Application of the hottest frequency converter in

2022-10-16
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Application of frequency converter in galvanized steel plate production line

key words: vector control synchronous control tension winding

1 introduction

in the control system selected for metal processing and production, the DC control system has occupied most of the market by virtue of its advantages such as hard torque characteristics and wide speed regulation range, but the DC control system also has the following weaknesses: large one-time investment, heavy workload of equipment maintenance, High quality requirements for maintenance personnel, etc. Many small enterprises often affect the normal operation of production due to their lack of technical strength or spare parts supply

the transmission system composed of Huichuan high-performance vector control frequency converter and ordinary asynchronous motor, in addition to the advantages of DC control system, at this time, the equipment will operate automatically, but also reduces the initial investment cost of the equipment, reduces the power loss of the factory, makes the equipment simple to operate and convenient to maintain, thus creating value for customers, and then obtains more and more development space in this field

2 galvanizing production process

hot rolled steel plates produced by steel mills are usually sold to galvanizing mills and then processed through the following processes: pickling, cold rolling, annealing, galvanizing. The process flow of galvanizing production line is shown in Figure 1

generally speaking, in the process from "surface treatment" to "winding", the production process has the following basic requirements for the control system:

(1) the synchronization of the system is required to be high, otherwise the plate will be broken

(2) the response characteristics of the system should be fast

(3) the tension on the material surface can be adjusted by the control system

in the past, DC control system was used to meet these requirements of production process

3 control scheme of frequency converter applied in galvanizing production line

the process from "surface treatment" to "winding" is shown in Figure 2

in Figure 2, "traction 1", "traction 2", "traction 3" and "winding" are all controlled by frequency converter and ordinary asynchronous motor. The following briefly introduces the implementation process of the frequency conversion control scheme:

traction frequency converter 1 and traction frequency converter 3 work in the open-loop vector control state to determine the running speed of the whole production line. The speed of the two transmission points is basically the same through one active and one driven, Rely on the "storage" function of the looper to balance the requirements of synchronization

the traction converter 2 works in the torque control mode and operates independently. The analog potentiometer signal is used as the torque control signal to ensure that the tension between traction 1 and traction 2 can be set at will according to the user's requirements

the winding part adopts md330 frequency converter with winding diameter calculation function for torque control to ensure the tension control requirements between traction 3 and winding

traction frequency converter 1 and traction frequency converter 3 adopt open-loop vector control mode, traction frequency converter 2 and winding frequency converter adopt closed-loop vector control mode with encoder closed-loop feedback

the control principle block diagram of frequency converter is shown in Figure 3

4 "traction frequency converter 2" torque control commissioning method

(1) setting of relevant parameters without load on the motor

correctly input relevant parameters of the motor without load on the motor for tuning operation. The relevant parameter settings are shown in Table 1

Table 1 setting of relevant parameters without load on the motor

serial number parameter type value description

1 f1--01 actual value input -- motor rated power

2 f1--02 actual value input -- motor rated voltage

3 f1--03 actual value input -- motor rated current

4 f1--04 actual value input -- motor rated frequency

5 f1--05 actual value input -- motor rated speed

6 f1--11 2 put this parameter Set it to 2, press the run key to conduct complete tuning of the motor

after tuning, press the run key to check the working current of the motor through the operation panel, and check whether the open-loop vector control operation of the frequency converter is normal (the factory setting of the frequency converter is the open-loop vector control operation of the frequency converter)

(2) connect the encoder wire correctly

set F to 1, correctly input the number of encoder pulses (set by F) for stretching, tightening, bending, tearing, shearing, 180 degree stripping and 90 degree stripping experiments, and press the run key to check whether the closed-loop vector operation of the frequency converter is normal. Check the working current of the motor at high speed and low speed through the operation panel. If the working current exceeds the rated current or the motor cannot run, check whether the wiring of the encoder is correct, whether the signal lines of phase A and phase B are connected reversely, whether the encoder and the motor shaft are concentric, and the relevant parameter settings are shown in Table 2

(3) setting of other functional parameters after the closed-loop vector operates normally

after the closed-loop vector operates normally, set other functional parameters, as shown in Table 3

Table 3 other function parameter settings

serial number parameter type numerical description

10 f0--02 1 terminal control is effective

11 F 8 set the acceleration time (set according to the actual situation)

12 F 8 set the deceleration time (set according to the actual situation)

13 F 1 torque control is effective

14 F 1 torque upper limit source Ai1

15 F 1 di1 is set as forward rotation command

16 F 4 di2 is set as inching signal

17 f 9 di3 is set as fault reset

18 F 2 stop key reset function is effective

5 winding frequency converter constant tension control debugging method

tension debugging is carried out after the frequency converter closed-loop vector debugging is completed according to the above method. The tension control parameter settings are shown in Table 4.Show

Table 4 tension control parameter settings

serial number parameter type numerical description

1 fh-00 1 open loop torque control mode

2 fh-01 0 winding control

3 fh-03 calculated value mechanical transmission ratio

4 fh-04 2 AI2 gives potentiometer signal for tension

5 fh-06 calculated value maximum tension

6 fh-07 10% zero speed tension rise, set according to the actual situation

7 fh-09 20% tension taper

fh-10 0 calculate the winding diameter through the line speed

8 FH-11 actual value maximum winding diameter

9 FH-12 actual value winding shaft diameter

10 FH-13 0 initial winding diameter source is set by fh-12~fh-15

11 fh-27 1 line speed input signal selects Ai1, and the Ao output of the previous

level frequency converter

12 fh-28 calculated value maximum linear speed

13 fh-33 1000 mechanical inertia compensation coefficient

14 fh-34 7800 material density

15 fh-35 1000 material width

16 fh-36 8% mechanical friction coefficient compensation

6 debugging instructions

(1) torque control mode refers to that the frequency converter controls the torque of the motor, not the frequency, and the output frequency changes automatically with the speed of the traction motor

(2) according to the formula f=t/r (where f is the material tension, t is the torque of the winding shaft, and R is the winding radius), it can be seen that if the torque of the winding shaft can be adjusted according to the change of the winding diameter, the tension on the material can be controlled, which is the basis for tension control in the open-loop torque mode

(3) MD series frequency converter can accurately control the motor output torque under closed-loop vector control (with speed sensor vector control). Using this control mode, encoder must be installed (the frequency converter should be equipped with PG card)

(4) in actual use, the set value of tear load (n) or tear strength (kn/m) of the tension measurement sample should correspond to the actual situation of the material used and the requirements of crimping forming, which should be set by the user. Tension taper can control the tension to decrease with the increase of coil diameter, which is used to improve the effect of winding forming

(5) during acceleration and deceleration, part of the output torque of the motor is used to overcome the rotational inertia of the winding roll. The inertia compensation part of the frequency converter can automatically compensate the torque according to the acceleration and deceleration rate through appropriate parameter settings, so that the system can still obtain stable tension during acceleration and deceleration. Friction compensation can overcome the influence of system resistance on tension

(6) traction 1 motor and traction 3 motor work in power generation state for a long time. Traction 1 frequency converter and traction 3 frequency converter must be equipped with braking unit and braking resistance to consume the energy fed back by the motor, otherwise the voltage on the DC bus of the frequency converter will exceed the voltage range limited by the frequency converter and alarm and shutdown

7 conclusion

the frequency conversion control scheme is adopted to replace the traditional DC drive control scheme, which makes the control system simple to operate, very convenient and fast to debug, and the control performance can fully meet the process requirements, reducing the investment cost of users, reducing the amount of equipment maintenance, and reducing the power loss, which is highly praised by users. (end)

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