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Stepper Motor System Basics

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step101.pdf pdf  


Driver Overview


The stepper motor driver receives step and direction pulses from the indexer or control system and converts them into analog signals to run the motor. One step pulse is required for every step of the motor shaft. In full step mode, with a standard 200 step motor, 200 step pulses are required to complete one revolution.


Likewise, in microstepping mode the driver may be required to generate 50,000 or more step pulses per revolution. In standard driver designs this usually requires a lot of expensive circuitry. (AMS is able to provide equal performance at low cost through a technology developed at AMS known as VRMC®; Variable Resolution Microstep Control).


Speed and torque performance of the step motor is based on the flow of current from the driver to the motor winding. The factor that inhibits the flow, or limits the time it takes for the current to energize the winding, is known as inductance. The lower the inductance, the faster the current gets to the winding and the better the performance of the motor. To reduce the effects of inductance, most types of driver circuits are designed to supply a voltage greater than the motor’s rated voltage.






Driver flow