JPS592805B2 - Air conditioning control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air conditioning control method for controlling the room temperature of an air conditioner.

Most of the room temperature controls in conventional air conditioners are on/off controlled by thermostats.

In this case, as is well known, the maximum fluctuation range of the room temperature up and down is ±2 degrees, which causes discomfort.

In addition, PID control is available for more precise control.

PID control is expressed by the following equation. However, tR: room temperature,
tS: Room temperature set value, e(t): Error, Kp: Proportional gain, TI: Integral time, TD: Differential time, m(t): Operation signal, t: Time, However, Kp and TI in equation (1), T.D.
It is very difficult to determine constants such as

Normally, constants are determined using the limit sensitivity method, but in this case, the operation must be brought into an abnormal state twice, and the constants must be changed each time the indoor dynamic characteristics change. This is extremely inconvenient.

What must be taken into account when controlling room temperature is whether the system is stable.

If the constant in equation 1) is not appropriate, the room temperature tR will diverge without converging to the room temperature set value tS.

This invention solves the various drawbacks of the above conventional method,
The purpose is to perform optimal room temperature control using a simple control method.

The present invention will be explained below.

The room temperature control system of the present invention is expressed by equations (3) and (4).

m(t)−K(t) ・e(t) ・
”・−”(3)e (t)=t S −tR・・・・
...(4) However, tR: room temperature, tS: room temperature set value, e(t): error, K(t): proportional gain, m(t
): operation signal, t: time, where equation (3) is similar in form to conventional P (proportional) control, but differs from conventional control in that the proportional gain K(t) is a function of time.

The present invention is characterized by the method for determining K (t).

Now, to make the explanation easier to understand, we fixed the magnitude of K(t), and the fluctuation of room temperature tR when the value of K(t) in P control is very small is shown in Figure 1. Figure 2 shows the fluctuation of room temperature tR when the value is very large, and also K(t)
The room temperature t when the value of t matches the dynamic characteristics of the room
The variations in R are shown in Figure 3.

As can be seen from the figure, when the proportional gain K (t) is small, the response of the room temperature tR is slow but smooth control is achieved, and conversely, when the proportional gain K (t) is large, the response of the room temperature tR is fast but fluctuates sharply. Become something.

By inversely utilizing such a phenomenon, the optimal proportional gain K(t) can be determined.

However, by considering changes in the dynamic characteristics of the room, K
It is necessary to provide the maximum value Kmax and minimum value Kmm of (t).

That is, the proportional gain K(t) varies between Kmax and Kmm.

This K(t) is determined by past data of the room temperature tR.

In the past, in order to investigate the fluctuation range of room temperature tR within a certain period of time,
The maximum value tRmax and minimum value tRmrr of the room temperature tR during that period are found.

If the difference is y, then y=tRmax-tRmm
・””(5).

That is, when the value of y is larger than a certain constant value C1 (C1>0), the fluctuation in the room temperature tR is large, so the proportional gain K(t) is made small.

Further, when the value of y is smaller than C1, the fluctuation in the room temperature tR is small, so the characteristic of the room temperature tR is good, but since it is not possible to immediately respond to the next sudden change in the indoor load, the value of K(t) is increased.

In the latter case, since the room temperature tR is almost equal to the room temperature set value tS, even if K(t) is increased, the fluctuation in the room temperature tR is minute.

Also, when starting the air conditioner, or when the room temperature tR
When the temperature deviates significantly from the room temperature set value tS, forcing the proportional gain K(t) to be Kmax results in coordinated control.

FIG. 4 shows room temperature control characteristics during cooling operation as an embodiment of the present invention.

In FIG. 4, j1yj2+t3. t4 is the time at which the proportional gain K(t) is determined, and if the start time of the air conditioner is t20, then tl-△t, t2-2△t+t3
=3Δ1.14=4Δt.

tRH is a value larger than the room temperature set value tS by C2 (C2>0), tRL is a value smaller than the room temperature set value tS by C2, and whether the room temperature tR is larger than tRH or the room temperature t
If R is smaller than tRL, the proportional gain K(t) is forced to be Kmax.

A1 is the room temperature tR at the start, and at the same time, the time t1
Maximum value tRmax of room temperature in △t1 hour until
FBl is △ from time t1 to the minimum value of room temperature in time tRmmy A2+B2 is the maximum value of room temperature in time tRmax and △ from time t to time t2, respectively
and the minimum value tRmm.

A3 and B3 are △ from time t2 to time 131, respectively.
The maximum value tRmax and the minimum value tR of room temperature in time
Showing coral.

Next, the operation will be explained with reference to FIG. 4. From the start until time t1, the room temperature tR is greater than tRH, so room temperature control is performed using equation (3) with K(t)=Kmax.

Next, at time t1, when examining the past Δ and the time room temperature tR, the maximum value is A1 and the minimum value is B1, so the difference y is very large and is greater than C1.

Therefore, K(t) must be set to a value one rank higher than Kmax, and in this state, room temperature control is performed according to equation (3) until time t2.

At time t2, when we similarly examine the past △ and the time room temperature tR, we find that it is the maximum value A2 and the minimum value B2, so the difference y
is larger than C1, and further lowers K(t) by one rank and operates until time t3, and y is 01 at time t3 as well.
If it is larger, the operation is performed with K(t) further lowered by one rank.

In this case, if K(t) becomes smaller than Kmm, it is natural that K(t)=Kmm.

At time t4, y is almost zero and smaller than C1, so K(t) is raised by one rank from the previous value.

Therefore, although the room temperature tR fluctuates a little, the range is very small.

Here, as an example of an air conditioner to which the control method of the present invention can be applied, a system configuration diagram shown in Japanese Patent Publication No. 47-2943 is shown in FIG. 5 and will be described.

In FIG. 5, 1, 2, 3, 4 are compressors, 5, 6, 7.
8 is a discharge pipe, 9 is a condenser, 10 is a refrigerant liquid pipe, 11 is an expansion valve, 12 is an evaporator, 13 is a refrigerant suction gas pipe, 14 is a bypass pipe, 16 is a constant pressure expansion valve, 19 is a control device, 20 is a thermostat (room temperature detection).

The operation when the control method of the present invention is applied to such an air conditioner will be described next.

The control device 19 generally includes a room temperature setting device 21, a calculation function, a memory function, and a timer function, and compares the signal from the room temperature detection thermostat 20 with the set value of the room temperature setting device 21 to turn on and off the compressor. At the same time, the timer function stores the maximum value of the change in the maximum and minimum temperature of the room temperature within a certain period of time immediately before, reads this at a certain time, and if y is larger than 01 (C1>0) during the maximum change, the proportional gain is applied. K(t) is decreased to make the operating signal m(t) smaller, the number of operating compressors is reduced, and if y is smaller than C1 during the maximum change, the proportional gain K(t) is increased to reduce the operating signal m(t).
) and increase the number of compressors in operation.

In this way, the capacity of the compressor (as a whole) is increased or decreased.

In addition to capacity control using multiple compressors as mentioned above,
“Refrigerating Mechanical Engineering/
・There are also devices that control the capacity by changing the rotation speed of the compressor, as shown in the section on capacity control devices in the Japanese book, and in any device, if the maximum change ``t'Jy is 01, The control method of the present invention can be applied by reducing the proportional gain k and increasing k if y is less than 01.

As mentioned above, the feature of this invention is the proportional gain K (
t), and when the fluctuation of the room temperature tR is large, the proportional gain K(t) is made small to smooth the room temperature fluctuation, and conversely, when the rate of change of the room temperature tR with respect to time is small, The proportional gain K(t) is increased to prepare for sudden indoor load fluctuations.

Therefore, even if the indoor dynamic characteristics change, it is possible to respond immediately and bring the room temperature tR closer to the room temperature set value tS.

Note that, as a matter of course, this control method can be applied not only to cooling operation but also to heating operation.

Furthermore, it goes without saying that it can be applied not only to room temperature control but also to humidity control.

[Brief explanation of the drawing]

Figure 1 shows the fluctuation characteristics of room temperature tR when the proportional gain is small in P control, Figure 2 shows the fluctuation characteristics of room temperature tR when the proportional gain is large, and Figure 3 shows the fluctuation characteristics of room temperature tR when the proportional gain is a suitable value. FIG. 6 is a diagram showing the fluctuation characteristics of room temperature tR. FIG. 4 is an embodiment of the present invention showing the control characteristics of the room temperature tR during cooling operation, and FIG. 5 is a configuration showing -fII of an air conditioner to which the control method according to the embodiment of the present invention can be applied. It is a diagram. The symbols A1 to A3 and B1 to B3 in the figure are the maximum and minimum values per unit time Δ.

Claims (1)

[Claims] 1. A proportional gain K (
In the control method of increasing/decreasing the capacity of the air conditioner according to the value m(t) (operation signal) by multiplying t) by If the width y is thicker than the constant value C1 (self>0), the proportional gain K (t) is decreased, and if the maximum change width y is smaller than the constant value C1, the proportional gain K (t) is increased, and the above operation signal m ( An air conditioning control method characterized by increasing the capacity as t) increases, and decreasing the capacity as m (t) decreases to bring the room temperature tR closer to the room temperature set value tS. 2 Proportional gain K (
t) and increases or decreases the capacity of the air conditioner according to the value m(t) (operation signal), in which the proportional gain K(t) is multiplied by a maximum value Kmax and a minimum value Km.
Set m, and divide the range between the minimum value Kmm and the maximum value Kmax into several stages, and calculate the room temperature tR at a certain period of time Δt in the past.
If the maximum change width y is larger than the constant value C1 (C1〉O), reduce the proportional gain K(t) step by step, and if the maximum change width y is smaller than the constant value C1. For example, the proportional gain K(t) is increased step by step, and when the operation signal m(t) increases, the capacity is increased, and when the m(t) decreases, the capacity is decreased, and the room temperature tR is set to the room temperature set value. An air conditioning control method characterized by bringing the temperature close to tS. 3 Proportional gain K to the difference between room temperature tR and room temperature set value tS
(t) and increases or decreases the capacity of the air conditioner according to the resulting value m(t) (operation signal). If the width of change y is larger than the constant value C1 (C1>0), the proportional gain K (t) is decreased, and if the maximum width of change y is smaller than the constant value C1, the proportional gain K (t) is increased, and the above operation signal m ( When t) increases, the capacity is increased, and when the above m(t) decreases, the capacity is decreased, and from the above room temperature set value tS, C2 (C2>0)
A value tRH that is larger by C2 and a value tRL that is smaller than tS by C2.
If the room temperature tR is larger than tRI (or the room temperature tR is smaller than tRL), the above K(t) is set as K(t)=Kmax, and the room temperature tR is set as the room temperature set value t.
An air conditioning control method characterized by making the air conditioner approach S.