KR100910461B1 - Electromagnetic Vibration Control Apparatus for controlling vibration of plating strip using self-tuned PID control - Google Patents

Abstract

The present invention relates to an electromagnetic vibration suppression apparatus for controlling vibration of a plated steel sheet through self-tuning PID control. The electromagnetic vibration suppression apparatus of the present invention generates a low lens force by adjusting an amount of current flowing according to an input current amount control command. Electromagnets to suppress the vibration by restraining the strip to be plated and conveyed through the strength of the magnetic field generated through the magnetic pad; A gap sensor measuring a gap between the magnetic pad and the strip; A PID control unit controlling the amount of current flowing through the electromagnet according to target target moving distance information and controlling the amount of current flowing through the electromagnet based on PID (Information Integral Differential) gain information inputted thereafter; And calculating PID gain information for controlling gain of the PID controller required to suppress vibration of the strip based on the gap information between the magnetic pad and the strip measured from the gap sensor, and based on the calculated PID gain information. And a PID gain control unit for controlling the vibration of the plated steel sheet through a PID control to control the gain of the PID control unit. It can be suppressed.

Plating, steel plate, zinc, self-tuning, PID, vibration, vibration suppression

Description

Electromagnetic Vibration Control Apparatus for controlling vibration of plating strip using self-tuned PID control

1 is a view showing an installation example of a typical continuous hot dip galvanizing line (CGL) equipment,

2 is a view showing an example of the control configuration of the general vibration suppression apparatus according to FIG.

3 is a diagram showing the relationship between the natural frequency and the control frequency of the strip; and

4 is a diagram illustrating an electromagnetic vibration suppression apparatus for controlling vibration of a plated steel sheet in a continuous plating process of the steel sheet according to a preferred embodiment of the present invention.

The present invention relates to an electromagnetic vibration suppression method of a steel sheet in the continuous plating process of the steel sheet, and preferably, to an electromagnetic vibration suppression apparatus for a higher quality steel sheet plating process in the continuous plating process of the steel sheet.

In general, a magnetic hot dip galvanizing line (CGL) is provided with a magnetic pad (magnetic pad) which is an electromagnetic damping device for suppressing the vibration of the steel sheet. The vibration isolator is installed for the purpose of suppressing the vibration of the plated steel sheet (hereinafter referred to as a 'strip') transferred between the plating roll (Pot Roll) and the cooling tower roll (Cooling Tower Roll). Such a vibration damping device vibrates in the vibration damping area by shifting its position to the responsiveness difference and instability area when controlled by a constant PID (Proportional Integral Differential) according to the size, steel grade, and tension of the strip. It will be moved to the diverging area.

1 is a view showing an installation example of a typical continuous hot dip galvanizing line (CGL) equipment.

As shown, the continuous hot dip galvanizing line (CGL) facility includes a plating bath roll (1), a stabilizing roll (2), a correcting roll (3), and a cooling tower roll ( and a cooling tower roll 4, a strip 5 to be plated and conveyed, an air knife 6, and a vibration damping device 7.

Continuous hot dip galvanizing line (CGL) equipment is a process line equipment that produces plating strips. The most important equipment is a zinc pot, and there are three rolls (1, 2, 3) in the plating bath, which serve to coat zinc on the strip 5 and control the bending of the strip 5. Have There is an air knife 6 in the upper direction of the strip 5 of the plating bath, which serves to control the thickness of the galvanizing coating by sweeping off the zinc coated on the strip 5. On top of the air knife 6 there is a cooling tower roll 4 which serves to cool the strip 5.

The air knife 6 serves to scrape the zinc on both sides of the strip 5, so that the strip 5 is sandwiched between the two air knifes 6 to ensure a uniform plating thickness. Pass through the center. In addition, since the strip 5 vibrates freely in the form between the plated roll roll 1 and the cooling tower roll 4, it is necessary to suppress the vibration to uniform the strip 5. One plating thickness can be secured. Accordingly, in the continuous hot dip galvanizing line (CGL) facility, a touch roll is installed to suppress vibration of the strip 5. In the figure, a magnetic pad, which is a non-contact electromagnetic vibration damping device 7, is provided as such a touch roll.

In FIG. 1, the damping device 7 is installed between an air knife 6 and a cooling tower roll 4. The spanned strip 5 between the plated bath roll 1 and the cooling tower roll 4 is the wind pressure of the air knife 6 and the plated bath roll. The vibration is generated by the driving of the roll (1). In order to prevent such vibration of the strip 5, a vibration damping device 7 is provided.

FIG. 2 is a diagram showing a control configuration example of the general vibration suppression apparatus 7 shown in FIG. 1.

The vibration damping device 7 aims to suppress the vibration of the strip 5 between the plating roll roll 1 and the cooling tower roll 4, and the control method is PID (Proportional). -Integral-Differential (proportional-differential-integral) control method.

The PID control unit 71 is a method of proportionally and integrally controlling the error between the target value and the performance value. Herein, a method of controlling the error between the target value and the performance value proportionally is called a proportional gain, and a method of integrating and controlling the error between the target value and the performance value is called an integration gain. Conventionally, the vibration damping device 7 uses a constant PID method that does not change once the proportional gain and the integral gain of the PID control unit 71 are determined.

However, when controlled by a constant PID according to the size (size) of the strip (5), steel grade, and tension size, the response difference occurs. Then, when PID control is close to the natural frequency region of the strip 5, the control unit shifts to an unstable region, whereby the vibration of the strip 5 is generated and becomes unusable because the vibration is moved from the vibration suppression region.

As shown, when the set target travel distance (D_ref) information is input, the PID control unit 71 controls the amount of current flowing through the electromagnet 72, this current generates a low lens force to restrain the strip (5) to vibrate Will be suppressed. At this time, the response speed of the strip 5 is determined by the control gain of the PID controller 71.

3 is a diagram illustrating a relationship between a natural frequency of a strip and a control frequency.

As shown, when the PID control gain of the PID control unit 71 is increased, it is closer to the natural frequency of the strip 5, and as the control is performed, the vibration of the strip 5 is increased.

This is because the natural frequencies of the strips 5 on the cooling tower rolls 4 are evenly distributed over 1.0 to 20 Hz, and when using a touch roll, the safety rolls and This is because the natural frequency of the strip 5 between the touch rolls (3 mm) becomes 20 to 150 Hz.

In the case of using the vibration damping device 7, it is judged to occur when the natural frequency of the strip 7 and the control frequency of the vibration damping device 7 coincide. The natural frequency of the strip 5 is 20 to 150 Hz, and the PID control frequency of the vibration damper 7 is 100 Hz.

A first object of the present invention for solving the above problems is to provide an electromagnetic vibration suppression apparatus for a higher quality steel plate plating process in the continuous plating process of the steel sheet.

It is a second object of the present invention to provide an electromagnetic vibration suppression apparatus capable of performing a higher quality steel sheet plating process by controlling vibration as the plated steel sheet is transferred in the continuous plating process of the steel sheet.

Electromagnetic vibration damping device for controlling the vibration of the plated steel sheet through the self-tuning PID control according to an embodiment of the present invention for achieving the above object, by adjusting the amount of current flowing in accordance with the current amount control command input lens force Electromagnets to suppress the vibration by restraining the strip is plated and transported through the strength of the magnetic field generated through the magnetic pad; A gap sensor measuring a gap between the magnetic pad and the strip; A PID control unit controlling the amount of current flowing through the electromagnet according to target target moving distance information and controlling the amount of current flowing through the electromagnet based on PID (Information Integral Differential) gain information inputted thereafter; And calculating PID gain information for controlling gain of the PID controller required to suppress vibration of the strip based on the gap information between the magnetic pad and the strip measured from the gap sensor, and based on the calculated PID gain information. And a PID gain control unit for controlling the vibration of the plated steel sheet through a PID control to control the gain of the PID control unit.

Preferably, the PID gain control unit may control the PID gain information parameter for controlling the gain of the PID control unit so as to be controlled under the condition that the vibration of the strip becomes '0' based on the interval information between the magnetic pad and the strip. Estimate in real time.

"(여기서, i : 전자석의 전류량, Xn : 무차원화된 간격량, A_n,B_n,C_n : 선형화된 2차 함수의 계수 값)이 되어, 상기 선형화된 2차 함수의 계수값(A_n,B_n,C_n)을 각각 '0'이 되도록 상기 PID 제어부를 제어한다. The PID gain control unit calculates a coefficient of the amount of current of the electromagnet according to the interval information between the magnetic pad and the strip in the second linear system, where the amount of current i in the electromagnet is "

(Where i is the amount of current in the electromagnet, Xn is the dimensionless spacing, A _n , B _n , C _n is the coefficient value of the linearized quadratic function) _n , B _n , C _n ) are respectively controlled to be '0'.

"(여기서, e(t)는 시간 t에서의 상기 자기 패드와 상기 스트립 간의 간격 오차로서 D_ref(t)가 시간 t에서의 상기 자기 패드와 상기 스트립 간의 목표 간격이고 D_fb(t)가 시간 t에서의 상기 자기 패드와 상기 스트립 간의 실제 간격일 때 e(t)=D_ref(t)- D_fb(t)로 정의되고, e(t-1)는 일정간격 이전시간인 t-1에서의 상기 자기 패드와 상기 스트립 간의 간격 오차이며, K_p : 비례제어게인, K_i : 적분제어게인, K_d : 미분제어게인)으로 나타낼 수 있다.The value? U (t) output from the PID control unit under the control of the PID gain control unit is "

(Where e (t) is the gap error between the magnetic pad and the strip at time t, where D_ref (t) is the target distance between the magnetic pad and the strip at time t and D_fb (t) is at time t Where e (t) = D_ref (t) −D_fb (t) when the actual distance between the magnetic pad and the strip of is defined, e (t-1) is the magnetic pad at time t-1 before a certain interval And the gap error between the strip and K _p : proportional control gain, K _i : integral control gain, and K _d : differential control gain).

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According to the present invention, a parameter for controlling the gain of the PID controller to measure the distance between the strip and the magnetic pad by using a gap sensor to control the vibration to a condition of '0' through the geo-tuned PID gain controller in real time. By suppressing the difference in responsiveness and transition to an unstable area generated by controlling the PID control unit by controlling it through the self-tuning self-tuned PID control unit, suppression of vibration caused by the vibration control device control error throughout the entire area can do.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are represented by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

In the present invention, the natural frequency of the steel sheet and the control frequency (bandwidth) of the vibration suppression controller when the vibration suppression apparatus is used as a way to suppress the resonance of the steel sheet when using the vibration damper. The natural frequency of the steel sheet varies depending on the tension of the steel sheet, the size of the steel sheet, and the position of the vibration damper. Here, the size of the steel sheet is not controllable because it is an uncontrollable operating condition, the tension of the steel sheet can be varied within a predetermined range, the position (installation height) of the vibration damper may be limited according to the field working environment. The natural frequency of the steel sheet is a factor that can control the tension. The natural frequency of the steel sheet can be changed by changing the control frequency of the vibration suppression controller. However, since it is practically difficult to manufacture a new device, it is possible to change the control frequency of the vibration suppression controller.

In other words, in order to change the control frequency, the natural frequency for each steel plate size when using the vibration damper must be calculated in advance. If it is determined, the control frequency (ie PID gain) of the vibration suppression controller should be changed and set optimally according to the size of the steel sheet in earnest. In the present invention, the self-tuning PID control, which is one of the adaptive control techniques, is automatically changed without performing such a series of procedures one by one, thereby automatically changing the optimum control frequency (PID gain).

4 is a diagram illustrating an electromagnetic vibration suppression apparatus for controlling vibration of a plated steel sheet in a continuous plating process of the steel sheet according to a preferred embodiment of the present invention.

The illustrated electromagnetic vibration damper detects the gap between the magnetic pad and the strip 5 at three positions of both edges and the sensor by using the existing gap sensor 140. By using the detected gap to configure the force of the strip 5 as a self-tuning control system, it is intended to improve the performance of the vibration suppression apparatus. To this end, we implement a mathematical model between the gap and the magnetic force applied to the strip 5, and based on this, the vibration control controller design parameters are constructed to control the system. At this time, since the force applied to the strip 5 is proportional to the amount of current of the electromagnet 120, it is replaced by the amount of current that is easy to measure.

In order to obtain a mathematical model between the interval information detected by the three sensors of the gap sensor 140 and the output of the amount of current applied to the electromagnet 120, the system is estimated using the input and output data, assuming the order and shape of the model. Use model identification techniques.

Assuming that the coefficient of the amount of current of the electromagnet 120 according to the input of the interval information is a secondary linear system, the amount of current in the electromagnet 120 can be expressed as Equation 1 below. Every time I / O data is sampled during operation, the system is estimated on-line to adapt to changes in the system.

Here, i: current amount of electromagnet, Xn: dimensionless spacing amount, A _n , B _n , C _n : coefficient value of linearized quadratic function.

Substituting the current value measured in each width direction position into Equation 1 can be expressed as Equation 2 below.

At this time, when equation 2 is solved in a row, equations 3 and 3 can be obtained for B _n and C _n .

At this time, if B _n and C _n can be controlled to be '0', the vibration of the strip 5 is suppressed.

The output of the discrete speed type PID control unit 110 used in the embodiment of the present invention can be expressed as Equation 4 below.

Here, when Z is the Z conversion symbol of the digital control, Δ = 1-Z- ¹ , and e (t) is an interval error between the magnetic pad and the strip at time t and D_ref (t) at time t. E (t) = D_ref (t) −D_fb (t) when e is the target spacing between the magnetic pad and the strip and D_fb (t) is the actual spacing between the magnetic pad and the strip at time t, e ( t-1) is a gap error between the magnetic pad and the strip at t-1, which is a predetermined time interval, K _p : proportional control gain, K _i : integral control gain, and K _d : differential control gain.

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 In the present invention, by using the gap sensor 140, not the size and steel grade, the size of the steel sheet as the input of the interval information between the strip 5 and the magnetic pad 130 as a PID to be controlled under the condition that the vibration is '0' By real-time estimating the parameter for controlling the gain of the control unit 110 through the synchronous tuning PID gain control unit 150, self-tuning self tuning that cannot be gained by a certain PID is possible. In this way, one can set the PID's control gain without having to experiment with strip size, steel grade and tension.

In the above, specific preferred embodiments of the present invention have been illustrated and described. However, the present invention is not limited to the above-described embodiments, and any person having ordinary skill in the art to which the present invention pertains may make various modifications and other equivalents without departing from the gist of the present invention attached to the claims. Implementation will be possible. Therefore, the true technical protection scope of the present invention should be defined only by the appended claims.

According to the present invention described above, by using a gap sensor to measure the distance between the strip and the magnetic pad through the parameter to control the gain of the PID control unit so that the vibration is controlled to a condition that is '0' By controlling the PID controller by real time estimation through the self-tuning self-tuned PID controller, there is no difference in responsiveness and transition to an unstable area, and vibration is generated due to vibration control device error in the entire area. Can be suppressed.

Claims (5)

An electromagnet which suppresses vibration by restricting a strip which is plated and transferred through the intensity of a magnetic field generated by generating a low lens force by adjusting a current amount flowing according to an input current amount control command; A gap sensor measuring a gap between the magnetic pad and the strip; A PID controller for controlling an amount of current flowing through the electromagnet; And Calculates PID (Proportional Integral Differential) gain information for controlling gain of the PID control unit required to suppress vibration of the strip based on the gap information between the magnetic pad and the strip measured from the gap sensor, and calculates the PID A PID gain control unit for controlling vibration of the plated steel sheet through a self-tuning PID control for controlling the gain of the PID control unit based on gain information; Including, The PID control unit initially controls the amount of current flowing through the electromagnet according to the initially set target moving distance information, and then controls the amount of current flowing through the electromagnet based on the PID gain information calculated by the PID gain control unit. Vibration damping device. The method of claim 1, The PID gain control unit, An electromagnetic parameter for estimating in real time the PID gain information parameter for controlling the gain of the PID controller so as to be controlled under the condition that the vibration of the strip becomes '0' based on the interval information between the magnetic pad and the strip Vibration damping device. The method of claim 2, The PID gain control unit, According to the spacing information between the magnetic pad and the strip, the coefficient of the amount of current of the electromagnet is determined in a linear system, where the amount of current i in the electromagnet is "

(Where i is the amount of current in the electromagnet, Xn is the dimensionless spacing, A _n , B _n , C _n is the coefficient value of the linearized quadratic function) _n , B _n , C _n ), respectively, to control the PID control unit to be '0'. The method of claim 3, wherein The value? U (t) output from the PID control unit under the control of the PID gain control unit is "

(Where e (t) is the gap error between the magnetic pad and the strip at time t, where D_ref (t) is the target interval between the magnetic pad and the strip at time t and D_fb (t) is at time t Where e (t) = D_ref (t) −D_fb (t) when the actual distance between the magnetic pad and the strip of is defined, e (t-1) is the magnetic pad at time t-1 before a certain interval And the gap error between the strip and K _p : proportional control gain, K _i : integral control gain, and K _d : differential control gain. delete

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