R: drsstc

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Original poster: "Vladimiro Mazzilli" <V.Mazzilli-at-aros.it> 




Now I have as sample (for UPS, the field where I actually work, they have a 
vce sat too high and I've to discard them)four half bridge brick 400A -at- 
80°C, from Semikron series '8' soft punch througt technology, that are not 
fast like '5' but not bad and I think to start with these devices. I've 
selected also 4 CM600HU24F (mitsubishi-powerex) for a full bridge tentative 
but they have a lot of gate capacitance 230nF max without Miller effect, 
6600nC total gate charge typical, and I've also the possibility to test two 
CM1400DU24NF but in this case too there are problem with the total gate charge.




  >I work daily with these brick and I noted that the type used or in plan to
  >use is not the better solution.

I know this. But builders of big coils tend to choose their IGBTs based on
what they can get cheap on the surplus market. They are just too expensive
to buy brand new. So we make do with the older, slower bricks, and design
the coils to have the lowest resonant frequency possible. Steve Ward's ISSTC
II ran at 40kHz (iirc?) for example.

It helps that we are running in pulsed mode with a low duty cycle, as the
devices can tolerate much higher switching losses than they could in
continuous running.

For smaller coils, where the cost of new silicon isn't prohibitive, and it's
hard to get a low resonant frequency, we use the latest fastest IGBTs like
the Fairchild SMPS I/II series.


  >In this moment in europe Semikron company has developed a new generation of
  >short tail IGBT.

I've been looking out for the Semikron '5' devices but they probably won't
be turning up on eBay for another few years yet :( I picked up some of the
'3' series ones a couple of months ago. They seem fairly fast, about equal
to Powerex 'H' series.

Steve C.