How voice coil motor works in speaker?

Loudspeakers were used to amplify or create a louder voice, thus the name “voice coil” stuck. Voice coil motors use similar technology to speakers, but they are designed to produce higher forces over larger distances or “strokes”. Voice coil motors do not have the commutator but uses a position sensor. These motors consist of two separate parts; the magnetic housing and the coil.

voice coils typically consist of:
1.non-magnetic center pole;
2.cylindrical coil connected to the power supply;
and an outer cylindrical permanent magnet.
3.The current running through the coil creates a magnetic field, which interacts with the field established by the permanent magnet.
The voice coil works because of the force between a static magnetic field and an electric current perpendicular to the field.

Voice Coil Motor Characteristics:
1. Reliability – side forces developed are negligible, so bearing loading can be very low to enable long life operation;
2. Simplicity – the voice coil motor is a single pole device requiring no commutation. Both the device itself, and the associated controller can be very simple and robust;
3. Flexible Configuration – the principle of operation lends itself to many different mechanical layouts allowing great flexibility in the design of associated systems;
4. Fast operation – Low electrical inductance, and low moving mass enable fast inflow of current and high acceleration. Acceleration of >500G is possible with custom devices;