8-wire stepper motor

Well, if I'm not wrong the series connection gives higher torque but lower speed due to the higher inductance. Parallel connection of the windings is suitable for high speed application.

Marco / iw2nzm

It all depends on the current you power supply can deliver, and the voltage it can generate across the windings.

Putting the coils in parallel means that you have to supply twice as much curret to generate the same torque, but the back-emf (in voltage per radian per second) is halved. Obviously, the inductance of the two coils in parallel is only a quarter of that of the two coils in series, so the time (and/or voltage) required to change twice the curent through the parallel coil) is halved.

If the driver can't deliver the higher current required by the parallel connection, it's speed advantage over the serial arrangement is purely theoretical.

Note the the back emf consant (in volts per radian per second) is - at least in theory - exactly the same as the torque constant in newton metres per amp (from conservation of energy).

-- Bill Sloman, Nijmegen

Thank you for your answer!

Marco / iw2nzm