Hybridization and Electric Vehicles 1/2

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En provenance du cours de École des Ponts ParisTech

Electric Vehicles and Mobility

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École des Ponts ParisTech

Electric Vehicles and Mobility

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The purpose of Electric Vehicles and Mobility is to help you, whatever your profile, your training or your country, find your own answers to questions such as: - Will electric vehicles be the last to be allowed in megalopolises in the 21st century? - Does the environmental gain from vehicle electrification justify heavy investment in charging infrastructure? - Are electric vehicles only for wealthy people in developed countries? This course will allow you to acquire elements from engineering science, sociology, environmental science, political science, economics, management science, in order to evaluate, analyze and implement the diffusion of electric vehicles where their use is relevant. This MOOC is the English version of Mobilités et véhicules électriques; in the lecture videos, the teachers speak in French, nevertheless their presentation is in English and English subtitles are available. Groupe Renault and ParisTech schools have been working together for almost 15 years on topics related to sustainable mobility. Together, they created two Master programs (Transport and Sustainable Development in 2004, Mobility and Electric Vehicles in 2010) and the Sustainable Mobility Institute Renault-ParisTech in 2009, to support ongoing changes. Electric Vehicles and Mobility is the result of this shared history and was developed from a course delivered within the Master Mobility and Electric Vehicles, led by Arts et Métiers ParisTech in partnership with Ensta ParisTech, Mines ParisTech and École des Ponts ParisTech.

À partir de la leçon

Chapter 6 - Prospective: The Road to Electrification

<p>In this chapter we will explore how the electric vehicle may be deployed over the course the 21st century. To do this, we will explicitly use a prospective approach aimed at exploring the future rather than predicting it.</p><p>We will begin by decomposing the main instruments to reduce the environmental impacts of transport through the ASIF (Activity Structure Intensity Fuel) approach, then study the crucial issue of the deployment of charging infrastructures. Finally, we will examine the role of hybridization as a transition technology to the electric vehicle.</p><p>The course is followed by an interview of an expert from AVERE-France to broaden our point of view on hybridization and to discover advances in battery life.</p><p>You will find in the following session the graded assessment for both chapter 5 and 6. This evaluation concerns only the videos <em>Lecture</em> and is required to obtain the certificate.</p>

Hybridization and Electric Vehicles 1/27:15

Hybridization and Electric Vehicles 2/29:18

Rencontrer les enseignants

Émeric FORTIN
Head of the Master in Transport and Sustainable Development
Direction of Studies, École des Ponts ParisTech
Virginie BOUTUEIL
Researcher
LVMT (City Mobility Transport Lab), École des Ponts ParisTech

-In this first part we will discuss vehicle electrification,

and more specifically the case of electric vehicles.

Vehicle powertrains can be summarized as follows:

first of all, energy storage is required on board,

then an energy transformer, that ensures the production

of mechanical energy, necessary to the motion of the vehicle.

If we now consider a conventional engine,

first we have a fuel tank, which provides the energy reserve

required for motion, for the range of the vehicle,

then a thermal engine that produces mechanical energy,

that provides the power necessary for the dynamics of the vehicle.

Recharging the energy is done very simply,

as the storage system is an open tank, it is simply filled with fuel

to recharge the vehicle and recover its full range.

This system has the disadvantage of emitting local nuisance,

notably pollutant exhaust emissions, and sound emissions

due to the operation of the thermal engine.

If we now consider an electric vehicle,

according to the same principle, on-board energy storage

is provided by a battery, with the particularity

that the battery provides both the storage of energy

and the supply of power.

It powers an electric machine, which provides the mechanical energy

required by the wheels.

Note that this system is reversible,

energy can be recovered from the braking of the vehicle.

This vehicle has the advantage of emitting no local pollutants,

and only extremely low noise levels in urban use.

Recharging the vehicle is done differently,

the battery is a closed system, and the recharging system

consists of an electric charger

that reinjects power into the battery during recharge.

Taking into account the balance of this vehicle

then requires a total life-cycle approach,

since there is production of electricity,

therefore decentralization of pollutant emission

to where the electricity is produced.

Let us now compare thermal and electric vehicles

in terms of on-board energy.

We have on this synthetic diagram first a conventional thermal vehicle,

with a 45-liter tank, and we see that the range of this vehicle

is approximately 1 000 km, and a very interesting factor,

a very short recharging time, since the fuel pump hose

represents a power of approximately 1 megawatt,

and you see that in a few minutes, 2-4 minutes,

the conventional vehicle can be fully recharged.

For both electric vehicles shown to the right,

you see that the storage masses are larger,

however the ranges are much lower, and an aggravating factor,

recharging time is much longer, as it is linked to the power

available from the network,

and we see that we can increase this power,

but this comes with many problems concerning the electric network

and the cost of recharging.

We see that recharging electric vehicles

takes approximately one hour, compared to a few minutes

for thermal vehicles.

Taking a closer look at an electric vehicle,

here we have the Renault Zoé, produced by Renault,

which has the particularity of having been designed from the start

as an electric vehicle, with a battery highly integrated

into the vehicle body, an electric machine

designed and produced by Renault,

and battery assembly also carried out by Renault.

It is interesting to note that the performances of this vehicle

are constantly improving, as you can see, year to year,

the energy content of the battery has increased,

thus increasing the range, which is now 300 km in real use,

with perspectives beyond 2020 of ranges over 400 km.

It is currently the best-selling vehicle in France and in Europe,

as we can see here.

It is important to note that for electric vehicles,

range and power consumption, which are directly linked,

are closely linked to the use made of the vehicle.

This diagram shows various cycles of use,

listed by average speed in increasing order.

We see that power consumption, and therefore range,

have an optimum for speeds around 20-30 km/h,

then deteriorate significantly at high speeds,

due to many losses, of aerodynamic notably.

They also degrade at low speeds, at which transmission losses occur,

notably via the auxiliaries.

Another point to note is the consumption of the auxiliaries,

that must notably provide electric vehicles with heat

for the heating system, and with cold for the air conditioning.

We see on this diagram, with the same axes as previously,

the importance of the power absorbed by this on-board network,

which can lead to range losses of 15 to 40% in urban driving,

which is significant.

An important particularity of electric engines

is regenerative braking.

This diagram shows the distribution of the energies

corresponding to the forces

that apply to a vehicle driving on a level road.

There are two main dissipative forces, linked to aerodynamics and rolling,

and a potential force that we try to recover during braking.

You can see that in urban use the corresponding energy

represents more than half of the energy required for motion.

This is not the case in motorway use where aerodynamic losses predominate,

and potential recovery is negligible,

around 15%.

When we look at the influence of energy recovery during braking

still as a function of use types, as shown here to the right,

we see that it is very important in urban use, with gains up to 30-50%

from the energy recovered during braking,

and that as we said earlier its impact is lower

for road or motorway cycles.

The issue that we saw about the electric vehicle

is essentially linked to the size of the battery

that is required on board to ensure maximum range,

which remains low and entails significant battery costs.

In the next part we will study hybrid powertrains,

that we will present as a solution enabling the vehicle

to retain all its capabilities, while eliminating,

or avoiding as much as possible, the issue of the battery

and of the cost linked to the battery on board the vehicle.

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