Still no cigar...
You get the same low-speed torque either way. In full coil operation use 1/2 the motor's rated current; in half coil operation use the rated current. Both ways ampere-turns are the same.
At high speeds hal coil operation gives twice the power as full coil at the same power supply voltage.
The reason is inductance. Full coil has 4 times the inductance as half coil.
Inductance has a property called inductive reactance. It is measured in Ohms, but unlike a resistor the value is proportional to frequency (read step rate). Ohms = 2*pi*f*L
Torque is proportional to current and inductive current (I = V/R) is inversely proportional to frequency.
Full coil operation has 4 times the inductance, so it has 1/4 the inductive current at a given speed compared to half coil operation. This current passes thru twice as many turns of wire, so the net impact is 1/2 the torque at high speed (and 1/2 the power).
At low speeds the drive limits current so there is no difference.
Mariss |