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Re: [TCML] Silicon Carbide MOSFET for SSTC designs



On 6/16/11 12:10 PM, Steve Ward wrote:
While these new SiC devices are very fast switching, they still have rather
poor conduction losses compared to even "cheap" MOSFETs and IGBTs.  Unless
you are trying some exotic, very high frequency SSTC (in the MHz range),
then i see no reason to use these SiC fets.  They will probably perform
worse than a 5 dollar MOSFET or IGBT that switches 2-3 times slower but has
2-3X less conduction loss.

I also dont see how this sort of thing could ever replace the IGBT, at least
for folks like me who exploit the IGBTs ability to handle tremendous peak
currents.  These SiC things look like they have a fixed on resistance, which
means their losses go up with the square of the current.  IGBTs maintain
relatively low voltage drop even with pulses 10X their average current
rating, and as far as i can see, SiC inherently cant do this.

$46 for one of those sounds pretty absurd, i bet they dont get used much
yet.



SiC is extremely useful if you have a high temperature or difficult to cool application. I haven't looked at the data sheet, but I'll be the Tj maximum is pretty high.
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