How does a servo motor work? What is the working principle of a servo motor?

Servo motor control drive principle:

Under the premise of developing frequency conversion technology, the servo drive has carried out more accurate control technology and algorithm operation than the general frequency conversion in the current loop, speed loop and position loop inside the drive (the frequency converter does not have this loop), and it is much more powerful than the traditional frequency conversion in terms of function, and the main point is that it can be accurately controlled. The speed and position are controlled by the pulse train sent by the upper controller (of course, some servos have integrated control units or directly set parameters such as position and speed in the drive through bus communication), and the algorithms inside the drive, faster and more accurate calculations, and better performance electronics make it superior to the inverter.

AC motors are generally divided into synchronous and asynchronous motors.

1. AC synchronous motor: that is, the rotor is composed of permanent magnet materials, so after rotation, with the change of the stator rotation magnetic field of the motor, the rotor also changes the speed of the response frequency, and the rotor speed = stator speed, so it is called "synchronization".

2. AC asynchronous motor: The rotor is composed of an induction coil and materials. After rotation, the stator produces a rotating magnetic field, the magnetic field cuts the induction coil of the stator, the rotor coil produces an induced current, and then the rotor produces an induced magnetic field, and the induced magnetic field follows the change of the rotating magnetic field of the stator, but the change of the magnetic field of the rotor is always less than the change of the stator.

Therefore, in AC asynchronous motors, there is a key parameter is the slip rate, which is the ratio of the speed difference between the rotor and the stator.

3. The corresponding AC synchronous and asynchronous motor inverter has synchronous inverter and asynchronous inverter, and the servo motor also has AC synchronous servo and AC asynchronous servo.

Referring to this encyclopedia, it is a type of synchronous motor.

A servo motor is a high-performance, high-precision motor, which is usually composed of a motor, a reducer, an encoder and an electronic control system. Compared with ordinary motors, the biggest feature of servo motors is that they have very high position, speed and acceleration control accuracy. Its working principle can be briefly described as follows:

The control system of the servo motor will detect the angle and speed information of the motor through the encoder or its uproar sensor according to the input command signal, and then calculate the error between the motor and the set value, and adjust the rotation state of the motor through feedback control, so that it rotates to the specified position or speed. This process requires the help of a closed-loop feedback system, usually using a PID control algorithm.

Specifically, the motor receives a pulse signal, grasps the initial position, and then rotates at a certain angle each time it receives a control signal; The feedback system continuously detects the state of motor rotation, compares the motor position with the preset target and calculates the error, and then sends the adjustment signal to the motor driver for more accurate control.

Overall, servo motors enable very fine position and speed control and are widely used in a wide range of industrial automation and robotics applications.

The servo motor is a three-phase AC motor, and a coaxial encoder is added to the rear end, and the encoder is mostly a resolver speed measurement.

The working principle of the servo motor: when the servo motor receives 1 pulse, it will rotate the angle corresponding to 1 pulse, so as to achieve displacement. Because the servo motor itself has the function of sending out pulses, the servo motor will emit a corresponding number of pulses every time it rotates at an angle.

In this way, it echoes the pulses received by the servo motor, or closed loop. In this way, the system will know how many pulses are sent to the servo motor and how many pulses are received at the same time.

It can control the rotation of the motor very precisely, so as to achieve precise positioning, which can be achieved. DC servo motors are divided into brushed and brushless motors.

The brush motor has low cost, simple structure, large starting torque, wide speed regulation range, easy control, and needs maintenance, but the maintenance is inconvenient, electromagnetic interference is generated, and there are requirements for the environment. Therefore, it can be used in cost-sensitive general industrial and civil applications.

The rotor of the servo motor is usually made into a squirrel cage type, but in order to make the servo motor have a wide range of speed regulation, linear mechanical characteristics, no "rotation" phenomenon and fast response performance.

Closed-loop control of position, speed and torque is realized; The problem of stepper motor out-of-step is overcome. It has strong anti-overload capacity and can withstand loads three times the rated torque, which is especially suitable for occasions with instantaneous load fluctuations and fast start-up requirements.

The servo motor can make the control speed, the position accuracy is very accurate, and the voltage signal can be converted into torque and speed to drive the control object. The rotor speed of the servo motor is controlled by the input signal, and is used as an actuator in the automatic control system, and has the characteristics of small electromechanical time constant, high linearity, starting voltage, etc., which can convert the received electrical signal into angular displacement or angular velocity output on the motor shaft.

Performance comparison. As an open-loop control system, stepper motor has an essential relationship with modern digital control technology. In the domestic digital control system, the stepper motor is widely used.

With the advent of all-digital AC servo systems, AC servo motors are also increasingly used in digital control systems.

In order to adapt to the development trend of digital control, most of the motion control systems use stepper motors or all-digital AC servo motors as executive motors. Although the two are similar in terms of control methods (burst and directional signals), there are major differences in performance and application. The performance of the two is now compared.

The above content reference: Encyclopedia - servo motor.