Land speed records have always provided an ideal opportunity for testing
technology to its limits. For ABB's drives and motors, the forthcoming
challenge by the British 'ABB e=motion' team on the world electric land
speed record will be no exception
An ABB industrial drive and two 40 kW IP23 through-ventilated ac motors
will be put to the ultimate test when they will be used to drive the ABB
e=motion electric car to speeds of over 300 mph. If the attempt succeeds,
it will be the first time that an electrically-powered vehicle has ever
broken the 300 mph limit. The car is due to be transported to the
Chott-el-Jerid salt flats in Tunisia in June 2004. It will be used by the
vehicle's designers, Mark Newby and Colin Fallows, to attempt to set the
new world electric land speed record and beat the current official FIA
world record of 245.523 mph held by the 'White Lightning' team from the
USA.
When building the car, Mr Newby and Mr Fallows were keen to use only
equipment that could be supplied off-the-shelf by any stockist, to help
reduce the cost of the project and to add to the prestige of the
challenge. Despite this, finding a company that could supply the
equipment needed to power the car proved frustrating.
Finding a company that could supply the necessary technology to drive
the car was the biggest single technical hurdle we faced in building it,
recalls Mr Fallows. Of the companies we originally approached, none
could provide the technology or expertise that justified a world record
attempt of this magnitude. In fact, one suggested a water-cooled drive,
which resulted in us extending the nose of the vehicle by some 1.5m, at
great expense. ABB's solution is extremely compact and means our car does
not even need to be the 10m that it is!
In order to set a new official world record, the car must perform two
recorded runs at better than 252 mph over a distance of one kilometre,
requiring the motors to reach speeds in excess of 6,000 rpm. To achieve
this, ABB has supplied 40kW induction motors capable of operating at
speeds of up to 9,000 rpm. ABB's system uses the drive to convert the
600V dc output from the car's four packs of lead acid batteries into ac
power for the two motors. Producing a combined output of more than
500bhp, the two motors have already helped propel the ABB e=motion car to
146 mph during testing, unofficially making it the fastest electrically
powered vehicle to have run on UK soil.
Commonly used for machine tool applications, the motors would normally
run at between 1,000 and 3,000rpm. To prevent overheating, each motor has
been adapted to include a force ventilation system. A 24V dc fan will be
used to cool the motors and ensure they do not exceed their maximum
operating temperature of 180ºC. Pt100 sensors fitted to each motor
winding provide real-time information about the motor operating
temperature.
A major consideration in designing the drive system was the need for the
car to be able to accelerate quickly to its maximum speed within the
permitted distance. To achieve this, ABB's drive system combines motors
with a high power-to-weight ratio with ABB's Direct Torque Control (DTC)
drive technology, which ensures that full motor torque is available even
at zero speed.
Other challengers to the record have commonly used gear-driven systems
in their cars to achieve the fastest possible acceleration, whereas the
technology we've supplied steadily controls torque across the entire
speed range says Frank Griffith, one of the team at ABB who helped to
develop the car's power system. Although a geared vehicle can achieve
100 mph in a few seconds, its rate of acceleration falls away much more
quickly compared to our system, which will continue accelerating,
provided sufficient battery power is available to drive the motors.
The ability of this system to provide the accelerati