Hi, think for a moment that I have a energy generator... but that generator is giving to me a little amperage (exactly some miliamperes). How can I increase the amperage of the generator? Moving magnets arround or anything similar?

I want to get the same voltage, or decrease the voltage minimum as possible.

I don't really know what an "energy generator" is, but in general, if you want to increase current without increasing voltage, you need to decrase output impedance.

P=IV, If V is the same, you can only increase I by generating more power.

I want to get the same voltage, or decrease the voltage minimum as possible.

By the equation that swansot has posted, you can clearly see that you get more amps by increasing the power (which I think means more rotations), or by decreasing the voltage since I is indirectly depended by V ([math]I=\frac{P}{V}[/math]).