JP2002358101A - Feedback control system and feedback control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a feedback control system and method capable of realizing smooth and stable control by preventing any overshoot or hunching when the setting of a target value is rapidly changed. SOLUTION: When a set target for an object to be controlled is changed, a change processing means 200 increases or decreases an intermediate target value Tr2 in order to make it gradually close from an initial set target Tr0 to a new set target Tr until the detected output of the state quantity of the object to be controlled reaches the new set target Tr. Then, the intermediate target value Tr is defined as a control input Tr1, and a deviation value ΔT between the control input Tr1 and the detected output of the object to be controlled is calculated, and the control signal is compensated according to the deviation value ΔT by a compensating means 85.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feedback control system and a feedback control method, and more particularly, to a method for avoiding overshoot or hunting and performing smooth and stable control when a target value is rapidly changed. It relates to a possible feedback control system and a feedback control method.

[0002]

2. Description of the Related Art FIG. 8 shows an overall simplified configuration diagram of an air conditioning system. The air conditioning system is mounted on, for example, a car. In FIG. 8, the evaporator 51 cools vehicle interior air by blowing air from a fan 52. In the variable capacity gas compressor 10, the refrigerant gas vaporized by the heat of the air in the vehicle compartment is pressurized and sent to the condenser 53.

The condenser 53 liquefies the refrigerant gas and releases the heat absorbed from the cabin to the outside of the vehicle. The expansion valve 54 sharply reduces the pressure of the refrigerant gas from a high pressure to a low pressure. The rotary shaft 11 of the variable displacement gas compressor 10 is configured to be driven to rotate by the shaft power of the engine 59 being transmitted by a belt 63.

FIG. 9 is a sectional view of the variable displacement gas compressor 10, and FIG.
FIG. The suction port 1 of the variable displacement gas compressor 10 is configured to suck refrigerant gas from an evaporator 51 connected to the outside. The cylinder 3 is sandwiched between the front head 5 and the rear side block 7. A rotor 9 is rotatably arranged in the cylinder 3.

[0005] The rotor 9 is fixed through the rotating shaft 11. A vane groove 13 is formed on the outer periphery of the rotor 9 in a radial direction, and a vane 15 is slidably mounted in the vane groove 13. When the rotor 9 rotates, the vane 15 is urged against the inner wall of the cylinder 3 by the centrifugal force and the oil pressure at the bottom of the vane groove 13.

In the cylinder 3, a rotor 9, vanes 15,
It is divided into a plurality of small rooms by 15. These small chambers are referred to as compression chambers 17, 17...

When the volume of the compression chambers 17, 17,... Changes as the rotor 9 rotates, the low-pressure refrigerant gas is sucked in from the suction port 1 and compressed by the change in volume.
A case 19 is fixed to the peripheral ends of the cylinder 3 and the rear side block 7, and a discharge chamber 21 is formed inside the case 19.

The high-pressure refrigerant gas compressed in the compression chamber 17 is
It is sent to the discharge chamber 21 via the discharge port 23 and the discharge valve 25. Then, the refrigerant gas is sent from the discharge chamber 21 to the external condenser 53 via the discharge port 27.

The variable displacement type gas compressor 10 has a variable displacement mechanism 30. The variable capacity mechanism 30 is capable of variably adjusting the discharge capacity of the refrigerant gas according to the vehicle interior temperature. FIG. 11 shows a configuration example of the variable capacity mechanism 30.

The control plate 29 is arranged in the front head 5 so as to face the side of the cylinder 3. Control board 2
9 is provided with two notches 29a. The notch 29a allows communication between the inside of the cylinder 3 and the suction chamber 31 communicating with the suction port 1. On the other hand, a compression chamber 17 is formed in a portion of the control plate 29 without a notch, an inner wall of the cylinder 3 and a space closed by the vane 15.

When the control plate 29 is rotated clockwise, the notch 29
By rotating a to the right, the position where the compression chamber 17 is formed also moves to the right, and the capacity of the compression chamber 17 at this time also decreases. As described above, by rotating the control plate 29, the discharge capacity can be adjusted.

The control plate 29 is rotated by a hydraulically driven drive shaft 39 via a pin 33. By adjusting the opening of the control valve 37, oil is injected from the discharge chamber 21 into the sleeve 35, and the drive shaft 39 is caused to linearly move by the oil pressure at this time. Then, the linear motion is converted into a rotational motion via the pin 33, and the control plate 29 is rotated.

The amount of oil to be injected can be changed by changing the opening of the control valve 37. This change in opening is
This is performed by changing the capacity control command value (duty ratio) shown in FIG. The control plate 29 is rotated in balance with the elastic force of the spring 38 in accordance with the pressure difference between the control pressure Pc in the sleeve 35 and the pressure Ps in the suction chamber 31.

In FIG. 8, for example, a temperature sensor 55 for detecting the air temperature at the outlet of the evaporator 51 is used.
Are arranged. A rotation speed sensor 57 is provided to detect the rotation speed of the engine 59.

The control circuit 61 calculates a displacement control command value based on the detection signal of the temperature sensor 55 and the rotation speed of the engine 59. This capacity control command value is amplified by a capacity control signal generation circuit 65 and then transmitted to the control valve 37 of the capacity variable mechanism 30.

Next, a control method of the variable displacement mechanism 30 will be described with reference to a flowchart of FIG. For simplicity, an example will be described in which the capacity of the variable displacement gas compressor 10 is reduced, such as when the rotation speed of the engine 59 increases.

Now, it is assumed that the detected temperature at the outlet of the evaporator 51 becomes lower than the target temperature at the outlet of the evaporator 51. In this case, it is necessary to lower the cooling capacity in order to prevent the vehicle compartment from getting too cold.

First, in step 1 (abbreviated as S1 in the figure, the same applies hereinafter), the target refrigerant flow rate of the variable displacement gas compressor 10 is calculated based on the temperature deviation between the target temperature and the detected temperature. The temperature deviation calculation at this time is performed by PID control or the like in the compensator.

Next, in step 3, the discharge speed of the variable displacement gas compressor 10 is determined in consideration of the rotational speed of the variable displacement gas compressor 10 or the engine 59 based on the calculated target refrigerant flow rate. Calculate the capacity.

In step 5, a rotational speed correction operation is performed based on a characteristic curve indicating the relationship between the discharge capacity and the capacity control command value (not shown) based on the discharge capacity. The command value is determined. At this time, the capacity control command value is commanded to decrease. as a result,
In step 7, the average current is reduced, and in step 9, the opening of the control valve 37 is reduced.

At this time, in step 11, the control pressure Pc in the sleeve 35 decreases. Therefore, step 13
, The drive shaft 39 is moved downward, and in step 15, the control plate 29 is rotated clockwise. As a result, in step 17, the discharge capacity of the variable displacement gas compressor 10 is reduced, and the cooling capacity is reduced. Thus, the control command is output so that the detected temperature becomes the target temperature.

[0022]

However, when the target temperature is set by a human, the target temperature may be suddenly and significantly changed. If the setting of the target temperature is suddenly changed, the change in the target temperature is directly input to the temperature deviation calculation of the compensator as the temperature deviation ΔT.

The compensator is optimized so that even a small deviation can be corrected immediately, so that when a large temperature deviation ΔT is input, a maximum control command is output so as to quickly match the target value. I do.

As a result, a rapid temperature change operation is performed,
A large overshoot occurs in the temperature change of the controlled object,
In addition, hunting may occur. Further, the control plate 29 of the variable capacity mechanism 30 makes a large movement in response to a sudden control output command. If this state is repeated, the life of the variable displacement gas compressor 10 may be shortened.

Such a situation is a problem common to feedback control systems. In addition, it is caused not only when a human intervenes but also when a target value is set by a system process. For example, it may occur when the processing unit for setting the target temperature breaks down and stops functioning or malfunctions.

The present invention has been made in view of such a conventional problem, and it is possible to avoid overshoot and hunting and to perform smooth and stable control when the setting of a target value is suddenly changed. It is an object to provide a possible feedback control system and feedback control method.

[0027]

SUMMARY OF THE INVENTION Therefore, the present invention (claim 1) provides a set target storing means for storing a post-update value of a set target set for a control target, and a state variable of the control target. Until the detection output reaches the set target, an intermediate target storage means for storing a previous value of the set target as an intermediate target value, and the post-value and the intermediate target storage means stored in the set target storage means. When the difference from the stored intermediate target value exceeds a predetermined value, the intermediate target value is gradually increased or decreased so as to be closer to the post-value, and the intermediate target value is set as the preceding value and the intermediate target value is set as the intermediate value. Change processing means for storing in the target storage means, deviation calculation means for calculating a deviation amount from the detection output with the intermediate target value processed by the change processing means as a control target of the control object, and the deviation calculation means Characterized in that a compensating means for compensating the control signal of the control object in accordance with the calculated deviation amount.

The set target storage section stores the updated value of the set target to be controlled, and the intermediate target storage section stores the pre-update value of the set target as the intermediate target value. When the set target is changed and the difference between the post-value and the intermediate target value exceeds a predetermined value, the change processing means increases or decreases the intermediate target value so as to gradually approach the post-value and sets the pre-value to the pre-value. And Using the intermediate target value as a control input, the deviation calculating means calculates a deviation amount from the detection output of the state quantity of the controlled object, and the compensating means compensates the control signal for the controlled object according to the deviation amount.

Therefore, even when the set target for the control object is suddenly changed, the control input is gradually changed toward the set target, so that stable and smooth feedback control can be performed while avoiding overshoot and hunting. It becomes possible.

Further, according to the present invention (claim 2), the change processing means increases or decreases the intermediate target value stored in the intermediate target storage means at a predetermined time step value at a predetermined value. Each time, a step processing unit for the control input is provided.

The step processing section can gradually change the intermediate target value with a simple configuration based on the step value increasing / decreasing processing.

Further, the present invention (claim 3) is characterized in that the set target storage means includes a computer processing unit for calculating and processing a post-set value of the set target by a computer.

Even when the set target storage unit outputs an abnormal target value due to malfunction or failure, excessive change operation by the compensating unit can be suppressed by the change processing unit. Therefore, system processing can be performed with a simple configuration without requiring a complicated mechanism for abnormality protection.

Further, according to the present invention (claim 4), the compensation means includes a plurality of control units having different compensation characteristics,
A mode switching means for switching the control unit according to the control input is provided.

The mode switching means receives a sequentially changing intermediate target value as a control input, and the control unit is sequentially switched according to the magnitude of the control input until the intermediate target value reaches a set target. Therefore, the feedback control system according to the present invention can control the control target with optimal compensation characteristics in the process until the detection output of the control target reaches the set target.

Further, according to the present invention (claim 5), the controlled object is a refrigeration system, and the set target storage means is:
A target temperature of the control target is stored as a post-value of the set target, and a feedback control process is performed on the post-value.

The feedback control system of the present invention is applied to a refrigeration system, and can smoothly respond to a sudden change in temperature setting in temperature control. In addition, even when a variable displacement gas compressor is used in the refrigeration system, smooth movement is ensured, and the life of a controlled object such as the gas compressor can be increased.

Further, the present invention (claim 6) is a feedback control method, which stores a post-update value of a set target set for a controlled object, and detects and outputs a state quantity of the controlled object to the set target. Until reaching, the previous value of the set target is stored as an intermediate target value, and when the difference between the post value and the intermediate target value exceeds a predetermined size,
The intermediate target value is gradually increased or decreased so as to approach the rear value, the intermediate target value is set as the previous value, and the intermediate target value is set as a control target of the control target, and a deviation amount from the detection output is calculated. Then, feedback control is performed by compensating the control signal of the control object according to the deviation amount.

According to this control method, even when the set target for the control object is suddenly changed, the intermediate target value as the control input is gradually changed toward the set target, so that overshoot and hunting can be avoided. As a result, stable and smooth feedback control becomes possible.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described. FIG. 1 shows a block diagram of a control device according to the first embodiment of the present invention. The same elements as those in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, a temperature sensor 55 is a thermistor, a thermocouple, or the like, and detects a temperature of a control target. The detected temperature signal is digitized by an A / D converter 71 and converted to an actual temperature Ts by an actual temperature converter 73.

For setting the target temperature, for example, a target temperature setting device 75 such as a slide type operation device by operating a knob is provided. The output signal of the target temperature setter 75 is sent to the A / D converter 7 via a signal detecting means (not shown).
7 and is converted to a target temperature Tr by a target temperature converter 79. The converted target temperature Tr is input to the control input T by the small step changer 200.
r1 is gradually changed. The small step changer 200 will be described later.

The subtracter 81 calculates a temperature deviation ΔT based on the actual temperature Ts and the control input Tr1.
The temperature compensator 85 is a control unit including a PID (proportional, integral, and differential elements) and a filter constant F of a low-pass filter. In the temperature compensating section 85, the temperature is compensated in accordance with the temperature deviation ΔT, and the capacity control command value Duty1 is output.

On the other hand, the engine 59 is detected by the rotation speed sensor 57.
Is detected. However, the rotation speed of the rotation shaft 11 of the variable displacement gas compressor 10 may be used. The rotation speed of the engine 59 is digitized by an A / D converter 87 and converted to a rotation speed Nc by a rotation speed converter 89.

The speed correction calculation section 91 stores speed correction characteristics. For example, a capacity control command value is calculated from the detected rotation speed Nc based on a predetermined speed correction characteristic, and a capacity control command value Duty2 is output.

The capacity control command value Duty1 and the capacity control command value Duty2 are added by the adder 103. The added signal Duty3 is determined by the saturation determination circuit 105 as to whether or not it is saturated. If the signal is saturated, the saturation signal is returned to the temperature compensator 85 to stop the integration operation. .

On the other hand, the addition signal Duty3 is
After the amplitude is limited at 07, digital / analog conversion is performed by the D / A converter 109. D /
The output signal of the A-converter 109 is input to the displacement control signal generating circuit 65 of the variable displacement gas compressor 10 to be controlled.

Next, regarding the operation of the control device according to the first embodiment of the present invention, the internal operation of the small step changer 200 will be described, and then the overall operation will be described. FIG. 2 shows a processing flowchart of the small step changer 200. FIG.
The same elements as those described above are denoted by the same reference numerals and description thereof is omitted.

In FIG. 2, step 201 (S in the figure)
Abbreviated as 201. In the following, the same applies), when a start signal for the control device is received, "1" is set to the discrimination variable i.
The determination variable i is a variable for determining the initialization processing.

At step 203, the discrimination variable i is checked. If i <2, in step 205,
For the initialization process, the after value Tr received from the target temperature setting device 75 is set to the previous value Tr2, and “2” is set to the discrimination variable i. The post value Tr is a current set target input from the target temperature setter 75. In addition, the previous value Tr2 is an intermediate target value determined as an actual target value of the control target separately from the set target of the control target.

The intermediate target value is changed according to the change of the set target, as described below. The initial value is the actual target value of the control target at the time of starting.
In this example, the target temperature Tr0 of the target temperature setter 75 at the start of the startup is stored as the initial value of the previous value Tr2 in order to control the control target according to the setting of the target temperature setter 75 from the start of the start.

In step 207, the rear value Tr and the front value Tr
The magnitude of 2 is checked. If Tr> Tr2, that is, if the subsequent value Tr is larger than the previous value Tr2 (change to a higher temperature), at step 209, a predetermined amount of step value tr is added to the previous value Tr2. This previous value Tr2 is calculated in step 211
And a subtractor 8 as a control input Tr1 for feedback control.
Sent to 1.

In step 213, it is checked whether Tr = Tr2, that is, whether the subsequent value Tr is equal to the previous value Tr2, and if so, step 211 is processed. Tr <T
If r2, that is, the subsequent value Tr is smaller than the previous value Tr2 (change to a lower temperature), the step value tr is reduced from the previous value Tr2 in step 215. The previous value Tr2 is output in step 211 as an actual target value of the control target.

Next, the cycle operation of the small step changer 200 will be described. In the small step changer 200, when the control device is activated, the process is performed on the subsequent value Tr sent from the target temperature setter 75 at a fixed sampling time interval.

First, in response to the activation signal of the control device, "1" is set to the discrimination variable i in step 201. In accordance with the discrimination variable i (in this case, “1”), step 205 is selected in step 203 to initialize the control device.
In step 205, the rear value Tr is set to the previous value Tr2, and “2” is set to the discrimination variable i. As a result, the initial value Tr0 of the rear value Tr, that is, the target temperature Tr0 at the start of the operation of the target temperature setting device 75 is set as the intermediate target value in the previous value Tr2.

Next, at step 207, the rear value Tr
And the magnitude of the previous value Tr2 are checked. Initially, Tr = Tr2 by the processing of step 205, so the selected intermediate value is output as the control input Tr1 in step 211 after checking in the selected step 213. This intermediate target value is the previous value Tr2, that is, the target temperature setter 75.
Is equal to the initial target temperature Tr0. This control input Tr1
Is sent to the subtractor 81.

The processing of the next cycle starts at a predetermined sampling time interval. In this new cycle, since the discrimination variable i = 2 in step 203, step 207 is selected first. Since Tr = Tr2 when the set target of the target temperature setter 75 is the same, the intermediate target value is set to the control input Tr1 in step 211 after checking from step 207 to step 213.
Is output. This control input Tr1 has a post value T
Until r is changed, it is similarly output repeatedly at regular time intervals.

Next, when the target set by the target temperature setter 75 is changed to a higher temperature, the post value Tr is changed to T
Since r> Tr2, the previous value Tr2 is increased in step 209 by the check in step 207. The previous value Tr2 is increased by a predetermined step value tr toward the set target Tr.
Is output as the control input Tr1. This process
The same is repeated until Tr = Tr2, and each time,
The previous value Tr2 is increased.

When the set temperature of the target temperature setter 75 is changed to a lower temperature, the post value Tr is changed and Tr
<Tr2, step 207 and step 2
By the check at 13, the previous value Tr2 is reduced at step 215. The previous value Tr2 is reduced by a predetermined step value tr toward the set target Tr, and is output as a control input Tr1 in step 211. This process is similarly repeated until Tr = Tr2, and the previous value Tr2 is reduced each time.

Therefore, the operation of the small step changer 200 when the set target of the target temperature setter 75 is changed, as shown in FIG. Step value t for each
r is added to the previous value Tr2. The intermediate target value is changed with the step value tr as an increasing width until it becomes equal to the subsequent value Tr, and the control input Tr1 is gradually increased.

If the subsequent value Tr is smaller than the previous value Tr2, the step value tr is subtracted from the previous value Tr2 at each sampling time, and the step value tr is reduced until the intermediate value becomes equal to the subsequent value Tr. The change processing is performed, and the control input Tr1 is gradually reduced.

As described above, when the setting of the target temperature is changed, the control input Tr1 is changed via the intermediate target value in the small step changer 200 using the step value tr as an increase / decrease range. By sending this control input Tr1 to the subtractor 81, a smooth and non-hunting response characteristic that changes with a predetermined step value tr as the change width can be obtained without being directly affected by the rapidly changing set target.

Next, the operation of the entire control device including the small step changer 200 will be described. For example, in the case of controlling the temperature in a vehicle interior, how a person perceives the temperature in the vehicle interior varies from person to person, and also changes depending on the situation. Therefore, the setting of the target temperature setting device 75 may be suddenly changed by the person's judgment. In such a case, the control device according to the present invention uses the small step changer 200 so that the temperature can be controlled smoothly and stably until the target temperature is reached.
It is provided with.

In FIGS. 1 and 2, when the setting of the target temperature setting device 75 is changed to a desired temperature in the vehicle interior, the control input Tr1 is changed by the small step changer 200 from the immediately preceding set target. It changes gradually until it is equal to the new set target. This is sent to the subtractor 81, and the capacity control command value Duty1 is calculated by the temperature compensator 85 in accordance with the temperature deviation ΔT = Ts−Tr1.

The capacity control command value Duty1 and the capacity control command value Duty2 calculated by the speed correction are added, and
The displacement control of the variable displacement gas compressor 10 is performed based on the displacement control command value Duty3 which is the added signal.

Therefore, even if there is a sudden change in the setting of the target temperature, the temperature compensator 85 performs a compensation operation based on the control input Tr1, so that a smooth control output is realized.
As a result, overshoot of a temperature change can be suppressed or hunting can be eliminated. Further, excessive operation of the control plate 29 and the like of the variable capacity mechanism 30 is avoided,
The durability of the controlled object such as the variable displacement gas compressor 10 is improved by the stable and smooth movement, and the life can be increased.

Next, a control device according to a second embodiment of the present invention will be described. FIG. 4 is a block diagram of a control device according to the second embodiment, and FIG. 5 is a flowchart including a refrigeration cycle. The same elements as those in FIG. 1 or FIG. 8 are denoted by the same reference numerals, and description thereof is omitted.

4 and 5, the second embodiment of the present invention is different from the first embodiment in that the temperature compensator 85 includes a plurality of control units, and the speed compensator 91
Is provided with a plurality of speed correction operation units, and the small step changer 200 is applied to mode switching control in which these are switched by the mode switching means 83 according to conditions.

The target temperature setting device 75 is, for example, a three-stage push button switch of strong cooling, medium cooling, and weak cooling. The output signal of the target temperature setter 75 is output to the target temperature signal detector 7.
6 is converted into a voltage value and output.

Then, the data is digitized by an A / D converter 77 and converted into a target temperature Tr by a target temperature converter 79. Further, when the target temperature Tr is smaller than the small step changer 200,
, The control input Tr1 is calculated. The temperature deviation ΔT is calculated by the subtractor 81 based on the control input Tr1.

The fan setting device 93 is, for example,
It is a three-stage push button switch for medium wind and low wind. The output signal of the fan setting unit 93 is supplied to a fan signal detecting means 95.
To be converted into a voltage value and output.

The data is digitized by the A / D converter 97 and converted to a Fan signal by the fan condition converter 99. The Fan signal is a signal indicating the currently set fan condition, and indicates which of the three stages of strong wind, medium wind, and weak wind is selected.

The temperature compensator 85 includes a plurality of control units 85
A, 85B, 85C, etc. In each control unit, a PID (proportional, integral, differential element) and a filter constant F of a low-pass filter are set corresponding to a target temperature and a setting condition of a fan, respectively, so as to perform optimum temperature compensation.

More specifically, as shown in FIG.
Three target temperatures of "medium" and "weak" and "strong", "medium" and "weak"
Nine types of control units (No. 1 to No. 9) are prepared in advance corresponding to the three-stage fan setting conditions.

The mode switching means 83 receives the control input Tr1 from the small step changer 200, and selects one corresponding to the control input Tr1 and the setting condition of the fan signal from the plurality of control units 85A, 85B, 85C and the like. Temperature deviation Δ
T is adapted to be input to the selected control unit. The control unit compensates for the temperature deviation ΔT and outputs a capacity control command value Duty1.

On the other hand, the speed correction operation section 91 is composed of a plurality of speed correction operation units 91A, 91B and 91C. Each of the speed correction calculation units 91A, 91B, and 91C stores a speed correction characteristic for calculating a displacement control value corresponding to the rotation speed.

The rotation speed Nc is calculated by the speed correction operation unit 9
1A, 91B, and 91C are input to one speed correction operation unit selected by the mode switching unit 83,
The capacity control command value Duty2 is output.

Next, the operation of the control device according to the second embodiment of the present invention will be described. At the time of startup, the target temperature Tr from the target temperature setting device 75 is
00 to the mode switching means 83.

In the mode switching means 83, the control input Tr1
The control unit of the temperature compensation unit 85 and the speed correction operation unit of the speed correction operation unit 91 are selected according to the push button switch of the fan setting unit 93. The capacity control command value Du is calculated by the control unit and the speed correction operation unit.
ty is output.

Here, when the push button switch of the target temperature setter 75 is changed, the small step changer 200
, The control input Tr1 is gradually changed. For example, when the target temperature setting is changed from “weakly cold” to “strongly cold” at the beginning, if the fan setting unit 93 is set to “weak wind” in accordance with the change of the control input Tr1, then Are sequentially switched to No. 3 through No. 6 from the control unit of No. 6.

That is, the continuity of the control characteristics is ensured by switching the control characteristics within the range that can be covered by the optimum control unit. Therefore, a sudden change in the control characteristics is avoided, and the advantage of the mode switching control that enables optimum control according to the conditions can be maximized.

Next, a third embodiment of the present invention will be described. FIG. 7 shows a block diagram of the third embodiment of the present invention. 7, the third embodiment of the present invention is different from the second embodiment in that a pressure sensor 111 is provided instead of the temperature sensor 55, and control is performed based on the pressure value.

The pressure sensor 111 is, for example, an inlet 1 of a pipe connecting the variable displacement gas compressor 10 and the evaporator 51.
It is located close to. A target pressure setting device 115 for setting the pressure is provided in the vehicle interior.

As described above, control based on the pressure value is also possible. Even in this case, the small-step changer 200 enables smooth and stable optimal control for a sudden change in the set target.

The small step changer 200 is not limited to the one that changes at a constant step value, but may be one that changes gradually and continuously. In addition, the target temperature setting device 7
5. The target pressure setting device 115 is not limited to a setting operation performed by a person, and may be configured to automatically process a target value by a computer or the like.

In this case, even when an abnormal target value is output due to a malfunction or failure of the computer or the like, excessive operation of the control unit is suppressed by the small step changer 200. Therefore, stable control can be performed without requiring a complicated mechanism for protecting an abnormality such as a malfunction.

[0087]

As described above, according to the present invention, when the set target for the controlled object is changed, the detected output of the controlled object reaches the new set target until the detected output reaches the new set target.
The change processing means increases or decreases the intermediate target from the initial set target so as to gradually approach the new set target. The intermediate target is used as a control input to calculate a deviation amount from the detection output of the control object, and the compensating means compensates the control signal according to the deviation amount.

Therefore, according to the feedback control system and the feedback control method of the present invention, even when the set target is suddenly changed, since the control input is gradually changed toward the set target, overshoot and hunting can be avoided. As a result, stable and smooth feedback control becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device according to a first embodiment of the present invention.

FIG. 2 is a processing flowchart of a small step changer.

FIG. 3 is an operation characteristic diagram of a small step changer.

FIG. 4 is a block diagram of a control device according to a second embodiment.

Fig. 5 Flow chart including refrigeration cycle

FIG. 6: Relationship between conditions and control unit

FIG. 7 is a block diagram of a third embodiment of the present invention.

FIG. 8 is an overall simplified configuration diagram of an air conditioning system.

9 is a sectional view of the variable displacement gas compressor of FIG. 9;

10 is a cross-sectional view of the variable displacement gas compressor taken along line AA in FIG. 9;

FIG. 11 shows a configuration example of a variable capacity mechanism.

FIG. 12: Capacity control command value (duty ratio)

FIG. 13 is a flowchart.

[Explanation of symbols]

 Reference Signs List 61 control circuit 65 capacity control signal generation circuit 75 target temperature setter 81 subtracter 83 mode switching means 85 temperature compensator 91 speed correction calculator 93 fan setter 111 pressure sensor 200 small step changer i discriminant variable Nc rotation speed tr step Value Tr After value (set target storage) Tr1 Control input Tr2 Previous value (intermediate target storage) Ts Control temperature ΔT Temperature deviation (deviation)

Continued on the front page F term (reference) 5H004 GA03 GA06 GA12 GB20 HA01 HA03 HA08 HA16 HB01 HB03 HB08 JA01 JA02 JA03 JA08 JA23 JA29 JB09 JB19 KA22 KA54 KA69 KB02 KB04 KB06 LA16

Claims (6)

[Claims] 1. A set target storage unit for storing a post-update value of a set target set for a control target, and the set target until a detection output of a state quantity of the control target reaches the set target. Intermediate target storage means for storing the previous value of the intermediate target value as an intermediate target value, and a difference between the post-value stored in the set target storage means and the intermediate target value stored in the intermediate target storage means is a predetermined magnitude. A change processing means for increasing or decreasing the intermediate target value so as to gradually approach the after value and storing the intermediate target value as the previous value in the intermediate target storage means; A deviation calculating means for calculating a deviation amount from the detection output using the intermediate target value processed by the control target as a control target of the control object, and a control signal of the control object according to the deviation amount calculated by the deviation calculating means. And a compensating means for compensating for the feedback. 2. The method according to claim 1, wherein the change processing unit increases or decreases the intermediate target value stored in the intermediate target storage unit by a predetermined step value at predetermined time intervals.
The feedback control system according to claim 1, further comprising a step processing unit serving as the control input. 3. The feedback control system according to claim 1, wherein the set target storage unit includes a computer processing unit that calculates and calculates a post-set value of the set target by a computer. 4. The apparatus according to claim 1, wherein said compensating means includes a control unit having a plurality of different compensation characteristics, and mode switching means for switching said control unit in accordance with said control input. The feedback control system as described. 5. The control target is a refrigeration system, and the set target storage unit stores a target temperature of the control target as a post-value of the set target, and performs a feedback control process on the post-value. The feedback control system according to claim 1. 6. A post-update value of a set target set for the controlled object is stored, and a previous value of the set target is set to an intermediate value until a detection output of a state quantity of the controlled object reaches the set target. When the difference between the post-value and the intermediate target value exceeds a predetermined value, the intermediate target value is increased or decreased so as to gradually approach the post-value. Is used as the previous value, the intermediate target value is set as a control target of the control target, a deviation amount from the detection output is calculated, and feedback control is performed by compensating the control signal of the control target according to the deviation amount. A feedback control method.