Stepper motor is basically driven by open loop circuit, used for position control. Stepper motor outside, in other words, especially of high precision stepper motor open-loop control positioning and did not do with open loop circuit only stepping motor driven motor. Brushless motor, for example, as switch phase, first need to detect the rotor position, need position closed loop circuit containing position sensor. And if in a certain speed drive, need to measure the speed of the rotor, the speed closed loop circuit; If you want to positioning control, need to contain position signal encoder sensor such as closed loop circuit, compared with the open-loop drive of stepper motor, closed loop circuit containing sensor cost is higher. So the stepper motor is called the low cost of speed control and position control drive system.
