Popularization and application of the hottest freq

The popularization and application of frequency converter in textile machinery

Abstract: This paper discusses the application significance of AC frequency conversion speed regulation in textile engineering, and promotes the technological progress of textile industry

key words: AC variable frequency speed regulation technology; Textile machinery

1 introduction

in recent years, with the fierce market competition and the continuous improvement of the electromechanical integration technology level of textile machinery, textile machinery at home and abroad has generally entered the era of variable frequency speed regulation drive. Variable frequency speed regulation has replaced the traditional mechanical structure, and the main technological processes and basic loom equipment, such as Qinghua, carding, slitting, roving, spinning, winding, warping, sizing, shuttleless looms, have been widely used. Moreover, almost all newly developed textile machinery have applied AC variable frequency speed regulation technology, which has greatly improved the reliability of textile machinery equipment, textile quality and automation

2 when the temperature reaches the upper limit, it can automatically stop heating. As an inevitable trend in the application of textile machinery, AC variable frequency speed regulation technology has the following obvious advantages:

(1) reduce power consumption, reduce cost, and have a significant power saving effect

(2) the asynchronous motor can realize stepless speed regulation

(3) the mechanical structure is simplified, and the production speed and efficiency are improved

(4) smooth startup eliminates the impact of machinery and improves the reliability of textile machinery equipment

3 application of variable frequency speed regulation technology

3.1 classification of drive characteristics of frequency converter

the motor of textile machinery controlled by frequency converter mainly uses three-phase induction AC asynchronous motor

(1) the open-loop control of asynchronous motor speed by frequency converter is called v/f form. This kind of circuit is simple and reliable, but the speed regulation range is small, the speed regulation accuracy is low, and the low performance is not ideal, so it is mostly used in knitting machines or textile machinery with low performance requirements

(2) adopt speed sensorless vector control frequency converter. The frequency converter has excellent low-speed performance, simple circuit structure and high reliability. At the same time, it has good acceleration characteristics, torque characteristics and current limiting characteristics, and is suitable for the speed regulation of printing and dyeing machinery

(3) vector frequency conversion with speed feedback is used to control asynchronous motor, and closed-loop frequency conversion speed regulation is adopted. The switching frequency of frequency converter is improved by using power insulated gate double stage transistor (IGBT) instead of general high power transistor (GTR). It realizes high-frequency response, high precision and intelligence, and is suitable for textile machinery with high speed regulation performance requirements and constant tension and constant linear speed

3.2 classification of textile application of frequency converter

according to the application of frequency converter to textile machinery, it is divided into three types:

(1) a host selects a frequency converter to control a motor, such as spinning frame, drawing frame, etc. (1 driven by 1)

(2) a host selects a frequency converter to control multiple motors, such as rotor spinning machine, doubling machine, etc. (more than one trailer)

(3) a host machine selects multiple frequency converters to control multiple motors, and the computer controls the coordination and synchronization of multiple motors to realize the winding and forming function, such as the slitting warping machine (multiple dragging)

4 technological progress brought about by variable frequency speed regulation

4.1 soft start

when the motor can be connected with the user local area to realize data remote output and power frequency direct start, it will produce 7 ~ 8 times the rated current of the motor. This current value will greatly increase the electrical stress of the motor winding and generate heat, thus reducing the service life of the motor. Variable frequency speed regulation can be started at zero speed and zero voltage (of course, appropriate torque should be given). Once the relationship between frequency and voltage is established, the frequency converter can drive the load to work according to v/f or vector control mode. Using variable frequency speed regulation can fully reduce the starting current, improve the bearing capacity of the winding, and reduce the maintenance cost of the motor

4.2 stepless speed regulation

in the spinning process, the electrical rotation of the processing equipment is required to be stable, and the inching, starting and lifting speed should be smoothly realized, so as to make the fiber drafting uniform and reduce the weight unevenness. In the rotating system of textile machinery equipment, it is undertaken by belts and gears. Due to the starting hardness of the motor, belt slip and gear impact will inevitably occur in the process of inching and starting. In mechanical transmission, the more gears, the greater the probability of gear damage. The application of AC frequency conversion technology can well realize smooth startup, eliminate the impact of mechanical startup, realize stepless speed regulation, meet the requirements of process production, improve the production efficiency and yarn quality, and reduce the operation cost. When using this technology to change the variety of yarn, there is no need to change the pulley, and the change of equipment process speed can be completed only through frequency conversion setting

4.3 optimize the process

using variable frequency speed regulation can optimize the process and change rapidly according to the process. It can also realize speed change through remote PLC or other controllers. Like controllable acceleration, in variable frequency speed regulation, the stop mode can be controlled, and different stop modes can be selected, so as to make the whole system more stable

5 textile engineering application examples

AC variable frequency speed regulation is applied to textile machinery, which can be said to be applied to machinery in almost all processes. For example, FA506 spinning frame, f1272 comber, FA201B carding machine, especially f1520 spinning frame 1008 spindles, the spindle speed can be controlled by 10 segment frequency converter. Due to the limitations of technical conditions, equipment manufacturing costs, market demand and other factors at that time, the old carding machine used in a cotton mill inevitably has some defects in its design. For example, due to the failure of the electromagnetic clutch in the transmission system, the main investment projects are located in Nanjing, Shanghai and Chongqing, with a high rate, which often leads to parking, and corrosive gas is produced when fire breaks down from time to time, It will cause certain losses to production efficiency and product quality, and a lot of human and material resources need to be invested to maintain and maintain it. The electromagnetic clutch of the inertia wheel is discarded, resulting in sliver, and in serious cases, edge breakage, cotton breakage and other phenomena, affecting the quality of sliver. In order to avoid this phenomenon, some operators used improper operation methods to make up for the defects of the above equipment, but caused a large number of waste strips, which greatly reduced the production efficiency. The adoption of AC variable frequency speed regulation technology has changed these phenomena and provided a good example for the transformation of old machines

for the spinning frame, because the forming cam in the forming mechanism is removed by using the frequency converter, the phenomena of peach bottom pause and peach top impact caused by the forming cam are overcome, making the spinning roll shape good, so as to facilitate the high-speed unwinding of the next process. At the same time, the frequency converter is used to control the speed of the spindle by controlling the speed change of the main motor, so that the speed of the spinning yarn changes in large, medium and small yarns, so as to reduce the yarn breakage rate and improve the production efficiency

6 Conclusion

the application of AC variable frequency speed regulation technology in textile equipment is necessary, and it is also feasible to promote the application of traditional textile equipment. At present, the application of AC frequency conversion technology in textile equipment engaged in production is less. The reasons are as follows: first, the textile industry has poor benefits in recent years and is unable to apply this new technology. In terms of equipment modeling and configuration, the equipment adopting new technology has been abandoned due to price difference and cost factors; Second, most of the textile equipment currently in operation was produced in the 1970s and 1980s, but this new technology had not been applied at that time; Third, the management level and maintenance force are insufficient, and they dare not choose equipment with high technical content. With the progress of society, the development of technology and China's entry into WTO, it is necessary to improve the equipment level of China's existing textile equipment, increase the technical content, and increase the competitiveness of textile products in the international market. Therefore, the high and new technology of AC variable frequency speed regulation will be widely used in textile equipment, so as to promote the technological progress of textile industry (end)