Application of Emerson frequency converter and pro

  • Detail

Application of Emerson Inverter and programmable controller on sizing machine

Abstract: Emerson tension inverter and programmable controller do constant tension winding control on sizing machine to reduce equipment wear. Ensure the stability and convenience of equipment winding

I. system overview

the application of Emerson PLC and frequency converter in sizing machine. This electrical system adopts PLC centralized management, decentralized control, centralized system, simplicity, strong controllability, and better reduce the failure rate

the scheme configuration is as follows:

plc system is composed of Emerson ec202416bar main module, 16 point digital input module and 4-channel analog output module

the operation interface adopts industrial LCD touch screen, which can dynamically modify the control parameters, so as to facilitate the display of the current speed, current race length, number of races and the dynamic operation state of the system

the side shaft motor frequency converter adopts the EV2000 series of high-performance universal type, and the weaving shaft winding TD3300 22KW tension frequency converter. This frequency converter is a special frequency converter for tension, with built-in tension control function. The independent frequency conversion mode is adopted, with simple structure, convenient maintenance and high stability, which ensures the tension and linear speed of winding, and is stable and reliable in the change process from small coil to large coil. The automatic compensation control in the acceleration and deceleration makes the tension more stable in the acceleration and deceleration. The operation experimental method is differentiated, and there is also a winding anti breaking procedure, which makes it easy to operate when winding up

advantages of this system:

· tension setting is set on man-machine, humanized operation

· use advanced control algorithm: recursive operation of winding diameter; The linear increase of tension when the hollow winding diameter is activated; Application of tension taper calculation formula; Dynamic adjustment of torque compensation, etc

· the real-time calculation of winding diameter has very high accuracy, which ensures the smooth performance of the output torque of the winding motor. In addition, the recursive operation of winding diameter is added in the calculation of winding diameter, so that when the operation is wrong, the winding diameter can be corrected to the correct value by itself

· because the moment of inertia of the winding device is very large, when the winding diameter changes from small to large. If the operator accelerates, decelerates, stops and reactivates, it is easy to cause yarn bursting and loosening, which will directly lead to yarn quality. After the transformation of variable frequency winding, the winding is very stable and the tension is always constant under the above conditions. Moreover, after the processing of PLC, some dynamic adjustment measures are added in the specific dynamic process to make the winding performance better

· on the basis of traditional mechanical transmission winding, it is transformed into frequency conversion winding, which is very simple and low cost, and there is basically no need to transform the original machinery. The transformation cycle is short, and basically the installation and commissioning can be completed in twoorthree days

· overcome the disadvantages of mechanical wear caused by mechanical winding, and prolong the service life of the machine. It is convenient to maintain the equipment

· all operating parts on the machine adopt safe electricity below 36V to ensure safety in operation

II. System block diagram

III. tension control principle

the so-called tension control, generally speaking, is to control how much force the motor outputs, that is, how many Newtons it outputs. The output torque of the motor can be controlled by reacting to the motor shaft. The real tension control is different from the system that forms tension by the speed difference between the front and rear power points. The essence of adjusting tension by speed difference is the PID control of tension, and tension sensors should be added. And in the large and small winding 2, the software functions of the tensile stripping experimental machine, such as moving, stopping, accelerating, decelerating and stopping, can not be adjusted like the effect of real tension control, and the tension is not very stable. It will definitely affect the quality of products

the essence of variable frequency winding is to complete tension control, that is, to control the running current of the motor, because the output torque of three-phase asynchronous motor t=cm φ Mia, which is proportional to the current. And when the load has a sudden change, it can ensure that the mechanical characteristic curve of the motor is relatively hard. Therefore, vector converter must be used, and encoder closed-loop control must be added. The essence of constant tension control with frequency converter is dead cycle vector control, that is, adding encoder feedback. The winding warp of winding changes from small to large. In order to ensure constant tension, it is required that the output torque of the motor should change from small to large when the transmission temperature of the motor is 6 ℃. At the same time, the corresponding torque compensation should be carried out in different operation processes. That is, customers will have such concerns when they have not purchased the experimental machine. At the moment of starting the small coil, accelerate, decelerate, stop, and start the large coil, different torque compensation should be carried out at different winding times, so as to make the whole process of winding very stable and avoid excessive tension during the small coil; The yarn loosens when the big roll is started

· calculation principle of winding diameter

calculate the winding diameter of winding according to v1=v2. Because v1= ω one × R1, V2= ω two × Rx。 Because in the same time, the length of the yarn passed by the length measuring roller is equal to the length of the yarn received by the winding. I.e. L1/Δ t=L2/Δ t, Δ n1 × C1= Δ n2 × C2/i

( Δ N1 --- number of cycles of traction motor in unit time Δ N2 --- the number of turns of the winding motor in unit time, C1 --- the perimeter of the length measuring roll, C2 --- the perimeter of the winding pan head, I --- the reduction ratio)

Δ n1 × π × D1= Δ n2 × π × D2/i

D2= Δ n1 × D1 × i/Δ N2, because Δ n2= Δ P2/P2

( Δ P2 --- the number of pulses generated by the winding encoder, P2 --- the number of turns of the winding encoder). Δ n1= Δ P1/p1 take Δ N1=1, that is, the length measuring roll rotates one circle, and the encoder is connected to the PLC. Then d2=d1 × i × P2/Δ P2. In this way, the winding diameter of the winding pan head is obtained

· analysis of the dynamic process of winding

to ensure the stability of the winding process, whether it is large winding, small winding, acceleration, deceleration, activation, parking can ensure the constant tension. Torque compensation is required. To activate the whole system, we must first overcome the torque generated by static friction, which is called static friction torque for short. Static friction torque only works at the moment of activation; In normal operation, it is necessary to overcome the sliding friction torque generated by sliding friction. The sliding friction torque always exists in operation, and its size is different at low speed and high speed. Compensation of different sizes is required. In order to overcome the inertia of the system when the system accelerates, decelerates and stops, corresponding torque compensation should also be carried out. The amount of compensation also has a corresponding proportional relationship with the running speed. At different speeds, the compensation coefficient is different. Namely, acceleration torque, deceleration torque, parking torque and activation torque; Overcome these factors, but also overcome the load torque. Divide the calculated real-time winding diameter by 2, multiply it by the set tension, and convert it to the motor shaft through the reduction ratio. In this way, the torque compensation process of the whole winding process is analyzed

summary: output torque of motor = static friction torque (activation moment) + sliding friction torque + load torque

· compensation standard of torque

1) compensation of static friction torque

because static friction torque only exists at the moment of activation, it disappears after the system is activated. Therefore, the static friction torque is compensated by multiplying the calculated motor output torque by a certain percentage

2) compensation of sliding friction torque

compensation of sliding friction torque plays a role in the whole process of system operation. The compensation is based on the rated torque of the winding motor. The magnitude of compensation is related to the speed of operation. Therefore, when processing in the program, it is necessary to compensate in segments

3) compensation of acceleration, deceleration and parking torque

compensation the rated torque of hard winding motor is the standard, and the corresponding compensation coefficient should be relatively stable with little change

· relevant calculation formula

IV. commissioning process

(1) first carry out self-tuning of the motor, and read the stator inductance, stator resistance and other parameters of the motor into the frequency converter

(2) connect the encoder signal to the frequency converter and set the number of turns of the encoder on the frequency converter. Then use the panel to set the frequency and start/stop control, and observe whether the displayed operating frequency fluctuates around the set frequency. Because the operating frequency is always close to the set frequency when using closed-loop vector control, the operating frequency fluctuates near the set frequency

(3) set the values of hollow core winding diameter and maximum winding diameter in the program. Calculate the maximum pulse (P2) and the minimum pulse (P2) generated by the encoder at the end of the motor through the formula of the previous winding diameter calculation. The speed of the winding motor is limited by the calculated maximum pulse amount, because if the maximum speed is not limited when the frequency converter is used as tension control, the winding motor will fly in case of yarn breakage. The lowest impulse is to avoid that the winding frequency converter operates below 2Hz, because when the frequency converter operates below 2Hz, the torque characteristic of the motor is very poor and jitter will occur

(4) through the dynamic process of the whole winding analyzed above, certain torque compensation is carried out in various stages of different winding diameters and different running speeds. The compensation is set as a percentage of the rated torque of the motor

v. parameter summary table attached table 1: TD3300 function parameter summary table

conclusion: as technology updates faster and faster, we must improve product performance so that our products can meet our process requirements. (end)

Copyright © 2011 JIN SHI