JPH1145120A - Position controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position controller which can be operated without trouble such as hunting at a relay for controlling a position proportional operating means even when an unsuitable position control parameter setting value is set by a user. SOLUTION: A position proportional operating means 4 is driven and controlled by controlling the ON/OFF of 1st and 2nd relays 6 and 7, and a discriminating means 21 is provided at a position control means 5a for performing control so that the driving position of the position proportional operating means 4 can be almost coincident with a manipulated variable MV. Thus, the suitability of a position control parameter setting value PP is discriminated based on a driving position S detected by a position sensor 8 and when it is not suitable, the ON/OFF of the 1st and 2nd relays 6 and 7 are controlled regardlessly of the position control parameter setting value PP so that the position proportional operating means 4 can be driven and controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position control device for controlling on / off (ON / OFF) of an open-side relay and a close-side relay, and driving control of an actuator such as a motor for opening and closing a valve or the like by this control. It is about.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a process control system in a case where the temperature of a process 2 is controlled by a conventional position control device disclosed in, for example, Japanese Patent Laid-Open No. 4-104034. In this figure, reference numeral 1 denotes ON / OFF control of an open side relay 6 and a close side relay 7, and this control
Is a position control device that controls the drive of a motor 4 for opening and closing the motor.

[0003] 2 is a process in which fuel such as gas supplied through a valve 3 is burned and heated, 3 is a valve whose opening and closing is controlled by a motor 4 via a link mechanism and the like, and 4 is turned on / off by a position control unit 5. The motor as a position proportional operation means that operates to open or close the valve 3 by controlling the forward / reverse rotation by the open-side relay 6 and the close-side relay 7 that are turned off.

Reference numeral 8 denotes a position sensor which is provided on the motor 4 and detects the opening of the valve 3 by detecting the rotation angle of the drive shaft of the motor 4. Reference numeral 9 denotes a predetermined position of the opening S detected by the position sensor 8. An opening degree input processing unit that samples at a period and outputs the position to the position control unit 5.

[0005] Reference numeral 10 denotes a temperature sensor for detecting the temperature of the process 2, reference numeral 11 denotes a temperature input processing unit which samples the temperature PV detected by the temperature sensor 10 at a predetermined cycle, and outputs it to a process control unit 12, and reference numeral 12 denotes a temperature PV. A process control unit that obtains an operation amount MV by performing a predetermined PID operation using the temperature target value SP set by the setting unit 13 and outputs the operation amount MV to the position control unit 5. .

Reference numeral 13 denotes an input key and an LCD (Liquid Cryst).
al Display) display, etc., and the user sets the target temperature SP
And a position control parameter set value PP. The set temperature target value SP is set to the process control unit 1.
2 is a setting unit that outputs the position control parameter set value PP to the position control unit 5.

The difference 5 between the manipulated variable MV output from the process control unit 12 and the opening S output from the opening input processing unit 9 depends on the position control parameter set value PP set by the setting unit 13. A position control unit 6 for controlling the drive of the motor 4 by turning on / off the open-side relay 6 or the close-side relay 7 so as to enter the stop range, thereby controlling the process 2 to keep the temperature substantially constant. Reference numeral 7 denotes an open-side relay that is turned on to drive the motor 4 in a direction to open the valve 3, and reference numeral 7 denotes a close-side relay 7 that is turned on to drive the motor 4 in a direction to close the valve 3.

However, the motor 4 as the position proportional operation means
Means not only a rotating motor but also an actuator in general. The type and manufacturer of the motor 4 and the position sensor 8 vary depending on the user.

Next, the operation will be described. Position control unit 5
Is the manipulated variable MV output from the process control unit 12,
The open-side relay 6 or the close-side relay 7 is turned on so that the difference from the opening degree S output from the opening degree input processing unit 9 falls within the stop range based on the position control parameter set value PP set by the setting unit 13. By turning on / off, the motor 4 is controlled.

At this time, the position control parameter set value PP used in the position control unit 5 is determined by: (a) the dead zone / operation gap of the operation of the relays 6 and 7;
OFF time (usually adjusted to the operation of the built-in relay, but in the case of an external relay, set by the user accordingly), (c) the time required from fully closing to fully opening the valve 3 (opening / closing time), (D) Fully closed resistance ratio / fully opened resistance ratio.

Such a position control parameter set value PP
In the control of the motor 4, the motor 4 is controlled on the assumption that the set value PP matches the control target (process 2 by opening and closing the valve 3). However, the following problems occur.

A case where the relationship between the dead zone / operating gap and the minimum ON / OFF time does not match the control target will be described. Referring to FIG. 9, generally, a dead zone a
The stop position determined from 1, 1 and the operation gaps b1 and b2 is: MV−a1 + b1 ≦ stop position ≦ MV + a2−b2 because the operation amount MV is the target opening.

Further, as shown in FIG.
, The minimum ON / OFF time dT [sec], and the opening / closing time T [sec
c], the change dS in the opening degree during the minimum ON / OFF time dT [sec] is dS = dT / T.

Now, dS> a1 + a2 (where a1 + a2
Is set to (user setting), the operation amount MV changes while the motor 4 is stopped, and the symbol S in FIG.
The relationship between the opening degree of the motor 4 and the operation amount MV is represented by S <M.
If V-a1 has been reached, the open-side relay 6 must be turned on because it is not within the stop range H1.

However, once the open side relay 6 is turned on, the opening degree S changes by dT / T.
When T / T> MV + a2, the stop range H1 is exceeded, and the close side relay 7 is turned on this time.

If the dead zone / operating gap is asymmetrical with respect to the manipulated variable MV, the motor may stop here. However, if dT / T is sufficiently larger than the stop range H1, the relays 6, 7 may be stopped.
ON / OFF is repeated, causing hunting.

A case where the opening / closing time does not match the control object will be described. As shown in FIG. 11, when the opening degree input cycle is Ts [sec], the motor output cycle is Tr [sec], and Ts ≧ Tr (there is no condition of Ts <Tr), Ts
For the change in the opening degree less than [sec], the ON / OFF time of the relays 6 and 7 is calculated using the set opening / closing time T and output to the motor 4.

Assuming that the relationship between the input opening degree S and the operation amount MV is S <MV-a1, the opening side relay 6 is turned on. The relay ON time t [sec] required to eliminate the difference between the opening S and the manipulated variable MV is t = T (MV-S). Further, when t <Ts, the next opening Since it is expected that S = MV before the input cycle, the open relay 6 is turned off at that time.

However, if the set opening / closing time T is too long compared to the actual opening / closing time T0, the motor 4 will move more than expected, so that the opening S
Is input, S> MV + a2 may be satisfied. In this case, the close-side relay 7 is turned on for the time that is expected to be S = MV. If T is sufficiently larger than T0, hunting occurs near the MV.

A case where the fully closed ratio and the fully opened ratio do not match the control object will be described. The opening degree S of the motor 4 is such that the current resistance ratio is R, and as shown in FIG.
The fully closed ratio indicating the resistance ratio at the time of [%] is Rc, and the opening degree is 1.
Assuming that the full open ratio indicating the resistance ratio at the time of 00 [%] is Ro, it can be obtained by S = (R−Rc) / (Ro−Rc).

When the full closing ratio Rc or the full opening ratio Ro is set outside the actual full closing ratio Rc0 or the full opening ratio Ro0, that is, when Rc <Rc0 or Ro> Ro0, the manipulated variable MV FIG. 1 obtained by using a totally closed ratio different from the actual one when is close to 0 or 100 [%].
Before the predicted opening degree shown in FIG. 2 reaches the operation amount MV, it may stop at the actual fully closed / fully opened position. The opening at this time is Sc = (Rc0−Rc) / (Ro−Rc) (Rc0> R
c) or So = (Ro0−Rc) / (Ro−Rc) (Rc0 <R
c)

Now, when the opening degree input cycle is Ts [sec], the motor output cycle is Tr [sec] and Ts> Tr, the opening degree S is Sc which is the actual fully closed state, and the operation amount MV is MV <S +
a2, the relay ON time T (S-MV) shown in FIG. 13 necessary to eliminate the difference between S and MV is the opening degree input period Ts
If it is less than T, the relay 7 between T (S-MV) is turned on, and the remaining relays 7 between Ts-T (S-MV) are turned off.

However, since the actual motor 4 is already fully closed, S = Sc always occurs when the opening degree is input, so that the relays 6 and 7 repeat ON / OFF.

[0024]

Since the conventional position control device is configured as described above, the user sets the position control parameter set value PP for the position proportional operation means (motor) 4, the position sensor 8, and the like. When setting an inappropriate value due to lack of knowledge of the user,
There were problems such as hunting of 7.

That is, when the set value PP does not match the control target, hunting of the relays 6 and 7 occurs,
There are problems such as shortening the life of the relays 6 and 7, and accelerating the resistance deterioration of the position proportional operation means 4.

Further, when the opening degree input cycle Ts is shortened to the output cycle Tr or shorter, or when a relay having a long life is used, the apparatus becomes expensive.

The present invention has been made in order to solve the above-mentioned problems. Even if an inappropriate position control parameter set value is set by a user, hunting of a relay for controlling position proportional operation means and the like can be performed. It is an object of the present invention to obtain a position control device that can be operated without causing the above problems.

Further, the present invention provides a position control device capable of controlling the output to the position proportional operation means so that hunting of the relay does not occur even if an inappropriate narrow dead zone is set for the control target. The purpose is to:

Further, the present invention provides a position control device capable of controlling the output to the position proportional operation means so that hunting of the relay does not occur even if a long opening / closing time is inappropriate for the control object. The purpose is to obtain.

Further, the present invention provides an output to the position proportional operation means so that hunting of the relay is minimized even if a small full closing ratio or a large full opening ratio, which is inappropriate for the control object, is set. It is an object to obtain a position control device that can be controlled.

[0031]

According to a first aspect of the present invention, there is provided a position control device for controlling the drive of a position proportional operation means by turning on and off first and second relays. The position control means for controlling the drive position and the operation amount to substantially coincide with each other determines whether or not the position control parameter set value is appropriate based on the drive position detected by the detection sensor. A determination means for controlling the drive of the position proportional operation means by controlling on / off of the first and second relays regardless of the above.

According to a second aspect of the present invention, in the position control device, the determination means determines that the minimum on / off times of the plurality of relays set as the position control parameter set values do not match the drive control of the control target. When it is determined, the first and second relays are on / off controlled without using the minimum on / off time.

According to a third aspect of the present invention, there is provided the position control device, wherein the determining means determines that the drive time required to drive the position proportional operation means from the minimum position to the maximum position, which is set as the position control parameter setting value, is controlled. When it is determined that the driving control is not suitable for the driving control, the driving time is corrected so as to conform to the driving control of the control target.

According to a fourth aspect of the present invention, in the position control device, the determining means determines that the position signal ratio of the minimum position and the position signal ratio of the maximum position set as the position control parameter setting value are the drive control of the control object. If it is determined that the first and second relays do not meet the conditions, the first and second relays are forcibly turned on or off for a predetermined time.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a block diagram showing a process control system when the temperature control of process 2 is performed by the position control device according to Embodiment 1 of the present invention. In this figure, reference numeral 1a denotes position control for ON / OFF control of an open-side relay (first relay) 6 and a close-side relay (second relay) 7, and drive control of a motor 4 for opening and closing the valve 3 by this control. Device.

Reference numeral 2 denotes a process for heating by burning fuel such as gas supplied through a valve 3 (object to be controlled); 3 a valve which is opened / closed by a motor 4 via a link mechanism or the like; A motor (position proportional operation means) that operates on the open side or the close side of the valve 3 by controlling the forward / reverse rotation by the open-side relay 6 and the close-side relay 7 that is turned on / off by 5a.

Reference numeral 8 denotes a position sensor provided on the motor 4 for detecting the opening angle of the valve 3 by detecting the rotation angle of the drive shaft of the motor 4. Reference numeral 9 denotes the opening degree (drive position) detected by the position sensor 8. ) Is an opening degree input processing section that samples S at a predetermined cycle and outputs it to the position control section 5a.

Reference numeral 10 denotes a temperature sensor for detecting the temperature (actually measured value) PV of the process 2, and reference numeral 11 denotes a temperature sensor 10 which samples the temperature PV detected by the temperature sensor 10 at a predetermined cycle and outputs it to a process control unit (process control means) 12. The temperature input processing unit 12 performs a predetermined PID calculation process using the temperature PV and the target temperature (control target value) SP set by the setting unit (setting unit) 13a, and sets the temperature PV to the temperature. Target value SP
Is a process control unit that calculates an operation amount MV for approaching the operation amount and outputs the operation amount MV to the position control unit 5a.

Reference numeral 13a denotes an input key and an LCD (Liquid Cry).
After the temperature target value SP and the position control parameter set value PP set by the user are stored in the memory 20, the stored temperature target value SP is stored.
Is output to the process control unit 12 and the position control parameter set value PP is output to the position control unit 5a.

5a is a setting unit 13a in which a difference between the operation amount MV and the opening S from the position sensor 8 via the opening input processing unit 9 is set.
The open-side relay 6 or the close-side relay 7 is turned on so as to enter the stop range based on the position control parameter set value PP set in the step (1).
N / OFF controls the driving of the motor 4 and thereby controls the process 2 to keep the temperature substantially constant. A position control unit (position control means) 21 is provided in the position control unit 5a, and an opening degree input is provided. The position control parameter set value P based on the opening S from the position sensor 8 via the processing unit 9
This is a judging means for judging the suitability of P, and when improper, controlling the relays 6 and 7 irrespective of the position control parameter set value PP to determine an operation signal for controlling the motor 4.

Reference numeral 6 denotes an open-side relay which is turned on to control the motor 4 to open the valve 3 in accordance with the control of the position control unit 5a. The closing relay 7 is turned ON to drive the valve 3 in the closing direction. However, the motor 4 as the position proportional operation means means not only a rotating motor but also an entire actuator. The type and manufacturer of the motor 4 and the position sensor 8 vary depending on the user.

Next, the operation will be described. Position control unit 5
a is the manipulated variable MV output from the process control unit 12.
And the opening-side relay 6 or the opening-side relay 6 so that the difference between the opening degree S and the opening degree S from the position sensor 8 via the opening degree input By turning ON / OFF the close side relay 7,
The motor 4 is controlled. However, the determination unit 21 of the position control unit 5a determines whether the set value PP is appropriate based on the opening degree S,
When the operation signal is inappropriate, the operation signal for controlling the motor 4 is determined by controlling the relays 6 and 7 regardless of the set value PP.

The position control parameter set value PP is
(A) Dead zone and operation gap of operation of relays 6 and 7, (b)
Minimum ON / OFF time of relays 6 and 7 (usually adjusted to the operation of the built-in relay, but in the case of an external relay, set by the user accordingly), (c) From fully closed to fully open valve 3 (D) the fully closed resistance ratio / fully opened resistance ratio, and the like.

Such a position control parameter set value PP
In the conventional control of the motor 4, the motor 4 is controlled on the assumption that the set value PP matches the control target (process 2 by opening and closing the valve 3), so that the set value PP does not match the control target. The hunting of the relays 6 and 7 described in the related art 1 to 7 has occurred.

Hereinafter, the operations for preventing hunting will be described with reference to the above. The operation in the case where the determination means 21 takes the minimum ON / OFF time of the position control parameter set value PP and determines whether or not it is appropriate to prevent hunting will be described with reference to FIG.

FIG. 2 shows the dead zone / operating gap and the minimum ON / OFF by the position control device according to the first embodiment.
It is a flowchart which shows the flow of operation | movement in the case of performing hunting prevention by the relationship with OFF time. However, FIG.
, A1 and a2 are dead zones, and b1 and b2 are operation gaps.

In step ST1, the motor output value 0 is determined as in the conventional case. However, the output value 0 is the
Is required to indicate “open”, “closed” or “OFF”. At this time, if the opening degree S falls within the operation gap of the motor 4, the output value 01 in the previous output cycle is used.

That is, the relationship between the opening degree S and the manipulated variable MV is S <
In the case of MV-a1, 0 = “open”. S> MV + a
In the case of 2, 0 = “closed”. MV−a1 + b1 ≦ S
In the case of ≦ MV + a1-b2, 0 = “OFF”.

MV-a1≤S <MV-a1 + b1
In this case, when 01 = “open”, 0 = “open”, otherwise 0 = “OFF”. Further, MV + a2-b2 <S
≦ MV + b2, 01 = 0 when “closed”
“Closed”, otherwise 0 = “OFF”.

Next, in step ST2, the output value 0
Is obtained as “open” and the previous output value 01 is not “open”, it is determined whether or not the stop can be performed within the stop range, and the minimum ON /
When the open side relay 6 is turned on for the OFF time (dT), the closed side relay 7 exceeds the stop range and the closed side relay 7 is turned on (S> MV + a
If the result is 2), change the output value 0 to “OFF”. That is, 0 = “open” and 01 ≠ “open” and S + dT
When / T> MV + a2, 0 = “OFF”.

Next, in step ST3, the output value 0
Is obtained as “closed”, and if the previous output value 01 was not “closed”, it is determined whether or not it is possible to stop within the stop range.
When the closed relay 7 is turned on for the OFF time (dT), the open relay 6 exceeds the stop range when the closed relay 7 is turned on (S <MV-a).
If it falls within 1), change the output value 0 to “OFF”. That is, 0 = “closed” and 01 ≠ “closed” and S-dT
When / T> MV-a1, 0 = “OFF”.

Next, in step ST4, the output time Tj is updated with the output cycle Tr and the minimum ON /
If the output has been longer than the OFF time dT, the previous output value 01 is updated to the output value 0 obtained above, and the previous output value 01 is output to the motor 4.

That is, after Tj = Tj + Tr, Tj ≧ Tj
When dT and 0 ≠ 01, 01 = 0 and Tj = 0. When 01 = “open”, the open side relay 6 is turned on, and the closed side relay 7 is turned off. Further, when 01 = “closed”, the open side relay 6 is turned off and the closed side relay 7 is turned on. Further, when 01 = OFF, both relays 6 and 7 are turned OFF.

That is, when the dead zone / operation gap is asymmetrical with respect to the operation amount MV, the stop may be performed here. However, when the dT / T is sufficiently larger than the stop range, the position control unit 5 controls the position control. Minimum O of parameter set value PP
Since the relays 6 and 7 were turned ON / OFF as indicated by reference numerals 25 and 26 in FIG. 3 according to the N / OFF time, hunting occurred as indicated by reference numeral 27.

However, in the operation described above, when the determination means 21 of the position control unit 5a determines that the minimum ON / OFF time of the position control parameter set value PP does not match the control object, the set value Without using PP, relays 6 and 7 are turned ON / OF according to the minimum ON / OFF time.
By determining the motor output value 0 so as not to cause F, the relays 6 and 7 are turned ON / OFF as shown by reference numerals 29 and 30 in FIG. 3, so that hunting as shown by reference numeral 31 does not occur.

As described above, according to the operation of the first embodiment, when the determining means 21 determines that the minimum ON / OFF time of the position control parameter set value PP does not match the control object, Relays 6 and 7 are minimum ON / OFF
Motor output value 0 so that it does not turn on / off according to time
Is determined and the relays 6 and 7 are turned ON / OFF, so that an effect that hunting does not occur can be obtained.

The determining means 21 takes the opening / closing time (driving time) from the fully closed (minimum position) to the fully open (maximum position) of the valve 3 of the position control parameter set value PP,
The operation when hunting is prevented by judging the suitability will be described with reference to FIG. Here, FIG.
5 is a flowchart showing a flow of operation when hunting is prevented by the opening / closing time of the valve 3 by the position control device according to the first embodiment.

First, in step ST1, the correction of the opening / closing time is performed only in the direction of shortening, so that the actual number of times M of the opening / closing time has an upper limit Mx. Is not done.
That is, if M ≦ Mx, the opening / closing time correction processing ends.

Next, in step ST2, when the same relay 6 or 7 has been kept ON for a sufficiently long time Tn,
The opening degree Si changed by the ON time Ti is obtained, and in step ST3, the actually measured opening / closing time T1 is calculated. That is, if Ti> Tn, the opening / closing time correction processing ends,
If Ti> Tn, T1 = Ti / Si is calculated.

Next, in step ST4, the number of huntings that occurs when the actual opening / closing time is short and the output in the reverse direction is exceeded by exceeding the target opening degree is n times (0 or 1).
(Ts / T) (T / T0-
1) The lower limit value T of the opening / closing time T satisfying the inequality ^{n + 1} ≦ a
Ask for 2. That is, T2 = T / ｛(aT / Ts) ^{1 / (n + 1)
)} Find +1.

Where T is the set opening / closing time, T
0: true opening / closing time, Ts: opening degree input cycle, a: dead zone width (for simplicity, dead zone widths a1 and a2 set on both sides of the target are assumed to be equal to a).

Next, in step ST5, the actually measured opening / closing time T1 is considered to be equal to the true opening / closing time T0. If T1 is less than T2, the hunting will exceed n times in step ST6. The opening / closing time T is corrected. At this time, since the actually measured opening / closing time is considered to have an error, it is corrected by applying a first-order lag filter. That is, if T1 <T2, T = (1
−α) T + αT1 and the process proceeds to step ST8.

On the other hand, if T1 is not T1 <T2 in step ST5, if T2 ≦ T1 ≦ Tx (opening / closing time upper limit) is satisfied in step ST7, it is determined that the condition is normal, and the opening / closing time correcting process is terminated. If not, the process proceeds to step ST8.

Then, in step ST8, the actual measurement number M is updated. That is, in the processing up to step ST7, M = M + 1 when normal or corrected.

In other words, when the opening / closing time from the fully closed to the fully opened position of the valve 3 is not proper, conventionally, as shown by reference numerals 33 and 34 in FIG.
The timing was delayed, which caused hunting as indicated by reference numeral 35.

However, in the above operation, for example, n =
When the determination unit 21 of the position control unit 5a determines that the opening / closing time of the position control parameter setting value PP is not appropriate when the value is set to 0, the opening / closing time is corrected to an appropriate value, and the corrected opening / closing time is used. Since the relays 6 and 7 are turned on and off as indicated by reference numerals 37 and 38 in FIG. 5, hunting does not occur as indicated by reference numeral 39.

As described above, according to the operation of the first embodiment, when the determining means 21 determines that the opening / closing time of the position control parameter set value PP is not appropriate, the opening / closing time is set to an appropriate value. Since the hunting is used after being corrected, an effect that hunting does not occur can be obtained.

The determination means 21 determines the fully closed ratio (position signal ratio at the minimum position) and the fully open ratio (position signal ratio at the maximum position).
The operation in the case where hunting is prevented by determining whether or not the hunting is not suitable for the control target will be described with reference to FIG. Here, FIG. 6 is a flowchart showing a flow of the operation when the position control device according to the first embodiment prevents hunting based on the fully closed ratio and the fully opened ratio of the valve 3.

First, in step ST1, when the motor output state is the normal state, in step ST2, the ON time To of the open side relay 6 and the ON time T
c is obtained, only one is ON and ON for a certain time Ty
Is continued. If the result of this determination is that the ON state has continued for a certain period of time or more, in step ST3, the opening degree change dS during that time is determined as the current opening degree S and the start opening degree Ss for determination.
Ask for. The opening change dS is calculated so that the change in the direction in which the operation should be performed is positive.

That is, when To> Ty and Tc = 0, di
Assuming that r = + 1, dS = dir × (S−Ss) is obtained,
When Tc> Ty and To = 0, dir = −1 and d
S = dir × (S−Ss) is obtained.

In step ST2, To ≠ 0
If Tc ≠ 0, the process proceeds to step ST5; otherwise, the process proceeds to step ST10.

Next, in step ST4, the opening change dS is compared with the change confirmation minimum opening Sn to determine the opening change d.
If S is large, it is determined that the motor 4 is operating normally, and both ON times To and Tc are determined in step ST5.
Is initialized to 0, and the determination start opening Ss is updated. That is, Ss = S.

On the other hand, if there is no change in the opening degree in step ST4, in step ST6, a transition is made to the forced state so that the output continues in the output direction used for the determination. Here, the reason why the output is not turned off is that the output is forcibly controlling the motor 4 by, for example, a protection relay. At this time, if the output is turned off,
Even if the protection relay passes the motor control to the controller, the output may remain OFF. This is to prevent this.

If the motor output state is not the normal state in step ST1, that is, if the motor is in the forced state, dS = dir × (S−Ss) is obtained in step ST7, and then dS> Sn in step ST8. It is determined whether or not there is, that is, if there is an opening change dS in the output direction, both ON times To and Tc are initialized to 0, the start opening Ss for determination is updated, and then the motor output state is changed. To normal. Also, when the operation amount MV is in the opposite direction to the direction in which the current opening degree S is output in the forced state,
That is, also in the case of dir × (S-MV)> Sn, a transition to the normal state is made similarly.

In step ST8, dS> S
If n or dir × (S-MV)> Sn, the process proceeds to step ST10.

Next, if the motor output state is normal in step ST10, the motor output value 0 is calculated in step ST11 in the same manner as steps ST1 to ST3 in FIG. ST1
In step 2, the output is performed in the output direction in the forced state. That is, if dir = + 1, 0 = open, and if dir = −1, 0 = closed.

Thereafter, in step ST13, FIG.
The minimum ON / OFF time process is performed in the same manner as step ST4, and then in step ST14, if 0 = open, To = To + Tr, and if 0 = close, Tc = Tc + Tr.

That is, conventionally, when the fully closed ratio or the fully opened ratio is set outside the actual fully closed ratio or the fully opened ratio, when the operation amount MV is close to 0 or 100 [%], Before the predicted opening obtained using the different fully closed ratios reaches the manipulated variable MV, it may stop at the actual fully closed or fully open position, so that the actual motor 4 is already shown in FIG. Since it is fully closed as indicated by reference numeral 42, when an opening degree is input, the opening degree is always fully closed.
As indicated by reference numeral 41, relays 6 and 7 are turned ON /
Had been repeatedly turned off.

However, in the above operation, the determination means 21 of the position control section 5a determines whether the position control parameter set value PP
If it is determined that the fully closed ratio and the fully open ratio are not appropriate, the relay 6 or 7 is forcibly stopped.
Is driven or stopped, for example, as shown by reference numeral 43 in FIG.
That is, hunting of the relays 6 and 7 does not occur.

As described above, according to the operation of the first embodiment, when the determination means 21 determines that the fully closed ratio and the fully open ratio of the position control parameter set value PP are not appropriate, the motor 4 is turned off. Forcibly driving or stopping, an effect is obtained that hunting does not occur.

[0081]

As described above, according to the first aspect of the present invention, the drive of the position proportional operation means is controlled by turning on / off the first and second relays. Position control means for performing control such that the operation amount and the operation amount substantially coincide with each other, based on the drive position detected by the detection sensor, to judge whether the position control parameter set value is appropriate or not. First, since the first and second relays are provided with a determination means for controlling the drive of the position proportional operation means by controlling on / off of the first and second relays.
Also, there is an effect that hunting of the second relay can be prevented.

According to the second aspect of the present invention, when the determining means determines that the minimum on / off times of the plurality of relays set as the position control parameter setting values do not match the drive control of the control target. Since the first and second relays are controlled to be turned on / off without using the minimum on / off time, hunting of the first and second relays can be prevented.

According to the third aspect of the present invention, the determining means determines that the drive time required to drive the position proportional operation means from the minimum position to the maximum position, which is set as the position control parameter setting value, is the drive control of the control object. If it is determined that the driving time does not match the driving time, the driving time is corrected so as to be suitable for the driving control of the control target, so that hunting of the first and second relays can be prevented.

According to the fourth aspect of the present invention, the determination means determines that the position signal ratio of the minimum position and the position signal ratio of the maximum position set as the position control parameter set values match the drive control of the control object. If it is determined that there is no
Since the second relay and the second relay are forcibly turned on or off for a predetermined time, hunting of the first and second relays can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a process control system when controlling a temperature of a process by a position control device according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing a position control device according to Embodiment 1 of the present invention;
It is a flowchart which shows the operation | movement in the case of performing hunting prevention by the relationship with FF time.

FIG. 3 is a diagram for explaining an effect of the operation of FIG. 2;

FIG. 4 is a flowchart showing an operation when the position control device according to the first embodiment of the present invention prevents hunting due to a valve opening / closing time.

FIG. 5 is a diagram for explaining the effect of the operation of FIG. 4;

FIG. 6 is a flowchart showing an operation when the position control device according to the first embodiment of the present invention prevents hunting based on a fully closed ratio and a fully opened ratio of a valve.

FIG. 7 is a diagram for describing an effect of the operation in FIG. 6;

FIG. 8 is a block diagram showing a process control system in a case where the temperature of a process is controlled by a conventional position control device.

FIG. 9 is a diagram for explaining that hunting occurs when the relationship between the operation dead zone / operation interval of the relay and the minimum ON / OFF time in the conventional position control device does not match the control target.

FIG. 10 is another diagram for explaining that hunting occurs when the relationship between the operation dead zone / operation interval of the relay and the minimum ON / OFF time in the conventional position control device does not match the control target.

FIG. 11 is a diagram for explaining that hunting occurs when the valve opening / closing time in the conventional position control device does not match the control target.

FIG. 12 is a diagram for explaining that hunting occurs when the fully closed ratio / fully opened ratio of the valve in the conventional position control device does not match the control target.

FIG. 13 is another diagram for explaining that hunting occurs when the fully closed ratio / fully opened ratio of the valve in the conventional position control device does not match the control target.

[Explanation of symbols]

 1a Position control device 2 Process (control target) 4 Motor (position proportional operation means) 5a Position control unit (position control means) 6 Open side relay (first relay) 7 Closed side relay (second relay) 8 Position sensor 12 process Control unit (process control unit) 13a Setting unit (setting unit) 21 Judgment unit S Opening degree (drive position) PV temperature (actual measurement value) SP Temperature target value (control target value) MV Operation amount PP Position control parameter setting value

Claims (4)

[Claims] 1. A position proportional operation means for operating an object to be controlled, first and second relays for driving / stopping the position proportional operation means by ON / OFF, and detection for detecting a drive position of the position proportional operation means. A sensor, a control target value of the control target and a position control parameter set value for controlling the drive position are set, and setting means for storing the set value;
Process control means for obtaining an operation amount for instructing the drive position so that the measured value obtained from the control target approaches the control target value, and a difference between the operation amount and the drive position detected by the position sensor, The first and second relays are turned on / off so as to enter a stop range according to the position control parameter set value, thereby driving and controlling the position proportional operation means. A position control device that performs control so that the amount substantially coincides with the position control device, wherein the position control device determines whether the position control parameter set value is appropriate based on the drive position detected by the detection sensor. Then, when inappropriate, the first and second relays are turned on / off regardless of the set value of the position control parameter, thereby controlling the drive of the position proportional operation means. Position control apparatus characterized by comprising a determination unit that. 2. The method according to claim 1, wherein the determining means determines that the minimum on / off time of the plurality of relays set as the position control parameter set value does not match the drive control of the control target. The position control device according to claim 1, wherein the first and second relays are turned on / off without using an on / off time. 3. The drive unit according to claim 1, wherein the drive time required for driving the position proportional operation means from the minimum position to the maximum position, which is set as the position control parameter setting value, does not match the drive control of the control target. If it is determined that
2. The position control device according to claim 1, wherein the drive time is corrected so as to be adapted to drive control of the control target. 4. The control means determines that the position signal ratio of the minimum position and the position signal ratio of the maximum position set as the position control parameter setting value do not match the drive control of the control target. 2. The position control device according to claim 1, wherein the first and second relays are forcibly turned on or off for a predetermined time.