Induction Motor (ASM)
An induction motor, also called an asynchronous motor or asynchronous machine (ASM), is an AC motor whose stator field induces electrical current in the rotor instead of relying on permanent rotor magnets.
Why it is asynchronous
The stator creates a rotating magnetic field. For that field to induce rotor current and produce torque, the rotor must turn at a different speed from the field. This difference is called slip; in normal motoring operation, the rotor turns slightly slower than the stator field. “Asynchronous” describes this speed difference, so ASM is not a separate motor type from an induction motor.
In an EV, an induction motor is one option for a traction drive. It differs from a Permanent-Magnet Synchronous Motors, where permanent magnets establish the rotor field and the rotor follows the stator field at synchronous speed during normal operation.
For the construction, control methods, EV use cases, and design trade-offs, see Induction (Asynchronous) Motors in EVs.