Electric motor for EVs that uses approximately 30% fewer rare-earth magnets

Toshiba Infrastructure Systems & Solutions Corporation*

To achieve compactness, lightness, and high torque, motors for electric vehicles*¹ make extensive use of magnets (neodymium magnets) that contain rare earths, which are expensive and can only be mined in limited areas. Toshiba Infrastructure Systems & Solutions Corporation has developed a rotor structure that reduces the amount of magnets used by approximately 30% (compared to our previous products), thus contributing to reducing motor costs.
The motor’s rotor is designed to efficiently transfer the magnetic flux from the magnet installed inside to the stator, but the thin-walled part (top bridge) on the rotor surface which was designed to increase mechanical strength was one cause of magnetic flux leakage.
Our recently developed rotor structure eliminates the top bridge while maintaining the rotor’s mechanical strength. This reduces the amount of magnets used by reducing the leakage flux and increasing the effective magnetic flux that contributes to torque generation in the motor.
We have established mass production technology for this rotor, and we delivered a prototype to an automobile manufacturer in 2023. Going forward, we will contribute to the spread of electric vehicles by providing motor products that offer improved environmental performance at low cost.

*Toshiba Infrastructure Systems & Solutions Corporation has been integrated into Toshiba Corporation on April 1, 2025.

• A general term for vehicles that use electrical energy stored in batteries as a power source, such as electric cars and hybrid cars.