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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