JP3137449B2 - Adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to P, PI or PID
(P: proportional, I: integral, D: differential) The present invention relates to an adjusting device that performs feedback control of a controlled object while executing a calculation operation, and particularly realizes an appropriate function of a proportional calculation operation and a proportional function when a speed type calculation method is used. The present invention relates to an adjusting device for improving a response characteristic according to a change in a gain.

[0002]

2. Description of the Related Art Generally, in such an adjusting device,
Leads to the target value SV _n and the controlled variable PV _n obtained from the controlled object to the deviation operation means, where e _n = SV _n -PV _n

[0003] comprising computing the removed error signal e _n by performing, introduced into velocity type regulation computing means. This adjustment calculating means, P for the deviation signal e _n for each predetermined sampling period, and executes calculation operation such as PI, after obtaining the velocity type adjusting operation signal △ MV _n, signals this adjustment operation signal △ MV _n Introduce to conversion means. Here, the signal conversion means: MV _n = MV _n-1 + △ MV _n

[0004] made into a position type adjustment signal by performing a calculation, applied to the controlled object to the position type regulating signal as an operation signal MV _n, the deviation signal _{e n = SV n -PV n =} 0
Is controlled so that That is, control is performed such that target value SV _n = control amount PV _n .

[0005]

By the way, in the conventional digital control system, the above-mentioned speed-type adjustment calculation method is frequently used. At this time, the basic speed-type calculation expression is as follows. It is represented by That is, when the P _{control, △ MV n '= K (} e n -e n-1) is represented by ... (1), whereas, when the PI _{control, △ MV n "= K {} (e n -e _n-1 ) + (1 / T _I ) en _n (2)

[0006] In the above formula _{△ MV n ', △ MV n} ": velocity type regulating operation signal, K: proportional gain, e _n = SV _n -P
V _n : current deviation, e _n-1 : previous deviation, T _I : integration time. However, when the above arithmetic expression is used, the following problem occurs.

[0007] b. While in the case of P computation operation only the steady-state deviation as shown in FIG. 2 occurs, the sampling time △ t _n-1 in this case for example the deviation signal, △ t each deviation e _n-1 of _n,
e _n is the same value, as a result, a substantially constant difference continues non-zero at each sampling _{point, (e n -e n-1} )
= 0 since the (1) be obvious by changing the proportional gain K to the equation _{△ MV n '= K (e} n -
e _n-1 ) = 0, and an adjusting device using only P control cannot be realized.

[0008] b. The same applies to the PI calculation operation. When there is a steady-state deviation, even if the proportional gain K is changed,
As described above, the output of the proportional operation becomes invariable,
The effect of the gain change does not appear in the proportional operation at all, but only the integral operation. Therefore, not only the response of the control becomes very slow, but also the proportional gain K
It is also possible to twist the integral calculation operation to modify the then load conditions or changes in process, or when the control characteristic is changed, on the contrary (e _n -e _n-1) too effectiveness Can be very dangerous and cause an accident.

The present invention has been made in view of the above circumstances, and can improve the response by changing the proportional gain even when a steady-state error occurs, and can perform any one of P-speed control, PI control, and PID control. It is an object of the present invention to provide an adjusting device capable of realizing the above.

[0010]

According to a first aspect of the present invention, a speed type adjustment operation is performed based on a deviation between a target value and a control amount from a control object.
In adjusting device the obtained velocity-type regulating operation signal is converted into a position type regulating signal applied to the controlled object as the operation signal, as the velocity type regulating computation _{operation, △ MV n = K n ·} e n -K n- _{1 · e n-1 ...... (} 3) or △ is _{MV n = P n -P n-} 1 ...... (4) composed of P (proportional) regulation device provided with a velocity type adjusting operation means for performing arithmetic operations. Next, the invention corresponding to claim 2, as the velocity type regulating computation _{operation, △ MV n = (K n} · e n -K n-1 · e n-1) + (1 / T I) K n · e _n ...... (5) or _{△ MV n = (P n -P} n-1) + (1 / T I) P n ...... made (6) PI (P: proportional, I: integral) arithmetic operation It is provided with a speed-type adjustment calculating means for performing.

However, in the above equations (3) to (6), △
MVn: speed-type adjustment calculation signal, Kn: current proportional gain, Kn-1: previous proportional gain (Kn-1ｎKn)
) , En: current deviation, en-1: previous deviation, Pn = Kn.en: current proportional operation output, Pn-1: previous proportional operation output.

[0012]

Accordingly, the invention corresponding to claim 1 employs the means described above to execute the P calculation operation of the equations (5) and (6) based on the deviation between the target value and the control amount. By doing so, by changing the previous proportional gain and the current proportional gain, the current proportional operation output becomes larger than the previous proportional operation output, and it works in the direction to remove the steady-state deviation. As a result, the responsiveness of the control can be improved, and a speed-based calculation method using only the P control can be realized.

Next, the same applies to the invention corresponding to claim 2, wherein the speed type adjustment operation is performed as described in (7).
If the PI calculation operation of the equations (8) and (8) is performed, the change in the proportional gain causes the current proportional calculation operation output to be larger than the previous proportional calculation operation output, thereby improving control responsiveness.
It is possible to realize a speed type calculation method of PI control.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. This adjusting device has the same configuration as the conventional one, as shown in FIG. That is, the deviation calculating means 12 calculates the target value SV _n and the control amount PV _n obtained from the control target 11.
The lead, wherein the removed error signal e _n by performing a e _n = SV _n -PV _n ...... made (7) operation, is introduced into velocity type regulation computing section 13.

[0015] constant in the velocity type regulating calculating means 13, a predetermined sampling (operation) P for each period for the deviation signal e _n, executes the arithmetic operation such as PI, as described later as an arithmetic method of this time and requests the velocity type adjusting operation signal △ MV _n by performing a proportional computation operation that immediately changes when subjected to changes of the proportional gain K, even upon occurrence of deviation. Then, signal conversion means 1 a velocity type adjusting operation signal △ MV _n obtained by the velocity type regulating calculating means 13
4 where MV _n = MV _n-1 + △ MV _n (8)

[0016] comprising computing by performing converted into a position type regulating signal MV _n, is applied to the controlled object 11 as an operation signal MV _n, and controls so that the deviation signal _{e n = SV n -PV n =} 0 configuration It is. Next, the calculation operation of the speed type adjustment calculation means 13 which is a main part of the apparatus of the present invention will
A description will be given using the I control as an example. First, the basic arithmetic expression of the entire PI control system is represented by MV = K {e + (1 / T _I ) edt} + MV ₀ (9) Here, MV: position type adjustment signal, MV ₀ : initial value of position type adjustment signal, e: deviation (SV−PV),
T _I : integration time.

Therefore, it can be said from the above equation that the adjustment operation output of the adjustment operation means 13 is the sum of the proportional operation operation output proportional to the deviation e and the integral operation operation output proportional to the integral of the deviation e. Become. Therefore, the mathematical expression is analyzed based on the expression (9), and the difference between the conventional device and the present invention will be described. In the case of the conventional device, the proportional gain K
Is treated as one constant. Based on this idea, when time-differentiating the equation (9), dMV / dt = K {(de / dt) + (1 / T _I ) e} (10) It is represented by Here, regarding the above equation, a minute section of the time axis △
When approximated by t,

[0018]

(Equation 1) It is represented by Here, the suffix n indicates the current time, and n
-1 indicates the previous time point. Further, substituting the expression (11) to _{(10), △ MV n "= K {} (e n -e n-1) + (1 / T I) e n} ... (12) becomes, which Is the same as the equation (2) explained in the conventional device, while the device of the present invention treats the proportional gain K as one variable and performs time differentiation in the same manner as in the conventional device, resulting in dMV / dt = {D (K · e) / dt} + (1 / T _I ) · (K · e) (13) Therefore, approximating this equation (13) in a minute section on the time axis,

[0019]

(Equation 2) Substituting the obtained equation (14) into the equation (13), ΔMV _n = (K · e) _n − (K · e) _n-1 + (1 / T _I ) · ( K · e) _n (15) And this equation (15) is

[0020]

(Equation 3) Equation (16) can be expressed as (15)
Substituting the equation, △ MV _n = become _{K n · e n -K n-} 1 · e n-1 + (1 / T I) K n · e n ...... (17). _{Further, K n · e n = P} n Distant, placing the previous value and _{P n-1, △ MV =} P n -P n-1 + (1 / T I) P n ...... (18) Become like Therefore, according to the configuration of the embodiment as described above, problems a and b of the conventional device can be solved. First, the problems Lee, from the equation (17) in the case of a P control _{only, △ MV n = K n ·} e n -K n-1 · e n-1 ...... (19)

## EQU2 ## Here, considering the steady-state deviation occurs, although e _n and e _n-1 are both substantially constant value other than zero, if the variable proportional gain K for each calculation cycle, the (19) proportional when the gain K is increased _{from, K n · e n> K} n-1 · e n-1 ...... (20)

Thus, the change in the proportional gain K is correctly reflected in the P control. That is, the speed-type adjustment calculation means 13 can realize the speed-type calculation method of the P control alone.

Next, it goes without saying that the same applies to the problem b. That is, _assuming that the proportional gain K is a constant, the proportional gain at each calculation time is K = K _n = K _n-1
, And when the steady-state deviation occurs, that is, when _en and e _n-1 are constant values other than zero, the proportional gain K increases in the time section between n and n + 1. changing to, K _n> K _n-1, and becomes a turn _{K n · e n> K n} -1 · e n-1 the relationship. Therefore,
When the proportional gain K is changed at the time of the steady-state deviation, the proportional operation is immediately performed, and the function is performed in a direction to remove the steady-state error. The problem that causes an unexpected accident can be solved by correcting the problem. In the above embodiment, the P control and the PI control have been described. However, it goes without saying that the same can be applied to the PID operation including the P operation. In addition, the present invention can be implemented with various modifications without departing from the scope of the invention.

[0024]

As described above, according to the present invention, if the proportional gain is changed at the time of the steady-state deviation, the P or PI calculation operation output functions in the direction of eliminating the steady-state deviation, and thus the control by changing the proportional gain is performed. The response can be speeded up, and it can be realized by any one of the P-type control, the PI control, and the PID control. Therefore, if such an adjusting device is applied to various parts of a plant, the operating performance of the plant can be enhanced, and this greatly contributes to various control fields.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control system showing an embodiment of an adjusting device according to the present invention.

FIG. 2 is a diagram illustrating control characteristics when a steady-state deviation occurs in a conventional device.

[Explanation of symbols]

11: control target, 12: deviation calculation means, 13: speed type adjustment calculation means, 14: signal conversion means.

Claims (2)

(57) [Claims] 1. A speed-type adjustment calculation operation is performed based on a deviation between a target value and a control amount from a control target, and the obtained speed-type adjustment calculation signal is converted into a position-type adjustment signal, and the control signal is obtained as an operation signal. In the adjustment device applied to the object, a speed type in which a P (proportional) calculation operation of ΔMVn = Kn · en−Kn−1 · en−1 or ΔMVn = Pn−Pn−1 is performed as the speed type adjustment calculation operation. An adjusting device comprising an adjustment calculating means. Here, in the above equation, △ MVn: speed-type adjustment calculation signal,
Kn: proportional gain at present, Kn-1: previous proportional gain (Kn-1ｎKn) , en: deviation at present, e
n-1: the previous deviation, Pn = Kn.en: the current proportional operation output, Pn-1: the previous proportional operation output. 2. A speed-type adjustment calculation operation is performed based on a deviation between a target value and a control amount from a control target, and the obtained speed-type adjustment calculation signal is converted into a position-type adjustment signal and converted into an operation signal. In the adjusting device to be applied to the object, as the speed-type adjustment calculating operation, ΔMVn = (Kn · en−Kn−1 · en) +
A speed-type adjustment calculating means for performing a PI (P: proportional, I: integral) calculating operation of (1 / TI) Kn · en or ΔMVn = (Pn-Pn-1) + (1 / TI) Pn is provided. An adjusting device characterized by the above. Here, in the above equation, △ MVn: speed-type adjustment calculation signal,
Kn: proportional gain at present, Kn-1: previous proportional gain (Kn-1ｎKn) , en: deviation at present, e
n-1: the previous deviation, TI: integration time, Pn = Kn
En: current proportional operation output, Pn-1: previous proportional operation output