Vehicle Electrification - December 18, 2013 - 20

Fuel cells for
auxiliary power

Anode modification greatly improves
performance and sulfur tolerance at systemrelevant conditions.
for the vehicle battery is to crank the engine,
but it is also used as an energy buffer for auxiliaries.
To be able to use an APU in a heavy-duty
truck, the truck needs additional components:
* A control panel needs to be installed in the
living part of the truck's cabin to enable remote start, set-points adjustment, monitoring,
alarming, and shutdown of the APU
* A dc/dc converter is needed to convert the
output voltage from the APU to a voltage suitable for charging the vehicle battery and a
SOC sensor measuring the state of charge of
the vehicle battery (if this is not already available on the vehicle)
* A system controller is needed that controls
the APU and dc/dc converter with the target
of keeping the battery SOC on a predefined
level.
Since the APU is an optional component,
all components need to be compatible with
the existing vehicle architecture.
The system controller can be implemented
as a stand-alone ECU or as a part of another
vehicle system ECU. The controller will nor-

December 18, 2013

mally use standard communication interfaces
such as CAN to interface with the APU, the
dc/dc converter, and the SOC sensor, as well
as other available sensors and actuators. An
example of other useful sensor information
could be the current power consumption of
auxiliaries in the cabin. An example of other
relevant actuators could be power relays that
could be used to isolate the APU from the vehicle electrical system in case of an error.
Due to the dynamic nature of the vehicle
battery and the APU, as well as a potentially
irregular power demand from vehicle auxiliaries, the task of keeping the battery SOC level
on a suitable level can be challenging. To be
able to develop, calibrate, and test the control
algorithms for the system controller, a system
model needs to be developed.
Within the DESTA project, the SOFC APU
systems from Eberspächer and AVL have
been significantly improved and thoroughly
tested over thousands of hours. Topsoe Fuel
Cell has improved SOFC stack technology
especially toward sulfur tolerance and thermal
cycling, which makes competitive products
possible. Volvo has prepared the vehicle integration by developing a dc/dc converter and
an energy management system.
Based on recent accomplishments, the
DESTA partners are confident that the truck
demonstration in 2014 will prove successful.
AVL and Eberspächer are planning a commercial U.S. market introduction of SOFC
APU systems in 2016/17.
This article is based on SAE International technical paper 2013-012470 written by Juergen Rechberger of AVL List GmbH, Andreas
Kaupert of Eberspächer Climate Control Systems, Christoffer Graae
Greisen of Topsoe Fuel Cell, Jonas Hagerskans of Volvo Group Truck
Technology, and Ludger Blum of Forschungszentrum Jülich.

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Vehicle Electrification - December 18, 2013

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