Search results
Results from the WOW.Com Content Network
A permanent magnet motor is a type of electric motor that uses permanent magnets for the field excitation and a wound armature. The permanent magnets can either be stationary or rotating; interior or exterior to the armature for a radial flux machine or layered with the armature for an axial flux topology.
[4] [5] A popular example of a magnet motor, although without rotating axis, was put forward by John Wilkins in 1670: A ramp with a magnet at the top, which pulled a metal ball up the ramp. Near the magnet was a small hole that was supposed to allow the ball to drop under the ramp and return to the bottom, where a flap allowed it to return to ...
A permanent-magnet synchronous motor (PMSM) uses permanent magnets embedded in the rotor to create a constant magnetic field. The stator carries windings connected to an AC electricity supply to produce a rotating magnetic field (as in an asynchronous motor). At synchronous speed the rotor poles lock to the rotating magnetic field.
A permanent magnet synchronous generator is a generator where the excitation field is provided by a permanent magnet instead of a coil. The term synchronous refers here to the fact that the rotor and magnetic field rotate with the same speed, because the magnetic field is generated through a shaft-mounted permanent magnet mechanism, and current is induced into the stationary armature.
The rotor (upper right) has been removed and turned upside-down. The gray ring inside its cup is a permanent magnet. This particular motor is an outrunner, with the stator inside the rotor. DC brushless ducted fan. The two coils on the printed circuit board interact with six round permanent magnets in the fan assembly.
The relatively low rare earth content (12% by volume, 26.7% by mass) and the relative abundance of neodymium and iron compared with samarium and cobalt makes neodymium magnets lower in price than the other major rare-earth magnet family, samarium–cobalt magnets. [3]
Paramagnetism, ferromagnetism, and spin waves. Ferromagnetism is a property of certain materials (such as iron) that results in a significant, observable magnetic permeability, and in many cases, a significant magnetic coercivity, allowing the material to form a permanent magnet.
The magnetic field is often created by a current-carrying coil of wire around the core. The use of a magnetic core can increase the strength of magnetic field in an electromagnetic coil by a factor of several hundred times what it would be without the core. However, magnetic cores have side effects which must be taken into account.