What is the working principle of servo motor?

1. A servo mechanism is an automatic control system that enables the output controlled quantities such as the position, orientation, and state of an object to follow any changes in the input target (or given value). The servo mainly relies on pulses for positioning. Basically, it can be understood this way. When the servo motor receives a pulse, it will rotate at an angle corresponding to the pulse to achieve displacement. Because the servo motor itself has the function of sending out pulses, the servo motor will rotate every time it receives a pulse. When you rotate an angle, a corresponding number of pulses will be emitted. In this way, it will echo the pulses received by the servo motor, or it is called a closed loop. In this way, the system will know how many pulses are sent to the servo motor, and how many pulses are received back at the same time. , In this way, the rotation of the motor can be controlled very accurately, thereby achieving precise positioning, which can reach 0.001mm. DC servo motors are divided into brushed and brushless motors. Brush motors have low cost, simple structure, large starting torque, wide speed range, easy control, and require maintenance, but they are inconvenient to maintain (changing carbon brushes), produce electromagnetic interference, and have environmental requirements. Therefore it can be used in cost-sensitive general industrial and civil applications.
Brushless motors are small in size, light in weight, large in output, fast in response, high in speed, small in inertia, smooth in rotation and stable in torque. The control is complex and easy to realize intelligence. Its electronic commutation method is flexible and can be square wave commutation or sine wave commutation. The motor is maintenance-free, has high efficiency, low operating temperature, very small electromagnetic radiation, long life, and can be used in various environments.
2. AC servo motors are also brushless motors and are divided into synchronous and asynchronous motors. Synchronous motors are generally used in motion control. They have a large power range and can achieve high power. Large inertia, maximum rotation speed is low, and decreases rapidly as power increases. Therefore, it is suitable for applications with low speed and smooth operation.
3. 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 rotates under the action of this magnetic field. At the same time, the encoder of the motor feeds back a signal to the driver. The driver responds according to the feedback value. Compare with the target value and adjust the angle of rotor rotation. The accuracy of the servo motor depends on the accuracy (number of lines) of the encoder.
The functional difference between AC servo motors and brushless DC servo motors: AC servo motors are better because they are controlled by sine waves and have small torque pulsations. DC servo is a trapezoidal wave. But DC servo is relatively simple and cheap.