Permanent Magnets in Traction Motors

Traction motors predominantly employ Permanent Magnet Synchronous Motors (PMSM) which utilize permanent magnets to generate their magnetic fields.

For PMSMs, the commonly used magnet materials include

• Samarium-Cobalt (SmCo) Magnets: Recognized for their high magnetic energy product, which reaches up to 30-35MGOe. They are favored for their high operating temperatures, safety, reliability, and stability, especially in high-speed rail transport surpassing 350km/h.
• Neodymium Iron Boron (NdFeB) Magnets: Widely incorporated in traditional PMSMs. However, they're gradually being replaced by SmCo magnets in the rail transport sector.

Popular magnet shapes for PMSM applications include

• Block Magnets: Installed on the motor's rotor, they interact with the stator's magnetic field.
• Laminated Magnets: Laminated magnets are designed as multiple layers to reduce eddy current losses at high speeds, lowering motor temperature and the risk of magnet failure.
• Arc Magnets: Suitable for PMSM applications where specific magnetic field generation is required.