list <tesla-at-pupman-dot-com> wrote:

  > Original poster: "Kreso Bukvic"
  > <kreso.bukvic-at-kc.htnet.hr>
  >
  > It was very wierd. It worked ok when i limited it
  > with a 100 W lightbulb. As
  > soon i remowed the lightbulb the fets exploded. I
  > tried even with 30 primary
  > turns and no luck. Maybe because i didnt have proper
  > GDT cores then...
  >
  > What is a maximal spark that could be expected with
  > a halfbridge with
  > IRFP460 (500 V 20 A).
  >
  > With TL494 and halfbridge of IRFP450 (500 V 10 A) i
  > got ~ 25 cm with alot
  > heating in the bridge in CW mode :)
  >
  >
  >