UK cuts rare metals from electric car motors
The Government is to fund the development of car traction motors that do not need rare-earth magnets.
The project, ‘Rapid design and development of a switched reluctance traction motor’, will be led by Cobham Technical Services and involve Jaguar Land-Rover and automotive design house Ricardo.
“Virtually all electric traction motors currently used in such applications employ permanent magnets made from materials such as neodymium-iron-boron and samarium-cobalt,” said Cobham. “Since switched reluctance motors [SRMs] do not use permanent magnets, they are likely to provide the ideal replacement technology.”
This said, SRMs use only the attraction between iron and an electromagnetic field, rather than the attraction and repulsion available between a magnet and an electromagnetic field, so they need to be larger and heavier for any given power output. They also traditionally suffer from acoustic ringing in the rotor.
“One of the main challenges of the project will be to produce a torque-dense motor that is also quiet enough for use in luxury vehicles,” conceded Cobham.
One of Cobham’s products is the electromagnetic modelling tool Vector Fields.
As part of its work in the project, and with data from the other two firms, Cobham will develop what it describes as “multi-physics software” to simulate, design and analyse the motors.
“Design software for switched reluctance motors is at about the same level as diesel engine design software when it was first introduced,” said Kevin Ward, director of Vector Fields at the firm. “Cobham will develop its existing SRM capabilities to provide the consortium with tools. We will investigate integration with our other multi-physics software to obtain more accurate evaluation of model-related performance parameters such as vibration.”
Cobham will also adapt its code for parallel computing to increase throughput, he added.
“It is important to understand the capability of switched reluctance motors in the context of the vehicle as a whole so that we can set component targets that will deliver the overall vehicle experience,” said Jaguar Land Rover research head Tony Harper.
£750,000 of funding for the three year project will come from the Government via the Technology Strategy Board and Department for Business Innovation and Skills; and an equal amount will be contributed by the combined partners.