A permanent magnet engine is a type of brushless electric electric motor that uses permanent magnets rather than winding in the field.

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

Long lasting magnet motors are more efficient than induction motor or motors with field windings for certain high-efficiency applications such as electric vehicles. Tesla’s Chief Motor Designer was quoted discussing these advantages, stating: “It’s well known that permanent magnet machines have the benefit of pre-excitation from the magnets, and for that reason you have some efficiency advantage for that. Induction devices have perfect flux regulation and for that reason you can optimize your efficiency. Both seem sensible for variable-speed drive Drive Chain single-gear tranny as the drive models of the cars. So, as you know, our Model 3 has a long term magnet machine now. The reason being for the specification of the overall performance and efficiency, the long lasting magnet machine better solved our price minimization function, and it had been optimal for the number and performance target. Quantitatively, the difference is usually what drives the continuing future of the device, and it’s a trade-off between motor price, range and battery cost that is determining which technology will be utilized in the future.
The magnetic field for a synchronous machine could 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 top of rotor core such that the magnetic field is definitely radially directed over the air flow gap. In other styles, the magnets are inset into the rotor core surface or inserted in slots just underneath the surface. Another form of permanent-magnet motor offers circumferentially directed magnets placed in radial slots offering magnetic flux to iron poles, which in turn create a radial field in the air gap.

The main 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 can handle precise speed and position control. Because of the lack of power losses in the rotor, in comparison with induction motor drives, also, they are highly efficient.

Permanent-magnet motors can be designed 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 definitely placed in slots in the rotor surface area to provide starting capability. Such a motor will not, however, have means of managing the stator power element.