JPS5912937B2 - Air conditioner control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a method for controlling an air conditioner equipped with a refrigerant compressor, an electric motor for driving the compressor, and a refrigeration cycle having a heat exchanger. In particular, the present invention relates to a method of controlling an electric motor that drives a compressor.

BACKGROUND OF THE INVENTION In conventional air conditioners, an induction motor is often used as the motor for driving the compressor, and the operation and stop of the motor is controlled according to the difference between the indoor temperature and the target temperature.

With this type of control method, the motor starts and stops frequently, a large current flows during startup, shortening the life of the motor, compressor, control equipment, etc., and the room temperature rises and falls significantly between starting and stopping. However, since the refrigerant does not flow to the heat exchanger during the period when the electric motor is stopped, there is a drawback that the heat exchanger idles unnecessarily.

On the other hand, if the rotation speed of the electric motor is continuously controlled according to the heating and cooling load, and the refrigerant flow rate of the heat exchanger is controlled, the heat exchanger will not play, improving the performance of the air conditioner, and reducing energy consumption. Power consumption operation is possible, and comfortable air conditioning with a constant room temperature and no vertical fluctuation can be realized.

FIG. 1 shows the relationship between the rotational speed of the electric compressor of such a continuously controllable air conditioner and the cooling capacity.

At a constant rotation speed N1 or higher, the cooling or heating capacity increases as the rotation speed increases, so by continuously controlling the rotation speed of the electric compressor, it is possible to operate the air conditioner according to the cooling or heating load. be.

However, as can be seen from this figure, when the rotation speed of the electric compressor is extremely low below a certain rotation speed N1,
The disadvantage is that the cooling or heating capacity is reduced, and power consumption is wasted just by operating the air conditioner.

Further, FIG. 2 shows the relationship between the electric compressor rotation speed and cooling or heating efficiency.

As can be seen from the figure, as the rotation speed decreases from the maximum rotation speed N4, the momme rate improves, but at a constant rotation speed N5 (Nl
On the contrary, efficiency decreases significantly as the size becomes smaller (larger).

Therefore, below the given rotation speed N2 (more than Nl), which has the same efficiency as the maximum rotation speed N4, the rotation speed and power consumption when the rotation speed of the electric compressor is continuously controlled as shown in Fig. 3. As is clear from the relationship, this is not a good idea in terms of power consumption.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a method for controlling an air conditioner that eliminates the drawbacks of the above-mentioned intermittent control and continuous control, consumes less power, and is comfortable.

Summary of the Invention The present invention provides a method for changing the rotation speed of a motor for driving a compressor between a maximum rotation speed N4 and a minimum rotation speed N according to the air conditioning load when the air conditioning load, that is, the cooling or heating load is above a certain level. When the air conditioning load is below a certain level, the air conditioner is controlled so that it operates intermittently with a hysteresis characteristic between the minimum rotational speed N and stop depending on the air conditioning load.

The minimum rotational speed N is desirably selected between N2 and N4, but may be larger or smaller depending on the design conditions of the air conditioner.

EXAMPLES OF THE INVENTION A method for controlling the rotational speed of a motor for driving a compressor in an air conditioner according to the present invention will be explained below using examples.

FIG. 4 is a block diagram illustrating an embodiment of controlling the room temperature in the air conditioner of the present invention, in which 1 is an indoor temperature detector such as a thermistor, 2 is an indoor target temperature setter,
3 is a temperature deviation detector, which constitutes an air conditioning load detection section 9.

4 is a speed signal generator, 5 is an intermittent control signal generator, and 6 is a speed control signal comparison/selection device, and these constitute the speed signal generation section 10.

These components collectively constitute a control command means 8 that generates an operation stop command and a rotation speed control command for the electric compressor 7, which will be described later.

The electric compressor 7 includes a compressor section, an electric motor section, and a drive section that receives the control commands and controls the electric motor.

Next, the control operation will be explained. First, indoor temperature detector 1
The indoor temperature detected by The corresponding rotational speed of the electric compressor 7 is determined by a relationship as shown in the corresponding example shown in FIG.

Further, the intermittent control signal generator 5 compares the levels of the temperature deviation signals, and as will be described in detail later, if the temperature deviation signal exceeds a certain level, an operation command is issued, and if it is below a certain level, a stop command is issued.

If the output signal of the intermittent control signal generator 5 is an operation command, the speed control signal comparison selector 6 sends it to the electric compressor 7, which is the electric compressor rotational speed signal output of the speed signal generator 4, and performs the intermittent control. If the output signal of the signal generator 5 is a stop command, the electric compressor rotational speed signal output of the speed signal generator 4 is cut and a stop signal is sent to the electric compressor 7. In this way, the electric compressor 7 is stopped. is operated according to the output signal of the speed control signal comparison and selection device 6.

FIG. 5 shows an example of how the speed signal corresponds to the temperature deviation of the speed signal generator 4 in FIG. 4. If the temperature deviation is larger than D4, the maximum rotation speed N4 is given; In this example, a value between the minimum rotation speed N and the maximum rotation speed N40 is given.

In Figure 5, the coordinate point (DI, N) * (D4, N4
) do not necessarily have to be connected by straight lines, but may be connected by curved lines, stepped lines, etc. depending on the operating characteristics and control objectives of the air conditioner.

FIG. 6 shows an example of the operation command for the temperature deviation of the intermittent control signal generator 5 in FIG. 4, and the temperature deviation is D2.
When the temperature deviation is lower than D1, an operation command is issued, and when the temperature deviation gradually decreases to Dl, a stop command is issued at that moment.This continues as long as the temperature deviation is below D1 or until it rises and exceeds D2. In other words, the operation command is generated at the moment when the
Indicates that it will be stopped.

In the first embodiment, when the air conditioning load is small and intermittent operation is performed, the speed command to the electric compressor when turned on after being turned off becomes a value larger than the minimum rotation speed N, and the air conditioning load is excessively large compared to the air conditioning load. Air conditioning capacity is available.

The second embodiment improves this, and as shown in FIG. 7, corresponds the temperature deviation, the electric compressor rotation speed command, and the intermittent command with hysteresis characteristics, and creates a constant value D2 with the temperature deviation.
When the temperature deviation is below D1, the electric compressor will maintain the minimum rotation speed N, and when the temperature deviation becomes smaller and becomes less than D1, the electric compressor will stop.On the other hand, when the temperature deviation becomes large and exceeds D2, the electric compressor will stop. It is designed so that it starts rotating at the minimum rotation speed N.

In the third embodiment and the fourth embodiment, as shown in FIGS. 8 and 9, respectively, the electric compressor rotational speed is changed according to the temperature deviation in the direction of the arrow.

In both the third and fourth embodiments, control is performed using the same characteristics as in FIG. 5 when the temperature deviation decreases.

When the temperature deviation increases, control is performed using the characteristics shown in the upper part of Figure 7 in the third embodiment, and the characteristics slightly modified from the upper part of Figure 7 in the fourth embodiment (Fig. 9). There is.

In both the third and fourth embodiments, starting and stopping when the temperature deviation is between Dl and D2 is the same as the method shown in FIG. 6 (or the lower part of FIG. 7).

The fifth embodiment is for cases where the air conditioning load is large, and the rotational speed of the electric compressor is changed as shown in FIG.

When the temperature deviation decreases from a state larger than D4 to a constant value D3, the rotational speed of the electric compressor is reduced to the maximum speed N.
4, and when the temperature deviation decreases below a certain value D3 and when the temperature deviation increases, the electric compressor rotational speed is controlled as explained in the first embodiment, and the rotational speed is controlled at the start of operation of the air conditioner. It has improved upper characteristics.

It is also possible to combine with the second to fourth embodiments.

Above, we have described a method for maintaining the indoor temperature at the target temperature by controlling the rotational speed of the electric compressor of the air conditioner, but in order for the occupants to spend time comfortably, it is necessary to control the indoor humidity, radiant temperature, The airflow distribution must be controlled so as to satisfy the 9 central conditions.

That is, even if the indoor temperature is maintained at the target temperature, if the humidity or radiant temperature is high or the wind speed is low, the room will feel hot, and if the opposite is the case, it will feel cold.

Therefore, the air conditioning load should be weighted to satisfy the temperature deviation and central droplet conditions in the above explanation. It is better to include humidity, radiant temperature, and airflow distribution conditions, or to change the target temperature.

According to the implementation of the present invention, the target to be controlled by the air conditioner, for example, the room temperature, is determined by the speed change control of the compressor driving motor when the air conditioning load is above a certain level, as indicated by the solid line in Fig. 11. maintained at a constant temperature.

Note that the broken line indicates the conventional example. Furthermore, when the air conditioning load is below a certain level, by providing intermittent control to the compressor drive motor with hysteresis characteristics, a certain level of vertical vibration in the room temperature remains as shown by the solid line in Figure 12, but the broken line This is not as large as the conventional intermittent control shown in , and the number of intermittent cycles is extremely reduced, resulting in extremely comfortable air conditioning with a long equipment life.

Furthermore, as described above, the operating performance of the air conditioner is greatly improved, resulting in a large saving in operating power.

The sixth embodiment, as shown in FIG. 13, combines the rotation speed control of the electric compressor with the rotation speed control of the indoor blower, and when combined with the embodiments shown in FIGS. 7 and 8. I will explain about it.

In FIG. 13, when the temperature deviation falls below a certain value D4, control of the rotation speed of the electric compressor is started, and as the temperature deviation becomes smaller, the rotation speed of the electric compressor decreases.

On the other hand, when the temperature deviation of the blower decreases to below D3, the rotation speed of the blower decreases in accordance with the value of the temperature deviation, and the blower air volume is controlled, and when the temperature deviation falls below D1, the electric compressor stops. The blower rotates at the lowest speed and maintains the lowest air volume W.

On the other hand, when the temperature rises, the temperature deviation of the blower fan is Dl.
When the temperature deviation exceeds D2, the electric compressor starts to increase, and when it exceeds D3, the maximum air volume W4 is maintained, but the electric compressor is started when the temperature deviation starts to exceed D2, and after that, the rotation speed is controlled according to the value of the temperature deviation.

The advantage of combining the air volume control of the blower with the rotation speed control of the electric clothing compressor is that the control range of air conditioning capacity is further expanded by controlling the air volume of the blower, and the frequency of starting and stopping of the electric compressor is further reduced. , extend the life of the equipment, and secondly, the air flow to the occupants is controlled, so when the room is warm, the wind blows strongly and gives a cool feeling, and when the room gets cold, the air current feels and eliminates the feeling of being too cold, making it more comfortable. The goal is to provide a sense of comfort.

The disadvantages are that the cooling (heating) efficiency may decrease slightly by reducing the blower air volume, but the electric compressor has a fairly low rotational speed range, so the power consumption of the electric compressor is low;
This is acceptable from the standpoint of power consumption, since the power consumption of the blower decreases due to the decrease in the fan rotation speed, and the total power consumption decreases.

Effects of the Invention As described above, according to the present invention, the rotation speed of the electric compressor is adjusted according to the value of the air conditioning load, and when it is above a certain level, the maximum speed N4 and the minimum speed N4 are adjusted according to this value. When the speed is below a certain level, depending on this value, the speed is controlled with hysteresis characteristics between the minimum speed N and stop, which is effective in terms of the lifespan of power-consuming equipment and comfort. A method of controlling an air conditioner with high performance can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram of the relationship between electric compressor rotation speed and cooling (heating) capacity.
Figure 2 is a diagram of the relationship between electric compressor rotation speed and cooling (heating) efficiency.
Fig. 3 is a diagram showing the relationship between electric compressor rotation speed and power consumption, Fig. 4 is a block diagram for explaining an embodiment of the control method for an air conditioner according to the present invention, and Fig. 5 is a diagram showing the speed in Fig. 4. An example diagram of the correspondence between the temperature deviation of the signal generator and the rotation speed of the electric compressor, Figure 6 is an example diagram of the correspondence between the temperature deviation of the intermittent control signal generator in Figure 4 and the operation stop, and Figures 7 to 10 are diagrams of the correspondence example It is a figure which shows the other Example of the rotation speed control method of the electric compressor of this invention. 11 and 12 are diagrams showing an example of room temperature control according to the present invention and a conventional method, and FIG. 13 is a diagram showing another example of the rotation speed control method of an electric compressor in the control method for an air conditioner according to the present invention. FIG. 1... Indoor temperature detector, 2... Indoor target temperature setter, 3... Temperature deviation detector, 4...
... speed signal generator, 5 ... intermittent control signal generator, 6 ... speed control signal comparison and selection device, 7.
...Electric compressor, 8...Control command means,
9... Air conditioning load detection section, 10... Speed signal generation section.

Claims (1)

[Claims] 1. The air conditioning load detection means detects the difference between the target value for air conditioning and the actual value as the air conditioning load, the speed signal generator generates a control signal according to the air conditioning load, and the control signal is used to control the air conditioning. In an apparatus that controls the speed of an electric motor for driving a compressor of an apparatus and performs indoor air conditioning, a speed signal is formed to operate the electric motor at variable speed according to the magnitude of the air conditioning load, and what is the speed signal? Separately, the air conditioning load is a predetermined value D1 corresponding to the minimum rotation speed N (>0) of the electric motor.
A stop command is formed in the following range, a run command is formed above a predetermined value D2 (D2>DI) with a certain hysteresis width, and when a stop command is output, a stop signal and a run command are output. When the speed signal is used as a control signal, the speed of the motor is? 1. A method for controlling an air conditioner, the method comprising: controlling an air conditioner;