JPS6345024B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a compressor for compressing refrigerant, an electric motor having a speed control drive section for driving the compressor, an outdoor heat exchanger, and an indoor heat exchanger. The present invention relates to an air conditioner that air-conditions a room using a refrigeration cycle, and particularly to a control system for a motor for driving a compressor of the air conditioner.

[Background of the invention]

In conventional air conditioners, a constant-speed induction motor is often used as the motor for driving the compressor, and the operation/stopping 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 lifespan of the motor, compressor, control equipment, etc., and the room temperature rises and falls significantly between starts and stops. However, since the refrigerant does not flow to the heat exchanger during the period when the motor is stopped, the heat exchanger has disadvantages such as idle play. On the other hand, if the rotation speed of the electric motor is 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 operating with low power consumption. This makes it possible to realize comfortable air conditioning with a constant room temperature and little vertical fluctuation.

Figure 1 shows the relationship between the rotational speed of the electric compressor and the cooling or heating capacity of an air conditioner equipped with a compressor driven by an electric motor whose rotational speed can be controlled (hereinafter referred to as an electric compressor). show. Constant rotation speed
At N ₁ or more, the cooling or heating capacity increases as the rotation speed increases, so by controlling the rotation speed of the electric compressor, it is possible to operate the air conditioner according to the cooling or heating load. However, as can be seen from this figure, when the rotation speed of the electric compressor is extremely low, below a certain rotation speed N ₁ ,
The disadvantage is that the cooling or heating capacity is reduced, and power consumption is wasted just by operating the air conditioner. Moreover, FIG. 2 shows the relationship between the electric compressor rotation speed and cooling or heating efficiency. Here, the cooling or heating efficiency η is defined as ηcooling or heating capacity/total operating power.

As can be seen from the figure, the efficiency improves as the rotational speed decreases from the maximum rotational speed N ₄ , but the efficiency decreases as the rotational speed decreases below a constant rotational speed N ₃ (greater than N ₁ ). Therefore, the rotational speed N ₂ (greater than N ₁ ) that gives the same efficiency as the maximum rotational speed N ₄
Even if the compressor is operated under the following conditions, it is not a good idea in terms of power consumption, as is clear from the relationship between the rotation speed and power consumption when the rotation speed of the electric compressor is continuously controlled as shown in FIG.

[Purpose of the invention]

The present invention eliminates the drawbacks of the above-mentioned intermittent control and rotation speed control, and provides a comfortable, cooling (heating) system with low operating power.
The purpose of the present invention is to provide an air conditioning method that improves the rise of the room.

[Summary of the invention]

The present invention stops the electric motor when the air conditioning load D is equal to or less than a predetermined value _D1 corresponding to the minimum speed (>0) of the compressor driving electric motor of the air conditioner, and also provides a predetermined value having a certain hysteresis width.
D ₂ (D ₂ > D ₁ ) or more, the electric motor is variably controlled using a speed control pattern that increases from the minimum speed N to the maximum speed N ₄ in response to the increase in the air conditioning load D. The corresponding speed is the maximum speed
When _{the air conditioning load D reaches the predetermined value D 3 (} ≧
Characterized by operating the speed of the electric motor at a maximum speed N ₄ until it decreases to D ₂ ). Here, the minimum rotation speed N is selected in consideration of the design conditions, performance conditions, etc. of the air conditioner.

By implementing the present invention, the target controlled by the air conditioner, for example, the room temperature, is kept constant as shown in FIG. 4 by controlling the rotation speed of the compressor driving electric motor when the cooling (heating) load is above a certain level. It maintains the same temperature and has the same start-up performance as conventional air conditioners, and when the cooling (heating) load is below a certain level, the compressor drive electric motor is controlled intermittently.
As shown in FIG. 5, a certain level of vertical vibration in the room temperature remains, but it is not as large as in conventional intermittent control, 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.

[Embodiments of the invention]

Hereinafter, a method for controlling the rotation of a motor for driving a compressor in an air conditioner according to the present invention will be explained using examples. FIG. 6 is a block diagram illustrating one 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
is an indoor target temperature setting device, 3 is a temperature deviation detector, 4 is
is a speed signal generator, 5 is an intermittent control signal generator, 6
1 is a speed control signal comparison and selection device, which constitutes a control command means 8 that generates an operation stop command and a rotational speed control command for the electric compressor 7, which will be described later. Further, 1 to 3 constitute an air conditioning load detection means 9, and 4 to 6 constitute a speed signal generation means 10. The electric compressor 7 includes a compressor section, an electric motor section, and a speed control drive section that receives the above control command and controls the electric motor. Next, the control operation will be explained. First, the indoor temperature detected by the indoor temperature detector 1 is compared with the target temperature set in the indoor target temperature setting device 2 in the temperature deviation detector 3 to determine the temperature deviation corresponding to the air conditioning load, and the speed signal is The generator 4 determines the rotational speed of the electric compressor 7 according to the temperature deviation based on the relationship shown in FIG. 7. In addition, the intermittent control signal generator 5
The levels of the temperature deviation signals are compared, and as shown in the example shown in FIG. 8, an operation command is issued if it exceeds a certain level, and a stop command is issued if it is below a certain level. The speed control signal comparison and selection device 6 is
If the output signal of the intermittent control signal generator 5 is a driving command, the electric compressor rotational speed signal output of the speed signal generator 4 is sent to the electric compressor 7, and the output signal of the intermittent control signal generator 5 is stopped. If it is a 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 It is operated according to the output signal.

FIG. 7 shows _an example of how the speed signal corresponds to the temperature deviation of the speed signal generator ₄ in FIG.
If the temperature deviation is smaller than D ₄ and between D ₁ , it indicates that a value between the minimum rotation speed N and the maximum rotation speed N ₄ will be given, but if the temperature deviation is larger than D ₄ , the maximum rotation speed N ₄ will be given. indicates that the maximum rotational speed _N4 is maintained until the temperature deviation falls below the predetermined value _D3 . In FIG. 7, the coordinate points (D ₁ , N) and (D ₄ , N ₄ ) do not necessarily have to be connected by a straight line, and may be connected by a line other than a straight line depending on the operating characteristics and control objective of the air conditioner. Further, the predetermined value _D3 may be a value as shown in FIG. 7, and there is no problem even if it is between _D1 and _D2 .

FIG. 8 shows the intermittent control signal generator 5 in FIG.
An example of how the operation command corresponds to the temperature deviation of is shown. When the temperature deviation is larger than D ₂ , an operation command is generated, and when the temperature deviation gradually decreases to D ₁ , a stop command is generated at that _moment . It continues as long as it is below or rises to exceed D ₂ , indicating that a driving command is issued at the moment D ₂ is exceeded.

FIG. 9 shows another embodiment of the invention, in which D ₃ and D ₂ of the previous embodiment are matched. Further, between _D1 and _D2 , the minimum speed signal N is generated to improve the operation rate of the electric compressor at low speeds when the air conditioning load is small.

〔Effect of the invention〕

As mentioned above, when the electric compressor is operated at variable speeds above the minimum speed N, and when the air conditioning load is large and the electric compressor is operated at the maximum speed _N4 , the air conditioning load will drop below the predetermined value. Since the electric compressor continues to operate at maximum speed until it reaches full speed, the electric compressor has the advantages of variable speed operation, which improves comfort, reduces operating power, and extends the life of the equipment. An improvement in feeling was obtained.

[Brief explanation of the drawing]

Figure 1 is a relationship diagram between electric compressor rotation speed and cooling (heating) capacity, Figure 2 is a relationship diagram between electric compressor rotation speed and cooling (heating) efficiency, and Figure 3 is a relationship diagram between electric compressor rotation speed and cooling (heating) efficiency. A relationship diagram of power consumption, FIGS. 4 and 5 are diagrams showing an example of room temperature control according to the present invention and a conventional method, and FIG. 6 is a block diagram for explaining an embodiment of the air conditioner according to the present invention. Figure 7 is an example of the correspondence between the temperature deviation of the speed signal generator in Figure 6 and the electric compressor rotation speed, and Figure 8 is an example of the correspondence between the temperature deviation of the intermittent control signal generator and the operation stop command in Figure 6. 9 are diagrams for explaining another embodiment of the present invention. 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 selection 7... electric compressor, 8... control command means. 9...Air conditioning load detection means.

Claims (1)

[Claims] 1 The air conditioning load D is detected from the difference between the target value and the actual value for air conditioning, and the speed of the electric motor for driving the compressor in the air conditioner is controlled according to the air conditioning load D, and the air conditioner for indoor air conditioning is controlled. In the harmonization method, the electric motor is stopped in a range where the air conditioning load D is equal to or less than a predetermined value D ₁ corresponding to the minimum speed N (>0) of the electric motor, and a predetermined value D ₂ (D _{2 )} having a certain hysteresis width is stopped. >D ₁ ) In the above, the minimum speed N to the maximum speed is increased in response to the increase in the air conditioning load D.
When the electric motor is variable speed controlled using a speed control pattern that increases up to _N4 , and the speed corresponding to the air conditioning load D reaches the maximum speed _N4 , the air conditioning load D reaches a predetermined value _D3 (≧ _D2 ) until the maximum speed decreases to N ₄
An air conditioning method characterized in that the speed of the electric motor is controlled by: