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power electronics technology
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hen power which convert the DC output from and have two SiC devices in each of
electronics solar panels into an AC form that is the systems - transistors and diodes.”
manufacturers launched their SiC suitable for connection to the grid. Single-phase inverters employ four
Schottky barrier diodes onto the These inverters operate at powers transistors and four diodes, while
market at the beginning of this ranging from one kilowatt up to 500 three-phase variants use six
decade they had one application in kW, a span that reflects the variations transistors and six diodes.
mind – switch mode power supplies in solar installations, which go from a
(SMPS). The existing supplies that handful of panels on the roof of a Inverters take the DC input from solar
converted AC mains into DC outputs house to massive arrays on a solar cells, possibly boost it, and then
for driving computer hardware farm covering many hectares. chop it at very high frequencies,
employed silicon diodes, and higher before the signal is filtered to
efficiencies could be realized by Like SMPS, the first solar inverters produce a rectified sine wave. The
switching to SiC equivalents. employed silicon devices, and again higher the frequency, the cleaner the
a switch to SiC products could output. However, higher frequencies
These gains in efficiency stem from increase efficiency. Although SiC mean higher switching losses,
the very low switching losses devices are more expensive than their primarily through higher switching
associated with SiC. The reverse silicon rivals, Brice Le Gouic, a losses in the power transistors, which
recovery charges and stored charges market and technology analyst at Yole are far lower for SiC devices than
are incredibly small, and the forward Développement that specializes in their silicon equivalents.
current and the frequency of the power electronics, believes that
switching speed has very little impact producers of inverters are willing to Another major benefit of switching to
on switching behavior. In short, SiC pay the additional cost. “The return SiC transistors is that it can lead to a
diodes possess an ideal set of on investment is the first word that reduction in the inverter’s bill of
characteristics. people are talking about,” says Le materials. Today’s silicon inverters
Gouic, and higher costs are typically operate at 16-18 kHz and Infineon
Sales of SiC diodes to builders of acceptable, so long as they are include large inductors and unveiled its
SMPS continue to grow. However, outweighed by increased efficiency. capacitors. Replacing the silicon third generation
SiC power electronic device Improving a solar inverter’s efficiency power electronics with SiC chips of SiC Schottky
manufacturers are not complacent - by just 1 percent in a 30 kW system allows a transition to even higher barrier diodes
they are looking to new markets to can yield an additional 3000 kWh operating frequencies, without this February.
generate additional revenue growth. over ten years, equating to a cost sacrificing efficiency, and also cuts The portfolio
One opportunity is in the hybrid saving of hundreds of dollars. the costs of the inverter thanks to includes
electric vehicle, which currently smaller inductors and capacitors that 600 V diodes
employs silicon chips to convert the Le Gouic says that the SiC market can be used at these higher operating at 3A,
DC output from the battery into an for solar is still in its infancy but will frequencies. 4A, 5A , 6A,
AC form that is suitable for driving grow to tens of millions dollars over 8A, 9A, 10A
the car. SiC electronics can operate the next decade. However, sales to and 12A
at higher temperatures, eliminating SMPS builders will continue to
the need for an independent, space- dominate this SiC marketand
consuming cooling system for the increase at a compound annual
electronics that takes up valuable growth rate of 60 percent between
space. Freeing-up space is a benefit 2010 and 2015. But the rocketing
that is highly valued by carmakers, growth of shipments of SiC products
but qualification times of eighteen to solar manufacturers will gnaw
months to two years mean that it will away at this sector, with sales to
a while time before SiC can make an SMPS makers declining from 88
impact on the automobile sector. percent of the market in 2010 to 55
percent in 2015.
Where SiC diodes are already
making inroads is in solar inverters, Emerging markets, such as solar
inverters and HEVs, also offer new
product opportunities for SiC.
Left: Infineon manufacturers its “SMPS manufacturers are mainly
third generation SiC Schottky interested in SiC diodes,” says Le
barrier diodes at its fab in Villach, Gouic “but all the other markets will
CREDIT: Infineon
Austria. CREDIT: Infineon be driven by the inverter application
September 2009 www.compoundsemiconductor.net 21
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