Using closed-loop drive, the efficiency can be increased to 7.8 times, the output power can be increased to 3.3 times, and the speed can be increased to 3.6 times. Higher running speed, more stable and smoother speed can be obtained than open-loop control. When the stepper motor stops, it will be completely still, without the micro-vibration phenomenon of ordinary servo. Where low-cost, high-precision positioning is required, it can replace the application of general-purpose servo systems. The closed-loop stepper motor automatically adjusts the winding current according to the load size. The heat generation and vibration are smaller than that of the open-loop stepper. The encoder feedback is provided, so the accuracy is higher than that of the ordinary stepper motor. The motor response is slower than the open-loop stepper and faster than the servo motor. There is a position error in the command, and the error will gradually decrease a few milliseconds after the command stops.