The servo mainly relies on pulses for positioning. When the servo motor receives a pulse, it will rotate the angle corresponding to the pulse to achieve displacement. Because the servo motor itself has the function of sending pulses, so every time the servo motor rotates an angle, it will send out a pulse. The corresponding number of pulses, in this way, forms an echo with the pulses received by the servo motor, or called a closed loop, so that the system will know how many pulses are sent to the servo motor, and how many pulses are received back at the same time, so that it can be quickly and precisely control the rotation of the motor to achieve precise positioning, which can reach 0.001mm.
DC servo motors are divided into brushed and brushless motors. Brushed motors are low in cost, simple in structure, large in starting torque, wide in speed regulation range, easy to control, and require maintenance, but they are easy to maintain (replace carbon brushes), generate electromagnetic interference, and have requirements for the environment. Therefore, it can be used in common industrial and civil occasions that are sensitive to cost.
The structure of the stator of the AC servo motor is basically similar to that of the capacitor split-phase single-phase asynchronous motor. The stator is equipped with two windings with a mutual difference of 90 degrees. One is the excitation winding Rf, which is always connected to the AC voltage Uf; the other is the control winding L, which is connected to the control signal voltage Uc. So the AC servo motor is also called two servo motors.
When the AC servo motor has no control voltage, there is only an active magnetic field generated by the excitation winding in the stator, and the rotor is stationary; when there is a control voltage, a rotating magnetic field is generated in the stator, and the rotor rotates in the direction of the rotating magnetic field. Under normal circumstances, the speed of the motor changes with the magnitude of the control voltage, and when the phase of the control voltage is opposite, the servo motor will reverse.
Although the working principle of the AC servo motor is similar to that of the split-phase single-phase asynchronous motor, the rotor resistance of the former is much larger than that of the latter. Therefore, compared with the single-machine asynchronous motor, the servo motor has a large starting torque, a wide operating range, There are three notable features of no rotation phenomenon.
The servo motor can be repaired. The maintenance of the servo motor can be said to be relatively complicated. However, due to the long-term continuous use of the servo motor or improper operation by the user, motor failures often occur. The maintenance of the servo motor requires professionals.