amz connection test

AMZ News
MARCH 2015
Rendering of flüela
Main Sponsors
Premium Sponsors
Sponsors
Favourers
3M AG
Evonik Industries AG
Jenny + Co. AG
Neuweiler AG
Thoma Folierungen
Argotec AG
Flugzeug-Union Süd GmbH
Jörg Hartmeier AG
OKEY AG
Trumpf Maschinen AG
BAUMANN Federn AG
Garage Stucki AG
Kistler Automotive GmbH
Pemat AG
Utzinger Mechanic
Berner Fachhochschule
GEDORE
Koppers Inc.
Rigi-Kühler AG
Bernina AG
General Dynamics
Kronoswiss
Rofam GmbH
BIBUS AG
Georg Utz AG
KTR Kupplungstechnik AG
RoViTec GmbH
Bossard AG
Gurit (UK) Ltd
LBC Composites AG
SAE Switzerland
Centre of Structure Technologies
H.A. Schlatter Fonds
Leuthold AG
SATW
Cytec Industries Inc.
HABA AG
Maagtechnic AG
Schreinerei Hunziker
distec ag
Hasler AG
maxon motor
Sika Deutschland GmbH
Durovis AG
Helly Hansen
MechaniXclub.ch
SKF Schweiz AG
Dynamic Test Center AG
ILSEBO Handels AG
Moderbacher AG
suter-kunststoffe AG
„Winning has nothing to do with racing. Most days don’t have races anyway. Winning is
about struggle and effort and optimism, and never, ever giving up.”
– Amby Burfoot
A season of superlatives
In 2014, the Academic Motorsports
Association Zurich was able to prevail
against strong international competition to achieve the greatest success of
its nine-year history. Along with overall
victories in Spielberg and Barcelona,
the team stood atop the podium in
Hockenheim for the very first time. The
crowning conclusion to the year was
the successful world record attempt in
November, where “grimsel” accelerated to 100 km/h in just 26 meters and
1.785s. This made it the fastest accelerating electric car in the world.
These achievements throw down
the gauntlet for the coming season, but
effectively count for nothing in the pursuit of the next victories. Resting on the
laurels of 2014 is not an option. Indeed,
the competition isn’t sleeping and will
be eager to reclaim pole position this
coming season. The team is fully aware
of the magnitude of the challenge and
more motivated than ever to extend the
hard-won success story by one chapter.
«flüela»
“flüela” further advances the evolutionary process that traces back to
the introduction of “julier” in 2013 and
“grimsel” in 2014. The scope of the associated changes and overhauls cannot be overstated: the requirements of
a substantially revised rule set in combination with ambitious internal performance targets led to huge challenges in
the design phase.
As every year, it was crucial to determine the key areas with the greatest
potential for improvement. This task is
proving more challenging from year to
year, as the limits set with the previous
designs need to be redefined once
again. At the same time, in order to
avoid unintended setbacks, it is vital to
keep questioning oneself in the relentless pursuit of progress.
New challenges
The design of “flüela” and the envisaged performance gains had to be
brought in line with a new ruleset that
features increased demands for safety
and reliability. This called for new in-
novations, especially in the domains of
lightweight construction and efficiency.
An intensive, milestone-based design
phase of four months has given birth to
“flüela”. The car combines a consistent
evolution of the electric drivetrain with
numerous structural, mechanical and
aerodynamical innovations.
We are proud and delighted to give
you a first detailed insight into “flüela”!
TECHNICAL SPECIFICATIONS
DRIVETRAIN
4x AMZ M5 wheelhub motor
CHASSIS
One-piece CFRP monocoque
FAHRWERK
One-Piece, 10¨ CFRP rims
Air spring-damper elements
POWER
4x 36 kW
WEIGHT
167 kg
ACCELERATION (0-100 KM/H)
2.0 s
TOP SPEED
126 km/h
BATTERY SPECIFICATIONS
6.46 kWh, 414 V nominal voltage
Drivetrain
The pride of AMZ, one of the most
successful motors in the history of Formula Student Electric, enters its next
stage in the form of the AMZ M5: four
wheel-hub motors, realized as permanent magnet inrunners, are at “flüela’s”
core and provide power and speed.
On the basis of an integrated wheel
hub and gearbox packaging in the upright, the team was able to increase
the maximal motor speed to 21’000
revolutions per minute while raising the
gear transmission ratio from 1:13.5 to
1:14.5. This allows to considerably improve torque at the wheel at low motor
speeds. At the same time, “flüela’s” top
speed grows by 5 km/h.
Besides the new transmission ratio,
a revised sealing concept that minimizes losses is deployed in the new gearbox. In the design of the motor geometry, special attention was paid to an
improved compatibility with suspension.
The result is a completely reengineered
splashguard, which enables a better
positioning of suspension attachment
points.
Another innovation of the new motor
design is the transfer of all pluggable
electrical connections into the motor
housing. This concept eliminates the
need for plugs on the monocoque and
results in an overall weight reduction of
800g.
Optimal control and a highly efficient
transmission of motor power onto the
track is made possible by a double inverter. The glass fibre reinforced plastic
housing is an in-house design optimized for lightweight.
By deploying a serial water-cooling
system, overheating of the electric drivetrain components is avoided.
Chassis
The mounting and connection of all
components is the job of the carbon
fibre reinforced plastic (CFRP) monocoque. The AMZ draws on profound
knowhow and excellent technical expertise of seven years in this specific
domain. One of the main advantages of
a CFRP monocoque design is its enormous potential for lightweight while still
maintaining high levels of rigidity and
driver safety. Another significant asset is
the fact that it allows for an almost unconstrained positioning of suspension
attachment points and numerous other
interfaces.
reover, new, lighter unidirectional prepreg is being employed.
Key features of the “flüela” monocoque are the sunk suspension attachment points. They deliver improved
aerodynamical characteristics and increase the rigidity of these attachments.
Finally, ergonomics, which were already very popular among our drivers in
the last two years, were further improved. Integrated cameras now open up a
new world of possibilities in the area of
driver training and race analysis.
The layup of the new monocoque
was fine-tuned and tailored to the new
rule set. By means of FEM simulations,
the team could locally reinforce the monocoque for specific load cases. Mo-
Suspension
The four wheel-hub motors leave
very limited space for the kinematics
design. This is why particular care was
taken to create the best possible conditions for the suspension layout.
In “flüela”, wishbones out of carbon
fibre reinforced plastics are deployed.
Last year, the team decided for steel
wishbones, as they allowed smaller diameters and thus a reduction in weight.
This year however, carbon wishbones
with the same diameter as the steel version were developed. This is made possible by higher wall-thickness, slightly
lower loads and the use of advanced
gluing technologies as well as highly
modular carbon fibres.
A motor size reduction in strategic
locations in combination with longer
wishbones also contributes to an optimization of suspension geometry.
After 2 years of casted uprights, “flüela’s” upright will be milled out of a solid
block of aluminium. Together with the
new wishbones and the sunk attachment points a higher overall suspension
stiffness is achieved.
In the antiroll bar, bending blades
replace the torsion springs found in
“grimsel”. This will enable easy and fast
customization of roll stiffness.
The concept of pushrod actuated
spring-damper elements has been adopted and further developed, resulting
in a more efficient use of installation
space. The adaptive dampers with magnetorheological fluid have been equipped with a self-engineered air chamber,
which greatly expands adjustment possibilities.
This year, more emphasis was put on
tire testing, which provides vital data for
tire selection. Moreover, the gained insights build the basis for the kinematics
design.
Batteries
The drivetrain’s heartbeat is delivered
by the accumulator in „flüela’s“ rear end.
Based on 448 high power lithium polymer cells, it offers an excellent balance
of power and energy density and can
hold a capacity of 6.46 kWh. By means
of an electric brake system, up to 30%
of the total energy spent can be recuperated and fed back into the cells.
In order to fulfil the rigorous requirements for structural strength and
safety, the mechanical design of the
entire accumulator container was revised. Thanks to an optimized sandwich
structure of glass, carbon fibre and a
honeycomb core, the team was able
to come up with a more robust inter-
nal structure as well as much stronger
attachment points to the monocoque,
with no weight gain.
The most important aspect of “flüela’s” accumulator design is its enhanced
reliability. Especially the cooling strategy
was overhauled. This allows “flüela” to
operate to its full potential, even under
adverse environmental conditions. By
means of extensive testing and modern
simulation tools, the team was able to
model the thermal behaviour of the cells
and design a more efficient and powerful cooling system.
Outstanding maintainability is achieved by a subdivision of the cells in several segments. In the case of a malfunction, a single segment can be easily
replaced in very little time. Voltage monitoring of every single cell and temperature monitoring of around 40% of the
cells further enhance reliability and safety. The amount of necessary printed
circuit boards to perform this monitoring
was halved.
Controls
Through a dynamic control of the
four motors, handling of the car can be
dramatically influenced. Various control
algorithms serve to adjust torque on
each of the four wheels individually, depending on the current driving situation.
This allows “flüela” to get its performance onto the track in the most efficient
way.
An advanced traction control ensures optimal grip on each wheel at any
time. Such a high level of control is
achieved by reading and processing
velocity, slip angle and contact forces
200 times per second. Moreover, a torque vectoring system helps to stabilize
the handling of the car. It also enables
higher cornering speeds. The control al-
gorithms takes into account numerous
environmental conditions and can be
tailored to the driver in order to optimize
the overall system. The car’s agility and
stability can be actively controlled with
an additional range of systems.
This season, the data gained from
tire testing will be more extensively implemented. As a result, motor torque
can be better adjusted to the current
slip angle and slip ratio and the tire can
be used to its full potential.
The control of the adaptive, magnetorheological dampers has been revised. It now reads out more sensors and
continually optimizes damping coeffi-
cients on the basis of the driving situation and track condition.
In order to achieve the team’s goal
of a more efficient use of testing time, a
data analysis software was developed.
It allows easy access to all test data and
enables a detailed analysis.
Electronics
Only after having interconnected all
drivetrain components does „flüela“
come to life. To unlock the car’s full potential and to be able to make optimal
use of it, a range of complex electronic
control-, monitoring- and communication systems are of vital importance.
The entire data transfer passes through 6 self-developed mini-CAN modules. The additional load caused by
more sensors, a faster adaptive damper control and CAN communication
couldn’t be handled by the old, 8-bit
microcontroller. Accordingly, the team
decided for a new, 32-bit processor.
This switch enables a much-improved
control of the adaptive spring-damper
elements, which can now be demagnetised actively. As a result, the system
becomes noticeably more agile.
In the domain of telemetry, a system that performs two main functions
was realized: On the one hand, the car
can be monitored during races. On the
other hand all data can be read out in
real time during testing. The car’s parameters can then be reprogrammed
wirelessly.
An overhaul of the electromagnetic
compatibility concept (EMC) greatly improves reliability. Potential interferences
are now filtered through a star-shaped
arrangement of the single systems.
As last year, the wiring harness is
designed in the virtual CAD model and
assembled using the monocoque negative mould. This eliminates possible
collisions and weak spots very early on
and allows a precise and organised assembly with regard to all interfaces.
The low-voltage was raised to 24V.
At identical power, currents are lower,
which results in lighter cables and limited losses. Weight is further reduced by
the use of aluminium cables in some
parts of the car.
Aerodynamics
Due to an extensively reworked rule
set, which drastically limits size and
area of this season’s Formula Student
aerodynamics packages, special care
was taken to design a robust aerodynamics concept that delivers as a package in all driving situations.
With the objective of minimizing airflow stall caused by the attachment
points, a new rear wing mounting
concept was developed. It features a
“swan neck” design, which was designed using modern structural optimization software.
The result is a completely redesigned, two-piece front wing with a design that focuses on efficient airflow to
the undertray, which is adopted from
“grimsel”, and to the rear wing.
“flüela’s” aerodynamics package is
completed by a revised sidepod, which
improves airflow quality towards the
rear end of the car including rear wing
while also ensuring good flow through
the radiators.
For a second consecutive year, a
drag reduction system (DRS) is employed on the rear wing. This concept was
proven by lap time simulations and offers considerable advantages in sprint
and endurance races. Indeed, the DRS
contributes to an improved balance
between high downforce and low drag.
Acknowledgement
Since the beginning of January, the
team is working hard on the practical
execution of the still virtual race car. The
anticipation for the day, when “flüela”
will come to life for the first time, is huge
and everyone is highly motivated to reach this milestone as quickly as possib-
le. However, numerous challenges that
will have to be overcome, are awaiting
the team on the way. Therefore we want
to thank all our sponsors, whose generous support means that “flüela” will not
forever be confined to a virtual model.
Our thanks also goes to the Institute of
Virtual Manufacturing at ETH Zurich, as
well as to the Lucerne University of Applied Sciences and Arts for giving us the
possibility to carry out this project in the
framework of our bachelor studies.
BAUMANN Federn AG
Cytec Industries Inc.
Garage Stucki AG
HABA AG
Kistler Automotive GmbH
Maagtechnic AG
Pemat AG
Schreinerei Hunziker
Utzinger Mechanic
Bernina AG
Durovis AG
General Dynamics
Helly Hansen
Kronoswiss
MechaniXclub.ch
Rofam GmbH
SKF Schweiz AG
Main Sponsors
Premium Sponsors
Sponsors
Favourers
3M AG
Bossard AG
Evonik Industries AG
Gurit (UK) Ltd
Jenny + Co. AG
LBC Composites AG
Neuweiler AG
SAE Switzerland
Thoma Folierungen
Argotec AG
Centre of Structure Technologies
Flugzeug-Union Süd GmbH
H.A. Schlatter Fonds
Jörg Hartmeier AG
Leuthold AG
OKEY AG
SATW
Trumpf Maschinen AG
Berner Fachhochschule
distec ag
GEDORE
Hasler AG
Koppers Inc.
maxon motor
Rigi-Kühler AG
Sika Deutschland GmbH
BIBUS AG
Dynamic Test Center AG
Georg Utz AG
ILSEBO Handels AG
KTR Kupplungstechnik AG
Moderbacher AG
RoViTec GmbH
suter-kunststoffe AG