# SiC (silicon carbide) transistors for AC drives



## Bowser330 (Jun 15, 2008)

please tell us more about this "boost converter"...laymans terms please


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## samborambo (Aug 27, 2008)

Bowser330 said:


> please tell us more about this "boost converter"...laymans terms please


http://en.wikipedia.org/wiki/Boost_converter

The wikipedia pages talks mostly about one-way, transistor+diode boost converters. For regenerative braking and battery charging you need a synchronous boost converter, transistor+transistor for bidirectional current. When the current is flowing in reverse, it becomes a synchronous buck converter.

I've made synchronous buck converters before using microcontrollers but nothing this size.


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## Tesseract (Sep 27, 2008)

SiC has real potential, no doubt about it, but I think it'll be a few more years before a wide range of products using it will be available.

Also, while SiC is intrinsically capable of tolerating very high junction temperatures, _none_ of the other components are, nor are the usual semiconductor packaging materials.

All of the development I have seen with SiC has been focused on its high voltage and speed capabilities, not so much on it's temperature tolerance.

Still, it *does* seem to be very promising.


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## yarross (Jan 7, 2009)

An interesting document about real hardware:
http://web.eecs.utk.edu/~tolbert/publications/apec_2006_SiC.pdf
Although only SiC Schottky diodes are used, but this seems to be the near term way of employing wide-gap materials.


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## tomofreno (Mar 3, 2009)

Interesting article! SiC devices have been used in the power industry for over a decade. It has interesting properties in addition to its high breakdown field and higher electron saturation velocity. When doped with Vanadium CVD SiC becomes semi-insulating with volume resistivity greater than 1 MOhm. This, with its thermal conductivity greater than aluminum makes it quite unique. Not so useful for devices, but for other applications where a dielectric with high thermal conductivity is required. 

I don't understand the emphasis on smaller size and lower weight for vehicle applications, as these devices add negligible weight to an electric vehicle. Seems it would be better to increase size to lower current density.


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