Next-generation electric motor hits the road
Is it possible to produce electric cars on a very large scale? At the moment, this can depend on costly materials that must be imported. More specifically, this concern relates to the rare earth magnets on which their motors tend to rely. EU-funded researchers have developed promising technology that works without them.
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The new technology was developed by the Armeva project, which had set out to develop a cost-effective alternative to leading designs. The goal we had set ourselves was to devise a solution that doesnt involve rare earth materials, but nonetheless performs at least as well as todays best electric motors, says project manager Saphir Faid of systems supplier Punch Powertrain.
Armeva ended in October 2016, having demonstrated the potential of its approach in a test application: the partners replaced the motor of an existing electric vehicle with their own technology. The results were compelling, Faid reports, and the partners are following up with work to optimise the performance and manufacturability of their system. First contacts with potential customers are under way, he notes.
No magnets needed
Armevas solution is based on a different principle than the electric motor designs that predominate at the moment. Most electric motors on the market today are based on the Lorentz force, Faid explains. So they exploit a principle by which a current going through a conductor placed in a magnetic field will produce a force perpendicular to the current and to the magnetic field.
In contrast, the technology proposed by the project partners capitalises on the principle of reluctance, a phenomenon that affects magnetic flux in a way similar to that of resistance in an electrical circuit. Basically, says Faid, it builds on the fact that an object in a magnetic field will align itself in such a way that the magnetic flux is maximised.
The movement of the flux-seeking object can be used to transform electricity into mechanical power, and there are various ways to do so. Following an analysis of three particularly promising methods, Armeva opted for switched reluctance. This is a technique by which a rotor spins as it adjusts to rapid changes in a magnetic field, and where these changes are induced by electronically switching power to the different motor poles in a manner synchronous with the actual position and movement of the rotor.
Its an approach that was known to hold potential, Faid notes, but there were major challenges to overcome not least in view of the complexity of the design and control of such a motor. Other issues included vibration and noise.
Armeva, says Faid, found ways to tackle these problems and trialled its technology by replacing the motor of a state-of-the-art electric vehicle with their own, which is similar in size and mass. The prototype passed all tests with flying colours and in particular was shown to offer the same performance, he reports.
A number of the experts who have test-driven the vehicle commented that it represented a big step forward, Faid recalls. Some described it as best in class in this technology.
Towards mass production
Rare earth materials are expensive, often unsustainably mined and generally sourced from abroad, placing Europe at risk of shortages, Faid explains. By dispensing with them, he notes, Armeva is offering a way to curb costs, further boost electric vehicles green credentials and pre-empt a supply issue that could limit the scope to produce such cars in sufficient quantities to decarbonise road transport.
However, there is still a lot to do. We are still evaluating and optimising this technology, says Faid. Further work in progress focuses on adapting the design in view of mass production. We do have interest from a number of potential customers, so we are discussing possible scenarios for commercialisation with them, Faid concludes.