Steppers, Series, Parallel

[Ricardoco]

At the moment I'm deep in doing the Electrics for my new machine. I have read that you can have the stepper motor coils in a series or parallel arrangement.

My questions are, which is preferable and why, and how much difference does it really make, and thridly would it be a feature to put in some relays to switch between the two wiring types..


Rick

[Jonathan]

My post here explains why, but the simple answer is that in most cases parallel is the best arrangement. You get slightly greater torque at low speeds from bipolar-series, but since the difference is small you're better off using parallel it gets better torque at high speed due to the lower inductance.

There might be something to gain by switching between the two, but I doubt it's worth the trouble here especially since switching whilst the driver it turned on could damage it.

[Ricardoco]

I assume the numbers will be reresented in a graph somewhere. As for the switching my panel is a one time sequenced progression so you can only progress to the next switch once you have made a choice on the previous one and if you make a mistake you must start again, so i would put that choice above the stepper power switch.. But it seems imaterial if there is so little difference..

Rick

[Ricardoco]

Also how do you tell the maximum voltage to drive the motors at and is this different with the two arrangements?

Rick

[JAZZCNC]

thridly would it be a feature to put in some relays to switch between the two wiring types..

Not that easy has the voltage requirements would change has well. Serial requires much higher voltage(roughly double parallel) also the chance of blowing the drive is great.
The switching would have to happen with the power to drives off has it's 99% sure the drives will pop.!!

Not required anyway so keep it simple.!!

[Ricardoco]

My drives can be take upto 80-vac or 100vdc but it appears the concensus is parallel so Parallel it is then...

Rick

[gavztheouch]

Parallel works best for me, you get faster rapids and cooler running motors.

I have blown up quite a few drivers running in series due to the back emf/motor inductance.

[Robin Hewitt]

Parallel works best for me, you get faster rapids and cooler running motors.

That's a surprise because I tried wiring in parallel once. Once being the operative word. I got little appreciable speed advantage and lots more heat.

Also, why is everyone worrying about Volts, our drivers already have lots of Volts? Parallel wiring requires twice the Amps.

[Jonathan]

That's a surprise because I tried wiring in parallel once. Once being the operative word. I got little appreciable speed advantage and lots more heat.

But aren't your motors on mains voltage, or something silly high, in which case it's hardly surprising that they would overheat in parallel?

Also, why is everyone worrying about Volts, our drivers already have lots of Volts? Parallel wiring requires twice the Amps.

See the post I linked to earlier - it's because the inductance is 4 times greater when in series, so you need a higher voltage to 'overcome' that.

[JAZZCNC]

Also, why is everyone worrying about Volts, our drivers already have lots of Volts? Parallel wiring requires twice the Amps.

They have what ever volts they are provided with.!! Give a 50V drive 24v and wire the motor in series and see how fast it goes or were it runs out of torque.!!

Volts make all the difference to a stepper and I'm surprised at that comment Robin.?