JP3254627B2 - Air conditioning control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to air conditioning control for controlling the opening of a control valve for controlling the flow rate of hot or cold water flowing through a heat exchanger of an air conditioner to determine the temperature of air to be supplied to an air conditioning control area. The present invention relates to an air-conditioning control system that determines the amount of supply air to an air-conditioning control area by controlling the blowing capacity of a blower together with the control of a system or a control valve.

[0002]

2. Description of the Related Art Air conditioning air supply temperature control is a temperature control technique for adjusting the temperature of air supplied to a room (hereinafter referred to as air supply). The air-conditioning control system that controls the air-conditioning air supply temperature
A device called a heat exchanger that can heat or cool air, and air mixed with indoor air and outside air is sent to this heat exchanger at an appropriate air volume, and the air heated or cooled by the heat exchanger is air-conditioned. It has a blower for sending it into the target room. As described above, in the air-conditioning control system, heated or cooled supply air is sent into the room. At this time, the temperature of the supply air is adjusted to realize room temperature adjustment.

[0003] The most typical configuration of the heat exchanger is a heat source device for processing water into hot or cold water,
Some have a piping portion (coil) in the heat exchanger and a pump for flowing hot or cold water from a heat source device into the coil. That is, at the same time as hot water or cold water is flowed into the piping by the pump, the air-fuel mixture is flowed into the piping by the blower. Thereby, when hot water is flowing in the pipe portion, the air is heated, and when cold water is flowing, the air is cooled, heat exchange is performed, and the heated or cooled supply air is supplied to the room. It has become. At this time, the temperature of the supply air supplied to the room needs to be adjusted to a desired temperature, but in the heat exchanger configured as described above, the flow rate of hot or cold water flowing through the pipe is determined by the opening degree of the valve. Adjust to get the desired temperature air charge. As a method of adjusting the opening of the valve, a basic feedback control method such as PID control is used.

In order to properly perform PID control in air-conditioning supply air temperature control, a proportional gain relating to the control characteristic,
It is necessary to adjust three parameters (PID parameters) of integration time and differentiation time to appropriate values. When these are appropriately adjusted, the integration time and the differentiation time can be determined depending on characteristics maintained relatively constant, such as the time constant of the temperature sensor, so that it is relatively easy to set them to appropriate values. . On the other hand, the proportional gain must be determined depending on the characteristic (process gain characteristic) of how much the supply air temperature changes with respect to the amount of change in the valve opening.
Factors affecting this characteristic include the temperature of hot or cold water, the temperature of the air sent into the heat exchanger, the amount of air passing through the heat exchanger by the blower,
There is a characteristic (flow characteristic) of the amount of water flowing according to the opening degree of the valve.

[0005] Among the above factors, the temperature of the hot water or the cold water is controlled by the above-mentioned heat source device, and generally does not fluctuate greatly. In addition, the air sent into the heat exchanger often returns air from the room, and the temperature of the returned air (hereinafter referred to as “return air”) is maintained at a relatively constant value because it is originally subjected to air conditioning. . Therefore, these are the factors that change the process gain characteristics,
This is not a big problem in actual air-conditioning air supply temperature control.

On the other hand, in a VAV (Variable Air Volume) method in which the supply air flow is increased or decreased simultaneously with the supply air temperature, the air volume fluctuates frequently. In addition, the flow characteristic of the valve generally shows a relatively extreme nonlinearity called a saturation characteristic in many cases. Due to the flow characteristics of the valve, the relationship between the valve opening and the supply air temperature shows a saturation characteristic (non-linearity) as shown in FIG. Therefore, these are major factors that cause the process gain characteristics to fluctuate, making it difficult to fix the proportional gain of the PID to a constant value.

Conventionally, with respect to the non-linearity of the valve opening-supply air temperature characteristic caused by the non-linearity of the flow rate characteristic of the valve,
A technique called operation amount correction has been used. This technique is
This is a technique in which, when an operation amount, which is a control output of a PID controller that controls the valve opening, is sent to the valve, the operation amount is corrected so as to cancel the above-mentioned non-linearity. However, conventionally, since a correction formula based on a combination of about two straight lines is used so as to prevent the operation amount correction from becoming too complicated (FIG. 9B), the non-linearity of the valve opening-supply air temperature characteristic is obtained. Correction cannot be performed according to the characteristics, and the deviation from the actual characteristics becomes large especially near the boundary point between the two straight lines, and the smooth correction is made when shifting from one straight line to the other straight line Can not do.

On the other hand, with respect to the fluctuation of the air volume in the VAV system, since the air conditioning controller determines the air volume, the air volume becomes a known amount, and a method of changing the proportional gain in accordance with the air volume is possible. is there. But in this case,
If the air flow is largely changed, the proportional gain also changes abruptly, so that the control calculation becomes inconsistent before and after the change of the proportional gain, which causes an abnormal operation. Further, the influence of the change in the air flow rate is also related to the saturation characteristic. For example, the process gain when the valve opening is in the first range at the first air flow rate is different from the process gain in the first range at the second air flow rate. On the other hand, the process gain when the valve opening degree is in the second range at the first air volume is smaller than the process gain at the second air volume at the second air volume. However, simple proportional gain correction cannot be used.

[0009]

As described above, in the conventional air-conditioning control system, it is not possible to appropriately correct the non-linearity of the valve opening-supply air temperature characteristic caused by the non-linearity of the valve flow characteristic. There was a problem. Also, if the proportional gain of the air conditioning controller is changed according to the air volume,
There is a problem that the control operation is adversely affected, and there is a problem that even a simple proportional gain correction cannot cope with a change in the air volume. The present invention has been made to solve the above problem, and has as its object to provide an air conditioning control system that can appropriately correct nonlinearity of a valve opening-supply temperature characteristic. It is another object of the present invention to provide an air conditioning control system capable of appropriately correcting the non-linearity of the valve opening-air supply temperature characteristic in accordance with a change in air flow without adversely affecting a control operation.

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided an adjusting method for adjusting a flow rate of hot water or cold water flowing through a heat exchanger of an air conditioner so as to remove an air conditioning load in an air conditioning control area. Controlling the opening of the valve to determine the temperature of the supply air to the air conditioning control area, and controlling the blowing capacity of the blower
In an air-conditioning control system including an air-conditioning control device that determines the amount of air supply to the air-conditioning control area, a control output of the air-conditioning control device that controls the control valve is a curve that approximates a control valve opening-supply air temperature characteristic. all SANYO provided with means for correcting, based on the approximate function, the curve fitting function, the blower
Ru function der with a blowing capacity as a parameter. As described above, by correcting the control output of the air-conditioning control device based on the curve approximation function approximating the control valve opening-supply air temperature characteristic, the control valve opening due to the non-linearity of the flow characteristic of the control valve is obtained. The non-linearity of the supply air temperature characteristic can be canceled. Ma
In addition, the curve approximation function is determined by the above parameters.
With this, it is possible to perform control output correction according to the change in air volume.
it can.

[0011] As described in claim 2, the upper SL curve approximation function is representative of the curve asymptotically converges to a certain value in a particular domain.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] Next, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram of an air conditioning control system showing an embodiment of the present invention. 1a is a hot water heat source for supplying hot water, 1b
Is a cold water heat source for supplying cold water, 2a is a hot water valve for adjusting the flow rate of hot water supplied from the hot water heat source 1a, 2b is a cold water valve for adjusting the flow rate of cold water supplied from the cold water heat source 1b, and 3a is a hot water valve 1a. A heating coil for heating the air with the supplied hot water, 3b is a cold water valve 1b
A cooling coil for cooling the air with cold water sent through the apparatus, 4 is a blower, 5 is a PID controller serving as an air conditioning control device, and 6 is an operation amount M output from the controller 5.
Air1 is a mixture of air (return air) returned from the room to the air-conditioning control system and outside air, and Air2 is air (air supply) supplied to the room.

The air-conditioning control system includes an air-fuel mixture Air1.
Is heated by the heating coil 3a or cooled by the cooling coil 3b, and the air supply Air2 is sent into the room which is the air-conditioning control area by the blower 4. PI
The D controller 5 calculates an operation amount MV ′, which is a control output, based on the supply air temperature set value r set by the operator and the supply air temperature PV measured by a temperature sensor (not shown), and outputs it to the valves 2a and 2b. I do. This operation amount is input to a converter (not shown) of each valve, and this converter drives the valve. In this way, by controlling the opening degrees of the valves 2a and 2b, that is, the flow rates of hot water and cold water,
Supply air temperature control is performed.

In such an air-conditioning control system, in the present embodiment, the PID controller 5 and the valve 2a,
2b, an operation amount correction arithmetic unit 6 is provided to correct the operation amount. FIG. 2 is a block diagram of the operation amount correction operation device 6, and FIG. 3 is a flowchart for explaining the operation of the operation amount correction operation device 6.

The operation amount signal input unit 11 takes in the operation amount MV 'output from the PID controller 5 (step 101 in FIG. 3). Subsequently, the manipulated variable correction calculation unit 12 calculates the manipulated variable MV by a natural logarithmic expression such as the following expression based on a curve approximation function (exponential function in the present embodiment) that approximates the valve opening-air supply temperature characteristic. ′ Is calculated (step 102). MV = −40 × ln (1−0.01 × MV ′) (1)

In equation (1), the manipulated variable MV 'and the corrected manipulated variable MV both take values from 0 to 100 (%). Then, the manipulated variable signal output unit 13 outputs the corrected manipulated variable MV output from the manipulated variable correction calculation unit 12 to the valves 2a and 2b (Step 103). The operation amount correction arithmetic unit 6 performs the above operation from the PID controller 5 using the operation amount M
This is performed for each control cycle in which V 'is output.

Next, the derivation of equation (1) will be described.
Saturation characteristics (non-linearity) of the valve opening-air supply temperature characteristics as shown in FIG. 9A due to the non-linearity of the flow rate characteristics of the valve
Is a convergence phenomenon to the limit value physically, so it is a reasonable approximation to approximate this saturation characteristic with an exponential function such as the following equation. Have been. PV = Tf + (Tr−Tf) × exp (−0.025 × MV) (2)

On the other hand, the ideal relationship between the correction manipulated variable MV 'output from the PID controller 5 and the supply air temperature PV is a linear characteristic, and this characteristic can be described as the following equation. PV = {(Tf−Tr) / 100} × MV ′ + Tr (3) Equations (2) and (3) hold true for either heating or cooling.

In equations (2) and (3), Tr is the temperature of the air-fuel mixture Air1, and Tf is the heating limit temperature or the cooling limit temperature. The temperature Tr of the air-fuel mixture Air1 is 0% valve opening.
Is the supply air temperature at the time of. That is, when the valve opening is 0%, no heat exchange is performed, so that the supply air temperature PV and the air-fuel mixture temperature Tr at this time are the same. The heating limit temperature and the cooling limit temperature Tf are the supply air temperature PV when the valve opening is at the maximum, and correspond to the asymptote when the saturation characteristic is approximated by an exponential function.

Next, from equations (2) and (3), the supply air temperature P
Erase V. Tf + (Tr−Tf) × exp (−0.025 × MV) = {(Tf−Tr) / 100} × MV ′ + Tr (4) By rearranging equation (4), the following equation is obtained. (Tr−Tf) × exp (−0.025 × MV) = − {(Tr−Tf) / 100} MV ′ + Tr−Tf (5)

Further, by rearranging equation (5), the following equation is obtained. exp (−0.025 × MV) = − 0.01 × MV ′ + 1 (6) Therefore, from equation (6), the manipulated variable correction equation for making the output of the linear controller 5 nonlinearly corresponded is as follows. Is determined. MV = − {1 / 0.025} × ln (1-0.01 × MV ′) (7)

Thus, equation (1) is obtained from equation (7). The manipulated variable MV 'output from the PID controller 5
Using Equation (1) means that the operation amount is corrected by natural logarithm, which is the inverse function of the exponential function (see FIG. 4).
(A)) and the exponential saturation characteristic shown in FIG. 9A can be theoretically completely linearized (FIG. 4B). As described above, the saturation characteristic of the valve opening-supply air temperature characteristic caused by the non-linearity of the flow rate characteristic of the valve is canceled, and the manipulated variable M
Since the relationship between V ′ and supply air temperature PV can be linearized, PID
The proportional gain of the controller 5 can be set to a constant value.

[Second Embodiment] In the first embodiment, the natural logarithmic expression is used for the operation of correcting the operation amount. 1 cannot be applied. Therefore, the following equation is used as the manipulated variable correction calculation in the manipulated variable correction calculation unit 12 instead of the equation (1).

MV = 394 × A ⁴ -1004 × A ³ + 976 × A ² −496 × A + 133 (8) In the equation (8), A = 1−0.01 × MV ′ and 0 <M
Equation (1) is approximated by a quartic function in the range of V '<100. As a result, since the arithmetic expression can be formed only by the four arithmetic operations, the operation amount correction can be realized even in hardware resources such as natural logarithm, which is difficult to perform special function processing.

[Embodiment 3] FIG. 5 is a block diagram of an air conditioning control system showing another embodiment of the present invention, FIG. 6 is a block diagram of an operation amount correction arithmetic unit 6a of FIG. 5, and FIG. It is a flowchart figure for demonstrating operation | movement of the quantity correction arithmetic unit 6a. The air conditioning control system of the present embodiment
This is intended to be applied to the air-conditioning air supply temperature control of the VAV system with the air volume change, and in the air-conditioning control system of FIG.
a, and an operation amount correction operation device 6a is used in place of the operation amount correction operation device 6.

The manipulated variable signal input unit 21 receives the manipulated variable MV 'output from the PID controller 5 (Step 101 in FIG. 6). The blower 4a includes a PID controller 5
At the same time, the fan speed is controlled by the air volume W determined by the host computer (not shown) of the VAV system which constitutes the air conditioning control device. The air volume signal input unit 22 takes in the air volume W determined by the host computer of the VAV system (Step 2).
02). The air volume W takes a value of 0 to 100 (%).

The parameter correction calculation unit 23 calculates a parameter P for determining a natural logarithmic formula which is an inverse function of an exponential function approximating the valve opening-supply air temperature characteristic from the airflow W as follows (step 203). ). P = 2.6-0.02 × W (9)

Subsequently, the manipulated variable correction calculator 24 calculates a corrected manipulated variable MV from the manipulated variable MV 'by a natural logarithmic equation such as the following equation determined by the parameter P (step 204). MV = − (40 / P) × ln (1-0.01 × MV ′) (10)

Then, the manipulated variable signal output section 25 outputs the corrected manipulated variable MV output from the manipulated variable correction operation section 24 to the valves 2a and 2b (step 205). The manipulated variable correction calculation device 6a performs the above operation for each control cycle in which the manipulated variable MV 'is output from the PID controller 5.

Next, the derivation of equations (9) and (10) will be described. Here, it is assumed that the non-linearity of the valve opening degree-supply air temperature characteristic as shown in FIG. 9A due to the non-linearity of the flow rate characteristic of the valve occurs at the airflow W = 80%. When the air volume W = 100%, the valve opening-air supply temperature characteristic changes as shown in FIG. The valve opening-supply air temperature characteristic at this time can be approximated by an exponential function such as the following equation.

PV = Tf + (Tr−Tf) × exp (−0.015 × MV) (11) When the air volume W = 50%, the valve opening-supply air temperature characteristic is shown in FIG. It changes as shown in a). The valve opening-supply air temperature characteristic at this time can be approximated by an exponential function such as the following equation. PV = Tf + (Tr−Tf) × exp (−0.04 × MV) (12)

Therefore, if the parameter P is determined as in equation (9), equations (2), (11) and (12) can be described by the following equation. PV = Tf + (Tr−Tf) × exp (−0.025 × P × MV) (13)

From the equation (13), the operation amount correction equation taking the air volume W into consideration is obtained using the parameter P as follows. MV = − {1 / (0.025 × P)} × ln (1−0.01 × MV ′) (14) Thus, Expressions (9) and (10) are obtained.

In the case of the example of FIG. 8A, the actual manipulated variable MV
Is 51.08% or less, the air flow W is larger than the air flow W = 100%.
= 80% has a larger process gain (that is,
(The slope of the valve opening-supply air temperature characteristic line is large.) 51.08
% Or more, the process gain becomes larger when the air flow rate W = 100% than when the air flow rate W = 80%. As described above, since the influence of the air volume is related to the saturation characteristic of the valve opening-air supply temperature characteristic, it is not sufficient to simply change the proportional gain of the PID controller by the air volume as in the conventional air conditioning control system. Become.

On the other hand, in the present embodiment, an exponential function approximating the valve opening-air supply temperature characteristic is determined according to the airflow W (in other words, the natural logarithmic expression which is an inverse function of the exponential function is determined by the airflow W The operation amount can be corrected according to the change in the air volume. Further, since the calculation is not related to the calculation in the PID controller 5, the correction can be performed without adversely affecting the control operation.

[Embodiment 4] As in the case of the embodiment 2, the equation (10) in the embodiment 3 can be approximated by the following equation. MV = (394 × A ⁴ -1004 × A ³ + 976 × A ² -496 × A + 133) / P (15)

The equation (15) is expressed as follows: A = 1−0.01 × MV ′
In the range of 0 <MV ′ <100, the expression (10)
Is approximated by a quartic function. As a result, since the arithmetic expression can be formed only by the four arithmetic operations, the operation amount correction according to the change in the air volume can be realized even in hardware resources such as natural logarithm, which is difficult to perform special function processing.

In the above embodiment, a PID controller has been described as an example of the air conditioning control device. However, the present invention is not limited to this, and another controller may be used.

[0039]

According to the present invention, the control output of the air-conditioning control device is corrected based on a curve approximation function that approximates the control valve opening-supply air temperature characteristic, as described in claim 1. The non-linearity of the control valve opening-supply air temperature characteristic caused by the non-linearity of the flow rate characteristic of the control valve can be offset, and the non-linearity can be appropriately corrected. As a result, the linear air-conditioning control device can be appropriately operated, and the parameter adjustment of the air-conditioning control device can be simplified. A parameter indicating the blowing capacity of the blower
By determining the curve approximation function by
Control output correction according to the
Of the control valve and supply air temperature depend on the capacity of the blower.
The optimal correction can be performed
You. In addition, the air volume changes regardless of the calculation in the air conditioning controller.
Therefore, the control operation is not adversely affected.

According to a second aspect of the present invention, a curve approximation is performed.
A function represents a curve that asymptotically converges to a certain value.
Control valve opening degree-saturation temperature
Characteristics can be easily approximated and this saturation
Can be corrected.

[0041]

[Brief description of the drawings]

FIG. 1 is a block diagram of an air conditioning control system showing an embodiment of the present invention.

FIG. 2 is a block diagram of the operation amount correction calculation device of FIG. 1;

FIG. 3 is a flowchart for explaining the operation of the operation amount correction calculation device of FIG. 1;

FIG. 4 is a diagram for explaining an operation amount correction using a natural logarithmic formula.

FIG. 5 is a block diagram of an air-conditioning control system showing another embodiment of the present invention.

FIG. 6 is a block diagram of the operation amount correction calculation device of FIG. 5;

FIG. 7 is a flowchart for explaining the operation of the operation amount correction calculation device of FIG. 5;

FIG. 8 is a diagram for explaining an operation amount correction according to a change in air flow.

FIG. 9 is a diagram for explaining conventional operation amount correction.

[Description of Signs] 1a: hot water heat source, 1b: cold water heat source, 2a: hot water valve,
2b: cold water valve, 3a: heating coil, 3b: cooling coil, 4, 4a: blower, 5: PID controller, 6,
6a: operation amount correction operation device, 11, 21: operation amount signal input unit, 12, 24: operation amount correction operation unit, 13, 25 ... operation amount signal output unit, 22: air amount signal input unit, 23: parameter correction operation Department.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F24F 11/02 102

Claims (2)

(57) [Claims] 1. An air supply temperature to an air conditioning control area by controlling an opening degree of a control valve for adjusting a flow rate of hot water or cold water flowing to a heat exchanger of an air conditioner so as to remove an air conditioning load in the air conditioning control area. And controlling the blower capacity of the blower
An air- conditioning control system including an air-conditioning control device that determines an amount of air supply to the air-conditioning control area , wherein a control output of the air-conditioning control device that controls the control valve is a curve that approximates a control valve opening-supply air temperature characteristic. Means for correcting based on an approximation function are provided , and the curve approximation function sets a parameter of the blowing capacity of the blower.
An air-conditioning control system characterized by being a function possessed as a function . 2. The air-conditioning control system according to claim 1, wherein the curve approximation function is a specific domain within a specific domain.
An air conditioning control system characterized by representing a curve that asymptotically converges to a value .