PMSM permanent magnet synchronous motor belongs to a type of AC motor. Its stator is powered by three‑phase alternating current, and its rotor adopts permanent magnets. Controlled by DC‑supplied alternating energy, it achieves precise motor regulation and avoids service‑life defects caused by carbon brushes.

The PMSM permanent magnet synchronous motor can be integrally installed on wheel shafts to build an integrated direct‑drive system. In this solution, a single shaft acts as the driving unit, removing the requirement for gearboxes.

Core Features of PMSM Permanent Magnet Synchronous Motor

• High energy efficiency and superior power factor.
• Low heat output, simple cooling system structure, compact overall dimension and low operating noise.
• Fully‑enclosed system construction: free from gear abrasion, gear‑generated noise and lubricating oil; it is virtually maintenance‑free.
• Tolerates large overload current for enhanced operational reliability.
• Reduced total weight of the whole drive system. It delivers lower unsprung mass compared with traditional axle transmission and higher power‑to‑weight ratio.
• Gearbox‑free design enables flexible layout options for steering rack systems, including flexible steering racks and single‑axle bogies, which greatly boost vehicle dynamic performance.

Working Principle of PMSM Permanent Magnet Synchronous Motor

First of all, the main magnetic field is established. Different from electrically excited synchronous motors, PMSM permanent magnet synchronous motor generates excitation magnetic fields via rotor‑mounted permanent magnets rather than DC‑energized excitation windings. Three‑phase symmetrical armature windings serve as power windings to carry induced electromotive force and induced current.

When the prime mover drives the rotor to spin, the rotating magnetic field produced by permanent magnets sequentially cuts stator phase windings. As a result, three‑phase symmetrical alternating electromotive force with periodically varied magnitude and direction is induced inside armature windings.