SU1474589A1 - Pneumatic regulator - Google Patents

Abstract

The invention relates to technical means of control, namely pneumatic controllers, and can be used in the automation of production processes. The purpose of the invention is to improve the accuracy of regulation. The controller has an integration unit consisting of adder 14 and link throttle 15 - capacity 16. The positive input of the adder 14 is connected to the output of the switching relay 7, the negative input - to the reference pressure channel of the setting device 4, and the output of the throttle 15 - to the output channel regulator. The use of the regulator allows to eliminate static errors in case of discontinuous disturbances in the SAR. 1 il.

Description

4H

С SD

00

with

The invention relates to technical means of control, namely pneumatic controllers, and can be used in the automation of production processes.

The purpose of the invention is to improve the accuracy of regulation.

The drawing shows a schematic diagram of the controller.

The regulator contains a proportional unit, assembled according to the standard scheme from elements 1 and 2 of the comparison and throttle adder 3, setpoint 4 of the reference pressure Pc, valve 5, adder 6 connected according to the input inversion scheme, switching relay 7, switching function forming unit, consisting of an 8 forward link link, comparison elements 9 and 10, and a logic scheme EQUITY, performed on relay 11 and 12, and an OR 13 element, an integration unit implemented according to the coverage scheme of adder 14 with positive feedback Erez drosel 15 16 s capacity.

The inputs of the proportional unit are connected to the channels of the variable variable Pn and the RZ task and the output Re through valve 5 is connected to the negative chamber of the adder 6 and one of the inputs of the switching relay 7, the other input of which is connected to the output of the adder 6, and the output Re to the positive chamber the adder 14 of the integration unit, the input of the drossel 15 of which (the output of the adder 14) is connected to the output channel of the regulator P OUT The output P0 of the setting device 4 is connected to the single input of the proportional unit, the positive cameras of the adder 6 and the negative camera of the adder 14 of the integra ation. The inputs of the switching function shaping unit are connected with the intermediate output Ppr of the proportional unit and the output of the setting device 4, and the output P c to the control chambers of the valve 5 and the switching relay 7.

The regulator works as follows.

According to the switching scheme, the intermediate P n and the main P and (the outputs of the proportional unit 1 are described by the expressions

etc

 Ro + Ј

Ri, Ro - KЈ,

where Ј Rzd- RP - error signal;

K - gain ratio of the proportional unit, the first setting.

The output Ps of the 8th foreground link defining the switching line is proportional to the sum of the instantaneous value of the error signal and its rate of change.

dЈ ps

where T is the lead time, the second

setting parameter. Using the elements 9 and 10 of the comparison, the sign of the error (P,) and the sign of the switch line (P 2) are displayed and, if they coincide, a single signal P to P, P 1 is generated at the output of the block.

In this case, the valve 5 is in the conducting state, the upper orifice of the switching relay 7 is open, and the input signal P "of the integrator is described by the law P to PM1 P0 - KЈ.

According to the switching circuit of the integration unit, when Р k 1, the output signal of the controller removed from the input of its throttle is changed according to the PI-law of regulation

40

Р Р

G 6IHI

-K (Ј + -1- J E dt.

where Rmo is the initial value of the integral component

at time t 0; Tp - constant integration of the block, the third parameter setting.

If the logic signals P1 and PЈ do not match, the output of the block goes to the zero state P k 0, the valve 5 closes, the output of the proportional block 1 is stored in the minus chamber of the adder 6,

corresponding to the moment of switching ts: P c, P, P o KLt and the output signal of the adder 6 P l P n +

+ KЈ.

42

By virtue of the fact that the lower nozzle of the switching relay 7 is open, a constant signal is generated at the input of the integrator

P “Ree. - Ro + KЈ

where B is the error signal value in

moment of switching ts. In this case, i.e. when P to O, the controller output signal

one

tic

us

K (-),

and ts

where PMS Rno +

s

+ f J Јdt

1 n ft

 const is the value of the integral component at the moment of switching ts; 1c - final end time

the transition process. Closed ATS is in equilibrium when the condition is fulfilled. P The latter is ensured only with zero static error, i.e. with R p RZA. Since the proportional block with the output signal P w provides the compensation of pulse disturbances for a finite time, the elimination of the static error at

intermittent perturbations in the SAR with

i

v

transfer function W (S) --- x

-f

x (TnS + 1) Wo5 (S) also occurs in a finite time.

In the proposed controller, by turning on the output of the throttles of the integration unit to the output channel of the controller, the corresponding purely integral control law can be achieved. This version of the regulator can have a significant effect in regulating objects whose transfer functions contain zeros (differential equations contain derivatives of the control action), since this eliminates abrupt changes in the derivatives of the controlled parameter at the time of switching the Q structure. Such changes are characteristic for SAR by the specified types of objects and P-, PI- and PID-regulators with variable structure.

Claims (1)

with formula of invention A pneumatic regulator containing a proportional unit, an actuator, a valve, an adder, a switching relay and a function shaping unit 0 switching, consisting of a link direct prefix, two elements of comparison and a logic circuit EQUITY, performed on two relays, and the element OR, and the inputs are proportional to The 5th unit is connected to the adjustable variable channels and the reference, and the output through the valve is connected to the negative chamber of the adder and one of the inputs of the switching relay, the other The Qth input of which is connected to the output of the adder, the setpoint output is connected to the single input channel of the proportional unit and the plus cameras of the adder, the inputs of the switching function generation unit are connected to the intermediate output of the proportional unit and the output of the setting device, and the output is connected to the control chambers of the valve and switching A relay, characterized in that, in order to increase the control accuracy, it is additionally equipped with an integration block, consisting of an adder and a link, a throttle — the capacitance as a reverse link and wherein the positive input of the adder is coupled to the output of the switching relay minus input - with the output pressure setpoint and the output - with output channel controller. five 0 five