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Application of frequency converter in synchronous speed regulation control system of dyeing and finishing equipment

printing and dyeing industrial production equipment includes gray fabric processing (scouring and bleaching), dyeing, printing and finishing equipment. Most of these equipment are multi unit combined processing machinery, each unit is driven by a motor, and all electric motors must operate synchronously to ensure the normal operation of production. This is called multi unit synchronous drive system. In the processing process, the process requires the product to maintain a constant linear speed and tension. Otherwise, the cloth is either broken or wrapped around the shaft, and the constant tension rule is closely related to the processing quality. It is related to the evenness, fastness, hand feel and shrinkage of printed, bleached and dyed fabrics. Therefore, advanced and excellent electric drive system is an important factor to meet the process production

I. characteristics of synchronous speed regulation system of domestic 74 type and imported DC drive dyeing and finishing equipment

continue to the positive maximum value. The synchronous system used by these printing and dyeing machines basically has the following two ways:

1 Common power mode. (SCR-D system)

the motors of all units are powered by a common adjustable DC power supply. The running speed of the whole machine changes with the change of the DC power supply. The constant tension synchronous coordination (self adjustment) between units is achieved by adjusting the magnetic field with the elastic frame. The advantages are simple and economical, while the disadvantages are ① poor speed responsiveness ② poor low-speed synchronous coordination capability ③ insufficient utilization of motor power

2. The sub power thyristor DC drive system (s-scr-d system)

each unit motor is powered by a single power supply that should replace the piston at the consuming equipment, and the magnetic field of the motor is constant to ensure that the motor can provide constant torque during operation. The speed difference of each unit is detected by the elastic frame, and the armature voltage of the unit is fine tuned to ensure the synchronous operation of the whole machine, Its advantages are: ① it is easy to realize the synchronization of the unit machine; ② the speed regulation accuracy and adaptability are good both at high speed and low speed; ③ the speed regulation range can exceed 1:20 (common power supply mode, generally only 1:5); its disadvantages are that each unit is equipped with a set of rectifier power supply; what kind of testing machine is used in the life prediction of rubber damping products; the investment cost of equipment is high, and the maintenance is difficult

in addition to the above two methods, the imported dyeing and finishing equipment is also represented by ① the synchronous drive system of DC motor with "common split" hybrid power supply and "magnetic and pressure regulating and tension regulating frame", such as the Dutch stork rd-iv circular printing machine ② the synchronous drive system of digital speed regulating DC motor, such as the West German monforts pre shrinking machine (fksg-2), etc

both the common power supply mode and the split current mode, because they are driven by DC motors, they all have the inherent limitations of DC motors. For example, due to the soft mechanical characteristics, it is necessary to form a speed closed loop, so the structure is complex, and the printing and dyeing plant has poor environment, high temperature, many corrosive liquids (gases), which makes the motor have short service life, high failure rate, large maintenance, etc

our company's existing lmh201a-180 clip mercerizing machine, Italian Arioli loose washing machine (sub power mode), Kyoto flat width color rendering soap washing in Japan, 5. The time machine that can be maintained by the automatic timing belt under the specified load, and R-type refining machine in Shandong Iron Institute of Japan need to be transformed due to the above limitations of the DC synchronous drive system and the process capacity problems

II. Selection and characteristics of AC variable frequency synchronous speed regulation mode

fully enclosed asynchronous motors are most suitable in the environment of high temperature and corrosive liquid (gas) in printing and dyeing plants. The development of AC variable frequency speed regulation technology also lays a foundation for the application of asynchronous motor in multi motor synchronous drive system. After comparison and selection, we selected samco-i series frequency converter of Sanken company. It solves the problems of poor reliability, small speed regulation range, weak synchronous performance and large maintenance of the original DC speed regulation system. Taking the samco-i series frequency converter of Sanken company as an example, the intelligent power module with drive circuit, overcurrent protection and high temperature protection circuit is adopted in its main circuit, the high-speed 32-bit reduced instruction microprocessor RISC is adopted as the CPU in its control circuit, and the ultra-high density large-scale integrated circuit is adopted. In terms of control mode, it is equipped with high-performance "speed sensorless control mode" and good high-performance v/f control mode. The low speed drive and high starting torque, which are difficult for ordinary frequency converters, can be realized. With this control mode, the frequency converter can drive the motor with more than 100% load torque from 1Hz. The starting torque can reach 150%, and the speed accuracy error of the motor is less than ± 1%, and the dynamic response is rapid

the good dynamic performance of DC motor is due to the magnetic flux of DC motor Φ And armature current ia can be controlled independently, which is a typical decoupling control. The ideal dynamic performance of AC asynchronous motor can be achieved by decoupling the magnetic field component and torque component of the stator current of asynchronous motor and controlling them separately by using vector control mode, imitating the control mode of DC motor

the vector control of asynchronous motor is based on the dynamic mathematical model, and the control quantity of equivalent DC motor is obtained through vector transformation Φ And IA, and then through inverse transformation, the three-phase currents IA, IB, IC of the asynchronous motor to be controlled can be obtained, that is, the asynchronous motor can be controlled by controlling the DC motor

speed sensorless control mode, through the motor parameters, motor voltage, motor current to complete the timing calculation of motor flux and speed, to achieve vector control

III. AC variable frequency speed regulation synchronous transmission principle

take our enterprise's transformation of Kyoto flat width color washing machine as an example. The process flow of the whole machine is: flat width feeding - horizontal two roll rolling car - reduction steamer - four grid stainless steel water washing tank - ventilation - soaking rolling steamer - small rolling car - soaking rolling steamer - small rolling car - soaking rolling steamer - small rolling car - ordinary washing tank - small and medium roll rolling car - three column dryer - Flat width cloth dropping

the original machine has a multi unit synchronous drive system composed of silicon controlled voltage regulator and fifteen DC motors. The synchronous control between DC motors is controlled by the elastic frame and maintains constant tension. The intermediate traction roller (ventilation frame, reduction steamer, etc.) adopts AC torque motor to reduce the tension difference of each part of the machine

after the transformation, the AC frequency conversion speed regulation synchronous transmission system uses small and medium-sized rolling cars as the main command unit, and the tension of the cloth can be stabilized by the mechanical part of the elastic frame (the cylinder has been used to replace the heavy hammer). The No. 10 rolling speed and the rolling speed of medium and small rollers are adjusted by the elastic frame, and the synchronous sensor is reversed

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