Permanent magnet synchronous motors can be integrally mounted on the wheel axle, forming a complete direct-drive system. Each wheel axle is a drive unit, eliminating the need for a gearbox.
Advantages of permanent magnet synchronous motors:
Permanent magnet synchronous motors inherently have high power efficiency and a high power factor;
Permanent magnet synchronous motors generate less heat, resulting in a simpler, smaller, and quieter cooling system;
The system uses a fully enclosed structure, eliminating gear wear and noise, requiring no lubrication and maintenance;
Permanent magnet synchronous motors allow for a large overload current, significantly improving reliability;
The entire transmission system is lightweight, with a lighter unsprung weight than traditional wheel axle drives, resulting in higher power per unit weight;
The absence of a gearbox allows for flexible bogie design, such as flexible bogies or single-axle bogies, greatly improving train dynamic performance.
Due to the use of permanent magnet poles, especially rare-earth metal permanent magnets (such as neodymium iron boron), their high magnetic energy product allows for higher air gap magnetic flux density, resulting in a smaller size and lighter weight for the same capacity. The rotor has no copper or iron losses, nor the frictional losses of slip rings and brushes, resulting in high operating efficiency.
It has a low moment of inertia, allowing for a large permissible pulse torque, enabling high acceleration, good dynamic performance, a compact structure, and reliable operation.