A prototype all-electric Lotus Elise, powered by
two internal, oil-cooled, brushless dc motors,
weighs just 875 kg. Simulations predict a 30-70 mph
time of five seconds for the vehicle and a range of
120 miles.
Made by Zytek Automotive Ltd., the motors are
mounted on lightweight aluminum single-ratio Zytek
gearboxes. Each weighs 13 kg. and the two together
produce a total of 200 bhp (brake horsepower), or
150 kW. A closed-loop, presurized cooling system
for the motors employs a comventional transformer
oil that flows through slots in the stator
laminations, and over the windings. This approach
removes heat produced in the stator winding by FR
losses. Zytek claims the motor is the first
production EV motor to use this technique to cool
critical components.
Power for the motors comes from a 300 V nickel
cadmium battery pack. Engineers selected nickel
cadmium technology to ensure steady voltage
throughout most of the discharge cycle. Recharge to
95% capacity will require 60 minutes. An electroic
control system made by Zytek coordinates all
power-related functions and provides both
regenerative braking and traction control.
Vehicle running gear, bodywork, and the extruded
and bonded aluninum chassis are retained from the
starndard Elise. In the future, passenger
compartment heating will be provided using heat
from the motor cooling oil, which is cooled by the
starndard Elise radiator.
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