Servo driver simply: is used to control a servo motor controller, its role is similar to the role of the inverter AC motor, is part of the servo system, mainly used in high-precision positioning system. Generally through the position, speed and torque control of the servo motor in three ways to achieve high-precision positioning of the transmission system, is currently the transmission technology of high-end products. Following this article for everyone to introduce the working principle of servo drives.

The servo drives all adopt the digital signal processor (DSP) as the control core, which can realize more complicated control algorithms and achieve digitalization, networking and intelligence. The power devices generally adopt the drive circuit designed with the intelligent power module (IPM) as the core, IPM integrated drive circuit, and over-voltage, over-current, overheating, undervoltage fault detection and protection circuit, the main circuit also joined the soft-start circuit to reduce the impact of the startup process on the drive.

First, the power drive unit rectifies the input three-phase power or commercial power by the three-phase full-bridge rectifier circuit to obtain the corresponding direct current. After the rectification of a good three-phase electricity or electricity, and then through the three-phase sinusoidal PWM voltage inverter inverter to drive AC servo motor. The whole process of power drive unit can be simply referred to as AC-DC-AC process. The main topology of rectifier unit (AC-DC) is a three-phase full-bridge uncontrolled rectifier circuit. Servo drives generally have three control methods: position control, torque control, speed control. Position control The position control mode generally determines the rotation speed by the frequency of an external input pulse. The rotation angle is determined by the number of pulses. Some servos can directly assign the velocity and displacement through communication. Since the position mode Can have a very strict control of speed and position, so the general application of the positioning device.

Torque control Torque control mode is to set the output torque of the motor shaft through the input of external analog input or direct address. The set torque can be changed by changing the setting of analog value in real time , But also through communication to change the value of the corresponding address to achieve. Application Mainly in the hands of the material has strict requirements winding and unwinding devices, such as winding devices or fiber-optic devices, the torque set according to changes in the radius of the winding change at any time to ensure that the force of the material is not Will change as the winding radius changes.

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Speed ​​mode The speed of rotation can be controlled by the analog input or pulse frequency. In the outer PID control of the upper control device, the speed mode can also be positioned. However, the position signal of the motor or the direct load position signal To the upper feedback to do with computing. The position mode also supports the direct loading of the outer ring to detect the position signal. In this case, the motor shaft end encoder only detects the motor speed and the position signal is provided by the direct final load end detection device. This has the advantage of reducing the intermediate transmission The error increases the positioning accuracy of the entire system.

■ If the speed of the motor, the position is not required, as long as the output of a constant torque, of course, is the torque mode.
■ If there is a certain accuracy requirement for the position and speed, but not for the real-time torque, the torque mode is not convenient, and the speed or position mode is better.
■ If the host controller has a good closed-loop control function, the speed control effect will be better, if its own requirement is not very high, or basically no real-time requirements, the use of position control. Servo feed system requirements

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