RE: IGBT SSTC finally possible?

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

Original poster: "Steven Ward" <srward16-at-hotmail-dot-com> 

Hi Greg,

New IGBTs are great, and i know that you've seen the ISSTC on my site... 
for those who missed it:

http://www.hot-streamer-dot-com/srward16/I_SSTCnew.htm

(i need to add that it now makes 52" sparks and pulls 1286W (measured) at 
120bps)

The ISSTC has much more peak current than a normal SSTC, hence why the 
sparks are much longer.  Using the small IR IGBTS your mentioned would 
require you to parallel them i think because of their ability to dissipate 
the high powers (though maybe im wrong... i just cant picture such a small 
device handling really high RMS power too well).  But IGBTs are fast enough 
now to work at up to 200khz or so.  The best trick is to slow down the turn 
ON and do not change the turn OFF (add a diode across the gate resistor).
In this manner you get a little bit of deadtime in there and will usually 
avoid shoot through.

Some tips for using IGBTs:

Higher gate drive (20-30V) this brings down the Vce at higher currents (if 
running pulsed duty like mine).

Be sure to use Zeners on the gates.  For awhile i had no problems with 
leaving these out until recently when i got into higher voltages.  Once i 
added the zeners to the ISSTC, it never blew an IGBT since.

TVS doesnt hurt either ;)

Also, IGBTs tend to be better for lower duty cycle higher current stuff, 
while mosfets might be equivilant in a more CW like operation.  So you 
might want to weigh your options there.

Also, i think tuned tank SSTCs are the way to go unless you really want the 
bushy spark output.

Hope this helps a bit,

Steve


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: IGBT SSTC  finally possible?
>Date: Fri, 23 Apr 2004 08:22:04 -0600
>
>Original poster: Mr Gregory Peters <s371034-at-student.uq.edu.au>
>
>Hello all,
>
>Forgive me if this topic has already been discussed, but I haven't read 
>any posts from the list for over a year.
>
>Just been looking at the international rectifier homepage, and in 
>particular the  IRG4PF50WD, a new "warp" speed IGBT that can be used in 
>hard switching applications up to 100kHz.
>
>http://www.irf-dot-com/product-info/datasheets/data/irg4pf50w.pdf
>
>Was thinking it would be nice to make a multi kW, ~600v input, SSTC with 
>some of these. Any reason why this isn't possible (turn-off time still too 
>long?) I was thinking it would be interesting to use some of these to 
>drive my 12" secondary which resonates well below 100kHz.
>
>What changes would need to be made to a regular mosfet SSTC circuit?
>
>Cheers,
>
>Greg Peters
>Department of Earth Sciences,
>University of Queensland, Australia
>Phone: 0402 841 677
>http://www.geocities-dot-com/gregjpeters
>