Control Methods For Stepper Motors
In stepper motor systems, if the available motor torque is not adequate to overcome the load, the motor will stall or skip over one or more pulses, creating a difference between the desired position and the actual position reached. To avoid this, stepper motors are often oversized to ensure there’s a large margin between the worst-case load torque and the motor’s available torque. But there is an alternative to oversizing the motor. By adding an encoder and operating in closed-loop mode, stepper motor systems can achieve position monitoring and control much like servo motors. The most straightforward way to operate a stepper motor in closed-loop mode is to compare the theoretical position which should have been reached based on the number of steps, with the actual position reached based on the encoder feedback. If there is a difference between the target and actual positions, the controller initiates a correction move. While the above method is reactive, correcting...