A method for controlling the operation of air-cooled multi-split units based on internal and external coordination of multiple parameters

Abstract

The present invention relates to an air-cooled multi-split unit operation control method based on multi-parameter internal and external coordination. The method mainly includes S1: compressor number control based on the number of indoor units in operation; S2: compressor operating frequency control based on the indoor unit evaporation / condensing pressure; S3: indoor unit electronic expansion valve opening control based on the indoor temperature; and S4: outdoor fan operating frequency cascade control based on the difference between the condensing temperature and the evaporation temperature and the rate of change of the outdoor unit evaporation / condensing pressure. The present invention not only ensures the liquid supply to the evaporator, but also achieves internal and external decoupling control of the air-cooled multi-split unit, improving the stability of the air-cooled multi-split unit operation. It also provides a control method for the optimal operation of the compressor and fan, the dominant equipment affecting the energy efficiency of the air-cooled multi-split unit, thereby improving the energy efficiency of the air-cooled multi-split unit.

Description

Technical Field

[0001] The present invention belongs to the field of air-cooled multi-split control, and 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 pipe 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 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 outdoor units, large system dynamic losses, poor oil return, and seriously affects the reliability and stability of 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 it ensures the reliability and stability of unit operation, due to the different indoor load characteristics of air-cooled multi-split units and changes in outdoor working conditions, the control idea of ​​constant evaporation / condensing pressure is difficult to make the air-cooled multi-split unit 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, 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 the compressors based on the evaporation / condensation pressure of the indoor units, S3, a method for controlling the opening of the electronic expansion valves 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, the compressor operating frequency control based on the continuous regulation of the indoor unit evaporation / condensation pressure, are as follows:

[0010] In cooling mode, when the indoor unit has the minimum superheat T sup,min Greater than the 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 the 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 minimum subcooling degree of the indoor unit 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 aforementioned S3, controlling the opening degree of the indoor unit electronic expansion valve based on the 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 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;

[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 specific control steps of 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, are as follows:

[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 fIf the condensing pressure change rate is greater than -η, the outdoor fan operating frequency is reduced 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 operating frequency of the outdoor fan 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 will be 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, its value range is 10.0~15.0℃;

[0024] The condensing pressure change rate can 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 independently regulates the dominant equipment that affects the stability of the air-cooled multi-split unit based on different parameters, thereby achieving internal and external decoupling control of the air-cooled multi-split unit and improving the stability of the air-cooled multi-split unit operation.

[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 to the evaporator;

[0029] The present invention determines the optimal evaporation pressure and condensation pressure of an air-cooled multi-split compressor in cooling and heating modes based on the minimum superheat / cooling degree of the indoor unit, thereby achieving 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 an air-cooled multi-split unit based on the change rate of the evaporation / condensation pressure, thereby achieving 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 This is a flow chart of a refrigeration operation control method for an air-cooled multi-unit 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 for an air-cooled multi-unit unit 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 the thermal operation of an air-cooled multi-unit machine based on internal and external coordination of multiple parameters according to another specific embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] Combine Figure 1 and Figure 2 As shown, in this embodiment, a refrigeration operation control method of an air-cooled multi-unit machine based on multi-parameter internal and external coordination is provided, wherein:

[0036] S1. Control 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°C, 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°C, 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 based on this, determine the optimal operating frequency of the compressor.

[0041] The aforementioned S3, controlling the opening degree of the indoor unit electronic expansion valve based on the 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 (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 (26.0-indoor temperature detection value)×1%.

[0043] The specific control steps of 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, are as follows:

[0044] When the difference between the condensing temperature and the evaporating temperature is less than the temperature difference set 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 set 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-unit heat exchanger based on the coordination of multiple internal and external parameters is provided, wherein:

[0047] S1. Control 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 degree of the indoor unit is greater than the subcooling degree setting value by 1.0℃, the compressor operating frequency decreases by (minimum subcooling degree of the indoor unit - 1.0) × 1Hz; when the minimum subcooling degree of the indoor unit is less than the subcooling degree setting value by 1.0℃, the compressor operating frequency increases by (1.0 - minimum subcooling degree of the indoor unit) × 1Hz.

[0051] The above control steps are based on the control of the minimum subcooling 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 based on this, determine the optimal operating frequency of the compressor.

[0052] The aforementioned S3, controlling the opening degree of the indoor unit electronic expansion valve based on the 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 specific control steps of 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, are as follows:

[0055] When the difference between the condensing temperature and the evaporating temperature is less than the set temperature difference of 10.0°C, the outdoor fan operating frequency is reduced by (10.0 - (condensing temperature - evaporating temperature)) × 1 Hz. When the difference between the condensing temperature and the evaporating temperature is greater than the set temperature difference of 10.0°C, the outdoor fan operating frequency is increased by 1 Hz. The system then determines whether the evaporating pressure change rate is greater than 5.0%. If so, the outdoor fan operating frequency is increased by 1 Hz. If so, the outdoor fan operating frequency is reduced by 2 Hz. The system then determines whether the evaporating pressure change rate is less than -5.0%. If so, the outdoor fan operating frequency is increased by 1 Hz. If so, 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] While 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 these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the operation of an air-cooled multi-split unit based on the coordination of multiple internal and external parameters, characterized in that The following steps are involved: S1, compressor number control based on the number of indoor units turned on; S2, compressor operating 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 aforementioned S1, control of the number of compressors based on the number of indoor units turned on, specifically comprises the following 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, based on the continuous regulation of the evaporation / condensation pressure of the indoor unit, is a compressor operating frequency control. The specific control steps are as follows: In the cooling operation mode, when the minimum superheat degree T of the indoor unit is sup,min Greater than the 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 the 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 minimum subcooling degree of the indoor unit 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, based on the indoor temperature indoor unit electronic expansion valve opening control, the specific control steps are as follows: 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 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 specific control steps of 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, are as follows: 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 is reduced 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 outdoor fan operating frequency 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 is reduced 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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