ABB has found a novel way to put its drives and motors to the ultimate test by 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, well in excess of the top speed of a Formula One car.
Producing a combined output of more than 500bhp, the two motors have already helped propel the e=motion car to 146 mph during testing. This unofficially broke the 139 mph UK record for the fastest speed travelled by an electric vehicle. The 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 is held by a team from the USA.
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.
The ABB solution could shorten the car!
The designers initially approached two of ABB's key competitors. "Of the companies we originally approached, none could provide either the technology or expertise that justified a world record attempt of this magnitude," says Mark Newby, the car's driver. "In fact, one suggested water cooled drive solution 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!"
The equipment:
To qualify as an official world record, the car must perform two 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 induction motors capable of operating at speeds of between 5,000 and 9,000 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 180ºC. 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 high power-to-weight ratio of the motors, coupled with ABB's Direct Torque Control (DTC) drive technology, provides excellent control of motor torque, with full motor torque available even at zero speed. This enables the car to accelerate faster to its record breaking speed.
The drive system developed for the e=motion car is the work of members of ABB's drives application engineering team, Frank Griffith, Steve Malpass and John Schofield. The team has 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.
Much calculation prior to testing:
"We had to develop our system without initially being able to physically test the car on a track," says 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, so we had to ensure that whatever we came up with was also compact."
To help tune the performance of the system, 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 the performance of our system in the same way as Formula One teams do with their cars," explains 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."
‘One hundred percent confident!’
"We initially approached ABB, via a mutual colleague, because we were aware of its profile in the world of electrical engineering," says Colin Fallows, the designer of the e=motion car. "Throughout the development of the car, we have constantly been able to call upon ABB's vast expertise and have been unbelievably impressed by what Frank, Steve and John have come up with. Based on what we've seen so far, we are 100% confident that ABB will be joining us in the record books when we break the world speed record."
Contact: James Haigh
ABB Ltd.,
9 The Towers, Wilmslow Road
Didsbury, Manchester M20 2AB
Tel: 0161 438 3036
Fax: 0161 445 6066
Email: [email protected]
Web: www.abb.com/motors&drives