European project finds virgin REE alternatives for permanent motors
April 23, 2025
The Sustainable Recovery, Reprocessing and Reuse of Rare-Earth Magnets in a European Circular Economy project, established in 2019, is evaluating rare earth elements (REEs) for new motors and developing designs to improve the recyclability of electric motors.
As EVs gain popularity, increased REEs are required to create their permanent magnet synchronous motors (PSMS), where the rotor has magnets embedded that are attracted to a rotating magnetic field using the battery’s power.
The recycling process
Because of the nature of the material, magnets can be difficult to separate from the rotor, breaking up into magnetised powder that sticks to ferrous scrap. Through the use of the newly developed hydrogen processing of magnet scrap (HPMS) – developed at Birmingham University – produces a non-magnetic, reusable powder without removing magnets from the rotor first.
The resultant rare earth-rich powder can then be reprocessed into new magnets, avoiding traditional energy-intensive methods. This means that the energy used to produce magnets is 12% of that needed to make them from virgin material.
Project member ZF, Friedrichshafen, Germany, has built and tested motors made using HPMS and reported that the performance of the magnets was almost identical to those manufactured using freshly mined materials.
Permanent magnet alternatives
Beyond recycling, the use of virgin REEs is can also be reduced by transitioning away from permanent magnets entirely. Externally (or separately) excited synchronous motors can replace the permanent magnets in rotors with electromagnetic windings. These have been used by Renault since the launch of the Zoe supermini electric car in 2012.
Feeding an electric current from the outside of the motor into the rotating core, however, involves the use of brushes so the motor isn’t ‘brushless’ like a PMSM. An alternative that avoids the use of brushes is ZF’s I2SM (in-rotor inductive excited synchronous motor). This has a small electronic generator called an inductive exciter, uniquely fitting inside the rotor shaft rather than on the end, which makes the motor longer.
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