A permanent magnet engine is a type of brushless electric electric motor that uses long term magnets instead of winding in the field.
This type of motor is utilized in the Chevy Bolt[1], the Chevy Volt, and the Tesla Model 3.[2] Additional Tesla versions use traditional induction motors motors.[3] Front motors in all-wheel drive Model 3 Teslas are also induction motors.
Long term magnet motors are more efficient than induction engine or motors with field windings for certain high-efficiency applications such as electrical vehicles. Tesla’s Chief Electric motor Designer was quoted discussing these advantages, saying: “It’s popular that permanent magnet machines have the advantage of pre-excitation from the magnets, and therefore you have some efficiency benefit for that. Induction machines have ideal flux regulation and therefore you can improve your efficiency. Both seem sensible for variable-velocity drive single-gear transmission as the drive products of the cars. So, as you know, our Model 3 includes a long term magnet machine now. This is because for the specification of the overall performance and efficiency, the long lasting magnet machine better solved our price minimization function, and it was optimal for the number and performance focus on. Quantitatively, the difference is definitely what drives the continuing future of the machine, and it’s a trade-off between motor price, range and battery cost that is identifying which technology will be used in the future.
The Auto Chain magnetic field for a synchronous machine may be provided by using permanent magnets manufactured from neodymium-boron-iron, samarium-cobalt, or ferrite on the rotor. In some motors, these magnets are installed with adhesive on the surface of the rotor core in a way that the magnetic field can be radially directed over the surroundings gap. In other designs, the magnets are inset in to the rotor core surface area or inserted in slot machine games just underneath the surface. Another type of permanent-magnet motor provides circumferentially directed magnets positioned in radial slots that provide magnetic flux to iron poles, which create a radial field in the air 
gap.
The primary application for permanent-magnet motors is in variable-speed drives where in fact the stator is supplied from a variable-frequency, variable-voltage, electronically controlled source. Such drives are capable of precise speed and placement control. Because of the absence of power losses in the rotor, as compared with induction electric motor drives, they are also highly efficient.
Permanent-magnet motors can be made to operate at synchronous rate from a supply of constant voltage and frequency. The magnets are embedded in the rotor iron, and a damper winding can be placed in slot machines in the rotor surface area to supply starting capability. This kind of a motor does not, however, have method of managing the stator power element.