What is the basic difference between a servo drive and a stepper motor drive?
The servo drive is a closed-loop control system. The servo motor has a resolver to measure displacement. The target and actual positions are constantly compared, with the result that the servo drive runs precisely in line with the specified movement profile. The servo motor has a high torque spanning the entire speed range and can be briefly overloaded by 2-3 times the nominal torque. The stepper motor drive is an open-loop control system. Positioning is carried out by specifying the number of control pulses. The torque decreases over the speed range and there is a danger of “step loss” if the range is exceeded.
