What is the difference between AC servo and DC servo, and what are their characteristics?

DC servo motor: It is to add the DC motor to the encoder to form a closed-loop control, and the motor changes the torque, speed and other parameters of the motor by changing the size of the electricity. The structure of the DC servo motor is similar to that of the ordinary DC motor, except that the DC motor adopts a slender armature, disc or coreless cup to meet the low inertia.

Or changed to a permanent magnet motor, which is the most ideal speed regulation system, which leads to the DC servo motor is relatively easy to achieve speed regulation, and the control accuracy is higher. The disadvantage is that the DC servo motor has carbon brushes, which is easy to cause wear and tear of the motor, and the maintenance cost is high and the operation is troublesome.

AC servo motor: is a kind of AC motor, through the vector control theory of the servo drive to control the torque, speed, position, etc. of the motor, the rotor resistance of the AC servo motor is generally very large, so that it can prevent rotation, when the control voltage disappears, due to the excitation voltage, there will be pulsating magnetic momentum in the AC servo motor at this time, AC servo is a synchronous motor with encoder, the effect is slightly worse than DC servo, but easy to maintain. The disadvantage is that the accuracy is not as good as DC!

It is recommended to use AC servo motor, DC servo motor is too hot, and the control accuracy is not good. Short service life.

Compared with the three-phase asynchronous motor of the traditional oil pump motor, under the average working condition of the injection molding machine, the efficiency of the original servo motor is 10% higher than that of the traditional oil pump motor, and the high speed and high response speed of the Guangzhou Nengzhiyuan servo system bring the highest efficiency improvement of the injection molding machine by 25%.

DC servo is a technology in the 40-50s, and AC servo is a technology that appeared in the 70-80s.

With the maturity of high-power power electronic devices, DC servo has been eliminated, and AC servo can completely replace DC servo technology.

Servo motor refers to the engine that controls the operation of mechanical components in the servo system, and is a kind of auxiliary motor indirect transmission device. There are AC servo motors to make a backup bucket with DC servo motors. Their differences are as follows:

First, the principle is different:

1. The stator three-phase coil of the AC servo motor is powered by the servo coding control circuit, the rotor is a permanent magnet type, and the steering, speed and rotation angle of the motor are determined by the coding controller.

2. The rotor of the DC servo motor is also powered by magnets, and the stator winding is powered by the table servo coding pulse circuit.

Second, the maintenance cost is different:

1. The AC servo motor is easy to maintain.

2. The DC servo motor is easy to achieve speed regulation and high control accuracy, but the maintenance cost is high and the operation is troublesome.

Third, the control mode is different:

1. There are three types of AC servo motor control, amplitude control, phase control and amplitude phase control.

2. There are two main control modes of DC servo motor: armature voltage control and excitation magnetic field control.

Fourth, the performance is different:

1. The characteristics of AC motor are relatively soft, when the rated torque is reached, if the load torque increases, it is easy to cause a sudden stall. However, the DC motor has a fast response, a large starting torque, and the performance of providing the rated torque from zero speed to rated speed. Although the AC tama motor does not have carbon brushes and commutators, it is maintenance-free, sturdy and widely used, but in terms of characteristics, it must be achieved by complex control technology if it wants to achieve the performance equivalent to that of a DC motor.

Today's semiconductor development is rapid, and the switching frequency of power components is much faster, improving the performance of drive motors.

2. DC servo motor, it comprises stator, rotor core, motor shaft, servo motor winding commutator, servo motor winding, tachometer motor winding, tachometric motor commutator, and described rotor core is superimposed and fixed on the motor shaft by silicon steel punching sheet. The DC motor has good and precise speed control characteristics, and can achieve smooth control in the entire speed range, with almost no oscillation, high efficiency, and no heat.

1. The servo motor is differentThe low inertia servo motor is relatively flat and long, and the spindle inertia is small, and when the motor does high frequency repeated movements, the inertia is small and the heating is small.

The servo motor with high inertia is relatively coarse and has a large torque, which is suitable for occasions with high torque but not fast reciprocating motion.

The inertia is related to the mass of the rigid body and the distribution of the mass relative to the rotating shaft. When choosing, the motor inertia is also an important indicator of servo motors.

2. The scope of application is differentGenerally speaking, the motor with small inertia has good braking performance, fast response to start and acceleration, good high-speed reciprocation, and is suitable for some occasions with light load and high-speed positioning.

Medium and large inertia motors are suitable for occasions with large loads and high stability requirements.

If the load is relatively large or the acceleration characteristics are relatively large, and the motor with a small inertia is selected, the damage to the motor shaft may be too great, and the choice should be selected according to the size of the load, the size of the acceleration and other factors.

3. The conditions of use are differentThe best value of the response control of the servo motor driver to the servo motor is the ratio of the load inertia to the rotor inertia of the motor is one, and the maximum value shall not exceed five times. Through the design of mechanical transmission, the ratio of load inertia to motor rotor inertia can be close to one or smaller.

When the load inertia is really large, and the mechanical design cannot make the ratio of the load inertia to the rotor inertia of the motor less than five times, the motor with a large rotor inertia can be used. With a motor with a large inertia, the capacity of the drive should be larger to achieve a certain response.

The upstairs is too loaded and professional enough DC servo motor Servo motor is better at adjusting the speed But in AC servo motor In the use of the power is not enough Rarely used servo motor AC and DC have both brushes and no brushes AC motors with brushes can adjust the power of the rotor to achieve the speed of the motor, but in the motor with brushes need to be used for a period of time to replace the brushes Each has its own advantages depending on where you use it

The AC servo system includes a servo motor, an encoder, a servo drive, and a position-given mechanism, which is a fast positioning system.