Sustainable Biz #8 - Magazine - Page 23
connection also offered exceptionally high
performance: the hub was designed for three
chargers with a total of over 2.5 megawatts.
To match the charging performance
of the CONCEPT AMG GT XX, the
Mercedes-Benz Charging Unit worked
closely with its partner Alpitronic, the
European market leader in high-power
charging. Alpitronic developed a special
prototype charging station for the project.
For the first time, this can transmit currents
of up to 1000 amps via a standard CCS cable
– twice as much as previously possible. This
was made possible, among other things, by
using an MCS dispenser originally designed
for trucks. In this case, the MCS cable
was replaced by a conventional CCS cable
utilizing enhanced cooling capabilities.
The charging system was developed jointly
with the vehicle itself. On a test bench in
Stuttgart-Untertürkheim, the development
team simulated real charging scenarios in
which vehicle components and the charging
station were tested and validated together.
This demonstrates Mercedes-Benz's holistic
development approach.
Intelligent software and record strategy
with expertise from Formula 1® Another
important factor in the mission was the
intelligent operating strategy, including
the Battery Management System (BMS).
It is based on the Mercedes-Benz software
architecture MB.OS. Experts at MercedesAMG in Affalterbach and Mercedes-AMG
High Performance Powertrains (HPP) in
Brixworth further developed it to keep the
battery within its optimal performance
window at all times.
The challenge: the internal processes of
individual battery cells cannot be measured
directly – yet these insights are vital for
developing an optimal strategy. To overcome
this, the team used specially modified cells
and sensors in advance to learn how the
cells behave during use. For this purpose,
the battery cells were measured and tested in
detail with special reference electrodes and
core temperature sensors. The collected data
fed directly into the BMS software, enabling
precise cell modeling and, for example,
further improving charging performance.
The simulations created “virtual sensors”
derived from the physical measurements.
With these virtual sensors, the BMS software
can simulate a real-time view into the core
of the battery cells during the entire drive.
In numerous simulations, the optimal
strategy for the extreme drive was developed
in advance. This included determining
the ideal driving speed of 300 km/h,
which offered the best balance of speed
and efficiency. The condition of each
individual cell could also be recorded in
the simulations and regulated via the BMS.
After the individual simulation cycles, the
team validated the results at the cell level,
then with real units on the e-Drive test
bench in Stuttgart-Untertürkheim, and later
also on the test track. With the knowledge
gained, the next simulation could be
optimized. This enabled even more accurate
forecasts for the real drive.
In addition, simulation experts at
Mercedes-AMG High Performance
Powertrains developed a tool that could
compare the pre-calculated operating
strategy live with the conditions on site.
During the endurance test in Nardò, the
HPP engineers monitored whether external
factors such as temperature and wind, dirt
on the road, or tire wear had an impact on
the drive and vehicle components. Since the
data was permanently transmitted to the
Mission Control Truck, the experts were
able to continuously adapt the strategy to
the real driving situation – and, for example,
flexibly extend or reduce the length of a
stint.
In close cooperation with HPP, the
development team of the CONCEPT AMG
GT XX also calculated a driving profile for
the individual stints. The basic principle is
derived from Formula 1®: At the beginning,
the vehicle accelerates to the target speed
of 300 km/h, which is maintained for a
pre-calculated number of laps. When it is
time for the next charging stop, the vehicle
uses recuperation of up to 0.6g to decelerate
and feeds the energy back into the battery.
This allows the CONCEPT AMG GT XX to
enter the pit at the optimal speed and stop
exactly at the charging station. Following the
rapid charge, it launches back to 300 km/h,
seamlessly resuming the cycle.
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