Page 23 - PEN eBook May 2023

SMART ENERGY DESIGN

value, which then justified reinvestment. Eventually, Additionally, fusion could play a role in mitigating the
computers were a mainstay in offices, then in homes, leftover long-lived radioactive waste that makes up
and now they are so effective and efficient that we ~2% of the remaining waste stream after recycling but
carry them in our pockets or handbags. which creates the requirement for impossibly
long-lived repositories. Fusion has the potential to take
This is just one example of the process that has radioisotopes that can take millions of years to decay
been used to commercialize big ideas. And while many and transform them into different radioisotopes that
private companies are set on making the giant leap to decay in years or less.
commercializing fusion energy in one bound, others are
determined to get there by scaling capabilities and cost ADVANCING CLEAN ENERGY ON THE
economics, which create value along the way. WAY TO FUSION POWER
Until fusion energy becomes possible, nuclear fission
For instance, fusion technology can be leveraged offers a carbon-free source of clean energy to reduce
today to produce vital medicine—including potentially dependence on fossil fuels and help combat climate
revolutionary cancer treatments—and to examine change. But the lack of a sustainable, closed-cycle fuel
roads, bridges and critical industrial parts for defects. pathway is one of the key inhibitors of its growth.

Other applications for fusion are coming, including This drawback could be solved by combining recycling
the potential to recycle nuclear waste—the radioactive technology with fusion technology. By continuing to
material leftover after it has been used in a fission scale, fusion technology companies can augment the
reactor, typically at a nuclear power plant. current momentum in the nuclear space—expanding Loss Distribution
fission’s scope, reach and impact while gaining valuable
Fusion companies in the nuclear medicine space are experience with fusion technology that will one day
gaining experience in separating valuable materials out power our futures. Among Paralleled GaN
of a radioactive stream. It is a process that could be
vital to separating fuel from waste so that the fuel can
be recycled back to reactors. HEMTs

By Saumitra Jagdale, contributing writer for Power Electronics News

Gallium nitride high-electron–mobility transistors switches. Due to their ultra-fast operation, GaN HEMTs
(HEMTs) are becoming increasingly popular in the are very sensitive to circuitry parasitics, and any
world of electronics due to their superior performance imbalance between these switches can lead to a loss
over traditional silicon-based transistors. GaN HEMTs of efficiency and increases the chances of damage to
can operate at higher switching frequencies, enabling the switches. Various research has proved that reliable
industries to lower the size of electronics used in the hard switching-on and switching-off transitions can
system. The superior thermal performance helps them be realized without slowing down or derating the GaN
in high-power applications like powertrains for electric HEMTs.
vehicles, transmission lines and motor drives.
Another important parameter while paralleling GaN
GaN HEMTs need to be paralleled in numerous HEMTs is to ensure accurate loss distribution. This
applications to increase power capabilities and article looks at the types of losses and ways to ensure
operational efficiency. But paralleling them comes proper monitoring and analysis of loss distribution in
with its challenges, such as unbalanced distribution parallel GaN HEMTs. The original article may be read
of losses between switches, which can lead to an here.
increase in temperature above safe limits. To parallel
any two switches, the drain-to-source resistance DISTRIBUTION LOSSES IN GaN
(R DS(on) ) of the switches is accurately matched to ensure HEMTs
equal distribution of load between the switches. Any The methods to measure losses in silicon MOSFETs
imbalance can lead to high-frequency oscillations and IGBTs have been well developed, but with the
between the switches and in turn their destruction. industry demanding faster and more efficient devices,
the focus has now shifted to wide-bandgap devices
In the case of GaN HEMTs, the higher switching like GaN. Just like silicon-based devices, the losses
frequency compared with silicon MOSFETs poses a in GaN can be divided into two categories: static or
greater challenge for researchers in paralleling these conduction losses and switching losses. Although the

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