movingmagnet

Movingmagnet refers to electromechanical devices in which a magnetic field moves relative to stationary conductors, usually coils, to convert mechanical energy into electricity through electromagnetic induction. The moving element is the magnet, distinguishing it from designs where the coil moves.

Operation relies on Faraday's law: movement changes the magnetic flux through a coil, inducing an electromotive force. The output voltage scales with the speed of the magnet, the magnetic field strength, and the coil turns, with the geometry of the magnetic circuit shaping the waveform.

Configurations include rotary movingmagnet machines, where a permanent-magnet rotor turns near stationary stator coils, and linear movingmagnet devices, where magnets slide along a track past fixed coils. Materials commonly used are permanent magnets such as NdFeB or SmCo, copper windings, and laminated iron cores. Design choices affect efficiency, temperature stability, saturation, and mechanical wear, and engineers seek to minimize losses and cogging.

Applications include bicycle dynamos, microgenerators for energy harvesting, and experimental linear generators for wave- or vibration-energy converters. Advantages of movingmagnet designs include straightforward construction and robust operation at suitable speeds; drawbacks include moving parts, wear, noise, and sensitivity to misalignment.

See also: electromagnetic induction; dynamo; generator; linear generator; permanent magnet motor.