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

This kind of motor is utilized in the Chevy Bolt[1], the Chevy Volt, and the Tesla Model 3.[2] Other 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 engine or motors with field windings for several high-efficiency applications such as electric powered vehicles. Tesla’s Chief Motor Designer was quoted discussing 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 devices have perfect flux regulation and therefore you can optimize your efficiency. Both seem sensible for variable-rate drive single-gear transmitting as the drive products of the cars. So, you may already know, our Model 3 includes a long term magnet machine now. The reason being for the specification of the performance and efficiency, the permanent magnet machine better solved our cost minimization function, and it had been optimal for the range and performance focus on. 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 determining which technology will be used in the future.
The magnetic field for a synchronous machine could be provided by using long lasting magnets made of neodymium-boron-iron, samarium-cobalt, or ferrite on the rotor. In a few motors, these magnets are mounted with adhesive on the surface of the rotor core such that the magnetic field is radially directed across the air gap. In other designs, the magnets are inset into the rotor core surface or inserted in slot machines just underneath the surface. Another form of permanent-magnet engine offers circumferentially directed magnets positioned in radial slots that provide magnetic flux to iron poles, which setup a radial field in the atmosphere gap.

The main application for permanent-magnet motors is in variable-speed drives where the stator comes from a variable-frequency, variable-voltage, electronically managed source. Such drives can handle precise speed and position control. Because of the absence of power losses in the rotor, as compared with induction motor drives, also, they are highly efficient.

Permanent-magnet motors can be designed to operate at synchronous acceleration from a supply of constant voltage and frequency. The magnets are embedded in the rotor iron, and a Drive Chain damper winding is usually placed in slots in the rotor surface to provide starting capability. This kind of a motor does not, however, have method of managing the stator power factor.