Drives-Inverters Technical Guides

What is Servo?

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What is AC Servo Motor?

AC Servo Motor is essentially a 3-phase electric motor rotating, operating on the principle of permanent magnet as the engine in a pump or fan. The difference of AC Servo Motor compared to conventional motors is that it is integrated with many electronic tools and sensors to transmit information and control such as amplifiers, controllers, encoders and monitors. . This increases the accuracy as well as the ease of control, which is one of the requirements for industrial production in the era of industrial revolution 4.0 today.

Structure of AC Servo Motor

AC Servo motors used in industries are mostly brushless dc motors. Servo motor has 3 main parts with the same step motors as Rotor,Stator and Encoder.

+ The rotor is a permanent magnet with a strong magnetic field.

+ The stator is a separate coil, powered to spin the rotor.

+ Encoder integrated into chasing motor helps to feedback position to control signals correctly

Principle of operation AC Servo Motor

AC Servo Motor operates according to the principle of PWM (Pulse width modulation), which means that its rotation angle is controlled by the number of output pulses. Basically the servo motor is made up of DC motor controlled by a variable resistor (potentiometer) and some gears.

Servo is the motor formed by closed loop feedback system. The motor output signal will be connected to a control circuit. When the engine is running, the speed and position will be feedbacked back to this control circuit. If the motor’s rotation is prevented for any reason. The feedback mechanism recognizes that the output signal has not reached the desired position. The control circuit will continue to adjust the deviation for the motor to achieve the most accurate point.

There are 3 motor control modes: Speed, position and moment, need to set according to the purpose of motor use.

In addition, each AC Servo Motor is only compatible with one genuine driver to be able to work. When a motor failure occurs, for example, a coil fire (commonly found in magnet motors) will not be able to rewind the wire by itself, as this will be incorrect with the specifications of the manufacturer. Ideally, when damaged, you should bring your engine to see the manufacturer for warranty or contact the company specializing in installation and warranty and repair.

Application of AC Servo Motor

Small but very important servomotor for use in applications that require precise position control. Here are some of the more common applications used today:

+ Application in mechanical processing industry: At present, mechanical processing industry, especially for processing high-precision products such as laser cutting machines or some other cutting machines, people will choose Servo motor instead of stepper motor as before. Besides, it is also applied a lot in other types of CNC Plasma cutting machines.

+ Electricity and electronics: Electronic components will need high speed and precision. Therefore, AC Servo will meet this requirement.

+ Garment, packaging, paper industry: Using Servo motor to control printing, printing, cutting, rolling, wrapping machines.

+ In transport control: As industries become industrialized and automated, transport equipment is an indispensable component in many fields. Meanwhile, Servo motor will help to control the movement speed of devices quickly or slowly depending on the purpose of use.

+ Food and beverage production: Due to the increasing demand for quality food processes and safety, Servo motors are used as an effective solution.

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