Re: Series Connection of IGBT / MOSFET Switches - SSSG

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Jan,

On 4 Nov 2002, at 8:16, Tesla list wrote:

 > Original poster: "Jan Wagner by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
<jwagner-at-cc.hut.fi>
 >
 > Hi,
 >
 >  > As a sidebar from the Chicago Power Electronics Conference,
 >  > I found this URL for an App. Note from IXYS concerning
 >  > applying IGBT's or MOSFET's in series for capacitive discharge
 >  > (OLTC) applications.
 >  >
 >  >   http://www.ixys-dot-com/t080698a.pdf
 >
 > Just curious, why isn't anyone considering GTO thyristors for this?
 > ok they do eat a lot of gate current, and switching time is around 10us
 > or longer, but, for "spark gap" replacement it should work very well. I
 > mean, something like 4kV 3kA-continuous is possible. GTOs being older tech
 > than igbts they should be comparatively cheap to get...

Unfortunately, they can't withstand the fast risetimes associated
with most coil resonant frequencies. I had to shelve a bunch of
hockey puck thyristors and diodes years ago after prelim calcs based
on the di/dt spec showed I would have to build a coil to run at
around 10kHz to take full advantage of their ratings. I may still try
them out in a more conventional frequency range but getting several
thousand Amps of primary currents is out of the question and I wonder
whether it is worth the effort apart from being of curiosity value.

Regards,
Malcolm