IEEE Power Electronics Magazine - June 2019 - 56

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large market. The prototype provided a very
high efficiency over a wide range of input and
output voltages. The primary innovation was
a creative design of the magnetic component,
including switching to use the same magnetic
element in different modes.
This series of presentations, including
the one just mentioned, might lead one to
believe that the quality of a power electronics designer is a strong function of his or her
10
ability to think originally about electromag0m
m
netic elements. But the very last paper of the
conference showed a strong argument for
Microfluidic Heat Sink
completely eliminating magnetics from the
product. The work, "Ultra-High Power Density Magnetic-Less dc-dc Converter Using
GaN Transistors," was presented by Dr.
Georgios Kampitsis of the École Polytechnique Fédérale de Lausanne, Switzerland.
GaN Transistors
The device was certainly quite compact
Silicon Microchannels
(Figure 6), and the claimed efficiency was
excellent. The major drawback was a very
FIG 6 A 1.2-kW dc-dc converter with no magnetic components. It uses a silicon
microchannel cold plate for heat sinking. (Source: Dr. Georgios Kampitsis, École
high device count. Partially offsetting this
Polytechnique Fédérale de Lausanne, Switzerland; used with permission.)
was the fact that each device processes only
a small portion of the total power. The economic
viability
of
the proposed design is far from clear, but, if
the resulting amplitudes before and after current zero. (The
compactness and efficiency are at a premium, this converter
simple test setup reported used a resistive load. It seems the
in some cases may be worthy of serious consideration.
researchers used the zero-crossing of voltage as a substitute for zero-crossing of current. The results are promising
enough to justify further work with nonunity power factor
About the Authors
loads.) No machine learning is required.
Ashok Bindra (bindra1@verizon.net) obtained his M.S.
The idea of modulating the energy stored in the filter
degree from the Department of Electrical and Computer Engicapacitors of inverter banks connecting wind farms or photoneering, Clarkson College of Technology (now Clarkson Univoltaic arrays to the ac mains, to provide the same frequencyversity), Potsdam, New York and M.Sc. degree in physics from
stabilizing function as the inertia of a turbine generator, is not
the University of Bombay, India. He is the editor-in-chief of
a new one. The paper "Stability Analysis and Improvement
IEEE Power Electronics Magazine and a Member of the
of Three-Phase Grid-Connected Power Converters With VirIEEE. He is a veteran freelance writer and editor with more
tual Inertia Control" was presented by a group from Nanying
than 35 years of editorial experience covering power electronTechnological University in Singapore and Aalborg University
ics, analog/radio-frequency technologies, and semiconductors.
in Denmark. This particular work was devoted to the analyHe has worked for leading electronics trade publications in
sis of a potential instability arising from when this so-called
the United States, including Electronics, EE Times, Electronvirtual inertia function is implemented in grids with relatively
ic Design, Power Electronics Technology, and RF Design.
high transmission impedance (weak grids). The instability
Tom Keim (tkeim@alum.mit.edu) is a late-career engiappears to be avoidable by appropriate control operation.
neer and a longtime Member of the IEEE. His specialty is
But a further contribution of the work is an impressive colhigh-performance electromechanical systems and the
lection of references to other publications on the subject. It
power systems that drive and control them. He has worked
appears that virtual inertia has moved beyond being a possifor a worldwide conglomerate, for a small (50 employees)
bility. It can substantially and perhaps completely remediate
innovative research and development company, for a major
the objection that increasing reliability on renewables for grid
research university, and for an engineering consulting compower contributes to system instability. This paper's extenpany. He has 50 publications and 11 patents and is currently
sive list of references is recommended to interested parties.
active as an author, inventor, and consultant.
Even at the end, APEC was able to hold one's interest. In
the last session, Intae Moon of MIT presented "A Wide OpReference
erating Range Converter Using a Variable-Inverter-Rectifier[1] A. Bindra and P. Vinciarelli, "A physicist leading power electronics indusTransformer With Improved Step-Down Capability." This
try for more than three decades," IEEE Power Electron. Mag., pp. 63-65,
paper reported a rectifier design with relevance for a very
Mar. 2019.

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IEEE Power Electronics Magazine - June 2019

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