GENERATOR

The system consists of a cantilever beam supported by the housing. The mass on the beam is made up of two magnets (one pole) mounted on a c-shaped core. Arranging the magnets in this way provides a uniform magnetic field in the air-gap. The main purpose of the core is to provide a path and guide the magnetic flux through it with a minimum of flux leakage. The coil is made up of a number of single solid core enamelled copper wires. It is placed in the air-gap between the magnets at right angles to the direction of the movement of the mass.

The operating principle of the device is as follows. As the housing is vibrated, a mechanical input force feeds into a second order mechanical system, the mass moves relative to the housing and energy is stored in the mass-beam system. This relative displacement, which is sinusoidal in amplitude, causes the magnetic flux to cut the coil. This in turn induces a motional electromotive force on the coil due to Faraday’s law. The magnitude of this voltage is proportional to the rate of change of the coil position. The electrical system involved is simply a first-order LR circuit with the inductance of the coil in series with the load resistance and the parasitic resistance of the coil.