The "snubber network does not need a resistor as the switch turns on at zero
volts, so for practicle purposes even the snubber does not produce
significant losses, but I actually meant in the fet.

George
----- Original Message -----
From: "Jan-Erik Soderholm XA (TN/PAC)" <jan-erik.xa.soderholm@ERICSSON.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Saturday, November 29, 2003 6:01 PM
Subject: Re: [PIC:] 220V Lamps with PIC- best switch


> gtyler wrote :
>
> > >
> > > Correct, it's the dv/dt that causes RMI. No matter if it's
> > > positiv or negative. Also no matter of it's an traic, mosfet, IGBT
> > > or whatever.
> >
> > That would be true if there is no snubber cap across the Fet or IGBT.
That
> > cap will allow a low dV/dT without causing losses in the fet.
>
> But are you not just moving the losses over to the snubber network ?
> Which is what you want realy, to protect the switching component, right ?
>
> (And yes, in triacs you must use a snubber network if the load is
> inductive to protect from false triggering of the triac, but that's
> another issue specific to triacs...)
>
>
> > Like this the switch-off losses are zero,
>
> Realy ? Both in the fet/igbt *and* the snubber network ?
>
> > and as you stitch on at zero
> > volts, the turn on losses are also zero.
>
> Agree, apart from the "also" :-)
>
> Jan-Erik.
>
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