JPS58144907A - Digital controller - Google Patents

Abstract

PURPOSE:To suppress an overshoot, etc. and to improve the control performance of a digital controller, by connecting successively an integrator and a limiter to the output side of a velocity type PID control arithmetic part and then providing an integrator initial value control part between the control output terminal obtained from the limiter and the integrator. CONSTITUTION:A velocity type PID control arithmetic part 8 receives the input of the target value j(k) and controlled variable c(k) and calculates a differential DELTAu(k) of controlled variable u(k). Then an integrator 9 adds the differential DELTAu(k) calculated at the part 8 to the (k-1)-th controlled variable u(k-1), i.e. the initial value of the integrator. Thus the manipulated valuable u(k) is calculated. A limiter 7 feeds the manipulated valuable u(k) and decides the control output uL(k) to give an input to an integrator initial value control part 10. In this case, the integral initial value is substituted within the k-th control period so that the value u(k) of the integrator is equal to the operation output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a digital control device LK, and particularly to a digital control device that performs PID control calculations and places limits on the results of the PID control calculations.

[Technical background of the invention]

The configuration of the digital control device will be explained based on Figure 11EI.The subtracter l is used to calculate the target value j (k)
) is inputted, and the deviation ｽ) is outputted to the PID control calculation section 2. The PID control calculation unit 2 inputs the deviation/k) and immediately outputs the manipulated variable U (k) to the controller 7. At this point, the PID control calculation unit 2 adds the integral II3 and the differential amount 4! ! 5
and a multiplier 6. The integrator 3 inputs the deviation m-)O and outputs the integration result to the adder 5. For the differential quantity 4, input the deviation -0c) and output the differential result to the adder. Adder 5 is the deviation/0IC
), integration results and differentiation results are input, ζ-are added, and the addition result is output to the multiplier 6. square wag
Inputs the addition jl# button, multiplies this addition result by the proportional rin, and outputs the manipulated variable U 佽) to ri(Vri7). output UL) to the controlled object.

Next, we will explain the operation of the conventional digital control device configured as described above.In the conventional digital control device, a series of operations described below are performed for each control cycle. =1, 2.3... A series of operations in the control cycle will be explained. The subtracter 1 manually inputs the target value j) and the control amount C) indicating the state of the controlled object, and calculates the deviation C) as shown in the following equation (1).

・to)=j伽)−cto)' ” −・−・・・・
-, (1) Next, the PID control calculation unit 2 uses an integrator 3, a differentiator 4, an adder 5, and a multiplier 6, and calculates the following equation (2).
As shown in K, the manipulated variable U (k) is calculated from the deviation (k).

UQc) = Ke(*(k) 10-[-(e (0) 10m
(1) 10・・・−・i 2 +−(・(k−1) 10(k))] @(k)−・(k−1) 174 , t) −−−−−° ------
=-=(2) However, in the above formula (2), Ke is the proportional r
in,! i represents integration time, Td represents differential time, and Δt represents control period.

Approximate calculation is performed using the trapezoidal formula. Further, the 4-differentiator differential is approximated. The adder 5 adds the deviation (Oc), the integration result, and the molding result, and the multiplier 6 multiplies the addition result by the ratio f1 dyne by 6.

Next, the first power I@so output (operated amount U) is manually input to the limiter 7, and the upper and lower limits OvZ as shown in the following formula (3)
The control target (ULOc) is
(not shown); however, ζζ - 1X is the upper limit of the manipulated variable), υml.

is the lower limit value of the manipulated variable (U).

The above is the operation of the conventional digital control device within one control cycle. The conventional digital control device performs the nine series of operations described above in each control cycle, and the control amount C) is equal to the VAg value j.
佽) The controlled object is controlled so that k-disperses.

[Background technique W; tO problems]

However, in the above conventional device, if the target value j
If 伽) increases in a large and step-like manner, then the deviation ・(
k) increases, and accordingly, the deviation (k) K (operated amount U, which is the result of PID control calculation) also increases, and finally exceeds the upper limit value Ufn□ of iq and continues to increase.

At this time, the signal value of the manipulated output υLOc) output to the controlled object increases only by U axt than the action K of the limiter 7, so the value of the manipulated variable U) is not sufficiently reflected in the controlled object, resulting in deviation and (k) continues to remain, and the integral value of the integrator 3 becomes excessive. As a result, even though the (turn) of the controlled variable finally exceeds the target value j) and the deviation □C) becomes a negative value, the integral value of integral 41#3 is an excessively positive value, so it is immediately K is the manipulated variable U (k) and the manipulated output υL (k) is a negative value, that is, the signal value does not indicate a decrease instruction, but remains a signal value indicating an increase instruction for a while. Therefore, in the conventional digital control device, as shown in Fig. 2, for a large sterig-like change in the target value jOc), the controlled variable ＠ｽ) responds with a large oscillatory response due to the opacity, and the target value j Oc) cannot be quickly converged.

In addition, if the target value j (k) suddenly decreases, there will be a large oscillatory response with undersheath, and the control amount C) will not be able to quickly converge to the target value j). 6 points
Riku.

[Purpose of the invention]

The present invention has been made in view of the above O1:LK, and even if the speed is To-), the controlled variable @ (rotation) has less overflow with respect to the target value J(k)K and is non-oscillatory. It is an object of the present invention to provide a digital control device that achieves continuous convergence.

[IIII] In order to achieve this object, the present invention connects a sequential integrator and an integrator in series on the output side of a speed-type PID control calculation, and obtains a control output from a limiter. K, the initial value of the K (k+1)th integrator between the control output terminal and the integrator.
Integrator initial value 111 to be replaced with the operation output of control period m
A feature of the present invention is that the provision of 1B suppresses overflow, overflow, etc., and improves controllability.

[Embodiments of the invention]

An example of this invention will be explained below using FIG. 3. speed type pxo*j1 part 8 to target value j) and control amount J
OC), and the difference in the manipulated variable ΔU (k) is input to the integrator 9.
Output to. The integrator 9 inputs the manipulated variable difference Δυ) and outputs the manipulated variable Uk) to the limiter 7. Limituta 7
ti manipulated variable U 佽) is input manually, and the manipulated output UL) is outputted to the controlled object and the integrator initial value adjustment section 10.

The integrator initial value adjustment unit 10 inputs the manipulated output UL(k) and replaces the manipulated output υL) with the initial integration value of the integrator 9.

Next, the operation of the embodiment fII of the present invention shown in FIG. 3 will be explained. In this embodiment, like the conventional digital control device, a series of operations are performed for each control period, and the object to be controlled is controlled by repeating this series of operations. Here, a series of operations in the 11th control cycle will be described as in the conventional example.

First, the speed-type PID control calculation unit 8 inputs the target value j) and the control amount C), and performs speed-type PID control calculation to calculate the difference #k) of the manipulated variable U (k). The speed PID control calculation will be explained below. Operation amount U
The difference ΔU (k) in (k) is expressed by the following equation (4).

ΔU(k)−U(k)−U(k−1) ・
・・・・・・・・・・・・・・・(4) Here, the above formula (4
) can be transformed into the following equation by using equation (2), which indicates the manipulated variable U 佽).

ΔU (k) or [(・(k)-1(k-1))...
・・・・・・・・・(5) In equation (5), using equation (1) showing the deviation
Assume that Kjoc)=j(k-1)-j(k-2),
When redefining the control r(), equation (5) can be expressed as follows.

ΔU 0c)=KP(c(k-1)-eｽ))+,
(j(k)−e传)]tenKo(2@(k−1)−@(h
-2)-e(k)) (phrase) The calculation shown by equation (6) is the speed-type PID control calculation.In the end, the speed-type PID control calculation unit 8 Now, perform the velocity type PID control calculation shown by equation (6), and calculate the manipulated variable U(k)
The difference ΔU(k) is calculated. Next, in the first integrator 9, the operation amount U(
k-1) K: The difference ΔU (k) between the manipulated variables U (k) calculated by the speed type PID control calculation section 8 is added to calculate the manipulated variable U (k). That is, the integrator 9 uses the following equation (
7) is being calculated.

U 伽)=Δυ斡)+U(k−1)・・・・
・・・・・・・・・(7) Next, input the manipulated variable U 佽) into limit and ri7, and as with the conventional y' innotal control device, (3
) Determining and outputting the control output U, <k) as shown in the equation 0. Next, the replacement of the integrator initial value, which is a feature of this embodiment, will be explained. The manipulated variable U(k+1) in the k+1st control period is expressed as the following equation (8) using equation (7).

U (k + 1) = Δu (k + i) + U [exist]) ...
(8) The integrator initial value adjustment section 10 (
In equation 8), the integrator initial value U (k) is the operation output UL
The initial value of the integral value is set to 0Its within the 11th fiIIJ control period so that the initial value becomes 0Its.

That is, the manipulated variable U(k+1
) becomes as follows.

υ (k+1) = ΔU (k+1) + UL)...
(9) In this embodiment, the series of operations explained above is performed every control cycle to control the controlled object so that the controlled amount C) matches the target value j). . in this case,
In any case, the integrator initial value is IJ Mitsutav's limit value Um! Or U. It never exceeds i. In other words, even when there is a sudden change in the target value j), the integral value does not become too large or too small, and the controlled variable (k) is less likely to overshade or unshade with respect to the target value j (k), resulting in non-vibration. This makes it possible to converge with a fast response speed. The case where the target value j) greatly increases in a step-like manner is as shown in FIG.

In addition, since speed-type PID control calculations are used, the output of the integrator 9 is an immediate manipulated variable υ (instant), and controllability can be easily improved by simply replacing the integrator initial value with the manipulated output ULOc. is possible.

〔Effect of the invention〕

As described above, according to the present invention, the control amount C(k) has less overshading and undersheeting with respect to the target value JOc), and there is a digital control device that is non-oscillatory and quickly converges. can get.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional digital control device.
Fig. 2 is a step response diagram of a conventional digital control device, Fig. 3 is a step diagram showing an embodiment of the present invention, and Fig. 4 is a step diagram of an embodiment of the present invention. ! It is a response diagram. 1... Li reducer, 2... PID control calculation unit, 3, 9
... Integrator, 4... Differentiator, 5... Adder, 6.
・・・Multiplier, 7...9i ivy, 8...speed type PID
Control calculation unit, lO...integrator initial value adjustment unit. (7317) Agent Patent Attorney Noriyuki Chika (and 1 others)
given name)

Claims (1)

[Claims] an arithmetic unit that inputs a target value and a controlled variable, performs a speed type PID calculation, and outputs a difference in manipulated variables; an integrator that inputs the difference in manipulated variables, performs integration, and outputs a manipulated variable; The integrator initial value M is equipped with a limiter that inputs a manipulated variable, applies a limit, and outputs it as a manipulated output, and an integrator initial value adjustment l1m that inputs the manipulated output and outputs it to an integrator. The initial value of the integrator for the eye control period is ki
A digital control device characterized in that the operation output of the 11th control cycle is substituted.