# Problems understanding stepper motor data

I have a stepper motor (M061-CE08) here, and I am a bit disturbed: The manual tells me that it has eight connections, and winding specifications for bipolar parallel connection are 0.89V and 5.4 Amperes. The total current should be between 7.5 A and 8.5 A. Does that mean that the total current through all coils should be between 7.5 A and 8.5 A? If I want to control it, which parameter should I choose for driving it, i.e. should my design be able to deliver 8.5 A max. for all connections, or for each connection? Which is the highest voltage level I can expect when the resistance is at 0.16 ohms?
You can find the manual I get my information from here: http://www.techkits.com/SuperiorM06.pdf

• @Tut: Added in the OP – arc_lupus Feb 16 '15 at 14:45

When driving a stepper motor, you should be using a current controller. When the motor is not stationary, the winding inductance has most effect on the current, since inductive reactance quickly outpaces the winding resistance. The winding resistance is, for the most part, inconsequential other than due to thermal constraints.

A stepper motor driven with constant-voltage source is thermally constrained at standstill, and will underperform as soon as it starts turning. You shouldn't be driving your motor that way.

• When designing the driver, what should I aim for? For max. 8.5 A equally distributed on all 4 power lanes, or on 5 A per lane? – arc_lupus Feb 16 '15 at 14:53
• @arc_lupus As I understand it, the current is usually specified as a total motor current, so it's assumed to flow through all windings. Imagine that you'd connect all windings in series, and driven them from a current source. – Reinstate Monica Feb 16 '15 at 15:00
• I.e. I have to use a driver with max. 2.1 A per winding? How much additional reserve should I calculate? – arc_lupus Feb 16 '15 at 15:05
• @arc_lupus If you have a driver with max. 2.1 A per winding, you may want to consider wiring your coils in series. This will give you a max 2.7A per coil so your driver will still not drive it to max, but can get closer. The downside is a higher inductance that could affect your maximum speed. – Tut Feb 16 '15 at 15:14
• @Tut: I haven't chosen the driver till now, so I am looking for the technical targets for it before I choose it. – arc_lupus Feb 16 '15 at 15:23