The application of universal transmission in paper machine

In recent years, with the improvement of China's automation technology, factory automation has also reached a new level. PLC, inverter due to stable performance, cost-effective, in the paper machine has been a lot of applications. The paper machine has high requirements for the electrical control system. In the speed, the speed of each part of the drive motor must be strictly synchronized, because as long as one of the motor speeds is inconsistent with other motors in the paper production process, the production cannot be maintained and the paper will break. , Or loose down, can not guarantee the quality of paper production. In production, there are many factors that can affect the speed of the motor, such as instability of the grid voltage, frequency changes, abrupt changes in the load, temperature changes, etc. The requirements of the control system are to overcome the influence of these interferences and ensure the stable operation of the motor. . The start-up of the paper machine is required to be stable, and the rotation speeds of the various parts of the motor are kept in synch. The thin paper or large-scale high-speed paper machine has a higher demand for the electrical control system.

Machine Control System Requirements

A rustproof packaging plant production packaging paper process requirements:

One roll of raw material reel control motor, one spraying speed control motor, two motors for drying speed control, one motor for rewinding speed control, six-pole AC asynchronous motor for motor, five drive points, and paper feed speed 0~ 120m/min, winder diameter D=100mm~1000mm, paper tension F=300~1000N. The speed of starting is required to be gentle, the tension is stable after starting, and the speed adjustment range of each motor is ±(10~15%).

Transmission System Features and Frequency Converter Selection

It can be known from the above system description that the transmission system has high requirements on the dynamic performance of the motor, and requires that the motor start smoothly, the speed is stable, and the synchronization performance is good. Therefore, a high-performance frequency converter must be selected to meet the demand. Vacon NX series inverters in Finland are high-performance vector control general-purpose inverters. It has the following features:

(1) Using advanced vector control algorithm, in conjunction with motor parameter settings, dynamically compensate for load fluctuations, can achieve rapid response and accurate control of motor torque, with extremely high precision and fast dynamic response, and can meet various types of high Transmission control requirements for performance applications.

(2) Vacon inverter has open programmable function. Programming tool Vacon NC1131-3 Engineering is a graphic programming tool conforming to IEC611131-3 standard, which can be used to design Vacon NX special control logic and parameters. It contains basic function modules and advanced function modules such as various filters, PI controllers and integrators. The NC1131-3 can create parameters, fault information and other application-related features. With its own LCD keyboard, not only can display the operating data and fault codes, but also can copy and download parameters, which is very convenient for debugging and later maintenance.

(3) A variety of expansion cards to meet user needs.

(4) Built-in RS485 interface, through the expansion board can access ProfiBus DP, ModBus fieldbus control system in line with international standards, to meet future networking requirements.

(5) Slim, space-saving design, flexible installation, integrated RFI filter can meet industrial grade ramp protection requirements.

Control system design

In the control system, the S7-200 series PLC is used to communicate and control the Vacon inverters in different segments using the ProfiBus DP protocol. The Vacon inverter controls the speed of the motor through frequency conversion, the raw material roll is controlled by a single inverter, and the spraying speed controls the inverter. Taiwan, two drying speed control inverters, one winding speed control inverter, inverter plus ProfiBus DP expansion board NXOPTC3, with A/D module and communication module outside PLC host, PLC collects tension sensor signal, control The speed of the inverter ensures that the tension remains unchanged. The system adopts the master-slave control, the winding speed control inverter is the main control inverter, and the other inverters are the slave inverters, so as to achieve the synchronous proportional transmission control of the paper machine. In the production process, according to the requirements of different papers, each motor is required to achieve speed proportional coordination, to ensure that the tension of the paper is stable, and to maintain the speed proportional coordination with high accuracy and reliability is an important condition to ensure product quality, any change in motor speed. Destruction of this ratio will reduce the quality of the paper. At the same time, the speed ratio coordination of the paper machine should continue to be maintained during acceleration and deceleration or when it is turned on, without re-adjustment. Secondly, this proportional coordination should have a fine-tuning function to adjust the speed difference between the adjacent two subdivisions to prevent the paper from being taut and slack during the transfer process. There should not be excessive advance and lag in the adjustment process. Ensure that fine-tuning speed should be reliable and sensitive. Using ProfiBus protocol communication control combined with PLC program to complete the motor control, to avoid the interference of the on-site signal and improve the system stability.

Master-slave synchronous control parameter design

The master-slave parameter group is designed using Vacon NX series inverter master-slave synchronous control application macro. The master-slave parameter communication does not have the signal sent back from the slave to the master through the system bus. The slave's fault output signal can be connected to the host external fault. Input. System bus communication failure The slave will trigger the #81 system bus error, and the slave will report the #80 error if the master alarm occurs. The parameters are described as follows:

(1) P2.12.1 master-slave selection: This parameter defines the master-slave connection drive relationship. Host This parameter is set to Master. The host will transmit the master-slave control word, speed reference, torque reference, etc. through the fiber channel. The slave is set to Follower and the control position parameter P3.1 is set to Systembus. Bus control is used.

(2) P2.12.2 Local System Bus ID Number: Used for system bus drive. 0~63 Each drive has a unique local system bus ID number.

(3) P2.12.3 slave system bus ID number: The next drive ID number in master-slave communication.

(4) P2.12.4 system bus communication speed: Set the system bus communication speed: 0=1.5Mbit/s, 1=3Mbit/s, 2=6Mbit/s.

(5) P2.12.5 Torque mode selection: The main machine is a typical speed control, and the slave can use torque control. The parameters can be selected as follows:

0 = not used 1 = speed control 2 = torque control 3 = torque reference and speed controller output minimum 4 = maximum torque reference and speed controller output

(6) P2.12.6 torque calibration: corresponds to the rated torque of the motor. The default value is 1000. The torque reference calibration factor for this parameter. Select 1000 to correspond to the rated torque reference.

(7) P2.12.7 Load distribution ratio: Percentage of load distribution torque reference. If set 100% = The load is distributed among the drives according to the rated torque.

(8) P2.12.8 Torque reference source selection: Slave torque reference source. Set to 1, select host control.

0 = not used 1 = master 2 = fieldbus 3 = analog 1 signal 4 = analog 2 signal (9) P2.12.9 Slave reference frequency: Slave speed reference source. Set to 1 to select the host reference frequency.

0 = slave reference frequency 1 = master reference frequency 2 = master output ramp (slave ramp does not work)

Conclusion

This system makes full use of the programmable functions of Vacon inverter. Write dedicated application macros for users to achieve the functions that other common frequency converters cannot achieve. The host speed control method is closed-loop vector control, PLC adds ProfiBus communication module, and Vacon inverter is used as the slave station of the DP network to improve the speed control accuracy of the paper machine motor and meet the requirements of the high-speed paper machine. The use of fiber optic cable between the master-slave inverters improves communication speed and immunity. Complete synchronization control and load distribution control. The entire control system has a good man-machine interface, the control system is stable and meets the requirements of users. In domestic small and medium-sized paper machines, Vacon NX series inverters will have broad application prospects.