SU1259208A1 - Three-position regulator - Google Patents

Abstract

This invention relates to the field of automation. The purpose of the invention is to simplify the design and expand the scope. The controller contains a parameter master, a reference element, a three-position relay unit and two power amplifiers. A trigger, a one-shot, three elements SH and two elements I are entered into it. The regulator allows controlling the object in the case when the delay is included in the structure of the control object. 3 il. NP SL CO tsD

Description

The invention relates to the technique of automatic regulation and can be applied in the regulation of various processes in heat and power engineering, chemistry and other industries if there is a clear delay in the control loop.

The purpose of the invention is to simplify the design and expand the field of application of the device.

1. an example of the practical implementation of the proposed device; FIG. 2 is a timeline of the adjustment process using the proposed device; FIG. 3 shows the phase portrait of the automatic control system using the proposed device.

The controller contains a variable parameter setting device 1, a reference element 2, a three-position relay unit 3, the first and second power amplifiers 4 and 5, a trigger 6, the one-oscillator 7, the first, BTopoii, and the third elements SH-8-10, the first and second elements 11 and 12, the Three-position switching unit 3 contains a non-linear element 13, the first and second valve elements 14 and 15 and the inverter 16,

Key elements are used as power amplifiers 4 and 5. The controller controls the operation of the actuator 17,

The operation of the controller is carried out as follows.

The regulator input receives the signal cf, which is proportional to the current value of the controlled parameter. For sensor 1, the set value of the adjustable parameter is set. At the output of the comparison element 2, a mismatch signal V is generated, proportional to the difference between the set value and the current value, of the controlled parameter. The signal V is fed to the input of the nonlinear element 13, which has the characteristic of a three-position relay element, generally having a dead zone a and hysteresis. If the signal V at the input of the nonlinear element I3 is within its deadband (a + U a), the signal Vp at the output of the nonlinear element 13 is O, the amplifiers 4 and 5 are disconnected and no control supply r to the actuation device is supplied.

When the mismatch signal Vj is exceeded, the dead zone of the nonlinear element 13 is triggered. For example, in the case that the controlled parameter is less than a predetermined value, a piecewise constant positive polarity signal is generated at the output of the three-position relay unit 3. The positive polarity signal p passes through the valve element 1A to the first inputs of the elements.

OR 8 and 9 and to the K.-input of the trigger 6, the signal Vj comes from the output of the element OR 9 to the control input of the amplifier 4, which connects the actuator 17 to the power circuit, causing a change in the controlled parameter in the direction of decreasing the error signal VJJ, Simultaneously occurs triggering trigger 6 and at its inverse output a signal V appears, arriving at the first input of the element 12 and preparing the further operation of the circuit. A signal appears at the input of the one-shot 7, but it does not start up, so

how the one-shot 7 is triggered on the rear edge of the input signal, t, e, when the input signal is reduced to zero level, influenced by the control action

at the output of the controller occurs

reduction of the error signal, At the time of the reduction of the error signal Vj, to a value less than the dead zone a of the nonlinear element 13, the signal Vp at its output becomes equal to 0, the amplifier 4 turns off and the single vibrator starts 7, the single-vibrator 7 output the duration of the Y arrives at the second input of the element 12. At the output of the latter, a signal U, arises, arriving at one of the inputs of the element OR 10, thanks to the appearance of the signal Vj at the output of the element

OR 10, the amplifier 5 is turned on and the control voltage is applied to the second input of the actuator over a period of time

When the polarity of the error signal V changes to the opposite, the controller works in a similar way, but when the polarity of the signal Vp changes at the non-3 output

element 13. In this case, the signal VP passes through the valve element 15 and the inverter 16, causing sequential operation of amplifiers 5 and 4. Inverter 16 in the example design ensures that the signals on the outputs of the three-position relay unit are identical by polarity. Thus, in the process of regulation, at each disconnection of the nonlinear element 13, the regulator output for a fixed time f is turned on for which the control signal of the nonlinear element 13 was not activated.

The essence of the invention is as follows. In the case of a three-position control of an object, its control is ensured by supplying control actions along two supply chains, the inclusion of which causes a change in the sign of the effect on the control object. In the presence of a pure lag in the automatic control system, the disconnection of any supply circuit by the three-position relay unit occurs with a delay of the lag time relative to the moment at which a trip would occur if there was no delay. In this case, the control object during the delay time is under the excessive influence of the corresponding supply chain. If, at the moment of power supply disconnection by a three-position relay unit, the other supply circuit is switched on for a fixed time, then with an appropriate choice of the duration of additional switching-on, the negative influence on the delay control process can be compensated in full or in part, as the control object brakes, providing compensation for the excess effect initial power up.

If there is no hysteresis in the characteristic of the three-position relay block, the duration of additional opposition should not exceed the time of pure delay, since otherwise self-oscillations in the system can occur at the border of the dead zone. Let's show it on the example of the system with line2592084

part described by the transmission

function

W (p)

TO

p (1 + Tr)

(one)

The differential equation describing the linear part of the system (without taking into account the delay) has the form

, l

et

, 4 d t

yuv

(2)

Let us determine the duration of the additional inclusion at which auto-oscillations at the boundary of the dead zone are impossible. Let the initial conditions in the system

Y (0) a; Y (0) Oh,

(3)

where d is the dead zone of the rail element.

Conditions (3) are the worst in terms of the possibility of the occurrence of a self-oscillatory regime at the boundary of the deadband. Due to the delay of the control object during the delay time, for example, the control action - B (if we consider the initial conditions for analyzing the possibility of self-oscillations on the other deadband, then it is necessary to perform an analysis when exposed to + B and initial

conditions y (0) and y (0) O. Solving equation (2} and taking i t nojpr-chim-j

, iY, -KB (,,. ():

40

V, a-kBt k & T i-e

(five)

At time i S, the effect is removed from the object and, due to the additional effect of another chain, time is applied to action + B, Resh equation (2) at. new initial conditions, corresponding to (4) and (5, and taking if receive 1

(6)

; B-hb (2nd) e,

f2 a-K6t +} + ic6j-K & T 2-e

/ L mlve

.1 (7)

- At the end of the additional action, free movement of the system occurs, and

Y (oo + PM

(eight)

In order for the system to avoid self-oscillations at the boundary of the dead zone, the condition must be met

Y (co) i a Set L (cx)) a, then hT

, o1 2 + tX2 a-kb (-y),

00

from where

year

Thus, auto-oscillations are not possible if

W. (12)

If a three-position relay element has a hysteresis of LA, then for the object being considered, the condition for the absence of self-oscillations at the deadband boundary is

(() q4-io (.. (53

Therefore, in the limiting case

(14)

and

(y-y yes

R

hb

ft

( five)

The above demonstrates the presence of a positive effect in the implementation of the proposed device.

FIG. Figure 2 shows the time dependences of the variation of the error signal when developing a control action and the corresponding time dependences of the change of the control signals.

From FIG. 2 that for the system considered as an example, the transfer function of an object of which, without taking into account the delay, is described by the expression

k 1

p (T + tG) p (T + 20r)

W (p)

(sixteen

at r 3c, at 3c, and 2, in ya. О, the application of the proposed controller allows to significantly improve the quality of regulation with the simplicity of technical implementation and with a delay in the control object, i.e. in the most significant case for practical application. This is due to the fact that with the application of the proposed controller design, the effect of the delay is completely compensated.

592086

the input of the error signal in the dead zone of the controller.

This is confirmed by the phase portrait of the automatic adjustment system, shown in FIG. 3, and corresponding to the system, the linear part of which is described without lagging into expression (16).

The construction of the phase portrait is carried out as follows. For a conventional three-point controller with no hysteresis, give T o the switch line equations are

Y

Y

-M (17)

and the phase trajectories are determined by solving the equation

 Y c-x-KT6 ti K-XT & f, - (18) where C is determined from the initial conditions.

If there are delays in the system, the switching lines are determined by the equations

0

five

0

five

. (e.) (. (e Jl

K-kT / BJ4-.k | B / L-a, 0

(nineteen)

Ce -) (x-tXT / 8 / -k / 6 / C-tci, X iOj, where X Tu.

Let us determine the expressions for the switching lines, which determine the end of the additional connection, which provides the correction of the system. The general form of equation (2) is

:20)

t x (CT & ((o),

(t, J (,. (obv (oHl-e |. 21}

WITH.

We define the equations for the additional switching lines, determine x (0) in expression (21) from (20) and take into account that the value y (0) is determined when the device is implemented in accordance; with (9). From here we get

 / ± 1

 X40;

H-with t

-1 + 2

(22)

(23)

/ if-G -

(e V-i) x-a-KfiT-biH.2e -e J

at.

The phase portrait of the system shows that at the time of the completion of the additional power supply circuit, which provides the opposite initial effect on the object, and

when choosing its duration in co-r-BBtcTBmi with (15) (in the example given at 4a o), the points A, Aj, A, and A appear on the same trajectories that they would have been in without any delay in the system, t , e. If you would disable the relay element. went to Egemeni moments, corresponding to points В ,, Ъ, В and B. This

shows the full compensation of the delay effect when the error signal enters the dead zone of the relay element. It is also seen from the phase portrait of FIG. 3 that with significant discrepancies, when the transit time of an insensitive tee by the error signal is equal to or less than the time of additional switching on (the equality is indicated-20 will give the first and second elements AND

time points characterizes the point C of FIG. 3), the operation of the system becomes similar to the operation of a two-position system with a reverse hysteresis of the relay element. This ensures an increased response time of the automatic control systems when applying the proposed controller design, F.

The three-position controller containing the setting control of the parameter

592088

pa, the reference element, the three-position relay unit, and the first and second power amplifiers, the input of the comparison element connected to the output of the setter, and the output to the input of the three-position relay unit, characterized in that, in order to simplify the design and expand the scope , it additionally contains a trigger, one-shot, three OR elements, as well as two AND elements, the first output of the three-position relay block is connected to the first inputs of the first and second OR elements and the trigger, the second output to the second inputs the first and third elements and OR trigger output of the first OR element connected. chen through the one-shot to the first in10

t5

the first and second outputs of the sub-switch trigger, respectively, to the second inputs of the first and second AND elements, the outputs of which are connected respectively to the second input of the second OR element and to the first input of the third OR element, the outputs of the second and third OR elements, respectively, through the first and second yci- controllers to the controller outputs.

I

.Sm.p.

I

ia-2

LCJ

fo

i

fCJ

-.

npuj O

VNIIGM Order 51j9 / 44 Circulation 836 Subscription Proiz-poligr. Ave, Uzhgorod, st. Project, 4

Claims (1)

Claim A three-position controller containing a control unit of an adjustable parameter output - to the second inputs of the first and third elements OR and the trigger, the output of the first element OR connected. through a one-shot to the first inputs of the first and second elements AND, the first and second outputs of the trigger are connected respectively to the second inputs of the first and second elements AND, the outputs of which are connected respectively to the second input of the second OR element and to the first input of the third OR element, the outputs of the second and third OR elements are connected respectively through the first and second power amplifiers to the outputs of the regulator. Figz ВНИИПИ Order 5119/44 Circulation 836 Subscribed Proiza polygon. ave, city of Uzhhorod, st. Project, 4