Basic Structure of Servo Motor - Diagram of Working Principle of Servo Motor
The function of a servo motor is to convert the input voltage signal (i.e. control voltage) into angular displacement or angular velocity output on the shaft. It is often used as an actuator in automatic control systems, so servo motors are also known as executive motors

The function of a servo motor is to convert the input voltage signal (i.e. control voltage) into angular displacement or angular velocity output on the shaft. It is often used as an actuator in automatic control systems, so servo motors are also known as executive motors. Its biggest feature is that when there is a control voltage, the rotor immediately rotates, and when there is no control voltage, the rotor immediately stops rotating. The rotation direction and speed of the shaft are determined by the direction and magnitude of the control voltage. Servo motors are divided into two categories: AC and DC.

1、 Communication servo motor

1. Basic structure

AC servo motors are mainly composed of a stator and a rotor.

The stator core is usually made of stacked silicon steel sheets. Two phase windings are embedded in the slots on the surface of the stator core, one of which is the excitation winding and the other is the control winding. The two phase windings have a 90 ° electrical angle difference in spatial position from each other. During operation, the excitation winding f is connected to the AC excitation power supply, and the control winding k is subjected to a control signal voltage Uk.

Mainly composed of stator, rotor, and detection element 8, etc

Working principle

When there is no control voltage, the AC servo motor only has a pulsating magnetic field generated by the excitation winding in the air gap, and the rotor is stationary without starting torque. When there is a control voltage and the control winding current is different from the excitation winding current, a rotating magnetic field is generated in the air gap and electromagnetic torque is generated, causing the rotor to rotate in the direction of the rotating magnetic field. But the requirement for servo motors is not only that they can be started under the control voltage, but also that the motor should be able to stop immediately after the voltage disappears. If the control voltage of the servo motor disappears and continues to rotate like a typical single-phase asynchronous motor, a loss of control phenomenon occurs. We call this phenomenon of self rotation due to loss of control self rotation.

Manufacturing method

Metaphysics can use the following three methods to control the speed and direction of rotation of servo motors.

(1) Amplitude control maintains the phase difference between the control voltage and the excitation voltage unchanged, only changing the amplitude of the control voltage.

(2) Phase control maintains the amplitude of the control voltage unchanged, only changing the phase difference between the control voltage and the excitation voltage.

(3) Amplitude phase control simultaneously changes the amplitude and phase of the control voltage.

Basic Requirements

1. High displacement accuracy

Displacement accuracy: refers to the degree of conformity between the displacement of the machine tool worktable required by the command pulse and the actual displacement of the worktable converted by the servo system from the command pulse

2. Good stability

Stability: refers to the ability of a servo system to reach a new or return to its original equilibrium state after a brief adjustment process under given input or external interference.

3. High positioning accuracy

Positioning accuracy: refers to the degree to which the output quantity can reproduce the accuracy of the input quantity

4. Fast response and good responsiveness

5. Wide speed range

Speed regulation range: refers to the ratio of the highest and lowest speeds that the mechanical device requires the electric motor to provide

6. Good system reliability

7. Low speed high torque