mamal_asimo:
Thanks for responding . But I really got nothing =(
would you please tell me more about this method ( that tells differences between bipolar and unipolar ) ???
Stepper motors come with 4 wires, 5 wires, 6 wires and 8 wires.
unipolar possible: 5 wires, 6 wires, 8 wires
bipolar possible 4 wires, 6 wires, 8 wires (series or parallel).
There are slow stepper motors with high impedance windings, often unipolar,
these are not optimized for speed but are easy to drive.
There are high-performance bipolar motors with low-impedance windings, usually
4 or 8-wire. These are meant to be driven with chopper driver from a high voltage
supply. The chopper drive is a current-control driver with automatic buck-regulation,
the high voltage supply allows back EMF from the motor to be overcome at high
speed.