Page 21 - Power Electronics News - December 2020

Semiconductors Semiconductors

longer; it matured with diodes

in power factor correction (PFC)
circuits very rapidly.

Silicon carbide (SiC) is a
next-generation material that
plans to significantly reduce
power losses and enable higher
power density, voltages, tem-
peratures, and frequencies

while reducing heat dissipation.
Figure 1: SiC device market projection. [Source: Yole developpement/UnitedSiC]. High-temperature operability Figure 2: differences of parameter values between generation 3 and generation 4 [Source: UnitedSiC].
Major advantages of Wide Bandgap semiconductor reduces the complexity of cooling systems and The interest in solutions with ever lower Rds(on) The new Gen 4 maintains its natural strength that
power switches include high current density, faster therefore, the overall architecture of the power is a strong demand from the market. SiC can distinguishes SiC from GaN and Silicon devices.
switching, and lower drain-source on-resistance supply system. withstand higher temperatures and has a thermal
(R DS(on) ). These device performance improvements conductivity which is about 3.5 times better than “Every time we make a new generation, we usual-
lead to significant system-level benefits from an UnitedSiC is focusing on some main areas such as Si to support high-temperature operation with high ly think about what we can improve from the past

end-customer perspective. In real-life applications, automotive traction inverters, the onboard chargers, voltage and power levels. Since SiC has breakdown generation. The first thing we observed was that
customers can achieve high-temperature oper- DC-to-DC converters. “We are still doing all the bat- field strength ten times higher than that of Si, high there was a large market developing at 750 volts,
ation, along with overall system size and weight tery charging business. We are pushing very hard with breakdown voltage devices can be achieved with a especially in the EV market. And we were not able
reductions. A tangible difference between SiC and our 650-volt products in the computer server busi- thin drift layer with high doping concentration. This to participate because we had 650V devices and
GaN is in packaging; SiC parts are commonly avail- ness and the 5G business. Although 5G did see some means, at the same breakdown voltage, SiC devic- then we had 1200V. And people would use our 1200
able in the TO-247 and T0-220 styles. As a result, slow down last year, hopefully, it will recover strongly es have quite low specific on-resistance (on-resist- volts solutions there, and that’s not cost-effective.
they can replace Si MOSFET in existing projects. this year. We have been pushing in the energy storage ance per unit area). We thus decided in Gen 4 the first thing that we
Comparing silicon carbide (SiC) to gallium nitride business even more than solar for renewables,” said would make is 750 volt.” Said Anup Bhalla.
(GaN) in particular, SiC has simply been around Anup Bhalla, VP of Engineering at UnitedSiC. When selecting semiconductor switches, it pays to

investigate the detail of datasheet specifications – The most significant improvement is the even
especially how critical parameters like R ds(on) changes lower resistance per unit area. In this way, the chip
with temperature. R DS(on) is the total resistance in the size is reduced by 40% if the resistance decreases
path from source to drain, is made up of a series of by a factor of two per unit area. The reduction in
resistances that traverses the path of current flow. size also reduces the capacitances, which in turn
improves all switching losses.
This will meet several require-

ments in the field of industrial
motor drives (Figures 2 and 3).

“The main reason is that since
our chips are so much smaller,
the total output capacitance of
this technology is lower than
GaN devices,” said Anup Bhalla.

Figure 3: on-resistance vs Temperature [Source: UnitedSiC].

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