Materials manufacturer Proterial and engineering services firm FEV have used simulation to evaluate an EV traction motor concept that combines Proterial’s amorphous alloy core material with its heavy-rare-earth (HRE)-free neodymium sintered magnets.

Amorphous alloy, a metal with no crystalline structure made by rapidly cooling molten alloy, has lower iron loss than the electrical steel sheets commonly used in motor cores. Proterial has developed a continuous lamination and bonding process that makes amorphous alloy ribbon suitable for punching into motor cores.

Proterial’s HRE-free neodymium sintered magnets for EV traction motors contain no heavy rare earths such as terbium and dysprosium, which face resource constraints and procurement risk. Proterial says the magnets combine high remanence flux density with high coercivity.

FEV built a reference model of a 230 kW drive unit, representative of modern passenger-car BEVs, with a silicon steel motor core, then evaluated the effect of amorphous alloy through electromagnetic simulation.

The concept is designed to make best use of the alloy’s lower iron loss at a higher maximum motor speed of 20,000 rpm, compared with 14,900 rpm for the reference. The reduction ratio is raised from 10.8 to 14.4 so that maximum torque and speed during vehicle operation are equivalent to those of the reference drive unit. The motor has 12 poles instead of eight and the same 72 slots and 200 mm stator outer diameter as the reference, and its active length is 77.1% of the reference’s length.

The companies say the simulations indicate the potential for peak power to increase from 230 kW to 300 kW and for motor weight to be reduced by 27%.

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