Application of the hottest SB80 frequency converte

2022-08-07
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The application of SB80 frequency converter in packaging paper machine

1 introduction explains the brand concept of "love" carried by the testing machine with action

in the ordinary paper multi motor divisional drive control system, based on speed control, the speed between each division needs coordinated control. According to the process requirements, the division using K-type press in the division shall be combined with the load distribution control, and the following requirements are required for the automatic control of electric drive:

(1) starting requirements

there are divisions with large transmission inertia in the paper machine, such as drying cylinder, which shall be started smoothly to avoid damage to the mechanical coupling

(2) speed requirements

the paper machine, from pulp to paper, needs to go through multiple divisions such as pressure jet sizing, pressing, drying, calendering and winding. It is a multi unit speed coordinated control system. The speed of each division has a strict speed proportional relationship. Otherwise, it will cause paper breakage or excessive relaxation, affect the physical indicators of paper forming, and cannot stabilize the quantitative control of paper, affecting the product quality. Therefore, each part of the paper machine should have high precision and stable speed performance

when the paper machine works normally, the adjustment range of process change speed is small, generally only 10-15%; During the adjustment of the paper machine, such as checking the adjustment cage and blanket, the dryer should crawl at a low speed when preheating. The speed is about 2. Break through the fixed thinking mode and concentrate on mobilizing resources at 0m/min. There is no requirement for stable speed

(3) requirements for divisional speed regulation

as shown in the process flow plan of the paper machine in Figure 1, the paper on the paper machine is subject to the action of traction force, which produces longitudinal elongation in the press and pressing parts, and continues to extend without reinforcing sheets in the drying part. When the water content of the paper decreases, the paper reduces the longitudinal elongation and deformation, and when the paper enters the calender and winder, the paper is pulled again and elongated, so in the whole paper machine production line, The speed of each segment is different, which can maintain the web tension. At the same time, the speed of each part of the paper machine must be adjustable, so as to avoid paper breaking due to loose or excessive tension of the paper web. Since the paper machine does not need to be started frequently, and the range of speed change required by the process is not large, the main goal of automatic control of paper machine electrical drive is to stabilize the speed

Fig. 1 plane diagram of paper machine process flow

in the control system, due to the need for synchronous control of multiple motors, the USS protocol of Siemens SPLC is used to control the frequency converters of different divisions to realize frequency conversion and speed regulation of motors, so as to achieve coordinated control of paper machine transmission. The specific configurations are cpu226plc, operation console, di/do expansion module, shielded twisted pair, SB80 frequency converter compatible with USS protocol, etc

Senlan SB80 frequency converter has rich control functions, which can meet the drive control needs of most industries. In this control system, PG free vector control mode and v/f control mode are used to drive each branch motor, and load distribution of the load chain of the press section is realized; Powerful communication function facilitates communication with upper computer, and supports MODBUS manufacturer protocol and USS protocol; Powerful programmable arithmetic logic unit, users can flexibly combine and design to meet the control requirements of complex processes; Multiple frequency setting modes: basic operation panel, communication setting, multi segment frequency setting, mop setting, simulation setting, etc

2 electrical control of the paper machine

2.1 speed control of the paper machine

as each division conveys the paper in the production process, according to the requirements of the papermaking process, maintaining the tension of the next level slightly greater than that of the previous level requires coordinated control of the linear speed proportion between each division. Maintaining this proportion coefficient with high precision and reliability can ensure the product output and quality. At the same time, this speed proportion coordination relationship of the paper machine should be maintained after changing the speed or restarting the machine after shutdown, without readjustment. Each segment is controlled independently and has sensitive adjustment functions such as micro rise, micro drop and tension, which is convenient for operation and adjustment of the speed difference between the front and rear segments to avoid excessive relaxation, tension and paper breakage during the transmission process. The relationship is as follows:

(1)

where: Ni is the speed of the I stage; Ki is the speed ratio of stage I to the previous stage; Δ Ni is the fine adjustment amount of stage I

in the paper machine control, USS protocol communication and PLC program are used to complete the speed chain control, which is convenient to realize the digital control given by the frequency converter, avoid the signal drift of the given link of the speed chain of the analog controller, and improve the stability

the paper machine in this example mainly produces packaging paper and has high requirements for speed stability and dynamic response. Because SB80 engineering inverter has good vector control characteristics, high frequency setting resolution and output frequency accuracy, and high static and dynamic control accuracy, it can meet the needs of continuous and efficient production and application

2.2 master slave load distribution control

in papermaking transmission control, multiple transmission points drive a cloth or multiple transmission objects, exert pressure on each other to form a certain torque and operate synchronously. In order to make each associated transmission motor bear the power output in proportion according to their respective configurations, the load distribution control form should be adopted. If the load distribution is not adjusted well, the load at each transmission point of the whole load loop will be unbalanced and the line speed will be out of sync, Unable to operate normally Load distribution control is shown in Figure 2. In this example, the re pressing lower roll of the part is used as the main drive, and the vacuum press is used as the auxiliary drive. The main drive adopts the basic speed control mode, and the secondary drive adopts the load distribution control. In the slave control, the SB80 internal PID is used to modify the frequency master setting, the torque output of the master drive is used as the PID setting value of the slave, and the torque output of the slave drive is used as the PID feedback value after low-pass filtering. In order to improve the control accuracy, the gain of PID given quantity and feedback quantity can be adjusted, such as 200%. This ensures the control accuracy and improves the system stability

Figure 2 load distribution control

3 commissioning and system parameter setting

3.1 RS-485 wiring

(1) shielded twisted pair is used, and the shielding layer is floating to the ground to avoid interference from the ground

(2) using the shielding layer of the shielding wire to form a low resistance signal loop for communication, which is only effective for high resistance common mode interference

(3) the motor and frequency converter shall be reliably grounded to reduce the interference of the motor to the frequency converter

(4) the GND and PE wiring of the frequency converter shall not form a loop

Figure 3 basic wiring connection map

3.2 parameter settings of each frequency converter

Table 1 basic parameter settings of each frequency converter

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