Stepper Motor Selection -

[vignesh274]

Hi All

I am currently selecting a stepper motor for my printer system. I have already found the load torque of the system and the acceleration torque at my required PPS. My intention is to select a bi polar stepper motor meeting these requirements and identify the max current using the max torque i need and the torque constant of that motor.

My concern is while selecting the motor I see the torque Vs Speed curve (Bi polar constant current chopper) is specified at a specific current. Does it mean that irrespective of the torque delivered by the motor, the driver will always supply the same current to the motor ? I was under the impression that the torque will vary directly with the current.

Can some one help me understand better.

Thanks

vig

 

[Nigel Goodwin]

For maximum speed and torque you feed the stepper motor with a constant current - often simply by feeding it off a much higher voltage via large wirewound resistors.

 

[vignesh274]

Hi Nigel

thanks for your reply. I am still not so clear... can you help me understand the following

For L/R driven stepper motor

I presume the current drawn by the motor is proportional to the torque required by system. Given by Kt.

For Constant current driven stepper motor

Is the torque proportional to the current applied. Like you said a constant current for max torque delivery at all times.

or

Does the motor draw a current which is proportional to the torque required by the system. Is it like this current is maintained a constant ?

 

[Nigel Goodwin]

I suggest you google for "stepper motor tutorial" there's a huge amount of information about them out there.

 

[ericgibbs]

hi,
This is a handy calculator:

https://www.linengineering.com/site/resources/onlinecalculator.htm