In Model 3 production, Tesla has ditched the well-proven induction motors and replaced them with a new type of IPM-SynRM motor. These motors differ from conventional permanent magnet motors in their rotor design. A synchronous reluctance motor has a series of electromagnets around the stator, but the rotor does not have any windings or permanent magnets. Learn Engineering/YouTube helps us understand how this design actually works.
The Synchronous reluctance motor, instead of the rotor, contains veins of a magnetic material interspersed with non-magnetic material, "arranged so that it has a preferred orientation in the magnetic field created by the stator." To turn the rotor, the motor sequentially activates the electromagnets, creating a rotating magnetic field that pulls the rotor forward.
The main advantage of SynRM is that there are no rotor cage losses or permanent-magnet (PM) losses, which allows a constant torque to be maintained that exceeds that of an induction motor of the same size.
Source: Learn Engineering/YouTube
Tesla engineers used the resistance property of iron. By placing the permanent magnet in the grooves of the synchronous motor deep in the iron core, Tesla was able to further reduce the magnet's effect on the stator winding and thereby reduce the electromotive force (EMF) or "voltage." This design is an internal constant beckon of a synchronous reluctance motor, that is, a Model 3 motor.
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