Learn to Speak EV: Electric Cars Explained for Gearheads

The rotor is, as the name implies, the rotating bit in an electric motor. Think of it kind of like the crankshaft of a combustion engine; forces in the motor cause the rotor to spin, and that spinning is the motor’s output.

The fixed parts surrounding the rotating part of an electric motor. The stator causes the rotor to spin by creating a constantly rotating magnetic field around its circumference. This rotating magnetic field interacts with the rotor’s magnetic field, causing it
to spin.

Permanent-magnet synchronous motor:
The rotor’s magnetic field is supplied by permanent rare earth magnets, and it rotates in sync with the stator’s rotating magnetic field, hence the “synchronous” part of the name.

Induction asynchronous motor:
Instead of permanent magnets, induction motors use electrical current to induce a magnetic field in a cage of metal bars on the rotor, similar to how an electromagnet works. In order for that electromagnetic induction process to happen, there has to be some slight misalignment between the fields of the stator and the metal bars on the rotor. This misalignment is known as “slip,” and it’s also what makes the motor “asynchronous.”

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