I. Introduction
In the field of industrial automation, servo drive as a key device to control the operation of the servo motor, the stability of its performance and control accuracy for the operation of the entire production line efficiency has an important impact. PLC (Programmable Logic Controller) as the core of industrial automation control, how to effectively control the servo drive, to achieve precise control of the servo motor, is one of the important direction of the development of industrial automation technology. In this paper, we will analyze in detail from the basic principle of PLC control servo drive, the main way, realize the steps and application examples.
II. PLC control servo drive basic principles
PLC control of the basic principle of servo drive is through the preparation of the corresponding control program to send control signals to the servo drive, thereby realizing the precise control of the servo motor. Specifically, the PLC receives external input signals (such as buttons, sensors, etc.), according to the preset control logic, the output of the corresponding control signals to the servo drive. Servo drive and then according to these signals to control the operation of the servo motor, such as position, speed, acceleration and so on.
III. PLC control servo drive the main way
PLC control servo drive has three main ways: torque control, position control and speed control.
Torque control
Torque control mode is through the external analog input or direct address assignment to set the size of the motor shaft external output torque. Specifically, the PLC can send a torque setting value to the servo driver through the analog output module, and the servo driver controls the output torque of the servo motor according to this setting value. The torque control method is suitable for applications that require precise control of the output torque, such as material handling and tension control.
Position control
Position control mode is generally used to determine the size of rotation speed through the frequency of external input pulses and the angle of rotation through the number of pulses, PLC can send pulse signals to the servo driver through the high-speed pulse output module, and the servo driver will control the position and speed of the servo motor according to these signals. The position control mode is suitable for applications that require precise positioning and speed control, such as machine tool processing and robot control.
Speed Control
Speed control mode is to control the rotation speed by analog input or pulse frequency, PLC can send the speed setting value to servo driver through analog output module or high-speed pulse output module, and servo driver will control the running speed of servo motor according to this setting value. Speed control mode is suitable for the need for continuous speed regulation of the occasion, such as conveyor belts, mixers and so on.
IV. PLC control servo drive realization steps
Determine the control requirements
First of all, you need to define the specific needs of the servo drive needs to be controlled, such as position, speed, acceleration, etc.. This is the basis for selecting the appropriate PLC and servo drive.
Select the appropriate PLC and servo drive
Select the appropriate PLC and servo drive according to the control requirements to ensure compatibility and performance matching between the devices. In the selection process, factors such as the brand, model, specifications, and performance parameters of the devices need to be considered.
Writing PLC control program
According to the control requirements and hardware equipment to write PLC control program. The program needs to include input signal processing, control logic judgment, output signal control and so on. In the process of writing, you need to understand the PLC programming language, programming software, programming specifications and other basic knowledge.
Connecting PLC and servo drive
Connect the PLC and servo drive correctly according to the wiring diagram and instructions provided by the equipment manufacturer. Connections mainly include digital input/output, analog input/output, high-speed counters/encoders, and communication buses.
Debugging and Testing
After completing the connection, debugging and testing are carried out. By simulating the actual working environment, test the effect and performance of PLC control servo drive. In the debugging process, you need to pay attention to check the correctness of the program, the correctness of the connection and the operating status of the device.
V. Application Examples
Take a machine tool processing production line as an example, the production line uses PLC to control the servo drive to achieve precise control of the machine tool. Specifically, the PLC receives external input signals such as sensor signals and button signals, and determines the operating status and demand of the machine according to the preset control logic. Then, the PLC sends pulse signals to the servo drive through the high-speed pulse output module, and the servo drive controls the position and speed of the servo motor according to these signals. In this way, precise control of the machine tool is realized, and the operation efficiency and machining accuracy of the production line is improved.
VI. Conclusion
PLC control servo drive is one of the important means to realize industrial automation control. By writing the corresponding control program, PLC can realize the precise control of the servo driver, thus realizing the precise control of the servo motor. In practical application, it is necessary to select the appropriate PLC and servo drive according to the specific control requirements and hardware equipment, and write the corresponding control program. At the same time, it is necessary to pay attention to the correctness of the connection and the adequacy of debugging to ensure the stability and reliability of the whole control system.