More Passenger
Capacity for
Electric Buses
AVL presents a new approach for integrating the battery
system into city buses. The innovative solution offers new
packaging solutions without decreasing battery capacity
and offers many advantages.
CO2 Reduction Becomes Core Challenge
Since commercial vehicles play an important role in CO�
emissions, the EU Parliament and its Member States Ministers
decided in May 2024 that CO� emissions of heavy-duty vehicles
m�st �e red�ced �y �� � in ���� com�ared wit� ����. �or
city ��ses, �� � o� newly registered ve�icles s�all �ave �ero
emissions in ����. ���s will �ave to �ay �eavy fines i� t�e �eet
consumption of their sold vehicles fails to meet requirements.
�or e�am�le, i� a man��act�rer wit� a mar�et s�are o� �� �
(approximately 50,000 vehicles) misses its target by just 1
gram, t�ey co�ld �e �aced wit� a fine o� over ����� million.
R&D Project by AVL to Tackle Challenge for Bus Sector
Battery electric trucks and buses will be key in complying
with CO� emissions regulation. This is why AVL started an
internal R&D project investigating one of the most challenging
demands� integrating t�e �attery system into t�e low �oor
of city buses. The current trend is to mount the batteries on
the roof of the bus. This is an easy solution, but there are
some disadvantages: The primary disadvantage is a heavier,
more complex and robust roof structure, resulting in a lower
passenger capacity for the bus. Roof mounting is also not ideal
in terms of higher center of gravity of the vehicles, which results
in poorer handling and tilting performance.
Integrating the Battery System into the Low Floor
City buses need the battery capacity for the daily driving range
as well as for heating and cooling the passenger compartment.
As doors are being opened frequently, both air conditioning in
summer and heating in winter consume a lot of energy. If the
�attery system were to �e �ac�aged into t�e low �oor wit�o�t
compromising the energy capacity, the chassis structure can
be designed at low weight and passenger capacity of the bus
can be increased. This would be a USP of the design. However,
geometrical boundaries must be respected. Certain dimensions
s�c� as gro�nd clearance and t�e �eig�t o� t�e ste�s or �oor in
t�e seating area are defined and cannot �e c�anged.
Achieving a Market-Leading Position and Ensuring Maximum
Safety
Considering all requirements such as battery cooling, high-
voltage harnesses, battery pack design, packaging, EMC,
etc., ��� was a�le to install more ca�acity into t�e low �oor
than currently available on the market. The battery pack was
designed to �e installed in low �oor city ��ses �solo and
articulated bus) as well as other bus types like low entry or
coach.
With this solution AVL leverages its battery competences
and development skills, which are steered by model-based
systems engineering methodology. In doing so, we are also
addressing one of the most important requirements for all
battery electric vehicles: thermal safety. The battery cell
design, the venting of gases in case of thermal runaway (TR),
the pack design in terms of modularity, the energy density,
and safety requires a multi-skills approach. The battery
management system (BMS) controls the state of health and
safety of the complete battery system. If the cell fails, the
�attery �ac� is set to a sa�e state, t�e fire e��a�st gases
are guided to a safe tailpipe and the thermal propagation is
restricted just to a single pack cell.
Virtually Verified and Scalable to Other Applications
The complete installation and controls are USPs of AVL.
Our battery management is an advantage for other
electric vehicles as well and can easily be tailored to other
a��lications. �or t�is, we o��er a ��ll verification met�odology
with a focus on virtual development. Our simulation method
also considers various physical side phenomena. This puts
design solutions in place for safe operation and to stop
thermal propagation.
Battery lifetime is considered beyond cell aging behavior as it
includes mechanical and performance degradation. State of
charge (SoC), state of health (SoH), state of failure (SoF) as
well as state of safety (SoS) are calculated based on model
a��roac�es. �inally, ve�icle �eet monitoring in t�e clo�d can
�e �sed �or li�etime o�timi�ation and �eet management.
“Our advanced batery
systems enhance capacity
and safety, transforming
complexity into security
and innovation into
industry-leading
standards.”
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2024