ABB is providing the main drive system for the British challenger to the world electric land speed record.
Comprising an inverter from ABB’s ACS 800 range and two 40 kW IP23 through-ventilated AC motors, ABB’s system will enable the e=motion electric car to travel at over 300 mph (482.8 kilometres), well in excess of the top speed of a Formula One car.
Producing a combined output of more than 500 bhp (brake horsepower), the two motors have already helped propel the e=motion car to 146 mph (234.96 kilometres) during testing. This unofficially broke the 139 mph (223.7 kilometres) UK record for the fastest speed travelled by an electric vehicle.
The 10 metre long car is due to be transported to Tunisia in September, where 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. The current world record of 247 mph (397.51 kilometres) is held by a team from the USA.
ABB’s system uses the drive to convert the 600 V dc output from the car’s four packs of lead acid batteries into ac power for the two motors.
To qualify as an official world record, the car must perform two runs at better than 252 mph (405.55 kilometres) over a distance of one kilometre, requiring the motors to reach speeds in excess of 6000 rpm. To achieve this, ABB has supplied induction motors capable of operating at speeds of between 5000 and 9000 rpm.
To prevent overheating, each motor has been adapted to include a force ventilation system comprising a 24V dc fan, which will be used to cool the motors to ensure they do not exceed their maximum operating temperature of 180 degrees C. PT100 sensors fitted to each motor winding provide real-time information about the motor operating temperature and also serve to protect the motors from overheating.
The drive system developed for the e=motion car is the work of members of ABB’s drives application engineering team, which worked closely with the e=motion engineers since November 2002. Developing the system involved a number of challenges, including the simulation of the vehicle dynamics and performance likely to be experienced during the land speed record attempt.
“We had to develop our system without initially being able to physically test the car on a track,” said Frank Griffith, consultant engineer. “This meant we had to model and calculate likely performance based on a set of estimated conditions involving factors such as rolling resistance, drag and battery discharge rate. Much of this information was extrapolated from data found on the Internet. Not only that, but we only had a limited amount of space available for installing our system in the car.”
To help tune performance, ABB is using data from the two independent four-channel data loggers incorporated within the drive. During recent testing performed at the Bruntingthorpe airstrip in Leicestershire, the data loggers have been extensively used to collect a range of data on drive and motor status, which is uploaded to a PC using ABB’s Drives Window tool. Once in the PC, the car’s performance data can be displayed graphically or exported if preferred.
“The data loggers allow us to improve performance in the same way Formula One teams do with their cars,” explained Steve Malpass, application engineer. “One of the data loggers is set to a rapid sampling rate of 1 sample per millisecond, which records all the actual events as they happen. The other logger, which is set to a slower rate, is used to record information on trends that occur throughout the duration of the tests being carried out, which gives us an overall picture of how the car is faring.”