Sensitivity Study on the Design Methodology of an Electric Vehicle 2012-01-0820
Reducing greenhouse gas emissions to alleviate global warming
will certainly be one of the major challenges of the 21st century.
Transportation plays a very important part in this, which is why
the European Commission and the European manufacturers have found
an agreement to limit the average emissions of vehicles to 130
gCO₂/km in 2012 and 95 gCO₂/km in 2020. Cutting vehicles'
consumption of hydrocarbons is becoming a critical issue to reach
these ambitious targets. Electric vehicles, characterized by zero
direct CO₂ emissions, seem to be a relevant way to achieve these
Despite their capabilities to emit no local pollution and to
operate silently, electric vehicles have also one important
drawback: the limited autonomy offered to the customer. As for
conventional vehicles, energy consumption for electric vehicles is
very dependant of driving conditions, such as driving cycles and
ambient temperature operating conditions for instance.
Consequently, assessment of the electric vehicle autonomy can be
very dependant of assumptions taken into account during its design,
which may be a real limitation to the use and deployment of these
types of vehicles.
The objective of this paper is to present a global methodology
to design an electric vehicle and to evaluate the sensitivity of
this sizing process to the assumptions and the requirements taken
into account. The presented methodology consists in transforming
vehicle and customer requirements towards objectives and
constraints on the electric powertrain. Several types of vehicle
requirements and driving cycles are taken into account. A tool able
to design the electric machine and to evaluate its efficiency has
been used in this study. Finally, the design phase leads to a final
electric powertrain adapted to the whole requirements while
optimizing its global efficiency and its dimensions.