Lightweight Electric/Hybrid Vehicle Design

Fig. 1.13 Turbo alternator.
Current EV design approaches 15
1.2.14 MODULAR SYSTEMS
From the foregoing considerations, it will be apparent that the motor car of the future needs power
electronics to be viable. Fortunately, we now have the technology to satisfy the most demanding
applications. There may be some rivalry between different types of power switches but cost will
be the final judge. A manufacturer who constructs the power electronics as an all-insulated system
in a single module permits module exchange as the first means of maintenance. Liquid cooling
also makes sense. It can cool the motor, warm/cool the sealed batteries and provide power steering
at the same time. This concept will make it possible to convert existing chassis as well as develop
new ones, thus enabling product to be brought to market quickly. Standard electronics packages
are the only way to achieve the unit costs necessary for product acceptance in the market.
Interchangeable batteries will make it possible for maximum vehicle utilization in intensive duty
applications, such as taxis and delivery vehicles. This method of construction also opens the door
to new methods of financing EVs; for example, the user buys vehicle then rents battery/power
electronics.
1.3 Selecting EV motor type for particular vehicle application
1.3.1 INTRODUCTION
Motor and drive characteristics are selected here for three different applications: an electric scooter;
a two-seater electric car and a heavy goods vehicle, from four motor technologies: brushed DC
motor, induction motor, permanent-magnet brushless DC and switched reluctance motor2 . Any of
the four machines could satisfy any application. This is not a battle of ‘being able to do it’, it is a
battle to do it in the most cost-effective manner. There are two schools of thought regarding EVs –
group A believe they should create protected subsidized markets for environmental reasons and
are not too concerned with cost. Group B realize that until this technology can compete with
Specification
Speed 60 000 rpm
Power 90 kW
Voltage 200 V
Frequency 2000 Hz
Weight 20 kg (housed)
Dimensions 150 mm OD x 175 mm long
Current 262 amps
Efficiency 99%
Resistance 14 milliohms
Inductance 15 microhenries
Cooling Liquid (oil or water)