(a good performance of a dynamo occurs when the displacement of the magnet is 2 to 3 m / S)
the law of induction does not fix an optimum, a priori, the higher the speed, and the more the coil has turns, the higher the tension, without limit,
http://fr.wikipedia.org/wiki/Induction_ ... C3%A9tique
but the dimensions and properties of the coils and magnets (surface, number of turns and resistance) set a minimum speed for a voltage.
We can have a very low speed, and a good tension, if the coils have a large number of turns and the output is set by the overall size of the coils and magnets.
The m / s is quite arbitrary.
The larger the coil, with all of its copper undergoing the variation of the magnetic field to its maximum, the higher the power obtained, thanks to the minimum possible coil resistance.
This fixes the size of the coils roughly close to the size of the magnets roughly, to have the magnetic field at the maximum which decreases quickly away from the magnets (like the reverse of the cube of the distance to the magnet).
At low speed, the power obtained is very low.
To have a constant voltage at roughly empty, you need a constant speed, or else use a number of turns which decreases with speed, or move the coils of the magnets which rotate a little, with a yield which decreases in this case.
For example mounting the magnets on leaf springs which spread them a little with the centrifugal force of the coils can allow the tension to be roughly regulated, if the springs are properly adjusted.
But you need a very nice collection of powerful magnets and coils all around which increase the price !!
$ 6000 for 1000 to 2000KWh per year, useful on site without electricity, because otherwise not amortized over the life of the wind turbine currently.
We must be able to use fewer magnets on a smaller diameter than the periphery for a much lower price with a wheel like that of a bicycle with simple blades, of variable inclination with the distance to the axis.
