Re: Transistor Veb rating... plus Patent Update

In article <t7gBh.7840$fa.3709@xxxxxxxxxxxxxxxxxxxx>,
Genome <mrspamizgood@xxxxxxxxxxx> wrote:

On the new page, with the new PFC circuit, I had to provide drive
waveforms that do what you describe to achieve the effect.

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

Yes ok thanks. A quick Run of newpfc shows that
the -20A pulse nicely straddles the mosfet drive
negative-going edge.

On the first page the turn off current source is -20.1A so only
100mA is available to turn the device off. Clamping the device
with a diode would mean that you don't provide sufficient
reverse bias to remove the stored charge.

But maybe some means of defining the maximum Veb
is going to be neccessary?

A quick glance at the IR data *** mentioned
earlier shows that there is some form of body
diode in an IGBT. Does your model contain that?

'Hmm... reminiscent of commutating an SCR.'

There was mention of that but I sort of discounted it. I suppose
they might be concerned that if what I am proposing for an IGBT
has already been done with SCRs then the patent might not be
valid on the grounds of obviousness. OTOH if it were so obvious
because it is done with SCRs why is it not being done with IGBTs?

Well, commutation is a generic word. Here you are
applying a form of commutation to the new and specific
application of speeding up the turnoff of an IGBT.

--
Tony Williams.
.

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