Application of the most popular frequency converte

2022-07-25
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The application of Yi Neng inverter in papermaking machinery I. Introduction the papermaking industry plays an important role in the whole national economy. However, the speed control of papermaking machinery has always been a weak link in the papermaking industry. The paper-making process requires that the linear speed of each part should be absolutely synchronized under their respective synchronous frequency points, so as to ensure that the paper is smooth, uniform in thickness, without wrinkling and breaking. The speed, stability and adjustability directly affect the output and quality of paper. Since DC excitation speed regulation accounts for a large proportion in the paper industry for many years, although DC excitation speed regulation motor has the advantages of good speed regulation performance and large starting torque, it has many disadvantages: high cost; It is difficult to maintain commutator and brush; Difficult to be used in harsh situations; The noise is too loud for operation

in today's energy shortage, most provinces across the country begin to limit power, especially in East China. As a major power consumer, the paper industry is also particularly energy-saving. Therefore, the rapid development of motor frequency conversion and speed regulation technology provides this possibility. However, for low-grade paper, in order to save costs, it is not necessary to use expensive imported equipment, host computers and any other controllers, The unique two-way analog synchronous control scheme of Yi Neng frequency converter can meet the requirements of the paper industry. The Yi Neng frequency converter can take one analog quantity as the main engine for unified adjustment and the other for individual fine adjustment

II. Case analysis

the following is an example of the transformation of a paper mill that mainly produces Kraft face paper by using the easy energy frequency converter

1. requirements of paper machine drive on electrical control system

the paper machine is composed of moving main press, drying section, calendering section and coiling section. There are 6 transmission points in total, with a total power of 120kw. The power of each transmission point and the model of frequency converter are shown in the attached table

2. Process requirements for the transmission system of the paper machine

in order to produce products with high quality standards, the paper machine has the following process requirements for the transmission system:

a) the working speed of the paper machine should have a large adjustment range: in order to make the paper machine have strong adaptability to products and raw materials (such as beating degree, slurry ratio and type, ration, paper grade, etc.), the paper machine transmission can adjust the speed evenly in a large range, and the speed adjustment range is d=1:8

b) the vehicle speed shall have a high stability margin: the total vehicle speed shall be steadily increased and decreased. The paper machine speed often fluctuates due to the changes of power supply voltage, frequency and paper machine load. In order to stabilize the quantity and quality of the paper and reduce the breakage of the paper web, the paper machine is required to be stable

c) adjustable and stable speed ratio among segments: when the paper web is in the press section and the press section, its longitudinal elongation and transverse contraction, while when drying the trunk, it shrinks in both directions. Therefore, the linear speed of each part of the paper machine is slightly different. The maximum fluctuation value of the speed ratio of each section of the paper machine is related to the factors such as slurry ratio, ration, speed, production process, tension of the non supporting leading section of the paper web between the sections, etc. Therefore, there should be an appropriate speed difference between the adjacent sections of the paper machine to form a good paper that is consistent with its own characteristics and environment. The speed of each section of the paper machine must be adjustable within ± 2013%. At the same time, in order to produce high-quality paper and reduce the breakage rate, it is necessary to maintain the stability of the speed ratio between the segments. In case of load change or other interference leading to speed change of a certain section, it shall be timely adjusted so that the change of speed ratio of the section does not exceed the specified range

d) the single branch point has the function of slight increase and decrease in speed, and the paper tightening function during the paper guiding operation. And in these divisions, it shall have single action and linkage functions. It can start and stop at the same time. Necessary display, such as line speed, current, operation signal, fault signal, etc

e) separate fine adjustment of each circuit in order to overhaul and clean the operating conditions of each segment, each segment shall be fine adjusted separately. At the same time, the speed of each segment in the synchronous speed shall be adjusted at different values, so as to achieve the future synchronous control

f) the paper machine drive is a constant torque load. The frequency converter with constant torque control performance and high resolution should be selected to meet the needs of the normal operation of the paper machine control system

3. Composition of electrical control system

(1) system hardware composition

eds2000 high-performance general frequency converter is used as frequency converter, and asynchronous motor is used as motor. The hardware composition of the system is shown in the figure below

(2) control of multi motor drive drafting synchronization

in papermaking equipment, it is based on determining the relative speed synchronization of each part. There is a main given signal. The goal of synchronous control when the length of steel hammer is less than 250mm is to ensure that the proportion of synchronization can be maintained in the process of acceleration, constant speed or deceleration

4. Synchronous control of analog quantity and fine adjustment of analog quantity segments

when a complete machine is required to be set at a master speed, all units work synchronously and harmoniously; A synchronous controller can be configured, which can adjust the transmission speed of each unit respectively to realize the synchronous operation of each unit at a certain proportional speed. The use of easy energy frequency converter can eliminate the need for synchronous controller. One of the two analog signals of easy energy frequency converter is given by VCI analog channel, which is responsible for synchronous control, while the other CCI is responsible for fine adjustment of each part

III. application and parameter setting of Yi Neng eds2000 series frequency converter in papermaking machinery

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