Air conditioning heat pump system and control method thereof

Abstract

The application discloses an air conditioner heat pump system and a control method thereof. The system comprises an unloading valve arranged on a second enthalpy-increasing air supplement pipe. A third enthalpy-increasing air supplement pipe connected to a second input end of an economizer is arranged on a pipeline between a first output end of the economizer and an input end of a second heat exchanger. An enthalpy-increasing expansion valve is arranged on the third enthalpy-increasing air supplement pipe. Compared with the prior art, the application can continue to reduce the air supplement amount of the system and achieve the effect of reducing the power of the unit when the enthalpy-increasing electronic expansion valve is at the minimum opening degree.

Description

Technical Field

[0001] This invention relates to the field of air conditioning system load adjustment devices, and more specifically, to an air conditioning heat pump system and its control method. Background Technology

[0002] Currently, domestically manufactured low-temperature air source heat pumps utilize enthalpy-increasing compressors. Under low ambient temperatures, the enthalpy-increasing circuit is activated to increase the amount of gas supplied to the compressor, thereby improving the unit's energy efficiency. Under certain operating conditions or low-frequency operation, the system does not require excessive enthalpy-increasing gas supply. Typically, heat pump manufacturers choose to either activate or deactivate the enthalpy-increasing function. When activated, the system's enthalpy-increasing electronic expansion valve closes to its minimum opening. Even so, the system's gas supply still exceeds its requirements. In this case, the system's heating capacity may exceed the user's needs, and the unit's power consumption will increase due to the opening of the enthalpy-increasing valve, thus increasing the user's electricity consumption.

[0003] Existing technology discloses a dual-cylinder variable-capacity compressor system, a variable-capacity enthalpy-increasing system, and a control method. This system includes a first control valve assembly to control the connection between the variable-capacity port and the exhaust port, or between the variable-capacity port and the intake port of the dual-cylinder variable-capacity compressor, enabling switching between single-cylinder and dual-cylinder operation. Simultaneously, a variable-capacity tank is located at the compressor's variable-capacity port. This tank performs gas-liquid separation on the gaseous refrigerant returning to the pipe connected to the compressor's variable-capacity port, preventing liquid refrigerant from entering the compressor and undergoing a phase change. The drawback of this solution is that connecting the refrigerant from the compressor's exhaust or return outlet to the enthalpy-increasing port essentially means the refrigerant circulates within the compressor to achieve unloading, but it does not address the issue that the system's gas supply still exceeds system requirements even at the minimum opening of the enthalpy-increasing electronic expansion valve.

[0004] Therefore, in light of the above requirements and the shortcomings of existing technologies, this application proposes an air conditioning heat pump system and its control method. Summary of the Invention

[0005] This invention provides an air conditioning heat pump system and its control method, which can adjust the traditional gas replenishment and enthalpy increase control logic, so that the enthalpy increase electronic expansion valve can continue to reduce the gas replenishment of the system even at the minimum opening, thereby achieving the effect of reducing the unit power and realizing a further reduction in capacity.

[0006] The primary objective of this invention is to solve the aforementioned technical problems. The technical solution of this invention is as follows:

[0007] The first aspect of this invention provides an air conditioning heat pump system, comprising: a compressor, an economizer, a gas-liquid separator, a first heat exchanger, a second heat exchanger, and a four-way valve; the first output port of the compressor is connected to the first input port of the four-way valve, the first output port of the four-way valve is connected to the input port of the first heat exchanger, and the output port of the first heat exchanger is connected to the first input terminal of the economizer; the first output terminal of the economizer is connected to the input terminal of the second heat exchanger via a pipe, an electronic expansion valve is installed on the pipe; the output terminal of the second heat exchanger is connected to the second input port of the four-way valve, and the second output port of the four-way valve is connected to the input terminal of the gas-liquid separator; the output terminal of the gas-liquid separator is connected to the first input port of the compressor; the second output terminal of the economizer is connected to the second input port of the compressor via a first enthalpy-increasing gas supply pipe, and to a third input port via a second enthalpy-increasing gas supply pipe.

[0008] Furthermore, an unloading valve is provided on the second enthalpy-increasing gas supply pipe, and a third enthalpy-increasing gas supply pipe is provided on the pipe between the first output end of the economizer and the input end of the second heat exchanger, which is connected to the second input end of the economizer. An enthalpy-increasing expansion valve is provided on the third enthalpy-increasing gas supply pipe.

[0009] Furthermore, the compressor is a dual-rotor gas-injection compressor or a dual-channel gas-injection compressor.

[0010] Based on the above technical features, the present invention can solve the problem that the capacity of the enthalpy-increasing electronic expansion valve in traditional heat pump air conditioners still exceeds the demand when the valve is opened to its minimum state at low ambient temperatures. In this state, the upper and lower compression chambers of the compressor will exhibit an asymmetry, which may cause compressor overcurrent problems.

[0011] Furthermore, the unloading device controls the connection or disconnection of the second enthalpy-increasing gas supply pipe based on the ambient temperature, inlet water temperature, outlet water temperature, enthalpy-increasing inlet temperature, enthalpy-increasing outlet temperature, and the actual frequency of the compressor; the ambient temperature is obtained by a first temperature measuring device installed on the second heat exchanger; the inlet water temperature is obtained by a second temperature measuring device installed on the first heat exchanger; the outlet water temperature is obtained by a third temperature measuring device installed on the first heat exchanger; the enthalpy-increasing inlet temperature is obtained by a fourth temperature measuring device installed on the second input terminal of the economizer; the enthalpy-increasing outlet temperature is obtained by a fifth temperature measuring device installed on the second output terminal of the economizer; and the actual frequency of the compressor is obtained by a detection device installed on the compressor.

[0012] Furthermore, the first heat exchanger is a shell-and-tube heat exchanger, and the second heat exchanger is a finned heat exchanger.

[0013] Furthermore, the unloading valve is a solenoid valve or an electronic expansion valve.

[0014] A second aspect of the present invention provides a control method for an air conditioning heat pump system, the method being used in the aforementioned air conditioning heat pump system, comprising the following steps:

[0015] S1. Obtain the ambient temperature T of the air conditioning heat pump system. a Inlet water temperature T i Outlet water temperature T o The enthalpy-increasing inlet temperature T1, the enthalpy-increasing outlet temperature T2, and the actual frequency P of the compressor are determined based on the ambient temperature T. a Inlet water temperature T i and outlet water temperature T o Set the target frequency P′ of the compressor at the current ambient temperature.

[0016] S2. Determine whether the actual frequency P of the compressor meets the first judgment condition. If so, control the enthalpy expansion valve (8) to close to the minimum opening. Otherwise, calculate the enthalpy superheat ΔT based on the enthalpy inlet temperature T1 and the enthalpy outlet temperature T2, and control the enthalpy expansion valve to open or close according to the magnitude of the enthalpy superheat ΔT.

[0017] S3. Determine whether the actual frequency P of the compressor meets the second judgment condition. If so, control the unloading valve to close and interrupt the second enthalpy-increasing gas supply pipe; otherwise, control the enthalpy-increasing expansion valve to close and interrupt the third enthalpy-increasing gas supply pipe.

[0018] S4. Repeat steps S2-S3.

[0019] Furthermore, the process of setting the target frequency P′ of the compressor at the current ambient temperature is as follows: the maximum value is set according to the frequency limit value of the cooling and heating ambient temperature. If there is no frequency limit condition in the middle, the unit will continue to rise to the highest frequency.

[0020] Furthermore, the first judgment condition is specifically: whether the relationship between the actual frequency P and the target frequency P′ satisfies P≤P'×70%; the second judgment condition is specifically: whether the relationship between the actual frequency P and the target frequency P′ satisfies P'×40%≤P≤P'×70%.

[0021] Furthermore, the calculation process for the enthalpy superheat ΔT is as follows:

[0022] ΔT=T1-T2

[0023] The process of controlling the opening or closing of the enthalpy-increasing expansion valve according to the magnitude of the enthalpy-increasing superheat ΔT is as follows:

[0024] When the enthalpy superheat ΔT meets the condition ΔT<0.5℃, the enthalpy expansion valve is controlled to close by 15N every 60s; when the enthalpy superheat ΔT meets the condition 0.5℃≤ΔT≤3℃, the enthalpy expansion valve is controlled to adjust according to the preset PID parameters; when the enthalpy superheat ΔT meets the condition 3℃<ΔT, the enthalpy expansion valve is controlled to immediately open by 10N, and then open by 6N every 30s.

[0025] Where N represents the opening degree of the enthalpy-increasing expansion valve.

[0026] Furthermore, the PID parameters are specifically as follows:

[0027]

[0028] Among them, K p K represents the proportionality constant. i K represents the integration constant. d Let represent the differential constant, e(t) represent the function of output change with time, and t represent time.

[0029] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0030] This invention provides an air conditioning heat pump system and its control method. By adding an unloading valve and an enthalpy expansion valve to the enthalpy injection pipe, the enthalpy capacity can be further reduced even when the enthalpy opening is closed to the minimum. This achieves the effect of reducing the unit power level under reduced partial load capacity, and solves the problem that the capacity of the enthalpy electronic expansion valve still exceeds the demand when the ambient temperature is low in traditional heat pump air conditioners. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of an air conditioning heat pump system according to the present invention.

[0032] Figure 2 This is a schematic diagram of the heating cycle process in one embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of the refrigeration cycle process in one embodiment of the present invention.

[0034] Figure 4 This is a flowchart of a control method for an air conditioning heat pump system according to the present invention.

[0035] Figure 5 This is a flowchart illustrating the adjustment of the enthalpy-increasing expansion valve based on the judgment result in one embodiment of the present invention.

[0036] Figure 6 This is a schematic diagram of a partial load unloading system for an air conditioning heat pump system according to the present invention. Detailed Implementation

[0037] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0038] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0039] Example 1

[0040] like Figure 1 and Figure 2 As shown, this invention provides an air conditioning heat pump system, which includes: a compressor 1, an economizer 2, a gas-liquid separator 3, a first heat exchanger 4, a second heat exchanger 5, and a four-way valve 6; the first output port 101 of the compressor 1 is connected to the first input port 601 of the four-way valve 6, the first output port 602 of the four-way valve 6 is connected to the input port 401 of the first heat exchanger 4, and the output port 402 of the first heat exchanger 4 is connected to the first input terminal 201 of the economizer 2; the first output terminal 202 of the economizer 2 is connected to the first... The input end 501 of the second heat exchanger 5 is equipped with an electronic expansion valve 9 on the pipeline. The output end 502 of the second heat exchanger 5 is connected to the second input port 603 of the four-way valve 6, and is connected to the input end 301 of the gas-liquid separator 3 via the second output port 604 of the four-way valve 6. The output end 302 of the gas-liquid separator 3 is connected to the first input port 102 of the compressor 1. The second output end 203 of the economizer 2 is connected to the second input port 103 of the compressor 1 via the first enthalpy-increasing gas supply pipe, and is connected to the third input port 104 via the second enthalpy-increasing gas supply pipe.

[0041] An unloading valve 7 is provided on the second enthalpy-increasing gas supply pipe. A third enthalpy-increasing gas supply pipe is provided on the pipe between the first output end 202 of the economizer 2 and the input end 501 of the second heat exchanger 5, which is connected to the second input end 204 of the economizer 2. An enthalpy-increasing expansion valve 8 is provided on the third enthalpy-increasing gas supply pipe.

[0042] Furthermore, the compressor is a dual-rotor gas-injection compressor or a dual-channel gas-injection compressor.

[0043] It should be noted that this invention modifies the compressor used in traditional low-temperature heat pump air conditioners, removing the enthalpy-increasing gas-liquid separator located between the second inlet 103 and the third inlet 104 of compressor 1. With the enthalpy-increasing valve closed to its minimum, the enthalpy-increasing capacity can be further reduced, achieving the effect of reducing the unit's power level under partial load. Through the above technical features, this invention solves the problem that in traditional heat pump air conditioners, even with the enthalpy-increasing electronic expansion valve open to its minimum in low ambient temperature conditions, the capacity still exceeds demand. In this state, the upper and lower compression chambers of the compressor will exhibit asymmetry, potentially causing compressor overcurrent problems.

[0044] In a specific embodiment, such as Figure 1 As shown, a filter is installed on the pipe between the first output end 202 of the economizer 2 and the input end 501 of the second heat exchanger 5, and a filter is also installed between the output port 402 of the first heat exchanger 4 and the first input end 201 of the economizer 2.

[0045] Furthermore, the unloading valve 7 controls the connection or disconnection of the second enthalpy-increasing gas supply pipe based on the ambient temperature, inlet water temperature, outlet water temperature, enthalpy-increasing inlet temperature, enthalpy-increasing outlet temperature, and the actual frequency of the compressor 1. The ambient temperature is obtained by the first temperature measuring device 701 installed on the second heat exchanger 5; the inlet water temperature is obtained by the second temperature measuring device 702 installed on the first heat exchanger 4; the outlet water temperature is obtained by the third temperature measuring device 703 installed on the first heat exchanger 4; the enthalpy-increasing inlet temperature is obtained by the fourth temperature measuring device 704 installed on the second input terminal 204 of the economizer 2; the enthalpy-increasing outlet temperature is obtained by the fifth temperature measuring device 705 installed on the second output terminal 203 of the economizer 2; and the actual frequency of the compressor 1 is obtained by the detection device 706 installed on the compressor 1.

[0046] In a specific embodiment, such as Figure 1 As shown, an electronic expansion valve is installed on the pipe between the first output end 202 of the economizer 2 and the input end 501 of the second heat exchanger 5.

[0047] It should be noted that the electronic expansion valve is used for the main circuit throttling process to facilitate the evaporation and absorption of heat; the enthalpy-increasing expansion valve 8 is used for enthalpy-increasing flow path throttling to facilitate the supply of low-temperature refrigerant to the main circuit of the economizer 2, thereby increasing the subcooling of the main circuit of the economizer 2.

[0048] Furthermore, the first heat exchanger 4 is a shell-and-tube heat exchanger, and the second heat exchanger 5 is a finned heat exchanger.

[0049] Furthermore, the unloading valve 7 is a solenoid valve or an electronic expansion valve.

[0050] It should be noted that under partial load conditions, the demand for the user's capacity is usually lower, so the unit operates at a lower frequency. When the frequency is lower than 70% of the current target frequency, the unit's enthalpy-increasing valve is closed to its minimum opening. When the frequency is lower than 60% of the current target frequency, the unit closes the unloading solenoid valve, leaving only the lower compression chamber for gas supply. When the frequency is lower than 40% of the current target frequency, the unit closes the enthalpy-increasing electronic expansion valve and no longer supplies gas.

[0051] It should be noted that the heating process of a heat pump air conditioning system is as follows: Figure 2 As shown, the main flow path at this time is as follows: the first output port 101 of the compressor 1 discharges, which is connected to the first input port 601 of the four-way valve 6. The first output port 602 of the four-way valve 6 is connected to the first heat exchanger 4. The first heat exchanger 4 is connected to the first input terminal 201 of the economizer 2. The first output terminal 202 of the economizer 2 is connected to the electronic expansion valve 9. The second heat exchanger 5 is connected to the input terminal 501 of the second heat exchanger 5. The output terminal 502 of the second heat exchanger 5 is connected to the second input port 603 of the four-way valve 6. The second output port 604 of the four-way valve 6 is connected to the input terminal 301 of the gas-liquid separator 3. The output terminal 302 of the gas-liquid separator 3 is connected to the first input port 102 of the compressor 1.

[0052] Enthalpy-increasing flow path: The first output terminal 202 of the economizer 2 is connected to the second input terminal 204 of the economizer 2 through the enthalpy-increasing expansion valve 8, and is connected to the unloading valve 7 through the second output terminal 203 of the economizer 2.

[0053] In a specific embodiment, a certain unit is operating in heating mode. At an ambient temperature of -20℃ and an outlet water temperature of 50℃, the target frequency of the unit is 100Hz. When the unit actively reduces the frequency to below 70Hz before shutting down at the reached temperature, this state is a partial load state.

[0054] It should be noted that the cooling process of a heat pump air conditioning system is as follows: Figure 3 As shown, the main flow path at this time is as follows: the first output port 101 of compressor 1 discharges into the first input port 601 of four-way valve 6, and is connected to the output terminal 502 of second heat exchanger 5 through the second input port 603 of four-way valve 6. The input terminal 501 of second heat exchanger 5 is connected to the first output terminal 202 of economizer 2 through electronic expansion valve 9. The first input terminal 201 of economizer 2 is connected to first heat exchanger 4, and is connected to the first output port 602 of four-way valve 6 through first heat exchanger 4. The second output port 604 of four-way valve 6 is connected to the input terminal 301 of gas-liquid separator 3, and the output terminal 302 of gas-liquid separator 3 is connected to the first input port 102 of compressor 1.

[0055] Enthalpy-increasing flow path: Electronic expansion valve 9 is connected to the second input terminal 204 of economizer 2 through enthalpy-increasing expansion valve 8, and is connected to unloading valve 7 through the second output terminal 203 of economizer 2.

[0056] In a specific embodiment, a certain unit is operating in cooling mode. At an ambient temperature of 35°C and an outlet water temperature of 7°C, the target frequency of the unit is 70Hz. When the terminal equipment is partially turned on and the equipment actively reduces the frequency to below 49Hz, this state is a partial load state.

[0057] In one specific embodiment, the unloading valve 7 can be replaced with an electronic expansion valve, which can improve the balance of the compression process in the upper and lower compression chambers by controlling the flow rate.

[0058] Example 2

[0059] Based on the above embodiment 1, combined with Figure 4 and Figure 5 This embodiment also provides a control method for an air conditioning heat pump system. The method is used in the aforementioned air conditioning heat pump system and includes the following steps:

[0060] S1. Obtain the ambient temperature T of the air conditioning heat pump system. a Inlet water temperature T i Outlet water temperature T o The enthalpy-increasing inlet temperature T1, the enthalpy-increasing outlet temperature T2, and the actual frequency P of compressor 1 are determined based on the ambient temperature T. a Inlet water temperature T i and outlet water temperature T o Set the target frequency P′ of the compressor at the current ambient temperature.

[0061] It should be noted that the current ambient water temperature corresponds to the target frequency, and its detection method is set by the logic of the main control computer board.

[0062] S2. Determine whether the actual frequency P of compressor 1 meets the first judgment condition. If so, control the enthalpy expansion valve 8 to close to the minimum opening. Otherwise, calculate the enthalpy superheat ΔT based on the enthalpy inlet temperature T1 and the enthalpy outlet temperature T2, and control the enthalpy expansion valve 8 to open or close according to the magnitude of the enthalpy superheat ΔT.

[0063] S3. Determine whether the actual frequency P of compressor 1 meets the second judgment condition. If so, control the unloading valve 7 to close and interrupt the second enthalpy-increasing gas supply pipe; otherwise, control the enthalpy-increasing expansion valve 8 to close and interrupt the third enthalpy-increasing gas supply pipe.

[0064] S4. Repeat steps S2-S3.

[0065] It should be noted that the purpose of step S4 is to dynamically adjust the enthalpy increase of the air supply to the air conditioning heat pump system.

[0066] Furthermore, the process of setting the target frequency P′ of the compressor 1 at the current ambient temperature is as follows: the maximum value is set according to the frequency limit value of the cooling and heating ambient temperature. If there is no frequency limit condition in the middle, the unit will continue to rise to the highest frequency.

[0067] Furthermore, the first judgment condition is specifically: whether the relationship between the actual frequency P and the target frequency P′ satisfies P≤P'×70%; the second judgment condition is specifically: whether the relationship between the actual frequency P and the target frequency P′ satisfies P'×40%≤P≤P'×70%.

[0068] Furthermore, such as Figure 4 As shown, the calculation process for the enthalpy superheat ΔT is as follows:

[0069] ΔT=T1-T2

[0070] The process of controlling the opening or closing of the enthalpy-increasing expansion valve 8 according to the magnitude of the enthalpy-increasing superheat ΔT is as follows:

[0071] When the enthalpy superheat ΔT satisfies ΔT<0.5℃, the enthalpy expansion valve 8 is controlled to close by 15N every 60s; when the enthalpy superheat ΔT satisfies 0.5℃≤ΔT≤3℃, the enthalpy expansion valve 8 is controlled to adjust according to the preset PID parameters; when the enthalpy superheat ΔT satisfies 3℃<ΔT, the enthalpy expansion valve 8 is controlled to immediately open by 10N, and then open by 6N every 30s.

[0072] Where N represents the opening degree of the enthalpy-increasing expansion valve 8.

[0073] Furthermore, the PID parameters are specifically as follows:

[0074]

[0075] Among them, K p K represents the proportionality constant. i K represents the integration constant. d Let represent the differential constant, e(t) represent the function of output change with time, and t represent time.

[0076] It should be noted that the output signal of the PID parameters is obtained by the input signal through the combined action of proportional, integral, and derivative coefficients. The significance of setting PID parameters is to ensure stable control of the unit during operation, by accumulating and predicting the unit's future change trends and proportionally scaling to offset the impact of these changes.

[0077] In one specific embodiment, when 0.5℃≤enthalpy superheat≤3℃, the enthalpy expansion valve 8 no longer operates.

[0078] Example 3

[0079] Based on Embodiments 1 and 2, this embodiment provides a control system for an air conditioning heat pump system, such as... Figure 6As shown, it includes: an environmental detection module, a first judgment module, and a second judgment module.

[0080] The environmental monitoring module acquires the ambient temperature T of the air conditioning heat pump system. a Inlet water temperature T i Outlet water temperature T o The enthalpy-increasing inlet temperature T1, the enthalpy-increasing outlet temperature T2, and the actual frequency P of compressor 1 are determined based on the ambient temperature T. a Inlet water temperature T i and outlet water temperature T o Set the target frequency P' of the compressor at the current ambient temperature.

[0081] The first judgment module determines whether the actual frequency P of the compressor 1 meets the first judgment condition. If so, it controls the enthalpy expansion valve 8 to close to the minimum opening. Otherwise, it calculates the enthalpy superheat ΔT based on the enthalpy inlet temperature T1 and the enthalpy outlet temperature T2, and controls the enthalpy expansion valve 8 to open or close according to the magnitude of the enthalpy superheat ΔT.

[0082] The second judgment module determines whether the actual frequency P of the compressor 1 meets the second judgment condition. If so, it controls the unloading valve 7 to close and interrupts the second enthalpy-increasing gas supply pipe; otherwise, it controls the enthalpy-increasing expansion valve 8 to close and interrupts the third enthalpy-increasing gas supply pipe.

[0083] The icons in the accompanying drawings that depict the structural positional relationships are for illustrative purposes only and should not be construed as limiting this patent.

[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An air conditioning heat pump system, the air conditioning heat pump system comprising: a compressor (1), an economizer (2), a gas-liquid separator (3), a first heat exchanger (4), a second heat exchanger (5), and a four-way valve (6); the first output port (101) of the compressor (1) is connected to the first input port (601) of the four-way valve (6), the first output port (602) of the four-way valve (6) is connected to the input port (401) of the first heat exchanger (4), and the first output port (402) of the first heat exchanger (4) is connected to the first output port (601) of the economizer (2). The first output end (202) of the economizer (2) is connected to the input end (501) of the second heat exchanger (5) via a pipe. An electronic expansion valve (9) is installed on the pipe. The output end (502) of the second heat exchanger (5) is connected to the second input port (603) of the four-way valve (6). The second output port (604) of the four-way valve (6) is connected to the input end (301) of the gas-liquid separator (3). The output end (302) of the gas-liquid separator (3) is connected to the first input port (102) of the compressor (1). The second output end (203) of the economizer (2) is connected to the second input port (103) of the compressor (1) via a first enthalpy-increasing gas supply pipe, and to the third input port (104) via a second enthalpy-increasing gas supply pipe. An unloading valve (7) is provided on the second enthalpy-increasing gas supply pipe. A third enthalpy-increasing gas supply pipe is provided on the pipe between the first output end (202) of the economizer (2) and the input end (501) of the second heat exchanger (5), which is connected to the second input end (204) of the economizer (2). An enthalpy-increasing expansion valve (8) is provided on the third enthalpy-increasing gas supply pipe. The control method for the air conditioning heat pump system is as follows: S1. Obtain the ambient temperature of the air conditioning heat pump system. Inlet water temperature Outlet water temperature Enthalpy Inlet Temperature Increased enthalpy outlet temperature and the actual frequency of the compressor (1) According to ambient temperature Inlet water temperature and outlet water temperature Set the target frequency of the compressor at the current ambient temperature. ; S2. Determine the actual frequency of compressor (1). If the first judgment condition is met, control the enthalpy expansion valve (8) to close to the minimum opening. Otherwise, based on the enthalpy-increasing inlet temperature and enthalpy outlet temperature Calculate the enthalpy superheat According to the enthalpy superheat The size of the enthalpy-increasing expansion valve (8) is controlled to open or close. S3. When the enthalpy-increasing expansion valve (8) is at its minimum opening, determine the actual frequency of the compressor (1). If the second judgment condition is met, control the unloading valve (7) to close and interrupt the second enthalpy-increasing gas supply pipe; otherwise, control the enthalpy-increasing expansion valve (8) to close and interrupt the third enthalpy-increasing gas supply pipe; the second judgment condition is specifically: judging the actual frequency. With target frequency Does the relationship satisfy? ; S4. Repeat steps S2-S3.

2. An air conditioning heat pump system according to claim 1, characterized in that, The compressor (1) is a dual-rotor gas-injection compressor or a dual-channel gas-injection compressor.

3. An air conditioning heat pump system according to claim 2, characterized in that, The unloading valve (7) controls the connection or interruption of the second enthalpy-increasing gas supply pipe according to the ambient temperature, inlet water temperature, outlet water temperature, enthalpy-increasing inlet temperature, enthalpy-increasing outlet temperature and the actual frequency of the compressor (1); the ambient temperature is obtained by the first temperature measuring device (701) installed on the second heat exchanger (5); the inlet water temperature is obtained by the second temperature measuring device (702) installed on the first heat exchanger (4); the outlet water temperature is obtained by the third temperature measuring device (703) installed on the first heat exchanger (4); the enthalpy-increasing inlet temperature is obtained by the fourth temperature measuring device (704) installed on the second input end (204) of the economizer (2); the enthalpy-increasing outlet temperature is obtained by the fifth temperature measuring device (705) installed on the second output end (203) of the economizer (2); the actual frequency of the compressor (1) is obtained by the detection device (706) installed on the compressor (1).

4. An air conditioning heat pump system according to claim 2, characterized in that, The first heat exchanger (4) is a shell-and-tube heat exchanger, and the second heat exchanger (5) is a finned heat exchanger.

5. An air conditioning heat pump system according to any one of claims 2-4, characterized in that, The unloading valve (7) is a solenoid valve or an electronic expansion valve.

6. An air conditioning heat pump system according to claim 5, characterized in that, The compressor's target frequency at the current ambient temperature The setting process is as follows: the maximum value is set according to the frequency limit value of the cooling and heating environment temperature. If there is no frequency limit condition in the middle, the unit will continue to rise to the highest frequency.

7. An air conditioning heat pump system according to claim 6, characterized in that, The first judgment condition is specifically: judging the actual frequency. With target frequency Does the relationship satisfy? .

8. An air conditioning heat pump system according to claim 7, characterized in that, The enthalpy superheat The calculation process is as follows: The above is based on the enthalpy superheat. The process of opening or closing the enthalpy-increasing expansion valve (8) is as follows: When enthalpy superheat satisfy At that time, the enthalpy-increasing expansion valve (8) is closed by 15N every 60s; when the enthalpy-increasing superheat... satisfy At that time, the enthalpy-increasing expansion valve (8) is adjusted according to the preset PID parameters; when the enthalpy superheat... satisfy At that time, the enthalpy-increasing expansion valve (8) is immediately opened by 10N, and then opened by 6N every 30s; Where N represents the opening unit of the enthalpy-increasing expansion valve (8).

9. An air conditioning heat pump system according to claim 8, characterized in that, The PID parameters are specifically as follows: in, Represents a proportionality constant. Denotes the integration constant. Represents the differential constant. This represents the function that changes the output over time, where t represents time.

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