Transistor Veb rating... plus Patent Update

This could almost be a first in that I don't often ask questions. Some of
you might remember my mention of a Patent what I have applied for. If you
don't then an explanation about it is here.

http://www.genomerics.org/patent/patent.html

I'm going to be putting up another page with a refined PFC circuit using a
modified method to achieve the same result later on.... soon. This one will
show a full model of a 2kW PFC circuit operating off a 90V line at 100KHz
with an IGBT with main power semiconductor losses in the order of 60W.

That's 97% efficiency..... It might get better than that if I used an SiC
diode but, at the moment, I'm implementing resonant turn off of the diode
and that's costing me 20W...... I wouldn't go so far as to say I'll get the
losses down to 40W as a result because I'll suffer switching losses
elsewhere.... and, of course this is just modelling.

Anyway, as I mention on the first page, I'm bothered about the Veb rating of
the transistor in the IGBT. I've had a 'touch' from a semiconductor
manufacturer and this problem has been mentioned. The concern is the figure
itself and possible reliability issues when driving the device as I have
suggested, they have no long term figures for this kind of operation.......

There are other 'issues' but for the moment this is the one I am looking
into. I suppose I should just accept that that is the problem. These people
have more experience than I do and therefore it is a non-starter......
However I do know that power switching transistors are operated in this way,
although there was some mention of differences in manufacturing in
particular passivation, with Veb being applied to achieve fast turn off.

Anyway, I'm off for a trog about the web to see if I can find any
information relating to reverse bias operation of IGBTs giving limits and
reliability information. I'm afraid my natural assumption is this is either
a wool pulling excercise or the person I am dealing with might be mumbling
because they are not absolutely certain themselves.

Specifically I'm looking for ratings and limits for transient rather than DC
operation. If anyone has thoughts on this or can point me in the direction
of something to read then I'd appreciate it.

Obviously, for those who care or Don Lancaster, I'm not losing sleep or
money over this. Just time and my time is free.

Thanks

DNA


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