Unipolar stepping engine driven by Arduino Motor Shield R3

Hello,

Im using the Arduino Motor Shield R3 to run a stepping engine...

This is the bord:

However this bord has 4 connectors for the stepping engine -> A+, A-, B+, B-

The engine which I want to utilize has 6 wires.

This is the scematic of the engine:

If I run the stepper as a bipolar (4 wire) stepper, respectively ignoring the common wire in the middle of the coil and just attaching the coil ends to the motor shild (A+,A-,B+,B-), the stepper works.

Now to the questions:

  • Are there any disadvantages using a unipolar (6 wire stepper) as a bipolar (4 wire stepper)?
  • Will this setup affect the steps per revulution value?
  • How would I connect a 6 wire stepper to the motor shild?

Thx, Andreas

Andreas1984:
Hello,

If I run the stepper as a bipolar (4 wire) stepper, respectively ignoring the common wire in the middle of the coil and just attaching the coil ends to the motor shild (A+,A-,B+,B-), the stepper works.

Now to the questions:

  • Are there any disadvantages using a unipolar (6 wire stepper) as a bipolar (4 wire stepper)?
  • Will this setup affect the steps per revulution value?
  • How would I connect a 6 wire stepper to the motor shild?

Thx, Andreas

The only disadvantage is that you need a bipolar driver circuit (more complex than unipolar)
An advantage is that you use all of the winding, not just half, so efficiency is better.

No effect upon steps/rev, and yes just ignore the centre-taps. Make sure the wires from one
winding go to A+/A- and from the other to B+/B-.

Do you know the ratings of the motor? Current and winding resistance?

The only disadvantage is that you need a bipolar driver circuit (more complex than unipolar)
An advantage is that you use all of the winding, not just half, so efficiency is better.

I think there is a misunderstanding between bipolar and unipolar - I meight be wrong, but as I have understood the output of my stepper research a bipolar stepper has 4 wires a and a unipolar stepper has 6 wires... So a unipolar stepper can also be used as a bipolar stepper by skipping the two middle coils...

The motor specs of my stepper tell that in unipolar mode the stepper takes 1A and in bipolar mode 0,7A... So I guess efficiency in unipolar mode (6 wires must be better)...

I want to bring up the efficiency as high as possible, so I am still interested in how to drive that thing in unipolar mode.

The question is, if the Arduino Motor Shield R3 is also capable of driving a stepper in unipolar mode without attaching additional hardware, and if how?

No effect upon steps/rev, and yes just ignore the centre-taps. Make sure the wires from one
winding go to A+/A- and from the other to B+/B-.

You are right. Yesterday I have tested it.
My stepper has 200 steps for one revulution - if I let it turn 200 steps, it moves back to the position it had been.

Do you know the ratings of the motor? Current and winding resistance?

unipolar mode: 1A
bipolar mode: 0,7A
resistance: 3,6Ohm
force: 27Ncm

I have discouvered another thing:
Actually in my hardware settup I am using an arduino due with a ethernet shild (I am just using the SD-Card from the ethernet shild) and two of the motor shilds, which I attached as side wagons.
First I am transmitting data (coordinates) over the serial interface and write it to the SD-Card - Then the two steppers are fed with the data on the SD-Card till the file is finished.

Well when just one stepper turns and the other shall stand still - one led of the stand still stepper is also kind of flashing (the stand still stepper does not turn, it is more like a slight vibration) - I think this is caused trough feedback Voltage from the turning stepper... Is there a easy way to avoid this feedback voltage phenomena? I thaught of using optocoppler to seperate the engines from the bord...

Thx,

Andreas