IEEE Spectrum November, 2013 - 10

DATA
BYTE

Showing off: The Spark-Renault SRT_01E
made its debut at the Frankfurt Auto Show
in September.

nOV 2013

nORTh aMERICan

200 kW

Amount of power Formula E cars
can use when passing other racers

"The problem is to have a very precise
prediction of the state of charge and state
of health of the battery," says electrical
engineering researcher Peter Spies of the
Fraunhofer Institute for Integrated Circuits,
in Nuremberg, Germany, whose control
system designs have attracted the attention of a leading Formula Student electric
car team called EVE. (Formula Student is
an international university-level engineering and motor sports competition run by
the Institution of Mechanical Engineers.)
His team is using new microcontrollers to
build onboard monitoring instruments that
in the past could be used only during pit
stops. Similar fine-tuned control systems
should enable Formula E teams to decide
just when to pull over for a charging, he
says. By season two of the series they may
be able to charge using a wireless system
from Qualcomm.
At least judging by what goes on in Formula
Student racing, the year-to-year progress in
Formula E may outpace that of Formula One.
ETH Zurich engineering graduate student
Julian Hügl, whose Formula Student electric

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car beat the gasoline-powered competition
this summer, says, "What we have seen in
electric racing is that the development is
much, much faster compared with combustion cars." He credits rapid advances in
control systems.
Another driver of innovation will be necessity. The series is cost-capped, meaning that
teams will have to invent rather than spend
their way out of at least some of the technical
bottlenecks. Indeed, McLaren Electronics
has had to develop high-grade switching
components to handle the high voltages
and power densities of the Formula E electric motor, says its managing director, Peter
van Manen. It has also invested in thermal
design and avoided exotic materials for cooling its motors, to ensure that the lessons
learned will apply to other EVs. "The same
approaches you develop to deal with the
[racing] challenges you can then reengineer
into something which is a little bit smaller
in terms of performance, a little bit more
cost-effective," van Manen says.
Make that a lot smaller: The SRT_01E is
even chunkier than its Formula One brethren:
The fairings around its 200-kg battery
and the electric motor bulge behind
the driver. Organizers predict the car
will take 3 seconds to reach 100 km/h,
compared with the 2.13-seconds record
achieved by a modified Formula Student
car in September. The SRT_01E's peak
speed of 225 km/h lags well behind that
of Formula One cars, which can exceed
360 km/h. The lower speeds may be
Formula E's "most problematic thing,"
says Hügl.
The real measure of success for racing cars, Hügl says, is the show they put
on, beginning in late 2013 with demonstration runs: "If I'm interested in
racing, I don't really care about the
drivetrain of the car. I want to see
wheel-to-wheel racing."
-lucas l aur sen

DAnIel RolAnD/AFP/Getty ImAGes

"I think motor sport is always a good place
to stress-test your innovation and your ideas
because it is a harsh environment, and it's a
very public environment, and it's repeated
frequently," she says.
Like most people involved in the series,
Andrew was coy when asked to put numbers
on the car's specifications. Series rules limit
the motor to 134 kilowatts (180 horsepower),
but they will allow drivers to use a "Push to
Pass" mode of 200 kW (270 hp) at certain
points, much as Formula One drivers are
allowed to alter their cars' aerodynamics
for short stretches.
The relative importance of the power train
versus the aerodynamics may be the most
important difference between the Formula E
series and Formula One racing, both of which
are run by the Fédération North americane
de l'Automobile. The main innovations in
Formula One for the past couple of decades
have been aerodynamic: Engineers have tried
everything from attaching dynamic spoilers
to strategically releasing exhaust over car surfaces to reduce drag. Given its lower speeds
and identical cars-at least in the first season-
Formula E's competition will center on how
the teams manage their electric resources.

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Table of Contents for the Digital Edition of IEEE Spectrum November, 2013