KR20000037566A - Method for controlling inverter compressor of air conditioner - Google Patents

Abstract

PURPOSE: A method for controlling an inverter compressor of an air conditioner is provided to efficiently and stably operate the compressor according to the difference of load due to the indoor/outdoor environmental changes by operating the compressor in a predetermined ratio of a highest operation frequency determined by the difference between the indoor/outdoor temperatures and user's preset temperatures. CONSTITUTION: A method for controlling an inverter compressor of an air conditioner includes the steps of determining a highest operation frequency of a compressor by sensing external environment such as a room temperature and an outdoor temperature, comparing the sensed external environment with a preset standard states according to cooling/heating mode, and obtaining a highest operation frequency for yielding a maximum efficiency on the basis of the compared value, and determining a target operation frequency for driving the compressor in an optimum state according to a difference between a temperature preset by a user and the room temperature without exceeding the highest operation frequency by calculating the difference and setting a target operation frequency on the basis of the difference value according to the cooling/heating mode.

Description

Inverter compressor control method of air conditioner

The present invention relates to a control method of an inverter compressor of an air conditioner, in particular, using the indoor air temperature and the outdoor air temperature to determine the maximum operating frequency that can operate the system without difficulty and the set temperature and room temperature by the user input Since the target operating frequency is determined and operated at a constant ratio of the highest operating frequency according to the difference between the inverter and the compressor of the air conditioner, which can operate the compressor efficiently and stably in response to the load change caused by the change of the indoor and outdoor environment. It relates to a control method.

In general, an air conditioner is a machine for indoor air conditioning, and there are many models for indoor air conditioning and heating, and additionally have functions such as dehumidification and cleanliness.

The air conditioner is roughly provided with an indoor and outdoor heat exchanger and a refrigeration system consisting of a capillary tube, a four-way valve, a compressor, and a condenser. The compressor is a device for compressing a refrigerant, and the rotation speed is determined by the frequency of a power source applied to the compressor. do.

In the above, if the frequency of the power applied to the compressor can be changed, the rotation speed of the compressor can be changed, so that the refrigerant flow rate can be freely controlled to directly control the capability of the air conditioner itself.

A compressor capable of changing the frequency of the compressor by changing the frequency as described above is called an inverter compressor.

Accordingly, the inverter compressor is capable of controlling the air conditioner's ability by changing the number of revolutions by changing the feed voltage or frequency. The inverter compressor takes a short time to reach the set temperature by rotating at a high speed. The continuous change of the number reduces the change in the room temperature and reduces the chance of power loss, improving the efficiency.The frost, which is attached to the outdoor heat exchanger during the heating operation and degrades the heating capacity, is removed in a short time by rotating the compressor at high speed. The heating operation can be efficiently performed, and the starting current is reduced by rotating the compressor at low speed during starting.

1 is a schematic configuration diagram of an air conditioner according to the prior art.

A conventional air conditioner for air conditioning is installed on the indoor side as shown in FIG. 1 to operate as an evaporator when cooling and to act as a condenser when heating, and the indoor heat exchanger 1 An indoor fan (2) installed at a rear side to generate a flow of air to help heat exchange of the indoor heat exchanger (1), and an indoor temperature sensor (3) installed at a room to sense a temperature of indoor air (3) It consists of

In addition, an outdoor fan installed at the outdoor side and operating as a condenser when cooling and an evaporator when heating, and an outdoor fan for generating a flow of air to help heat exchange between the outdoor heat exchanger 4 and the outdoor heat exchanger 4. fan (5), a motor (not shown) for driving the indoor fan (2) and the outdoor fan (5), and a compressor (6) for sucking and discharging gas refrigerant of low temperature and low pressure into a gas refrigerant of high temperature and high pressure And, the four-way valve (7) for switching the direction of movement of the refrigerant in accordance with the cooling operation and heating operation, the capillary tube (8) is expanded as the refrigerant is moved, the input from the user and the room temperature sensor (3) And a control unit (not shown) for controlling the operation of the compressor 6 and the switching of the four-way valve 7.

Referring to the operation of the conventional air conditioner configured as described above are as follows.

First, when the user selects the heating operation, the operating frequency of the compressor 6 is determined by the difference between the temperature of the indoor air detected by the indoor temperature sensor 3 and the set temperature set by the user. The four-way valve 7 is switched to adjust the moving direction of the refrigerant to be suitable for heating operation.

Thereafter, the high-temperature, high-pressure gaseous refrigerant compressed by the compressor (6) is condensed while passing through the indoor heat exchanger (1) to dissipate heat into the room, and is converted into a high-pressure, medium-temperature liquid refrigerant, Expanded while passing through the capillary tube (8) is a mixture of low-temperature, low-pressure gas and liquid is transferred to the outdoor heat exchanger (4), the refrigerant transferred to the outdoor heat exchanger (4) is a heat transfer from the outdoor air It is evaporated while being absorbed, and becomes a refrigerant in a low-temperature, low-pressure gas state, and is sucked into the compressor 6.

The low-temperature, low-pressure gas refrigerant sucked into the compressor 6 is repeatedly compressed to a high-temperature, high-pressure gas refrigerant, and then repeatedly discharged to continuously supply heat to the room.

In the above, when the room temperature approaches the set temperature, the operating frequency of the compressor 6 is dropped, and when the room temperature is higher than the set temperature by a predetermined temperature or more, the control unit stops the operation of the compressor 6. 6) to control.

On the other hand, when the user selects the cooling operation, the operation frequency is determined by the difference between the room temperature and the set temperature as in the case of the heating operation, and the four-way valve 7 is switched to the cooling operation, and then the compressor ( The high temperature and high pressure refrigerant discharged from 6) passes through the outdoor heat exchanger 4, releases heat, expands while passing through the capillary tube 8, and is transferred to the indoor heat exchanger 1, and the indoor heat exchanger ( In 1), the temperature of the room is lowered by repeating the cycle of absorbing the heat of the indoor air and evaporating it after being sucked into the compressor 6 and compressing it again.

In the above, when the room temperature is close to the set temperature, the operating frequency drops, and when the room temperature is lower than the set temperature by more than a predetermined value, the control unit controls to stop the operation of the compressor 6.

In addition, the specifications of the components constituting the cycle in the conventional refrigeration cycle of the air conditioner is designed according to the standard heating and cooling standard, the standard state is the room temperature is 27 ℃ and the outdoor temperature is 35 ℃ during cooling, heating In city, indoor temperature is 20 ℃ and outdoor temperature is set to 7 ℃.

However, the conventional air conditioner is designed and operated on the basis of a standard state, which may be significantly different from the actual operating environment.

Therefore, the conventional air conditioner operates at the optimum point of the cooling and heating cycle because the operating frequency of the compressor 6 is determined and operated according to the room temperature, the set temperature, and the standard state already set without considering the actual operating environment. It is difficult to operate with high efficiency, and therefore, it is unable to actively cope with overload conditions or other external load fluctuations, so that the power supply element may be damaged due to overcurrent or the stop or burnout of the compressor 6 due to overheating during operation. The problem is that the whole system is paralyzed.

The present invention has been made to solve the above problems of the prior art, by using the indoor air temperature and the outdoor air temperature to determine the optimum frequency of the maximum efficiency and the optimum by the difference between the user set temperature and room temperature Since the target operating frequency is determined by the constant ratio of the frequency to operate the compressor, it provides an inverter compressor control method of the air conditioner that can efficiently and stably operate the entire system by actively responding to load changes indoors and outdoors. There is this.

1 is a schematic configuration diagram of an air conditioner according to the prior art,

2 is a schematic configuration diagram of an air conditioner according to the present invention;

3 is a block diagram of a control unit which is a part of an air conditioner according to the present invention;

4 is a control flowchart of the compressor according to the present invention.

<Explanation of symbols about main part of drawing>

51 Compressor 52 Indoor heat exchanger 53 Outdoor heat exchanger 54 Electronic expansion valve 55 Outdoor temperature sensor 56 Indoor temperature sensor 57 Outdoor fan 58 Indoor fan 59 Four-way valve 60 Control unit 61 Microcomputer 62 Key input 63: Drive drive F _d : Target operating frequency F _max : Maximum operating frequency F _mim : Minimum operating frequency F _sh : Maximum frequency in heating standard state F _sr : Maximum frequency in cooling standard state k: Constant coefficient α1, α2, α3: Correction value

The present invention is the maximum operating frequency determination step of determining the maximum operating frequency of the compressor that can achieve the maximum efficiency by sensing the indoor temperature and the outdoor temperature, and the maximum operating frequency in accordance with the difference between the set temperature and the room temperature set by the user Characterized in that it comprises a target operation frequency determining step of determining a target operating frequency for driving the compressor in an optimal state in the range not exceeding.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

2 is a schematic configuration diagram of an air conditioner according to the present invention, FIG. 3 is a block diagram of a control unit which is a part of the air conditioner according to the present invention, and FIG. Is a control flowchart of the compressor.

As shown in FIGS. 2 and 3, the air conditioner according to the present invention is a compressor 51 in which a gaseous refrigerant is sucked and compressed into a gaseous refrigerant at a high temperature and high pressure, and operates as an evaporator at cooling time and at heating time. An indoor heat exchanger (52) acting as a condenser, an outdoor heat exchanger (53) acting as a condenser when cooling, and an evaporator when heating, and a refrigerant to expand so that the refrigerant can evaporate and absorb heat from the environment. Electronic expansion valve 54, an outdoor air temperature sensor 55 installed outdoors to sense the outdoor temperature, an indoor air temperature sensor 56 installed indoors to sense the indoor temperature, and the outdoor heat exchanger An outdoor fan 57 installed at the rear of the 53 to generate the flow of outdoor air to assist the heat exchange, and generated at the rear of the indoor heat exchanger 52 to generate the flow of the indoor air to assist the heat exchange. Letting indoor (58), a motor (not shown) for supplying rotational power to the outdoor fan (57) and the indoor fan (58), and a four-way valve (59) for determining a moving direction of the refrigerant according to the cooling operation mode and the heating operation mode. And a control unit 60 for controlling the operation of the air conditioner.

Here, the control unit 60 receives the data on the outdoor temperature and the indoor temperature from the outdoor air temperature sensor 55 and the indoor air temperature sensor 56 and at the same time according to the cooling and heating mode and the set temperature input by the user The drive drive 63 and the four-way valve 59 which drive the 51 are controlled.

In the above, the air conditioner according to the present invention configured as described above is operated such that the refrigerant movement in the opposite direction in accordance with the cooling and heating mode as in the conventional air conditioner.

In particular, the control configuration of the present invention will be described with reference to FIG. 3, the temperature value detected by the indoor air temperature sensor 56 and the outdoor air temperature sensor 55 is read from the micom 61 and the micom 61. Is calculated based on this value to calculate the maximum operating frequency (F _max ), and compares the set temperature value and the indoor air temperature value input by the user through the key input unit 62 of the maximum operating frequency (F _max ) The compressor 51 is driven at the optimum frequency by driving the compressor driving drive 63 by determining the target driving frequency F _d , which is the optimum driving frequency within the range.

The control sequence as described above is described in detail as follows.

First, when the data on the temperature detected by the indoor air temperature sensor 56 and the outdoor air temperature sensor 55 is input to the controller 60, the maximum operating frequency (F) that does not overwhelm the compressor (51). _max ).

In the above, the determination of the maximum operating frequency (F _max ) is determined in consideration of the cooling overload conditions, heating overload conditions and heating low temperature conditions on the basis of the frequency at which the capacity is the maximum in the standard condition of heating and cooling.

In addition, in order to determine the maximum operating frequency (F _max ), the concept of Δt is introduced. The cooling Δt and the heating Δt are determined as follows.

That is, cooling Δt = (sum of indoor temperature / outdoor temperature in the cooling standard state)-(sum of indoor / outdoor temperature in the cooling standard state), and heating Δt = (sum of indoor temperature / outdoor temperature in the heating standard state)- (The sum of the current room temperature and the outside temperature).

Here, the indoor temperature of the cooling standard state is 27 ℃, the room temperature of the heating standard state is 20 ℃, the sum of the outside air temperature is detected by the indoor air temperature sensor 56 and the outdoor air temperature sensor 55 Sum of temperatures. Therefore, the cooling Δt and the heating Δt have a concept of an operating environment index reflecting the current outside air environment.

Capacity classification cooling heating Δt〉 0 Δt <0 Δt〉 0 Δt <0 2.0 horsepower 52 Hz 52- (0.35 * Δt) 62+ (2.55 * Δt) 62- (0.67 * Δt) 2.5 horsepower 74 Hz 74- (0.35 * Δt) 76+ (2.55 * Δt) 76- (0.67 * Δt) 3.0 horsepower 90 Hz 90- (0.35 * Δt) 81+ (2.55 * Δt) 81- (0.67 * Δt)

When the cooling Δt and the heating Δt are determined as described above, as shown in Table 1, when cooling Δt is positive in cooling, the sum of the indoor and outdoor temperatures is lower than the sum of the indoor and outdoor temperatures in the cooling standard state, resulting in overloading during operation. Since there is no state, the maximum frequency (F _sr ) of the cooling standard state already set is determined as the maximum operating frequency (F _max ) at that state.If the cooling Δt is negative, the sum of the current indoor and outdoor temperatures is equal to the cooling standard state. Since the temperature is higher than the sum of indoor and outdoor temperature, the cooling overload tends to be increased. Therefore, the maximum operating frequency (F _max) is subtracted from the maximum frequency (F _sr ) of the cooling standard state by multiplying the experimental value α1 (0.35) by the absolute value Δt Decide on) In other words, if Δt is negative, it is close to the cooling overload condition. Therefore, a value lower than the maximum frequency (F _sr ) of the cooling standard state is determined as the maximum operating frequency (F _max ) for the protection of the air conditioner system. will be.

In addition, as shown in Table 1, in the case of heating, if the heating Δt is a positive value, the sum of the current indoor / outdoor temperature is lower than the sum of the indoor / outdoor temperature in the heating standard state and thus close to the low-temperature heating condition. The maximum frequency (F _sh ) of the heating standard state is added to the value multiplied by the value Δt, and the value is determined as the maximum operating frequency (F _max ). When the heating Δt is negative, the sum of the current indoor and outdoor temperatures is equal to the heating standard state. Since it is higher than the sum of indoor and outdoor temperature, it tends to overheat the heating. Therefore, the maximum operating frequency (F _sh ) is subtracted from the experimental value α3 (0.67) multiplied by the absolute value Δt. _max ). In other words, if Δt is negative, the heating overload condition is close, so that the frequency lower than the maximum frequency (F _sh ) of the heating standard state is determined as the maximum operating frequency (F _max ) to protect the air conditioner system.

In the above description, α1, α2, and α3 are frequency conversion constants that conceptualize compensation values for changing the difference between the standard state and the current outside air state into a numerical value for frequency.

As described above, when the maximum operating frequency (F _max ) for operating the compressor 51 is determined, and the user inputs a set temperature through the key input unit 62, refer to Tables 2 and 3 shown below. In this state, the target operating frequency F _{d that} can operate the compressor 51 in an optimal state and efficiency is determined.

Temperature difference (Δt _d ) Constant coefficient (k) 2.0 <Δt _d 1.00 1.5 <Δt _d ≤2.0 0.75 1.0 <Δt _d ≤1.5 0.50 0.5 <Δt _d ≤1.0 0.25 0.0 <Δt _d ≤0.5 F _d = 38 Hz -0.5 <Δt _d ≤0.0 F _d = 35 Hz -0.1 <Δt _d ≤-0.5 Compressor stops after 3 min extension to F _d = 30 Hz Δt _d ≤-1.0 Compressor stop

Temperature difference (Δt _d ) Constant coefficient (k) 3.0 <Δt _d stop 2.5 <Δt _d ≤3.0 0.00 2.0 <Δt _d ≤2.5 0.17 1.5 <Δt _d ≤2.0 0.33 1.0 <Δt _d ≤1.5 0.50 0.5 <Δt _d ≤1.0 0.67 0.0 <Δt _d ≤0.5 0.83 Δt _d ≤0.0 1.00

In the above, Table 2 is a table used in the case of the cooling operation, Table 3 is a table used in the case of the heating operation.

In addition, Δt _d is a value obtained by subtracting the set temperature from the room temperature during heating and cooling, F _d represents the target operating frequency, k represents a constant coefficient, of course, the constant coefficient (k) is set to a value between 0 and 1 The target operating frequency F _d is determined between the highest operating frequency F _max and a minimum operating frequency F _{mim that} can be operated without difficulty in the device in the air conditioner system.

When the constant coefficient (k) is determined according to Tables 2 and 3 as described above, the target operating frequency (F _d ) is the case when the minimum operating frequency (F _mim ) of the cooling standard state at the time of cooling is 40Hz

Determined by the formula F _d = 40 + (F _max -40) * k,

When heating, when the minimum operating frequency (F _mim ) of the heating standard state is 35Hz, the target operating frequency (F _d ) is

F _d = 35 + (F _max -35) * k. Of course, the value of the constant coefficient (k) in the above is obtained in Tables 2 and 3 according to the heating and cooling.

In the above, the minimum operating frequency of the cooling, heating state 40Hz, 30Hz can be changed because it depends on the characteristics of the device, the above equation for obtaining the target operating frequency (F _d ) is an embodiment for achieving the present invention Therefore, in implementing the present invention, the target driving frequency F _d may be determined according to Δt _d in a lower frequency band without considering the minimum driving frequency F _mim .

As described above, when the target driving frequency F _d is determined according to the condition of the external environment of cooling and heating, the compressor 51 is driven according to the target driving frequency F _d , and when the external environment changes, The compressor 51 is driven by modifying the target driving frequency F _d to suit the environment.

In addition, in Table 2, when Δt _d is between −0.1 and −0.5, the target driving frequency F _d is extended to 30 Hz for 3 minutes, and then the compressor 51 is stopped. This is to prevent the compressor 51 from being stopped by an error value.

As described above, in the inverter compressor control method of the air conditioner according to the present invention, the maximum operating frequency (F _max ) is determined according to the indoor and outdoor air temperature during the heating and cooling operation, and the maximum operating frequency ( Since the target driving frequency F _d is determined by a constant ratio of F _max ), the compressor 51 is driven, so that the load is changed by the change of the indoor / outdoor environment so that the load is rapidly changed even when the overload condition or the low temperature condition occurs. By modifying the maximum operating frequency (F _max ) and the target operating frequency (F _d ), and by operating the compressor 51 in an optimal state, it is possible to stably control the entire air conditioner system.

Claims (9)

The maximum operating frequency determination step of determining the maximum operating frequency of the compressor that can achieve the maximum efficiency by detecting the indoor temperature and the outdoor temperature, and does not exceed the maximum operating frequency in accordance with the difference between the set temperature and the room temperature set by the user Inverter compressor control method of the air conditioner comprising a step of determining a target operating frequency for determining a target operating frequency for driving the compressor in an optimal state in the range. The method of claim 1, The determination of the maximum operating frequency may include: an external environment detection step of sensing indoor air temperature and outdoor air temperature, and a comparison between the external environment detected in the external environment detection step and a standard state already set according to cooling operation and heating operation, respectively. Inverter of the air conditioner characterized in that the comparison step, and the maximum operating frequency calculation step of calculating the maximum operating frequency for the best efficiency based on the comparison value obtained by comparing the external environment and the standard state in the comparison step Compressor control method. The method of claim 2, In the comparison step, a cooling value is obtained by subtracting a sum of indoor and outdoor temperatures detected in the external environment detection step by subtracting the sum of indoor and outdoor temperatures sensed in the external environment detection step. The method of claim 1, wherein the sum is obtained by subtracting the sum of indoor and outdoor temperatures detected in the external environment sensing step as a comparison value. The method of claim 2 or 3, The peak operating frequency calculation step includes an overload determination step for determining whether an overload is applied to the compressor, and if it is determined that the overload is determined in the overload determination step, a frequency smaller than the highest frequency in a standard state already set is determined as the highest operating frequency and overload Inverter compressor control method of the air conditioner, characterized in that consisting of a frequency correction step of determining the highest frequency in the standard state as the highest operating frequency if it is determined that the state. The method of claim 4, wherein In the overload determination step, if the comparison value calculated in the comparison step is greater than zero, it is determined that the compressor is not overloaded, and if the comparison value is less than zero, it is determined that the compressor is overloaded. Inverter compressor control method. The method of claim 4, wherein The frequency correction step may determine that the maximum frequency of the cooling standard state is the highest operating frequency when the comparison value is zero or more during the cooling operation. Determining the maximum operating frequency by multiplying the frequency conversion constant; If the comparison value is zero or more during heating operation, the highest frequency in the heating standard state is multiplied by the product of the second frequency conversion constant greater than 1 to determine the maximum operating frequency, and if the comparison value is less than zero, And a frequency obtained by multiplying the comparison value by a third frequency conversion constant smaller than 1 at the highest frequency in the heating standard state is determined as the maximum operating frequency. The method of claim 1, The target operation frequency determining step includes: a calculation step of calculating a difference between a set temperature inputted by a user and a sensed indoor temperature; and a goal of setting a target driving frequency according to a cooling and heating operation mode based on the difference value calculated in the calculation step. Inverter compressor control method for an air conditioner, characterized in that the operation frequency calculation step. The method of claim 7, wherein The calculating of the target driving frequency may include the highest operating frequency or lower than the operating frequency when the difference value is equal to or greater than the predetermined value when the cooling operation is performed. Calculating a target operating frequency so that the compressor is stopped if the difference is less than zero; In the case of heating operation, the compressor is stopped when the difference value is greater than or equal to a certain number greater than zero, and when the difference value is less than zero, the maximum operating frequency is set, and when the difference value is greater than zero and less than the predetermined value. Inverter compressor control method of the air conditioner, characterized in that to calculate a frequency lower than the maximum operating frequency as a target operating frequency. The method of claim 8, If the difference value is less than zero in cooling operation, the compressor is stopped for a predetermined time at a predetermined low frequency if the difference value is within a predetermined value range to prevent the compressor from being stopped by an error value. Inverter compressor control method of the air conditioner, characterized in that.