- Linear alternator
A linear alternator is essentially a
linear motor used as anelectrical generator . (Analternator is a type ofalternating current (AC) electrical generator.) The devices are often physically equivalent. The principal difference is in how they are used and which direction the energy flows. An alternator convertsmechanical energy toelectrical energy , whereas a motor converts electrical energy to mechanical energy. Like most electric motors and electric generators, the linear alternator works by the principle ofelectromagnetic induction . However, most alternators work with rotary motion, whereas "linear" alternators work with "linear" motion (i.e. motion in a straight line).Theory
When a
magnet moves in relation to a coil of wire, this changes themagnetic flux passing through the coil, and thus induces the flow of anelectric current , which can be used to do work. A linear alternator is most commonly used to convert reciprocating (i.e. back-and-forth) motion directly into electrical energy. This short-cut eliminates the need for acrank orlinkage that would otherwise be required to convert a reciprocating motion to a rotary motion in order to be compatible with a rotary generator.Applications
The simplest type of linear alternator is the
Faraday Flashlight . This is a torch (UK) orflashlight (USA) which contains a coil and apermanent magnet . When the appliance is shaken back and forth, the magnet oscillates through the coil and induces anelectric current . This current is used to charge acapacitor , thus storing energy for later use. The appliance can then produce light, usually from alight-emitting diode , until the capacitor is discharged. It can then be re-charged by further shaking.Other devices are under development which use linear alternators to generate electricity; these devices include the opposed-piston free-piston engine, known as the
Stelzer engine , and the free-piston Stirling engine.ee also
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Alternator
*Linear motor Links
* [http://classes.engr.oregonstate.edu/eecs/fall2003/ece441/groups/g12/White_Papers/Eric.doc]
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