Ac Servo Motor Vs Dc Servo Motor


Ac Servo Motor working principle

The rotor inside the AC 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. Compared with the target value, adjust the angle of rotation of the rotor. The accuracy of the servo motor depends on the accuracy (number of lines) of the encoder.

Dc Servo Motor working principle

The structure of a DC servo motor is basically the same as that of a DC motor. Just to reduce the moment of inertia, the motor is made slender. The difference is that the armature resistance is large, and the mechanical characteristics are soft and linear (the resistance is large, it can start with the weak magnetic field, and can start directly).

AC servo motor and DC servo motor difference

A Servo motor is a motor that controls the operation of mechanical components in the servo system, it can be divided into two kinds of DC servo motor and AC servo motor, the difference between these two kinds of the servo motor is mainly reflected in the following aspects.

1, Structure is different

The structure of an AC servo motor is similar to that of an AC asynchronous motor, there are two excitation windings and control windings on the stator with a 90° electric angle of phase space displacement, connected to constant AC voltage, using the AC voltage or phase change applied to the windings to achieve the purpose of controlling the operation of the motor.

The structure of a DC servo motor is similar to a DC motor, including a stator, rotor core, motor shaft, servo motor winding commutator, servo motor winding, speed motor winding, and speed motor commutator, said rotor core is composed of silicon steel punching sheet laminated fixed on the motor shaft.

2, Principle is different

AC servo motor stator three-phase coil is powered by the servo code control circuit, the rotor is permanent magnet type, and the motor’s steering, speed, and angle are determined by the code controller.

DC servo motor rotor is also a permanent magnet, stator winding is powered by the servo code pulse circuit.

3, Different classification

DC servo motor is divided into two kinds of brushed DC servo motor and brushless DC servo motor according to the presence or absence of carbon brushes; AC servo motor is a brushless motor, divided into synchronous and asynchronous motors.

4, Different control methods

AC servo motor control mode has three, amplitude control, phase control, and amplitude-phase control; DC servo motor control mode mainly has two: armature voltage control, and excitation field control.

5, Maintenance costs are different

AC servo motor is easy to maintain; DC servo motor is easy to achieve speed regulation and high control accuracy, but high maintenance costs, and operation trouble.

6, Mechanical characteristics are different

The characteristics of an AC servo motor are relatively soft, when the rated torque is reached, if the load torque increases, it is easy to cause a sudden stall. But the DC motor has a fast response, a large starting torque, from zero speed to rated speed with the performance of rated torque can be provided. Although AC motors do not have carbon brushes and rectifiers, maintenance-free, robust, and wide application, the characteristics of the DC motor achieve the equivalent of the performance of complex control technology to achieve.

Servo motor AC good or DC good

DC servo motors and AC servo motors are servo motors, and both motors have certain advantages and disadvantages.

1, AC servo motor advantages and disadvantages

(1) Advantages: good and accurate speed control, but also in the speed zone to achieve smooth control, almost no oscillation, relatively high efficiency, but also not easy to heat, but also has a stable operation, good controllability, fast response, high sensitivity and mechanical characteristics and regulatory characteristics of the non-linearity of the indicators are strict. In the rated operating area, constant torque, low inertia, low noise, no brush wear, and maintenance-free (for a dust-free, explosive environment) can be achieved.

(2) Disadvantages: control is more complex, the drive parameters need to adjust the PID parameters to determine the site, the need for more connection.

2, Advantages and disadvantages of DC servo motor

(1) Advantages: accurate speed control, torque-speed characteristics are very hard, simple control principle, good linear adjustment characteristics, fast time response, easy to use, cheap.

(2) Disadvantages: brush commutation, speed limitations, additional resistance, and the generation of wear particles (dust-free and explosive environments are not suitable for use).

As can be seen, the two servo motors are not necessarily which is better, mainly depending on the field of use, different fields may have different requirements for the model, and you can choose the right servo motor according to demand.

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