IEEE Power Electronics Magazine - June 2015 - 47

operation similar to a MOSFET, stable dynamic on-resistance, efficient
GaN devices are
gate drive circuitry, and efficient controllers. GaN will have to compete
gaining momentum in
for low-to-medium power applicahigh-speed
tions, where lateral double-diffused
MOS can still be viable. The silicon
applications such as
[complementary MOS (CMOS)] conRF power amplifiers.
troller is here for a long time to come
because of its low power losses.
High-Power Conversion
To summarize, SiC devices will have
Goes Multilevel
the edge for high-power application;
Another dream for PE engineers is to
GaN devices will have an edge in high-speed applications;
have an inverter that can produce a sinusoidal output withand CMOS will still have an edge for low-power, high-effiout much filtering. This dream is also coming true for us in
ciency applications.
the success of multilevel power converter technology.
Figure 7 shows a PWM-controlled output waveform
with the traditional two-level conversion technique. For
About the Author
the untrained eye, it is hard to see a sinusoid there. In
Don Tan is a distinguished engineer/power products
Figure 7(b), a three-level conversion output waveform is
development manager with Northrop Grumman Aerospace
shown. It is clear that this is an ac waveform. In Figure 7(c),
Systems (NGAS). He earned his Ph.D. degree from the Calia nine-level conversion output waveform is shown. It is
fornia Institute of Technology. He is an authority in power
evident that the output is sinusoidal. Only small filters are
management technology and electrical power systems
needed to remove the residual high-frequency noise in the
within NGAS, NASA, the U.S. Air Force, government comwaveform. In Figure 7(d) and (e), we show the versatility
munities, and the space power industry. He served as the
of the multilevel power conversion technology. A multipresident of the IEEE Power Electronics Society from 2013
level converter allows low-voltage rated parts to be used
to 2014 and is the founding editor-in-chief of IEEE Journal
for high-voltage levels by series stacking them, together
of Emerging and Selected Topics in Power Electronics. His
with static and dynamic voltage share circuitry. A mulrecent recognitions include NGAS Distinguished Engineer
tilevel converter can also have multiple parallel strings
in 2011, the Chinese Institute of Engineers USA Asianto accommodate for more power (current), as shown in
American Engineer of the Year Award in 2010, the AmeriFigure 7(e).
can Institute of Aeronautics and Astronautics Space SysThe ability to configure the devices in series or in paraltem Award in 2008, the Joint Army Navy NASA Air Force
lel strings for multiphase configuration opens wider applicaOutstanding Achievement Award in Spacecraft Propulsion
tions. In some sense, this scenario parallels that of classic
in 2007, and the NGAS Distinguished Patent Award in 2002.
multiphased ac transformers, where a designer can mix and
His technology was licensed to a major telecom company.
match various different phases to optimize the design for a
He is a Fellow of the IEEE.
particular application (requirements). Multilevel power conversion is dominant in high-power applications in industrial
References
drives, grid applications, HVDC, and many others.
[1] D. Tan. (2014, Mar.). Power electronics for emerging applications. IEEE
multicore architecture. It is anticipated that product offerings of the monolithic integrated power converters will
come to market in 2016 or 2017.
This success represents a dream
come true for PE engineers, that is,
to have a monolithic switching converter on an IC.

APEC Plenary Keynote. [Online]. Available: http://www.apec-conf.org/about/

Wide-Bandgap Devices Are
Going Mainstream

previous-years/apec-2014/apec-2014-plenarysession

Wide-bandgap semiconductor devices are gaining
momentum in real-world applications (Figure 8). Serious
product offerings are gaining market share in mainstream applications. These are generally in two areas:
high power and high speed. For high-power applications,
silicon carbide (SiC)- and gallium nitride (GaN)-based
switching devices will gain the upper hand relative to
MOS-based devices because of its ability to switch fast
and withstand high voltages and high temperatures. SiCbased devices are ahead of the curve in terms of product
availability in the market.
GaN devices are gaining momentum in high-speed applications such as RF power amplifiers. The challenges
for GaN power switching devices are enhancement-mode

cations," to be presented at the ECCE Plenary Keynote, Sept. 2015.

[2] D. Tan, "AEPS: A resilient DC microgrid for mission-critical space appli[3] D. Tan, Electronictization: A Foundation for Grid Modernization (ECE
Distinguished Speaker Series). UC Riverside, Jan. 2015.
[4] M. Davies, M. Dommaschk, J. Dorn, J. Lang, D. Retzmann, and D. Soerangr, "HVDC Plus-Basics and principle of operation," Technical Article, Siemens Energy Sector, 2009.
[5] M. Callavik, A. Blomberg, J. Häfner, and B. Jacobson, "A hybrid HVDC
breaker," Technical Paper, ABB Grid Systems, Nov. 2012.
[6] E. A. Burton, G. Schrom, F. Paillet, J. Douglas, W. J. Lambert, K. Radhakrishnan, and M. J. Hill, "FIVR-Fully integrated voltage regulators on
4th generation Intel core SoCs," in Proc. 29th Annu. IEEE Applied Power
Electronics Conf. Expo., 2014, pp. 432-439.

June 2015

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Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - June 2015