Not all drivers are suitable to run all motors, so when designing a motion control system the driver selection process is critical. There are numerous types of drivers, with different voltage and current ratings and construction technology.
Steppers should be sized according to published torque curve, which is specified by the manufacturer at particular drive voltages or using their own drive circuitry. How quickly the torque falls off at faster speeds depends on the winding inductance and the drive circuitry it is attached to, especially the driving voltage. The rated voltage will produce the rated winding current at DC: but this is mostly a meaningless rating, as all modern drivers are current limiting and the drive voltages greatly exceed the motor rated voltage.Ī stepper's low speed torque will vary directly with current.
Stepper motors nameplates typically give only the winding current and occasionally the voltage and winding resistance.