WELCOME TO THE SECOND annual
Ideas for Design issue, celebrating
one of our most popular departments.
This issue includes additional
IFDs, written by readers like
you, and feature stories by staff
and industry contributors alike. All
of these authors got their start as
engineering students, learning how
to put together their first designs.
Today, students still have to complete
senior projects as part of
their initiation into the real world
of engineering—and some of them
are winning prizes for their work.
ENGI BOUS PRISE
Established last year by Texas
Instruments and named after
recently retired TI chairman Tom
Engibous, the Engibous Prize doles
out $150,000 in annual awards
to students who design the most
innovative electronics systems
using analog semiconductors. TI
says the prize is the largest of its
kind. It’s awarded in three regions
of the world—North America,
Europe, and Asia.
One of the award winners for
2009 is a group of students
from the University of Arkansas,
who submitted a project called
“Photovoltaic Array with Maximum
Power Point Tracking.” The system
consists of a dc-dc boost converter
and H-bridge design with a passive
filter and step-up transformer.
The dc-dc converter utilizes an
MPPT algorithm, charging a dc bus
capacitor. The H-bridge maintains
a constant voltage on the dc bus
capacitor and outputs a pulse-width
modulation (PWM) signal, which
is then conditioned by a low-pass filter. The output voltage, current,
and power are monitored and displayed
on an LCD, and a USB drive
enables the history of the system
to be uploaded to a PC.
Seniors John Damron, Brady
Delperdang, Tristan Evans, Jordan
Greenlee, and Lauren MeGee all
took part in the project. According
to McGee, the idea came from
American Electric Power via one
of the group’s professors. The
company is interested in renewable
resources and suggested the students
develop a system that could
take the energy produced by solar
panels and transfer that energy to
the grid.
When I read their paper, which
you can download from the Texas
Instruments Web site, I was struck
by the variety of talents displayed
in regards to both the hardware
and software and wondered
how the team was assembled.
Essentially, McGee said their professor
told the class that American
Electric Power was interested in
sponsoring a project and asked
who might be interested in renewable
energy and power electronics.
As it turned out, these five
students were interested in taking
on the project, so that was it. The
selection process was not based
on skill sets, but on interest.
So how did they divvy up the
project? McGee said that four of
the students had been travelling
the electrical engineering path,
while one had switched over from
computer engineering—good thing,
since the project demanded some
programming talent. “He had a
background in programming that
the rest of us didn’t have, so consequently
he did the instrumentation
part of the project and other
software,” she said. “As far as
skill sets, none of us really knew
what we were getting ourselves
into. Only one member of the
group had taken a class in power
electronics. The rest of us had
never seen many power circuits or
techniques.”
They did what any good engineer
does when faced with a dearth of
knowledge. They divided up and
began to research their respective
parts of the project. McGee and
another member studied H-bridge
circuits, another took on boost converters,
and another filter design.
The former computer engineer
looked into data acquisition. But
the team soon found out that a
divide-and-conquer approach wasn’t
the best way to attack the design.
“We realized that we all needed
to have at least a basic understanding
of all the parts,” McGee
said. “They weren’t four separate
projects. They needed to be integrated
as one. That took some
teamwork and forced all of us to
learn more about how the parts fit
together. So we all became familiar
with the entire project but had key
areas that we focused on.”
Design tools played a big role
in the project. The group used
Matlab, Simulink, Spice tools, a
Web-based heatsink tool, TI’s Code
Composer Studio, C, and Visual
Basic. As mentioned, part of the
project entailed implementing the
MPPT algorithm. Maximum power
point tracking is a technique that
draws the most power possible
out of a photovoltaic array. The
students used Matlab, Simulink,
and Code Composer Studio to
program the algorithm on a TI
TMS320F2808 DSP, which controlled
the power electronics. The
students didn’t invent this technique,
of course, but wanted to
learn more about it by incorporating
it into their project.
After the design work was done,
the group had to develop a prototype.
They selected a printed-circuit
board (PCB) manufacturing company,
which provided them with a free
PCB layout program. McGee said
the team populated the boards
that were needed to complete the
project, using soldering techniques
they had to learn as well.
“In the beginning of the project,
during the first semester, the hardest
part was taking all the information
that everyone had, putting it all
together and everyone understanding
how the system was supposed
to work. That took a lot of collaboration
and was more research and
work for all of us,” McGee said.
“In the second semester, the
biggest challenge was testing the
project and making modifications.
Things always go wrong that you
didn’t account for. But I’d also say
that’s where we learned the most.
Getting in there, learning how to
test in stages, making mistakes
while testing, and learning from
that. It was really difficult, it was a
long process, but I would say it’s
really invaluable to have. I’m really
glad that we all went through that.”
This is a telling comment, as we
often learn more when things go
wrong than when they go right.