A permanent magnet engine is a kind of brushless 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] 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 better than induction engine or motors with field windings for several high-efficiency applications such as electric powered vehicles. Tesla’s Chief Engine Designer was quoted talking about these advantages, stating: “It’s popular that permanent magnet machines have the benefit of pre-excitation from the magnets, and for that reason you involve some efficiency advantage for that. Induction machines have ideal flux regulation and therefore you can improve your efficiency. Both make sense for variable-acceleration drive single-gear transmitting as the drive units of the cars. So, as you know, our Model 3 includes a long term magnet machine now. It is because for the specification of the efficiency and efficiency, the long term magnet machine better solved our cost minimization function, and it had been optimal for the number and performance focus on. Quantitatively, the difference is definitely what drives the future of the device, and it’s a trade-off between motor price, range and battery price 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 made of neodymium-boron-iron, samarium-cobalt, or ferrite on the rotor. In a few motors, these magnets are mounted with adhesive on the top of rotor core in a way that the magnetic field is definitely radially directed over the surroundings gap. In other styles, the magnets are inset in to the rotor core surface or inserted in slot machines just underneath the surface. Another form of permanent-magnet engine provides circumferentially directed magnets Stainless Steel Chain placed in radial slots offering magnetic flux to iron poles, which in turn create a radial field in the surroundings gap.
The primary application for permanent-magnet motors is in variable-speed drives where in fact the stator comes from a variable-frequency, variable-voltage, electronically managed source. Such drives can handle precise speed and position control. Due to the absence of power losses in the rotor, as compared with induction motor drives, they are also highly efficient.
Permanent-magnet motors could be made to operate at synchronous speed from a supply of constant voltage and frequency. The magnets are embedded in the rotor iron, and a damper winding is certainly placed in slot machines in the rotor surface to provide starting capability. This kind of a motor does not, however, have means of managing the stator power element.