JPH0618100A - Control method and control device for air conditioner - Google Patents

Abstract

PURPOSE:To provide a control method and a control device, which are capable of controlling a controlled object excellently when a controlled variable has a saturation area, and an air conditioner. CONSTITUTION:At air conditioner is provided with a first fuzzy operating means 1, operating a controlled target value (rf) based on a controlled variable (y) outputted from a controlled object 9 having a saturating area, a comparing means 2, comparing the controlled target value (rf) with the controlled variable (y), two sets of fundamental control means 3A, 3B, operating two different manipulated variables UA, UB based on the result of the comparison, and a second fuzzy operating means 8, operating the manipulated variable Uf of the controlled object 9 based on the operated two manipulated variables UA, UB while considering the controlled variable (y).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for a controlled object having a controlled variable having an upper limit value, a lower limit value, or both, and an air conditioner using the control method.

[0002]

2. Description of the Related Art Conventionally, in order to control a nonlinear quantity,
Non-linear control is used. The non-linear control is to analyze a dynamic characteristic of a non-linear control amount in detail and construct a control system suitable for the characteristic.

As a simple and practical method, there is a method of linearly approximating the nonlinearity of the control amount in a minute section.
A control system is constructed that linearly approximates the nonlinear dynamic characteristics of the control amount and that can control well even if the dynamic characteristics are slightly different from the approximate linearity. As such a control method, with respect to the control deviation which is the difference between the control amount and the control target value,
Proportional operation, integral operation and proportional operation, differential operation and proportional operation are performed, and the operation amount is determined by the sum of the operation results.
The so-called PID control method is widely adopted. The structure is shown in FIG. In the figure, the comparison means 2 detects the control deviation e using the control target value r and the control amount y which is the output from the controlled object 9. The detected control deviation e is the PID
It is input to the controller 3. The PID controller 3 internally inputs the control deviation e to the proportional calculation means 4, the integral calculation / proportional calculation means 5, and the differential calculation / proportional calculation means 6, and the respective calculation results are added by the addition means 7 to thereby manipulate the operation amount u. Is output. The control target 9 is operated using the operation amount u. Here, Kp, Ki, and Kd are the coefficients of the proportional calculation in each calculation means 4, 5, and 6.

[0004]

In the case of non-linear control, good control performance can be obtained by sufficiently analyzing the non-linear behavior of the control amount for each manipulated variable. However, when the control amount is a non-linear amount having an upper limit value or a lower limit value (having a saturation region) such as the degree of superheat or the degree of subcooling of the refrigeration cycle, the operation amount and the control amount shown in FIG. It is not possible to uniquely determine the manipulated variable when the controlled variable is the upper limit value and the lower limit value, unlike the points a and b of the characteristic curve indicating the relationship. Therefore, there is a problem that it is difficult to sufficiently analyze the nonlinear behavior of the controlled variable, and it is difficult to construct a nonlinear control system with good performance.

On the other hand, in the linear control typified by the PID control method, when the control amount is a non-linear amount having an upper limit value or a lower limit value such as the degree of superheat or supercooling of the refrigeration cycle, the control amount is When the upper limit value and the lower limit value are not reached, the difference in dynamic characteristics is too large to obtain good control performance. As can be seen from the relationship diagram between the manipulated variable and the controlled variable shown in FIG. 3, when the controlled variable is at the upper limit value and the lower limit value, the controlled variable hardly changes even if the manipulated variable is changed. Therefore, if you configure the controller so that the control amount quickly matches the target value for the control amount when the upper limit value and the lower limit value are not reached, the Even if the amount is changed to some extent, the controlled amount is not affected, so that it takes a considerable time for the controlled amount to match the target value other than the upper limit value and the lower limit value. Conversely, if the controller is configured so that the control amount quickly matches the target value for the control amount when the upper limit value and the lower limit value are reached, the manipulated variable will change significantly even if the control amount changes slightly. Therefore, when the control amount does not reach the upper limit value and the lower limit value, there is a problem that the operation amount and the control amount hunt.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a control method, a control device, and an air conditioner capable of controlling a controlled object well even when the controlled variable has a saturated region. It is a thing.

[0007]

According to the present invention of claim 1, a control target value is selected on the basis of a control amount output from a control object having a control amount having a saturation region, and the selected control target value is selected. And the control amount are compared, the operation amount of the control target is calculated based on the comparison result, and the control target is controlled by the calculated operation amount.

According to a fourth aspect of the present invention, a controlled variable output from a controlled object having a saturated control area is compared with a predetermined control target value, and a plurality of manipulated variables of the controlled object are compared based on the comparison result. This is a control method in which one operation amount is calculated based on a plurality of calculated operation amounts while performing the calculation by various kinds of operation methods and considering the control amount, and the control target is controlled by the one operation amount. .

According to a sixth aspect of the present invention, a target value selecting means for selecting a control target value based on a control amount output from a controlled object having a saturated control region, and the selected control target value. The control device includes a comparison unit that compares the control amount and a control calculation unit that calculates the operation amount of the control target based on the comparison result.

According to the present invention of claim 8, a comparison means for comparing a control amount output from a control target having a saturation region of the control amount with a predetermined control target value, and an operation of the control target based on the comparison result. A plurality of control calculation means for calculating the quantity by a plurality of kinds of calculation methods and a manipulated variable calculation means for calculating one manipulated quantity based on the plurality of calculated manipulated quantities while considering the control quantity are provided. It is a control device.

According to the present invention of claim 9, the control amount is the suction superheat degree of the compressor, the control target value is the superheat degree, and the operation amount is the expansion capacity of the expansion function of the refrigerant. It is an air conditioner using the control method of.

[0012]

According to the present invention, the control target value to be compared with the control amount is selected based on the control amount. Therefore, when the control amount of the controlled object is in the saturation region or in the vicinity thereof, the control amount is quickly set to the control target value. The amount of operation that can be matched is calculated.

Further, since the manipulated variable of the controlled object is computed by a plurality of types of computing methods and one manipulated variable is computed based on the manipulated variables while considering the controlled variables, the controlled variable of the controlled subject is saturated. When it is in the region or in the vicinity thereof, an operation amount that allows the control amount to quickly coincide with the control target value is calculated.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 is a block diagram showing the basic configuration of a control device (or control method) according to an embodiment of the present invention, FIG.
FIG. 3 is a configuration diagram of an air conditioner using the same control device (or control method). That is, the control device of FIG. 1 includes first fuzzy calculation means 1 for calculating a control target value based on the control amount y, comparison means 2 for comparing the calculated control target value rf with the control amount y, and The comparison result e can be changed by 2
Basic control means 3A, 3B for calculating one manipulated variable UA, UB
And a second fuzzy computing means 8 for computing one manipulated variable Uf from these manipulated variables UA and UB in consideration of the controlled variable y. Further, the manipulated variable Uf is input to the controlled object 9, the controlled object 9 is controlled, and the controlled variable y is output from the controlled object 9.

The air conditioner shown in FIG. 2 has a compressor 10 for compressing a refrigerant, a four-way valve 13 connected to the refrigerant outlet side of the compressor 10, and a heat source side heat exchange connected to the four-way valve 13. It is composed of a vessel 11 and a use side heat exchanger 12, and an electronic expansion valve 14 connected between the heat source side heat exchanger 11 and the use side heat exchanger 12. Further, a superheat detection means 15 is provided at the refrigerant inlet portion of the compressor 10. In the above-described configuration, the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 passes through the four-way valve 13 (here, heating is performed, and the connection is shown by a solid line), and then enters the use-side heat exchanger 12. Here, the gas refrigerant releases heat to the outside air (for example, indoor air) and condenses into a liquid refrigerant. After that, the pressure is reduced by the electronic expansion valve 14 to become a gas-liquid two phase, the heat source side heat exchanger 11 absorbs heat from the outside air and becomes a gas refrigerant again, and passes through the four-way valve 13 to the compressor 10. Inhaled. At this time, since heat is released from the use side heat exchanger 12,
The air conditioner operates in heating mode. On the other hand, when the four-way valve 13 is switched to the broken line side, the flow path of the refrigerant is reversed, and the heat source side heat exchanger 11 releases heat to the outside air, and the use side heat exchanger 1
In 2 the heat is absorbed, so the air conditioner is in cooling operation.

Next, the operation of the above embodiment will be described when it is used in the air conditioner of FIG.

First, the superheat detection means 15 located near the suction port of the compressor 10 detects the intake superheat (control amount) of the compressor 10 (see the curve shown by the dotted line in FIG. 3 for the characteristic of the control amount). . According to the value of the detected degree of superheat (control amount), the first fuzzy calculation means 1 calculates the membership value μ _i for each control target value r _i , and which target value is adopted at what ratio. It is determined based on (Equation 1). Here, the control target value r ₁ is set to a value larger than the normal control target value, and when the degree of superheat becomes near 0 deg (indicating the saturation region which is the lower limit value), the corresponding membership The value μ ₁ increases. The control target value r ₂ is a normal control target value, and when the degree of superheat is much larger than 0 deg (the control target value to be controlled originally), the corresponding membership value μ ₂ becomes large.

[0019]

## EQU1 ## r _f = Σμ _i * r _i [0 ≤ μ _i ≤
1, i = 1, 2] r _f is a target value used in actual control μ _i is a membership value with respect to the control target value r _{i The} target value r _f and the degree of superheat obtained from the calculation result of the first fuzzy calculation means 1 The comparison means 2 compares the degree of superheat (control amount) detected by the detection means 15 to obtain the control deviation e.
Using the control deviation e, the basic control means 3A, 3B calculate respective manipulated variables u _A , u _B by using respective control methods. Both the basic control means 3A and 3B use PID controllers, and the control deviation e is internally calculated by the proportional calculation means 4A and 4A.
B, each integral calculation and proportional calculation means 5A, 5B, each differential calculation and proportional calculation means 6A, 6B, each calculation result is added by each addition means 7A, 7B, each manipulated variable u _A ,
Determine u _B. Then, in accordance with the value of the degree of superheat (control amount) detected by the degree of superheat detection means 15, the second fuzzy operation means 8 calculates the membership value for each operation amount, and which operation amount is to be adopted at what ratio. Is determined based on (Equation 2). Here, the basic control means 3A is configured so that the control amount rapidly coincides with the control target value, and when the degree of superheat approaches 0 deg, the corresponding membership value μ _A becomes large. The basic control means 3B is configured so that the control amount gently matches the control target value, and when the degree of superheat is much larger than 0 deg, the corresponding membership value μ _B becomes large.

[0020]

## EQU00002 ## u _f = Σμ _i * u _i [0 ≤ μ _i ≤
1, i = A, B] u _f is an operation amount (expansion valve opening) μ _i used for actual control is a membership value with respect to a control target value r _i . The calculation result u _f of the second fuzzy calculation means 8 is expressed by an electronic formula. Control target (air conditioner) as the opening degree (operation amount) of the expansion valve 14
Drive 9

With such a control structure, the degree of superheat is 0.
When it becomes close to deg, the control target value becomes large, and since the basic control means selects the one in which the control amount rapidly matches the control target value, the opening degree of the electronic expansion valve 14 with respect to the change in the superheat degree is selected. The change amount of becomes large, and the degree of superheat approaches the target value quickly. Further, when the degree of superheat becomes larger than 0 deg, the control target value becomes a normal control target value, and the basic control means selects the one whose control amount gently matches the control target value. The amount of change in the opening degree of the electronic expansion valve 14 is small, and the degree of superheat can be smoothly matched with the control target value without hunting.

As described above, when the intake superheat of the compressor 10 in the refrigeration cycle is near 0 deg, the controller gain may be increased or the target value may be increased to reduce the change in the control amount. The expansion capacity of the expansion mechanism is changed significantly, and conversely, the intake superheat is 0 de
When it is much larger than g, the gain of the controller is made small, and the normal target value is used so that the expansion capacity of the expansion mechanism is not changed so much even if the change of the control amount is large, and the switching is performed by the fuzzy logic. When the control amount (intake superheat degree) is set to the upper limit value or the lower limit value (0
Even when it becomes deg), the control amount (suction superheat degree) can be quickly and smoothly matched with the control target value.

Further, even when there is a disturbance or a change in the operating state, the intake superheat of the compressor 10 quickly reaches the target value,
Since it does not become 0 deg for a long time, the possibility of liquid compression is reduced, and the reliability and efficiency of the device can be improved.

In the above embodiment, an example in which the control method or the control device is used for the air conditioner has been described, but the present invention is not limited to this, and control of process amounts such as temperature and pressure in production equipment and vehicles such as automobiles. Of course, it may be applied to speed control or the like.

Further, in the above embodiment, the fuzzy logic is used for changing the control target value and calculating the manipulated variable of the controlled object, but the present invention is not limited to this, and may be calculated by weighting calculation, for example.

Further, in the above embodiment, the method of switching the two basic control means using the PID control by the fuzzy logic and changing the two control target values input to the basic control means by the fuzzy logic is used. Although explained, the control method and number of basic control means and the number of control target values are not limited to this. Further, only one of the switching of the basic control means and the change of the control target value may be used.

In the above embodiment, the suction superheat degree of the compressor has been described as an example of the control amount. However, the control quantity is not limited to this, and the superheat degree at the outlet of the evaporator or the supercooling degree at the outlet of the condenser is also used. Can be obtained.

In the above embodiment, the air conditioner has one
The one-to-one air conditioner including the heat source side heat exchanger 11 and the one use side heat exchanger 12 has been described, but the present invention is not limited to this, and a plurality of use side heat exchangers are connected. It is clear that the same effect can be obtained with an air conditioner or duct system. In particular, the control method itself can be applied not only to the air conditioner, but also to control of process amounts such as temperature and pressure in production equipment and speed control of vehicles such as automobiles.

Further, in the above embodiment, the control device is constituted by dedicated hardware, but the same function may be constituted by software using a computer.

[0030]

As is apparent from the above description, according to the present invention, the control target value to be compared with the control amount is selected based on the control amount, or the operation amount of the controlled object is calculated by a plurality of kinds of calculation methods. Since one manipulated variable is calculated based on the manipulated variables while considering the controlled variables, there is an advantage that the controlled object can be well controlled even when the controlled variable has a saturation region.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a control device (or control method) according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an air conditioner using the control method of the embodiment.

FIG. 3 is a diagram showing a relationship between an operation amount and a control amount when the control amount has an upper limit value and a lower limit value.

FIG. 4 is a block diagram showing a configuration of a conventional control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st fuzzy operation means 2 Comparing means 3A, 3B Basic control means 4A, 4B Proportional operation means 5A, 5B Integral operation and proportional operation means 6A, 6B Differential operation and proportional operation means 7A, 7B Addition means 8 2nd fuzzy operation means 9 Control target (air conditioner) 10 Compressor 11 Heat source side heat exchanger 12 Utilization side heat exchanger 13 Four-way valve 14 Electronic expansion valve 15 Superheat detection means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Nakatani 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (9)

[Claims] 1. A control target value is selected based on a control amount output from a control target whose control amount has a saturation region, and the selected control target value and the control amount are compared,
A control method comprising calculating an operation amount of the controlled object based on the comparison result, and controlling the controlled object according to the calculated operation amount. 2. The control method according to claim 1, wherein the control target value is selected by using fuzzy logic. 3. The control target value is changed from a predetermined control target value when the control amount is at or near the saturation region, based on the control amount output from a controlled object having a saturation region. Comparing the changed control target value and the control amount, calculating an operation amount of the control target based on the comparison result, and controlling the control target by the calculated operation amount. And control method. 4. A control amount output from a control target having a saturation region of control amount is compared with a predetermined control target value, and the operation amount of the control target is calculated by a plurality of types of calculation methods based on the comparison result. A control characterized by calculating one operation amount based on the calculated plurality of operation amounts while considering the control amount, and controlling the control target by the one operation amount. Method. 5. The control method according to claim 4, wherein the calculation of one operation amount is performed by using fuzzy logic. 6. A target value selecting means for selecting a control target value based on a control amount output from a control target having a control area having a saturation region, and the selected control target value and control amount. A control device comprising: comparing means for comparing; and control calculating means for calculating an operation amount of the controlled object based on the comparison result. 7. The control target value is changed from a predetermined control target value when the control amount is at or near the saturation region, based on the control amount output from a controlled object having a saturation region. A target value changing means, a comparing means for comparing the changed control target value with the control amount, and a control calculating means for calculating an operation amount of the controlled object based on the comparison result. Characteristic control device. 8. A comparison means for comparing a control amount output from a control target having a control amount with a saturation region with a predetermined control target value, and a plurality of operation amounts of the control target based on the comparison result. A plurality of control calculation means for calculating by a calculation method, and an operation amount calculation means for calculating one operation amount based on the plurality of calculated operation amounts while considering the control amount. Control device. 9. The control method according to claim 1, wherein the control amount is a suction superheat degree of the compressor, the control target value is a superheat degree, and the operation amount is an expansion capacity of the expansion function of the refrigerant. An air conditioner characterized by being used.