IEEE Power Electronics Magazine - September 2014 - 4

From the Editor

by Ashok Bindra

Meeting
New Challenges

fficient energy use has been
driving light-emitting diode
(LED) bulbs into a number of
applications ranging from automotive
to home lighting. With improvements
in performance, longer life, and falling
costs, LED bulbs are slowly replacing
conventional incandescent lightbulbs.
As a result, market analysts are predicting a brighter future for LED bulbs.
In addition, this growth will continue
for many more years to come.
It sounds good, but LED lighting
has a problem called flicker, which is
defined as a rapid repetitive change
in brightness. Flicker is not just a
distraction or something that makes
you uncomfortable. Studies have
shown that flicker can also sometimes become a health hazard. While
the occurrence of headaches is most
common, flicker can also lead to
epileptic seizures and other such
health-related problems.
In this issue of IEEE Power
Electronics Magazine, Prof. Brad
Lehman and Arnold J. Wilkins address the problem of flicker in LED
lighting in their article "Designing
to Mitigate the Effects of Flicker in
LED Lighting"-a problem that is
mainly caused by pulsewidth-modulated (PWM) drive circuitry. The
authors show that when there is a
PWM current passing through the
LEDs, the biological effect of light

Digital Object Identifier 10.1109/MPEL.2014.2332211
Date of publication: 5 September 2014

IEEE POWER ELECTRONICS MAGAZINE

Power Forum. Besides describing the
flicker becomes noticeable during
origins and basic operations of the PMrapid eye movement.
Bus, White also discusses the latest
In presenting criteria that could
revision of the PMBus specifications,
mitigate the biological effects from
the PMBus 1.3, and examines the most
light flicker, Lehman and Wilkins idensignificant addition in Revision 1.3,
tify generalized low-risk and no-effect
the AVSBus specification. Per White's
flicker regions that are independent of
conclusion, the PMBus has taken an
both task and lighting applications. Beimportant step that offers system mancause flickering levels of the LED bulbs
ufacturers a new tool
depend on the type of
for reducing energy
driving method uticonsumption.
lized to convert the
The PMBus has taken
In the "A Look
ac line input to the
an important step
Back" column, my
required dc through
that offers system
article, "Pulsewidth
the LEDs, the authors
manufacturers a new
Modulated Controlpresent criteria for
tool for reducing energy
ler Integrated Cirpercentage modulaconsumption.
cuit: Four Decades
tion of drivers that
of Progress," reviews
would minimize flickt he prog re s s t he
er and, thereby, have
PWM controller chip has made in
a minimal human biological impact.
the last 39 years. From a simple monoAnother article by Krishna Shenai
lithic bipolar chip in 1975, it has grown
focuses on the performance, cost,
to be a sophisticated power supply in a
and reliability of the power electronpackage with an eye toward power supic module (PEM), the key building
ply on a chip.
block of power electronic systems.
Adding excitement to the issue are
This article provides a status report
three of our regular columns: "Patent
on advanced silicon and wide-bandReviews," "Entrepreneur Viewpoint,"
gap PEMs and discusses the key
and "White Hot." While the "Patent
challenges that must be addressed
Reviews" column examines the rules
when developing future compact
the law imposes on intellectual proppower electronics systems targeted
erty to prevent it from undermining
for deployment in the emerging enthe general rule, the "Entrepreneur
ergy economy.
Viewpoint" column reveals an early
Robert V. White's article "PMBus: A
challenge for entrepreneurs: getting
Decade of Growth" takes us through
the product right. Likewise, the "White
the evolution of the power manageHot" column asks a simple question:
ment bus protocol, which was intro"To bit or not to bit?"
duced ten years ago at the Darnell

 September 2014

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - September 2014