Air-cooled multi-split air conditioner operation control method based on multi-parameter internal and external coordination

Abstract

The invention relates to an air-cooled multi-split air conditioner operation control method based on multi-parameter internal and external coordination, which mainly comprises the steps of S1, compressor number control based on the number of started indoor units, S2, compressor operation frequency control based on indoor unit evaporation / condensation pressure, S3, indoor unit electronic expansion valve opening degree control based on indoor temperature, and S4, air-cooled multi-split air conditioner operation control based on indoor temperature. And S4, performing cascade control on the operation frequency of the outdoor fan based on the difference between the condensation temperature and the evaporation temperature and the evaporation / condensation pressure change rate of the outdoor unit. The liquid supply amount of the evaporator is guaranteed, internal and external decoupling control over the air-cooled multi-split air conditioner is achieved, the operation stability of the air-cooled multi-split air conditioner is improved, the control method is provided for optimal operation of the compressor and the draught fan which influence the energy efficiency of the air-cooled multi-split air conditioner and have the leading function, and the energy efficiency of the air-cooled multi-split air conditioner is improved.

Description

Technical Field

[0001] The invention belongs to the field of air-cooled multi-split control, in particular to an air-cooled multi-split operation control method based on multi-parameter internal and external coordination. Technical Background

[0002] Air-cooled multi-split units are widely used in small and medium-sized commercial office buildings, high-end villas and other buildings due to their small refrigerant pipeline diameter, small space occupation, easy installation, high degree of automation, easy independent metering and convenient management. However, the energy efficiency of existing air-cooled multi-split units is relatively low during actual operation, which is mainly due to the following two aspects: (1) During actual operation, air-cooled multi-split units operate at a relatively low partial load rate most of the time, which is far below their design capacity, resulting in low compressor efficiency and reduced system energy efficiency; (2) There is a lack of efficient air-cooled multi-split unit operation control methods. Most of the existing air-cooled multi-split units adopt on-off control and continuous control methods based on constant evaporation / condensing pressure. Among them, on-off control causes frequent start and stop of the outdoor unit, large system dynamic loss, and poor oil return, which seriously affects the reliability and stability of the unit operation; the continuous control method based on constant evaporation / condensing pressure uses a certain constant evaporation pressure (when cooling) or condensing pressure (when heating) to regulate the unit. Although the reliability and stability of the unit operation are guaranteed, due to the different indoor load characteristics of the air-cooled multi-split unit and the changes in outdoor working conditions, the control idea of ​​constant evaporation / condensing pressure makes it difficult for the air-cooled multi-split unit to operate efficiently. With the in-depth research on air-cooled multi-split units, people have proposed an air-cooled multi-split unit configuration that combines a variable frequency compressor and a fixed speed compressor, which effectively solves the problem of low energy efficiency of air-cooled multi-split units at low load rates. However, efficient operation control methods for air-cooled multi-split units have rarely been reported. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide an effective operation control method for improving the quality and efficiency of air-cooled multi-split units.

[0004] To achieve the above-mentioned objectives, the present invention provides an air-cooled multi-split operation control method based on multi-parameter internal and external coordination, which mainly involves a control method for the dominant equipment affecting the stability and efficiency of the air-cooled multi-split unit, including compressor number control, compressor operating frequency control, indoor unit electronic expansion valve opening control, and outdoor fan operating frequency control.

[0005] The specific control steps are: S1, a method for controlling the number of compressors based on the number of indoor units turned on, S2, a method for controlling the operating frequency of compressors based on the evaporation / condensation pressure of the indoor units, S3, a method for controlling the opening of the electronic expansion valve of the indoor units based on the indoor temperature, and S4, a method for cascade controlling the operating frequency of the outdoor fan based on the difference between the condensing temperature and the evaporation temperature and the change rate of the evaporation / condensation pressure of the outdoor units.

[0006] The specific control steps of S1, the control of the number of compressors based on the number of indoor units turned on, are as follows:

[0007] When the ratio of the number of indoor units turned on to the total number of indoor units is less than 50.0%, the air-cooled multi-split system turns on one variable frequency compressor;

[0008] When the ratio of the number of indoor units turned on to the total number of indoor units is greater than 50.0%, the air-cooled multi-split system turns on one fixed-speed compressor and one variable-frequency compressor.

[0009] The specific control steps of S2, compressor operation frequency control based on continuous regulation of indoor unit evaporation / condensation pressure, are as follows:

[0010] In cooling mode, when the indoor unit minimum superheat T sup,min Greater than superheat setting value T sup,s , the compressor operating frequency decreases (T sup,min -T sup,s )Δf c Where Δf c The change value of the compressor operating frequency setting; when the indoor unit minimum superheat T sup,min Less than superheat setting value T sup,s , the compressor operating frequency increases (T sup,s -T sup,min )Δf c ;

[0011] In heating mode, when the indoor unit has the minimum subcooling degree T sub,min Greater than the subcooling setting value T sub,s , the compressor operating frequency decreases (T sub,min -T sub,s )Δf c ; When the indoor unit minimum subcooling degree T sub,min Less than the subcooling setting value T sub,s , the compressor operating frequency increases (T sub,s -T sub,min )Δf c ;

[0012] The superheat setting value T sup,s Adjustable, the values ​​include 1.0, 1.5, 2.0, 2.5, 3.0℃;

[0013] The subcooling setting value T sub,s Adjustable, values ​​include 1.0, 1.5, 2.0, 2.5, 3.0℃.

[0014] The above-mentioned S3, indoor unit electronic expansion valve opening control based on indoor temperature, has the following specific control steps:

[0015] In cooling mode, when the indoor temperature detection value T r,t Greater than the indoor temperature setting value T r,s , the opening of the indoor unit electronic expansion valve increases (T r,t -T r,s )Δζ, where Δζ is the change value of the electronic expansion valve opening setting; when the indoor temperature detection value T r,t Less than the indoor temperature setting value T r,s , the opening of the indoor unit electronic expansion valve decreases (T r,s -T r,t )Δζ;

[0016] In the heating mode, when the indoor temperature detection value T r,t Greater than the indoor temperature setting value T r,s , the opening of the indoor unit electronic expansion valve decreases (T r,t -T r,s )Δζ; When the indoor temperature detection value T r,t Less than the indoor temperature setting value T r,s , the opening of the indoor unit electronic expansion valve increases (T r,s -T r,t )Δζ;

[0017] The indoor temperature setting value T r,s Adjustable, the value range is 15.0~32.0℃.

[0018] The S4, cascade control of the outdoor fan operating frequency based on the difference between the condensing temperature and the evaporating temperature and the outdoor unit evaporation / condensing pressure change rate, has the following specific control steps:

[0019] In cooling mode, when the condensing temperature T c and evaporation temperature T e The difference is less than the temperature difference setting value ΔT s , the operating frequency of the outdoor fan decreases (ΔT s -(T c -T e ))Δf f Where Δf f The change value set for the outdoor fan operating frequency;

[0020] When the condensation temperature T c and evaporation temperature T e The difference is greater than the temperature difference setting value ΔT s , the outdoor fan operating frequency increases by Δf f , and further determine whether the condensing pressure change rate is less than -η, where η is the set value of the pressure change rate. If the condensing pressure change rate is less than -η, the outdoor fan operating frequency increases by Δf f; If the condensing pressure change rate is greater than -η, the outdoor fan operating frequency decreases by 2Δf f , and further determine whether the condensing pressure change rate is greater than η. If the condensing pressure change rate is greater than η, the outdoor fan operating frequency increases by Δf f , if it is less than η, the operating frequency of the outdoor fan remains unchanged;

[0021] In heating mode, when the condensing temperature T c and evaporation temperature T e The difference is less than the temperature difference setting value ΔT s , the outdoor fan operating frequency decreases (ΔT s -(T c -T e ))Δf f ;

[0022] When the condensation temperature T c and evaporation temperature T e The difference is greater than the temperature difference setting value ΔT s , the outdoor fan operating frequency increases by Δf f , and further determine whether the evaporation pressure change rate is greater than η. If it is greater than η, the outdoor fan operating frequency increases by Δf f ; If it is less than η, the operating frequency of the outdoor fan is reduced by 2Δf f , and further determine whether the evaporation pressure change rate is less than -η. If it is less than -η, the outdoor fan operating frequency increases by Δf f , if it is greater than -η, the operating frequency of the outdoor fan remains unchanged;

[0023] The temperature difference setting value ΔT s Adjustable, the value range is 10.0~15.0℃;

[0024] The condensing pressure change rate may be replaced by the condensing pressure change amount;

[0025] The evaporation pressure change rate may be replaced by the evaporation pressure change amount.

[0026] Beneficial effects of the present invention:

[0027] The present invention separately regulates the leading equipment that affects the stability of the air-cooled multi-split unit based on different parameters, realizes the internal and external decoupling control of the air-cooled multi-split unit, and improves the stability of the operation of the air-cooled multi-split unit.

[0028] The present invention can ensure sufficient pressure difference before and after the electronic expansion valve by regulating the operating frequency of the outdoor fan, thereby ensuring the liquid supply of the evaporator;

[0029] The present invention determines the optimal evaporation pressure and condensation pressure of the air-cooled multi-split compressor in the cooling and heating operation modes based on the minimum superheat / cooling degree of the indoor unit, thereby realizing the optimal operation of the air-cooled multi-split compressor under different indoor and outdoor working conditions;

[0030] The present invention determines the optimal operating frequency of the outdoor fan of the air-cooled multi-split unit based on the change rate of the evaporation / condensation pressure, thereby achieving the optimal operation of the outdoor unit of the air-cooled multi-split unit under different indoor and outdoor working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of a refrigeration operation control method of an air-cooled multi-split unit based on multi-parameter internal and external coordination according to an embodiment of the present invention;

[0032] Figure 2 This is a flow chart of a refrigeration operation control method of an air-cooled multi-unit machine based on multi-parameter internal and external coordination according to a specific embodiment of the present invention;

[0033] Figure 3 This is a flow chart of a method for controlling thermal operation of an air-cooled multi-unit machine based on multi-parameter internal and external coordination according to another specific embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Combination Figure 1 and Figure 2 As shown, in this embodiment, a method for controlling refrigeration operation of an air-cooled multi-split unit based on internal and external coordination of multiple parameters is provided, wherein:

[0036] S1. Control of the number of compressors based on the number of indoor units turned on. The specific control steps are as follows:

[0037] When the ratio of the number of indoor units turned on to the total number of indoor units is less than 50.0%, the air-cooled multi-split system turns on one variable-frequency compressor; when the ratio of the number of indoor units turned on to the total number of indoor units is greater than 50.0%, the air-cooled multi-split system turns on one fixed-speed compressor and one variable-frequency compressor.

[0038] S2. Compressor operating frequency control based on continuous regulation of indoor unit evaporation / condensation pressure. The specific control steps are as follows:

[0039] When the minimum superheat of the indoor unit is greater than the superheat setting value by 1.0℃, the compressor operating frequency decreases by (minimum superheat of the indoor unit - 1.0) × 1Hz; when the minimum superheat of the indoor unit is less than the superheat setting value by 1.0℃, the compressor operating frequency increases by (1.0-minimum superheat of the indoor unit) × 1Hz.

[0040] The above control steps are based on the control of the minimum superheat of the indoor unit, so as to determine the optimal value of the evaporation pressure of the air-cooled multi-split unit under different operating conditions, and determine the optimal operating frequency of the compressor based on this.

[0041] The above-mentioned S3, indoor unit electronic expansion valve opening control based on indoor temperature, has the following specific control steps:

[0042] When the indoor temperature detection value is greater than the indoor temperature setting value of 26.0℃, the opening of the indoor unit electronic expansion valve increases by (indoor temperature detection value-26.0)×1%; when the indoor temperature detection value is less than the indoor temperature setting value, the opening of the indoor unit electronic expansion valve decreases by (26.0-indoor temperature detection value)×1%.

[0043] The S4, cascade control of the outdoor fan operating frequency based on the difference between the condensing temperature and the evaporating temperature and the outdoor unit evaporation / condensing pressure change rate, has the following specific control steps:

[0044] When the difference between the condensing temperature and the evaporating temperature is less than the temperature difference setting value of 10.0℃, the operating frequency of the outdoor fan is reduced by (10.0-(condensing temperature-evaporating temperature))×1Hz; when the difference between the condensing temperature and the evaporating temperature is greater than the temperature difference setting value of 10.0℃, the operating frequency of the outdoor fan is increased by 1Hz, and it is further determined whether the condensing pressure change rate is less than -5.0%. If it is less than -5.0%, the operating frequency of the outdoor fan is increased by 1Hz; if it is greater than -5.0%, the operating frequency of the outdoor fan is reduced by 2Hz, and it is further determined whether the condensing pressure change rate is greater than 5.0%. If it is greater than 5.0%, the operating frequency of the outdoor fan is increased by 1Hz. If it is less than 5.0%, the operating frequency of the outdoor fan remains unchanged.

[0045] The above control steps realize the determination of the optimal value of the condensing pressure of the air-cooled multi-split unit under different operating conditions, and based on this, determine the optimal operating frequency of the outdoor fan.

[0046] like Figure 3 As shown, in this embodiment, a method for controlling the thermal operation of an air-cooled multi-split machine based on the coordination of multiple parameters inside and outside is provided, wherein:

[0047] S1. Control of the number of compressors based on the number of indoor units turned on. The specific control steps are as follows:

[0048] When the ratio of the number of indoor units turned on to the total number of indoor units is less than 50.0%, the air-cooled multi-split system turns on one variable-frequency compressor; when the ratio of the number of indoor units turned on to the total number of indoor units is greater than 50.0%, the air-cooled multi-split system turns on one fixed-speed compressor and one variable-frequency compressor.

[0049] S2. Compressor operating frequency control based on continuous regulation of indoor unit evaporation / condensation pressure. The specific control steps are as follows:

[0050] When the minimum subcooling of the indoor unit is greater than the subcooling setting value by 1.0℃, the compressor operating frequency decreases by (minimum subcooling of the indoor unit - 1.0) × 1Hz; when the minimum subcooling of the indoor unit is less than the subcooling setting value by 1.0℃, the compressor operating frequency increases by (1.0-minimum subcooling of the indoor unit) × 1Hz.

[0051] The above control steps are based on the control of the minimum supercooling degree of the indoor unit, so as to determine the optimal value of the condensing pressure of the air-cooled multi-split unit under different operating conditions, and determine the optimal operating frequency of the compressor based on this.

[0052] The above-mentioned S3, indoor unit electronic expansion valve opening control based on indoor temperature, has the following specific control steps:

[0053] When the indoor temperature detection value is greater than the indoor temperature setting value of 20.0℃, the opening of the indoor unit electronic expansion valve is reduced by (indoor temperature detection value-20.0)×1%; when the indoor temperature detection value is less than the indoor temperature setting value of 20.0℃, the opening of the indoor unit electronic expansion valve is increased by (20.0-indoor temperature detection value)×1%.

[0054] The S4, cascade control of the outdoor fan operating frequency based on the difference between the condensing temperature and the evaporating temperature and the outdoor unit evaporation / condensing pressure change rate, has the following specific control steps:

[0055] When the difference between the condensing temperature and the evaporating temperature is less than the temperature difference setting value of 10.0℃, the outdoor fan operating frequency is reduced by (10.0-(condensing temperature-evaporating temperature))×1Hz. When the difference between the condensing temperature and the evaporating temperature is greater than the temperature difference setting value of 10.0℃, the outdoor fan operating frequency is increased by 1Hz, and further judged whether the evaporation pressure change rate is greater than 5.0%. If greater than 5.0%, the outdoor fan operating frequency is increased by 1Hz; if less than 5.0%, the outdoor fan operating frequency is reduced by 2Hz, and further judged whether the evaporation pressure change rate is less than -5.0%. If less than -5.0%, the outdoor fan operating frequency is increased by 1Hz. If greater than -5.0%, the outdoor fan operating frequency remains unchanged.

[0056] The above control steps realize the determination of the optimal value of the condensing pressure of the air-cooled multi-split unit under different operating conditions, and based on this, determine the optimal operating frequency of the outdoor fan.

[0057] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the operation of an air-cooled multi-connected unit based on the coordination of multiple parameters, characterized in that The following steps are involved: S1, compressor number control based on the number of indoor units turned on; S2, compressor operation frequency control based on indoor unit evaporation / condensation pressure; S3, indoor unit electronic expansion valve opening control based on indoor temperature; S4, cascade control of the outdoor fan operating frequency based on the difference between the condensing temperature and the evaporating temperature and the outdoor unit evaporation / condensing pressure change rate, wherein: The S1, control of the number of compressors based on the number of indoor units turned on, has the following specific control steps: when the ratio of the number of indoor units turned on to the total number of indoor units is less than 50.0%, the air-cooled multi-split system turns on one variable-frequency compressor; when the ratio of the number of indoor units turned on to the total number of indoor units is greater than 50.0%, the air-cooled multi-split system turns on one fixed-speed compressor and one variable-frequency compressor; The S2, the compressor operation frequency control based on the continuous regulation of the indoor unit evaporation / condensation pressure, has the following specific control steps: in the cooling operation mode, when the indoor unit minimum superheat T sup,min Greater than superheat setting value T sup,s , the compressor operating frequency decreases (T sup,min -T sup,s )Δf c , where Δf c The change value of the compressor operating frequency setting; when the indoor unit minimum superheat T sup,min Less than superheat setting value T sup,s , the compressor operating frequency increases (T sup,s -T sup,min )Δf c ; In heating mode, when the indoor unit minimum subcooling degree T sub,min Greater than the subcooling setting value T sub,s , the compressor operating frequency decreases (T sub,min -T sub,s )Δf c ; When the indoor unit minimum subcooling degree T sub,min Less than the subcooling setting value T sub,s , the compressor operating frequency increases (T sub,s -T sub,min )Δf c ; The S3, indoor unit electronic expansion valve opening control based on indoor temperature, has the following specific control steps: In the cooling operation mode, when the indoor temperature detection value T r,t Greater than the indoor temperature setting value T r,s , the opening of the indoor unit electronic expansion valve increases (T r,t -T r,s )Δζ, where Δζ is the change in the electronic expansion valve opening setting. When the indoor temperature detection value T r,t Less than the indoor temperature setting value T r,s , the opening of the indoor unit electronic expansion valve decreases (T r,s -T r,t )Δζ; In heating operation mode, when the indoor temperature detection value T r,t Greater than the indoor temperature setting value T r,s , the opening of the indoor unit electronic expansion valve decreases (T r,t -T r,s )Δζ; When the indoor temperature detection value T r,t Less than the indoor temperature setting value T r,s , the opening of the indoor unit electronic expansion valve increases (T r,s -T r,t )Δζ; The S4, cascade control of the outdoor fan operating frequency based on the difference between the condensing temperature and the evaporating temperature and the outdoor unit evaporation / condensing pressure change rate, has the following specific control steps: In cooling mode, when the condensing temperature T c and evaporation temperature T e The difference is less than the temperature difference setting value ΔT s , the operating frequency of the outdoor fan decreases (ΔT s -(T c -T e ))Δf f , where Δf f The change value of the outdoor fan operating frequency setting when the condensing temperature T c and evaporation temperature T e The difference is greater than the temperature difference setting value ΔT s , the outdoor fan operating frequency increases by Δf f , and further determine whether the condensing pressure change rate is less than -η, where η is the set value of the pressure change rate. If the condensing pressure change rate is less than -η, the outdoor fan operating frequency increases by Δf f ; If the condensing pressure change rate is greater than -η, the outdoor fan operating frequency decreases by 2Δf f , and further determine whether the condensing pressure change rate is greater than η. If the condensing pressure change rate is greater than η, the outdoor fan operating frequency increases by Δf f , if the condensing pressure change rate is less than η, the operating frequency of the outdoor fan remains unchanged; In heating mode, when the condensing temperature T c and evaporation temperature T e The difference is less than the temperature difference setting value ΔT s , the operating frequency of the outdoor fan decreases (ΔT s -(T c -T e ))Δf f ; When the condensation temperature T c and evaporation temperature T e The difference is greater than the temperature difference setting value ΔT s , the outdoor fan operating frequency increases by Δf f , and further determine whether the evaporation pressure change rate is greater than η. If the evaporation pressure change rate is greater than η, the outdoor fan operating frequency increases by Δf f ; If the evaporation pressure change rate is less than η, the outdoor fan operating frequency decreases by 2Δf f , and further determine whether the evaporation pressure change rate is less than -η. If the evaporation pressure change rate is less than -η, the outdoor fan operating frequency increases by Δf f , if the evaporation pressure change rate is greater than -η, the outdoor fan operating frequency remains unchanged.

2. The air-cooled multi-split operation control method based on multi-parameter internal and external coordination according to claim 1 is characterized in that: The superheat setting value T sup,s Including 1.0, 1.5, 2.0, 2.5, 3.0℃.

3. The air-cooled multi-split operation control method based on multi-parameter internal and external coordination according to claim 1 is characterized in that: The subcooling setting value T sub,s Including 1.0, 1.5, 2.0, 2.5, 3.0℃.

4. The air-cooled multi-split operation control method based on multi-parameter internal and external coordination according to claim 1 is characterized in that: The indoor temperature setting value T r,s The range is 15.0~32.0℃.

5. The air-cooled multi-split operation control method based on multi-parameter internal and external coordination according to claim 1 is characterized in that: The temperature difference setting value ΔT s The range is 10.0~15.0℃.

6. The air-cooled multi-split operation control method based on multi-parameter internal and external coordination according to claim 1 is characterized in that: The condensing pressure change rate may be replaced by the condensing pressure change amount.

7. The air-cooled multi-split operation control method based on multi-parameter internal and external coordination according to claim 1 is characterized in that: The evaporation pressure change rate may be replaced by the evaporation pressure change amount.

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