A permanent magnet electric motor is a kind of brushless electric motor that uses permanent 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 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 better than induction electric motor or motors with field windings for several high-efficiency applications such as for example electrical vehicles. Tesla's Chief Electric motor Designer was quoted talking about these advantages, Drive Chain saying: “It’s popular that permanent magnet devices have the advantage 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 optimize your efficiency. Both seem sensible for variable-swiftness drive single-gear transmission as the drive systems of the cars. Therefore, you may already know, our Model 3 has a long lasting magnet machine now. The reason being for the specification of the efficiency and efficiency, the long term magnet machine better solved our cost minimization function, and it was optimal for the number and performance target. Quantitatively, the difference is definitely what drives the future of the device, 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 permanent magnets manufactured from neodymium-boron-iron, samarium-cobalt, or ferrite on the rotor. In some motors, these magnets are mounted with adhesive on the surface of the rotor core such that the magnetic field is usually radially directed over the surroundings gap. In other styles, the magnets are inset into the rotor core surface or inserted in slot machines just below the surface. Another type of permanent-magnet motor offers circumferentially directed magnets placed in radial slots that provide magnetic flux to iron poles, which create a radial field in the atmosphere gap.
The main application for permanent-magnet motors is in variable-speed drives where the stator is supplied from a variable-frequency, variable-voltage, electronically controlled source. Such drives are capable of precise speed and placement control. Due to the lack of power losses in the rotor, as compared with induction electric motor drives, also, they are highly efficient.
Permanent-magnet motors can be designed to operate at synchronous speed from a way to obtain constant voltage and frequency. The magnets are embedded in the rotor iron, and a damper winding is placed in slot machines in the rotor surface to provide starting capability. This kind of a motor does not, however, have means of controlling the stator power factor.