Students electrify the future of motorsport
ArcelorMittal powers Formula Student entry with iCARe® electrical steels
A team from the University of Laval in Canada is using ArcelorMittal’s iCARe® Save electrical steel to maximise the power of their vehicle. Designed and built by students, the Laval vehicle uses four in-wheel motors and ArcelorMittal’s top of the range electrical steels. The performance is outstanding: the car won – among other prizes – best self-made car, best newcomer, second place for its efficiency, and fourth place overall after the 2015 Formula Student events in Europe.
ArcelorMittal provided the Laval team with our iCARe® Save 20-13 electrical steel. Developed by ArcelorMittal specifically for electric mobility solutions, iCARe® Save 20 - 13 demonstrates the lowest losses of almost any 0.20 mm gauge electrical steel currently available. “High performance motors are only possible with high performance steels such as iCARe® Save,” notes engineering student Simon Roy who designed the motors on the Laval vehicle from scratch.
High power density possible
ArcelorMittal steel enabled the Laval team to improve the efficiency of their traction machines, make them lighter, and generate higher power density. This was important as Laval’s vehicle has four in-wheel motors rather than one central engine. “Although it is cheaper to have one motor, we wanted the extra performance and grip we could achieve with four-wheel drive,” explains Simon Roy.
“Four motors allow us to control the vehicle dynamically,” notes Emmanuel Bogner who designed the gearbox which sits between the motors and the wheel. “We can effectively control each motor separately. For example, we can direct torque to each wheel to control the yaw rate. That is a big advantage for safety as you can control the car in any situation. The handling is amazing!”
Each wheel is driven by an independent electric motor featuring iCARe® Save.
As well as leaving more space for the driver and the battery, in-wheel motors allow more acceleration. Performance is enhanced significantly. While in-wheel motors are a good solution for vehicles which only run on paved roads, they are unlikely to make their way into future production cars as Simon Roy explains: “There is ongoing research but effectively, each motor is an un-sprung mass. That gives the passengers a very bumpy ride on rough surfaces and increases wear to the suspension and the motors.”
The motors use high rotor speed and electrical frequency to generate maximum speed and power. “A disadvantage to high electrical frequency is that losses increase,” explains Simon Roy. “We needed steel which demonstrates low iron losses and iCARe® Save meets this requirement.” This helped the Laval team win second place in the efficiency category at the Formula Student Austria event.
2015 University of Laval car racing team with Sigrid Jacobs from ArcelorMittal
Oil cooling increases efficiency
One of the unusual features of the electric motor design is the cooling mechanism. Coil windings in the motor are normally water cooled, however, the Laval team chose to use oil to cool the motor. “The cooling mechanism comes into direct contact with the motor winding which increases heat transfer by 35% compared to water cooling,” explains Simon Roy.
The rotor is air-cooled using a fan. When the rotor turns, the fan pushes air into the gap between the rotor and stator to enhance cooling. The design saw the team win the most innovative cooling system prize at Formula Student Austria.
The result is a vehicle which stands out from the competition due to its extremely high performance. Each motor turns at around 16,000 rpm and has 8 poles which provide a base frequency of about 1 kilohertz at maximum power. “That’s equivalent to high performance road vehicles,” notes Sigrid Jacobs, ArcelorMittal Global R&D’s portfolio director for electrical steels. “The high yield strength of our iCARe® Save grades has been developed to cope with this level of performance.”
2015 University of Laval car racing in Europe
Working with innovative steels
For both Simon Roy and Emmanuel Bogner, the Formula Student competition has provided a wealth of valuable experience for the future. “I didn’t know much about electric motors before the competition. I’ve learned design, manufacturing and many other skills. It will be very useful for the future and has already helped me secure my first job in the industry,” says Simon Roy.
“New graduates usually have no experience,” notes Emmanuel Bogner. “But building an entire powertrain from scratch gives you an overall view of the job of engineering and is interesting to employers. And we get to work with innovative technologies and products such as iCARe® Save.”