# Large Stepper motor

hello

I want to control a stepper with the arduino and was going to use adafruits motor shield but the stepper needs too much current.

The motor is the 57SH76-2AM (http://docs-europe.origin.electrocomponents.com/webdocs/08f8/0900766b808f8981.pdf) but i dont know what i would need to drive it :( im not too experienced with this so any help would be much appreciated.

also the motor data sheet says rated voltage=4.5 V, current/phase is 2 A and resistance/phase=2.25 ohm. the speed torque graph says 30V so is the current 30/2.25=13.3A? i need to run it at around 5 rev per sec and torque around 1Nm is required. am i completely missing something here or..?? Someone i know said that all i need is an amplifier connected between the arduino and stepper.. help please? :)

thanks.

data sheet says rated voltage=4.5 V, current/phase is 2 A and resistance/phase=2.25 ohm.

That is what it takes to put 2A through the motor.

. the speed torque graph says 30V so is the current 30/2.25=13.3A?

No. You still can only put 2A through the coils but to get the current into the coils quickly you feed it with 30V. After the current reaches this value you drop the voltage so that it doesn't exceed 2A. In this way you can get the maximum speed from the motor. To do this you need a current limiting stepping motor controller not just any old amplifier. (your friend knows nothing)

For a look at a stepping motor driver see:- http://reprap.org/bin/view/Main/Stepper_Motor_Driver_2_3

you are much more helpful than any site i have read! :D another question.. i read that running the motor in series has higher torque at lower speeds and parallel has higher torque at higher speeds because of inductance... any idea what kind of speeds that would be? i want to drive it at 2000 pps. also, do you know what effect it would have on the torque curve because that is in parallel? the reprap site says it doesnt recommend parallel connection.

Parallel is the best method if you can run it like that because it is the configuration that gets the current into the coils quicker. However it makes more demands on the controller. The speed / torque depends on many things but is ultimately down to the motor and controller. If it's not on the data sheet you will have to measure it.

i see i see.. do you think it will have a big effect on the torque? dont really want to buy it and find out that i cant use it..

do you think it will have a big effect on the torque?

Yes, torque is a function of the current, the more of one, the more of the other. Torque drops off with speed (always) it drops off less quickly if fed with a bigger voltage because the current gets in faster. It is when the step time is less than the time taken to get the full current into the coil torque will start to fall rapidly. Look on the rep rap forum for discussions on this.