Basic knowledge of AC servo motors

The editor has introduced the types of DC servo motors before. It can be seen that there are many types of DC servo motors, and they are also different in performance from AC servo motors. So today I will mainly introduce the basic knowledge of AC servo motors, hoping to expand everyone's motor knowledge.

The rotor inside the servo motor is a permanent magnet. The U/V/W three-phase electricity controlled by the driver forms an electromagnetic field. The rotor rolls under the action of this magnetic field. At the same time, the encoder of the motor responds to the signal to the driver. The driver responds to the target based on the feedback value. Compare the values ​​and adjust the rotor rotation angle. The accuracy of the servo motor depends on the accuracy of the encoder (number of lines).

Basic knowledge of AC servo motors:

The structure of AC servo motor can be mainly divided into two parts, namely the stator part and the rotor part. The structure of the stator is basically the same as that of the rotary transformer. In the stator core, two-phase windings are also placed at an electrical angle of 90 degrees to each other. One group is the excitation winding and the other is the control winding. The AC servo motor is a two-phase AC motor.

When the AC servo motor is used, a stable excitation voltage Uf is applied to both ends of the excitation winding, and a control voltage Uk is applied to both ends of the control winding. When voltage is applied to the stator winding, the servo motor will soon start rotating. The current flowing into the excitation winding and control winding generates a rotating magnetic field in the motor. The direction of the rotating magnetic field determines the direction of the motor. When the voltage applied to any winding reverses the phase, the direction of the rotating magnetic field changes, and the direction of the motor changes. The direction has also changed.

In order to form a circular rotating magnetic field in the motor, it is required that there should be a 90-degree phase difference between the excitation voltage Uf and the control voltage UK. Commonly used methods are:

1) Use the phase voltage and line voltage of the three-phase power supply to form a 90-degree phase shift.

2) Utilize any line voltage of the three-phase power supply.

3) Choose a phase-shifting network.

4) Connect a capacitor in series in the excitation phase.

Its structure is as follows:

The structure of the stator of an AC servo motor is basically similar to that of a capacitive split-phase single-phase asynchronous motor. The stator is equipped with two windings whose positions are 90° different from each other. One is the excitation winding Rf, which is always connected to the AC voltage Uf; the other Is the control winding L, connected to the control signal voltage Uc. Therefore, the AC servo motor is also called two servo motors.