What is the working principle of servo motor? Is a servo motor an AC motor or a DC motor?

Servo motor is a motor that absolutely obeys the command of the control signal, and the word servo comes from the Greek. General servo motor consists of stator and rotor, every rotation of an angle, will send out a corresponding number of pulses, and the servo motor to accept the pulse formed an echo, so that the servo system will know the pulse sent and received, so as to accurately control the rotation of the motor. There are two types of servo motors, AC and DC, each with its own advantages. Here's a look at what is the working principle of servo motor.

Why the name Servo?

Servo motor is a commonly used motor, it is a kind of motor absolutely obey the command of the control signal, before the control signal is issued, the rotor is stationary; when the control signal is issued, the rotor immediately rotates; when the control signal disappears, the rotor can instantly stop rotating. Servo motor is named because of this absolute obedience to the characteristics of the control signal, "servo" a word derived from the Greek word "slave" meaning.

Second, what is the working principle of servo motor

Servo motor as a special type of motor, unlike most other motors, it is designed for precise positioning rather than controllable speed, its structure principle is:

1, the structure of servo motor

Servo motor is generally composed of stator and rotor, there are two windings on the stator, namely excitation winding and control winding, two windings in space differ by 90 ° electrical angle, the internal current, angle, eccentricity and other signals, through a cable connected to the server, the server to correct the drive signal to the servo motor.

2、The principle of servo motor

Servo motor itself has the function of sending out pulses, servo mainly relies on pulse to position, servo motor every rotation angle, will send out the corresponding number of pulses, so that, and the servo motor to accept the pulse formed an echo, or closed loop, so that the system will know how many pulses sent to the servo motor, and at the same time how many pulses back, so that it can be very accurate control of the rotation of the motor. Thus, it can achieve accurate positioning, which can reach 0.001mm.

Third, the servo motor is an AC motor or DC motor motor motor can be divided into DC motor and AC motor two, servo motor both DC motor and AC motor.

1, AC servo motor

AC servo motor internal rotor is a permanent magnet, the driver control U / N / W three-phase electricity to form an electromagnetic field, the rotor under the action of this magnetic field rotation, while the motor comes with the encoder feedback signal to the driver, the driver according to the feedback value and the target value for comparison, adjust the rotor rotation angle. The accuracy of the servo motor is determined by the accuracy of the encoder.

2、DC servo motor

DC servo motor includes stator, rotor core, motor shaft, servo motor winding commutator, servo motor winding, speed measuring motor winding, speed measuring motor commutator, rotor core is made of silicon steel punching laminated and fixed on the motor shaft. DC motor has good and accurate speed control characteristics, but also smooth control in the entire speed zone, almost no oscillation, high efficiency, no heat.

When comparing AC servo motor and DC servo motor, AC servo is better in terms of function, because it is sinusoidal wave control with small torque pulsation, while DC servo is trapezoidal wave. But the advantage of DC servo is that it is simpler and cheaper.