JPS6032201B2 - Pulse width controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a PI-operated pulse width controller.

A PI-operated pulse width controller is a controller suitable for driving an electric valve, and a PI-operated analog controller combined with a turtle positioner is also commonly used as a type of this type of controller. .

In this type of pulse width controller, the fin positioner compares the output of the analog controller with the feedback signal corresponding to the opening of the solenoid valve, and based on the comparison result, pulses are generated to drive the valve motor in an on-off manner. A width output is generated to control the opening degree of the electric valve so that the control deviation given to the input of the analog controller is reduced. By the way, with conventional PI-operated pulse width controllers, the output cycle becomes longer when the control deviation becomes smaller in one operation, but the drawback is that the output pulse width does not become smaller than a certain value. I couldn't adjust it. The present invention provides a novel PI-operated pulse width controller that does not have the above-mentioned drawbacks by making the output pulse width in one operation proportional to the control deviation and adjusting the proportionality coefficient arbitrarily using a variable resistor. This has been achieved. FIG. 1 is a connection diagram showing an embodiment of the pulse width controller of the present invention.

In the figure, AC is a PI-operated analog controller, PO is a roaring positioner, HB is a hysteresis width setting circuit, and CV
is an operating section that includes a valve motor that is turned on and off by the pulse width output of the Kasumi positioner, and an electric valve whose relationship is controlled by the valve motor. In the analog controller AC, AE is a control deviation detection circuit consisting of an operational amplifier OP, which receives a measurement signal Em and a setting signal Es at its input terminal, and outputs each control deviation at its output terminal. AP is a proportional amplifier, which consists of an operational amplifier OP2 and a voltage dividing resistor RP for feeding back the output of the operational amplifier OP2, which generates an output voltage of Kp proportional to the control deviation applied to the input terminal, and a proportionality constant Kp. can be set by RP. The mountain is a proportional-integral arithmetic circuit, which has an integrator circuit consisting of an operational amplifier OP3 and a capacitor CI connected to its feedback circuit, and a parallel circuit of the proportional amplifier AP output Kp, capacitor CM, and resistor RI on the input side. The output voltage 8c corresponding to the sum of the voltage proportional to Kp and the integral voltage of Kp is produced at the output terminal. In the thunder positioner PO, AD is an adder consisting of an operational amplifier OP4, which applies a feedback voltage Ef corresponding to the opening degree of the electric valve to the output Ec of the analog controller AC.
is added differentially.

COM-1 and COM-2 are each a comparator, and COM-1 is an operational amplifier OP5 with positive feedback provided by a resistor common 5.
COM-2 has an operational amplifier OP6 to which positive feedback is provided by a resistor R6, and operates in a range in which the output Ed of the adder AD is positive polarity, and COM-2 operates in a range in which the adder output Ed is negative polarity. Operate. The adder output Ed is applied to the input (10) of OP5 via the resistor R, and a constant voltage -Eh is applied via the resistor R, and the input (1) is connected to the hysteresis width setting circuit HB. The output Ea is applied via the resistor R54. The adder output Ed is applied to the input (1) of OP6 via the resistor R62, and a constant voltage 10Eh is applied via the resistor R93, and the hysteresis width setting circuit HB is applied to the input (1) of OP6.
An output Eb from the output terminal is applied via a resistor R64.
Therefore, in COM-1, the adder output Ed increases and the upper limit value (
= Eh + Ea>, it turns on and the output transistor Q. Turn on, Ed decreases and the lower limit value L (=Eh)
When it reaches , it turns off and Q also turns off. Also COM-
2 turns on when Ed reaches the upper limit value (=Eh-Eb), turning on the output transistor Q2, and turns off when Ed reaches the lower limit value -L (=-Eh), and Q2 also turns off. . In other words, the hysteresis width of COM-1 is Ea
Then, the hysteresis width of COM-2 is Eb. The output transistors Q,,Q2 are turned on by relays RY,,R
Y2 closes the energized contact. The valve motor of the operating part CV rotates in the forward or reverse direction by the pulse width output by closing these contacts, increasing or decreasing the opening degree of the motor-operated valve, and in either case, the motor-operated valve moves in the direction to reduce the deviation. do. V
F is a circuit that generates a feedback signal Ef corresponding to the opening degree of the electric valve, and the output signals of COM-1 and COM-2 drive switches SW, SW2, respectively, and
Positive or negative step voltage Ep synchronized with on/off of 2
, a resistor Ro to which Ep is added, and a capacitor C
It consists of a first-order delay circuit of D. When COM-1 (or COM-2) is turned on and the electric valve's relationship increases (or decreases), at the same time a positive (or negative) step voltage Ep
The feedback voltage Ef that is added to the first-order lag circuit and its output is
increases (or decreases), corresponding to the relationship of the electric valve. This feedback voltage Ef is differentially added to the output Ec of the analog controller AC through the adder AD'. The hysteresis width setting circuit HB surrounded by a chain line is connected to the operational amplifier O.
It has P7. The input (1) of OP7 has a resistance value 7 for each deviation and a variable resistance R? It is provided through two series circuits. In addition, the output of OP7 is applied to the input (1) of OP7 via a series circuit of forward-connected diode D and resistor 73, and the output of OP7 is applied to the series circuit of reverse-connected diode D2 and resistor R74. It has been added through. A bidirectional Zener diode ZD and a switch SW3 are connected in parallel between the connection point of the resistors R7 and R72 and a reference point. SW3 has comparators COM-1 and COM
-2 outputs are added through the OR gate OR and COM
SW3 is configured to be closed when either one of -1 and COM-2 is on. Blood is resistance R7,,R7
This is to limit the maximum value (for example 2V) of which control deviation is applied to OP7 via V2. When the control deviation is negative, a positive hysteresis width setting voltage Ea is taken out from the connection point between the diode D and the resistor R73, and when the control deviation is positive, a negative hysteresis width setting voltage Eb is taken out from the connection point between the diode D2 and the resistor R74. is taken out. Ea and Eb are Z
``Remi I Go Tsurungo E2'' where the voltage of D is E2D
. In the l range, R73
[11Ea = R seat available for rain R74
'21Eb=R double sword horse, Ea, E
b is proportional to each deviation, l > IR7, 1R72E2
.

-R72 in the range of - Ea = Heron E20 (3’ Eb = Heron E2D t4) Therefore, Ea and Eb are constant.

The operation of the controller of the present invention constructed in this way will be explained below.

Now, there is a control deviation between the measurement signal Em and the setting signal Es (
However, if this occurs, the analog controller AC
produces an output Ec. This output Ec is Kamame positioner P
The adder output Bd is added to the adder AD of O and the adder output Bd is added to the comparator CO
When the upper limit date of M-1 is exceeded, COM-1 turns on,
The subsequent relay RY operates to move the electric valve of the operating part CV, and a positive step voltage +Ep is generated, and the feedback voltage Ef corresponding to the function of the electric valve increases exponentially. Since Ef is added to the adder AD differentially with the AC output Ec, the adder output Ed decreases, resulting in Ed
When reaches the lower limit value L, COM-1 is turned off, the subsequent relay RY is also opened, the motor-operated valve is stopped, the positive step voltage Ep disappears, and the feedback voltage Ef stops increasing. Thereafter, the analog controller output Ec increases due to the integral action of AC, and when the adder output Ed exceeds the upper limit value of COM-1, COM-1 is turned on again, the electric valve moves, and the feedback voltage Ef also increases. In this way, the electric valve of the operating portion CV is turned on and off so that the control deviation becomes small, and a PI operation is performed as shown in FIG. 2. In Fig. 2, A is the state of the output Ed of the adder AD, and the port is the relay RY,
, and C is a diagram showing changes in the opening degree of the electric valve, and the output due to time LI gives a proportional P operation, and t2
An output of 10 W gives an integral action. In the integration operation, the off time t2 and on time t3 of the pulse width signal
are given by the following equations.

・=c, R, Ken ■ He=C.

R. However, as long as the hysteresis width setting voltage Ea is within the range of the limiter including ZD (≦ Sanseisho 3E2D), it is proportional to each deviation as shown in formula ■. C, R, long
Nora=C.

R. Mother 1 ■Compare, k = electric appliance; Therefore, the rima is constant and t3 is proportional to the deviation.

In addition, since Ea is constant in the range where the deviation is > Sanseisho 2E2D, ra is inversely proportional to the deviation, and t3 is constant. Furthermore, even if the deviation is positive, the integral action is proportional to each deviation within the range of Gomi Sanseisho 3E2o. Therefore, by adjusting the variable resistor K72, the pulse width in the integral operation can be adjusted to the characteristics shown in FIG. In other words, the control characteristics can be narrower, that is, the characteristics of an analog controller can be made close to those of an analog controller, and R72 can be increased. Also, if you do not want to move the control end CV frequently, reduce R72.
All you have to do is roughen the control characteristics. In addition, if R7 is made variable instead of making R flower variable, the characteristics shown in Fig. 4 will be obtained,
If R7, , R72 are fixed and R73, R74 are made variable, the characteristics shown in FIG. 5 will be obtained. In addition, in the range where the deviation is large, the hysteresis width is set to - constant, so that when a step deviation occurs, a proportional operation is immediately output. If the maximum value of the deviation is not limited, there will be an inconvenience that the output of the proportional operation will not be output immediately when the proportional band is large and the deviation is large. Note that if the variable limiter circuit shown in FIG. 6 is used instead of the signer diode DZ, the characteristics shown in FIG. 7 will be obtained. In the above description, the case where the step voltage Ep is applied to the adder AD via the first-order delay circuit is illustrated, but as shown in FIG. 8, the step voltage Ep generated in synchronization with the output pulse is applied via the variable resistor RD. It may be applied to the input of an integrating circuit of a PI-operated analog controller AC to obtain a voltage Ec-Ef at the analog controller AC.

According to this embodiment, the integration circuit is also used as an adder and a first-order delay circuit, and the adder AD and the capacitor C
This has the advantage that o is not needed and the overall configuration can be simplified.
Further, in FIG. 8, manual operation and automatic operation can be switched bumplessly. In other words, during manual operation, A
Switch the /M changeover switch S^M to the manual side M, and operate the manual operation switches MS, MS2 to adjust the output pulse. At this time, the capacitor C of the integrating circuit is
In addition to discharging the charge stored in , the parallel circuit of capacitor CM and resistor R is disconnected from the integrating circuit and connected to the reference point, so that the input and output of the integrating circuit is kept at zero. . Therefore, when switching from manual operation to automatic operation, both comparators COM-1 and COM-2 are turned off regardless of the magnitude of the control deviation, allowing bumpless switching. As explained above, in the present invention, when the absolute value of the control deviation is small, by making the hysteresis width of the comparator proportional to the control deviation, the pulse width of the output in the integral operation is made proportional to the deviation, and the pulse width of the output in the integral operation is made proportional to the deviation. Since the coefficient is configured to be adjustable using a variable resistor,
A new PI that allows you to arbitrarily adjust the roughness and fineness of control characteristics.
A pulse width controller of operation is obtained.

[Brief explanation of drawings]

FIG. 1 is a connection diagram showing one embodiment of the controller of the present invention, FIGS. 2 to 5 are diagrams explaining its operation, FIG. 6 is a connection diagram showing another example of the limiter used in the present invention, and FIG. The figure is an explanatory diagram of its operation, and FIG. 8 is a connection diagram showing another embodiment of the controller of the present invention. AC: PI-operated analog controller, P0...
...Positioner, CV...Operation unit, HB...
...Hysteresis width setting circuit. 〆/Figure〆〆J Zukyu Figure 4〆〆 Z Figure〆J Zukyu Figure 7〆〆Figure 3〆〆Figure 8

Claims (1)

[Claims] 1. An analog controller that responds to a signal proportional to the control deviation and generates an output signal that is the sum of the proportional operation output and the integral operation output, and a feedback signal that corresponds to the opening degree of the electric valve of the operation section to the analog controller. means for differentially adding to the output; means for generating a pulse width output for controlling the opening of the motor-operated valve according to the difference between the analog controller output and the feedback signal; A pulse width adjustment for PI operation, comprising means for extracting a step voltage obtained by turning the voltage on and off according to the output of the comparator through a first-order delay circuit and generating a feedback signal corresponding to the opening degree of the motor-operated valve. 1. A pulse width controller, characterized in that the hysteresis width of the comparator is made proportional to the control deviation when the absolute value of the control deviation is below a certain value, and means is provided for setting the proportionality coefficient by a variable resistor.