A permanent magnet motor is a kind of brushless electric electric motor that uses long term magnets instead of winding in the field.

This kind of motor is used in the Chevy Bolt[1], the Chevy Volt, and the Tesla Model 3.[2] Various other Tesla models use traditional induction motors motors.[3] Front motors in all-wheel drive Model 3 Teslas are also induction motors.

Long term magnet motors are better than induction engine or motors with field windings for several high-efficiency applications such as electric vehicles. Tesla’s Chief Engine Designer was quoted talking about these advantages, saying: “It’s well known that permanent magnet devices have the advantage of pre-excitation from the magnets, and for that reason you have some efficiency advantage for that. Induction machines have perfect flux regulation and for that reason you can enhance your efficiency. Both seem sensible for variable-quickness drive single-gear tranny as the drive devices of the cars. Therefore, you may already know, our Model 3 has a long term magnet machine now. This is because for the specification of the performance and efficiency, the long lasting magnet machine better solved our price minimization function, and it was optimal for the number and performance target. Quantitatively, the difference can be what drives the future of the machine, and it’s a trade-off between motor price, range and battery cost that is identifying which technology will be utilized in the future.
The magnetic field for a synchronous machine could be provided by using long term magnets manufactured from neodymium-boron-iron, samarium-cobalt, or ferrite on the rotor. In a few motors, these magnets are installed with adhesive on the top of rotor core in a way that the magnetic field is radially directed across the atmosphere gap. In other styles, the magnets are inset in to the rotor core surface or inserted in slot machines just below the surface. Another form of permanent-magnet motor provides circumferentially directed magnets positioned in radial slots that provide magnetic flux to iron poles, which in turn set up a radial field in the atmosphere gap.

The primary application for permanent-magnet motors is in Auto Chain variable-speed drives where in fact the stator comes from a variable-frequency, variable-voltage, electronically managed source. Such drives are capable of precise speed and placement control. Due to the absence of power losses in the rotor, in comparison with induction engine drives, also, they are highly efficient.

Permanent-magnet motors could be made to operate at synchronous acceleration from a supply of continuous voltage and frequency. The magnets are embedded in the rotor iron, and a damper winding is placed in slots in the rotor surface area to supply starting capability. This kind of a motor will not, however, have method of managing the stator power factor.