Lightweight Electric/Hybrid Vehicle Design

1.1 Introduction
LIFE EXPECTANCY YEARS
80
5T
40
20
1
Poorest Third
World State
Current EV design approaches 3
Current EV design approaches
The environmental arguments for electric propulsion become more compelling when they can be
supported by an economic case that will appeal to the vehicle buyer. Here the current technology
of electric and hybrid drive is reviewed in a way that shows the technical imperatives alongside
the economic ones. After an analytical study of drive system comparisons for different vehicle
categories, ‘clean-sheet-design’ integrated vehicle electric-drive systems are reviewed for small
and medium cars and a concluding section encapsulates a procedure for optimizing motor, drive
and batteries in the form of a power-pack solution.
A section on electric-drive fundamentals, establishing basic terminology, appears in the Introduction.
In the preface to the case study chapters (5 and 6), contained in the second half of Chapter 4, the
whole macro-economics of electric vehicles is discussed, with the wider aspects of the fuel infrastructure,
as is a full analysis of competing electric-drive and energy-storage systems, for EVs.
1.2 Case for electric vehicles
1.2.1 ENVIRONMENTAL IMPERATIVE
The current world population of motor vehicles stands at 700 million, of which over 600 million
are owned in G7 economies1 . This number is set to increase to around 1000 million in the next ten
years. The bulk of this growth is expected to occur in Second World countries where per capita
income is reaching levels where car ownership is known to commence. This has two serious
implications (Fig. 1.1): a large increase in the usage of hydrocarbon fuels and an increase in
Fig. 1.1 Life expectancy related to energy
usage, as seen by the World Bank.
20T
5T G7
Economies
.01 .1 1 10 100
ENERGY USAGE
LOG ENERGY USAGE
TONS/ANNUM
COAL EQUIVALENT