German centennial automotive component manufacturer Mahle recently announced to have developed a magnet-free motor, which does not derive internal losses, and is only second to Formula E motors in terms of efficiency. The more important aspect is that this motor is able to reduce the demand for rare-earth elements.

Mahle recently announced that the the company is currently researching and developing a contact-free electric motor. The particular design no longer requires permanent magnets, and possesses an exceedingly high efficiency at an operating point of 95%, which is only attainable by the motors for Formula E among various existing electric vehicles. 

▲Wireless current actuates the rotor to spin and generate power upon entry so as to achieve the contact-free and magnetic-free target. 

Most electric cars and scooters in the market are adopted with permanent magnets, and propel rotor spinning through the magnetic property to generate power accordingly. Among various forms of permanents magnets, rare-earth magnet is able to provide the strongest magnetic field, of which the two primary composition of NdFeb magnet and SmCo magnet require rare-earth elements. 

Numerous manufacturers are developing motors that require no permanent magnets seeing how China is the major exporting country in rare-earth elements and the country with the fastest development in electric vehicles, though a propulsion in the rotor will have to rely on the power of magnetic field without the presence of permanent magnets, and the particular design requires copper wire wound rotor, whereas the electricity is transmitted through the slip ring. However, the point of contact between the slip ring and the rotor will induce  unavoidable losses. 

The new design proposed by Mahle this time claims to resolve two issues at the same time: free of rare-earth magnets, and free of contact. This new motor adopts current steering to actuate rotation for the 6 units of internal copper wire wound rotors alongside the electrode. “The motor has no point of contact to transmit electrons, losses, accumulation of dust, and mechanical losses”, commented Martin Berger, VP of Research and Advanced Engineering at Mahle, who also said that a replacement of rotor will not be too difficult during repair despite almost no losses. 

▲A wound-rotor motor design that is similar to traditional adoption, and is differentiated where Mahle sends current into the motor wirelessly. 

Mahle claims that this new motor achieves an operating point of 95%, which can go up to 96%, under general usage scenarios, making it applicable on most electric vehicles. However, it is probably not suitable for electric bicycles and electric heavy-duty trucks.

There is no information to which manufacturers will be adopting the new motor, though Mahle commented that this contact-free motor is expected to enter mass production after 2.5 years, and we anticipate boldly that European automotive manufacturers such as BMW, Mercedes-Benz, and Porsche, who pursue low pollution during the production process, would be very interested in this motor. 

(Photo source: Mahle)