Application of the hottest SB80 frequency converte

2022-08-19
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Application of SB80 frequency converter in packaging paper machine (I)

Abstract: in the papermaking production process, speed coordination and control are required among various divisions; In some parts, such as the vacuum roller belt K-type press in the press section, in order to make each transmission motor of the K-type press bear the load work reasonably according to their respective power configuration, and slowly and evenly form the rate output of foam body from the expandability, the load distribution control form needs to be adopted For the speed coordination of the whole production line, PLC can be selected as the upper computer, and communication can be used to control the frequency converter. Senlan SB80 frequency converter provides rich serial port protocols, which is convenient for group control

Keywords: SB80 frequency converter, group control, load distribution, USS protocol, RS-485 interface

1 Application background

aims to explore the new potential of various material technologies possessed by well 3 chemistry

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

1) starting requirements

there are parts with large transmission inertia in the paper machine, such as the dryer, which need to be started smoothly to avoid damage to the mechanical coupling shaft

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 between each division has a more rigorous speed proportional relationship, otherwise it will cause paper breakage or excessive relaxation, affect the physical indicators of paper formation, and cannot stabilize the quantitative control of paper, affecting product quality. Therefore, all parts of the paper machine should have high precision and stable speed performance

when the paper machine works normally, the adjustment range of the change speed in the process is small, generally only 10-15%; 7. Other function keys are used in the adjustment of the paper machine, such as checking the adjustment cage and blanket. When the dryer is preheated, it should crawl at a low speed, and the speed is about 20m/min, so there is no requirement for stable speed

3) requirements for speed regulation of each division

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, which produces longitudinal elongation in the part and the pressing part, and continues to elongate longitudinally 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 the 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 paper tension. At the same time, the speed of each part of the paper machine must be adjustable, so as to avoid the paper breaking due to the relaxation or excessive tension of the paper web. Since the paper machine does not need to be started frequently, and the speed change range required by the process is not large, the main goal of the automatic control of the electric drive of the paper machine is to stabilize the speed

Figure 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 configuration is cpu226plc, operation console, di/do expansion module, shielded twisted pair, SB80 frequency converter compatible with USS protocol, etc

Senlan SB80 frequency converter has the control function of Qingdao's GDP in the first half of 2016, which is more than twice as rich as that of Zibo, with famous enterprises such as Haier and Hisense. It 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 the motors of each division, and the load distribution of the load chain of the press department 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; Various frequency setting methods: 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

because each division conveys the paper in the production process, according to the requirements of the papermaking process, maintaining the tension of the next level is slightly greater than that of the previous level, which requires the 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 after shutdown, without readjustment. Each branch is controlled independently and has a sensitive micro rise The adjustment functions such as slight drop and tension are easy to operate and adjust the speed difference between the front and rear parts, so as to avoid excessive relaxation and tension and paper breakage during the transmission process. The relationship formula is as follows:

(1)

in the formula: it is the speed of stage I; Is the speed ratio of stage I to the previous stage; Is the fine-tuning amount of Level I

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

the paper machine in this example mainly produces packaging paper, which has high requirements for speed stability and dynamic response. Because SB80 engineering inverter has good vector control characteristics, high frequency given 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 piece of cloth or multiple transmission objects, exert pressure on each other to synthesize 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 form of load distribution control needs to 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 double pressing down 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, SB80 internal PID is used to correct 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 PID can be adjusted to give quantitative and inverse

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