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Topic: 5-wire unipolar stepper + H Bridge (Read 1 time) previous topic - next topic

34DOL

Can I use an H Bridge with a 5-wire unipolar stepper motor?  If so how do I wire it up?

dc42

Although a 5-wire stepper is designed to be used in unipolar mode, I think it should work OK in bipolar mode driven by an H-bridge, if you ignore the common wire and connect the two windings to the H-bridge as if it were a bipolar stepper. I say this (although I've never tried it) because although the centre taps of the 2 windings are connected together (at the common wire), they would both be at the same potential even if they were not connected.
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MarkT

Not that simple - H-bridges can be driven in various configurations, some may work with 5-wire, others may not.

In general if you drive the H-bridge so that one winding is fully open-circuit and the other is on, or if both are
on, or if both are open-circuit, or both in brake-mode, the connection between windings isn't crucial, but if
one winding is driven and the other is in brake mode (this happens with some styles of PWM for microstepping), you will get
current flowing between the windings on the common line, which I don't think is good.  Perhaps I'm
being pessimistic.

The one thing that definitely won't work is using a chopper-driver with such a motor, definitely to be avoided.
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dc42

#3
Jun 11, 2013, 05:09 pm Last Edit: Jun 11, 2013, 05:12 pm by dc42 Reason: 1

Not that simple - H-bridges can be driven in various configurations, some may work with 5-wire, others may not.
...


Quite right, I was assuming the basic driving scheme in which both windings are always energized, which I believe is what the Stepper library does.
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