Control method and device of air conditioning system, storage medium and air conditioning system

Abstract

The application provides a control method and device of an air conditioning system, a storage medium and the air conditioning system. The control method comprises the following steps: judging whether the air conditioning system is currently in a target operating state; if it is judged that the air conditioning system is not currently in the target operating state, determining a target opening degree of a first throttling device, a target opening degree of a second throttling device and a target opening degree of a third throttilling device according to a detected operating parameter of the air conditioning system, a preset throttling device flow correction coefficient, a preset compressor displacement, a preset target control parameter and a predetermined fitting parameter; controlling the first throttling device to operate at the target opening degree of the first throttling device, controlling the second throttling device to operate at the target opening degree of the second throttling device, and controlling the third throttling device to operate at the target opening degree of the third throttling device. The scheme provided by the application can decouple the control of the three throttling devices and improve the energy efficiency of system operation.

Description

Technical Field

[0001] This invention relates to the field of control, and more particularly to a control method, apparatus, storage medium, and air conditioner for an air conditioning system. Background Technology

[0002] The regulation of electronic expansion valves can control whether the air conditioning system is operating at its optimal state, and also ensure that the compressor is not damaged due to liquid carryover or excessively high discharge temperature. Existing electronic expansion valves typically adjust based on the compressor's suction or discharge superheat, using the superheat difference and employing feedback control strategies such as PID control to achieve system control. This method is very effective for a single-stage system where a single valve controls a single suction temperature (discharge temperature). However, when multiple electronic expansion valves are coupled to control multiple suction temperatures, conventional control strategies are no longer applicable. Summary of the Invention

[0003] The main objective of this invention is to overcome the deficiencies of the aforementioned related technologies and provide a control method, device, storage medium, and air conditioner for an air conditioning system, so as to solve the problems of strong coupling, complex operation control, and high difficulty in the control of three electronic expansion valves in the dual evaporation temperature air conditioning system in the related technologies.

[0004] This invention provides a control method for an air conditioning system, characterized in that the air conditioning system includes: a compressor, an outdoor heat exchanger, a first throttling device, a second throttling device, a third throttling device, a flash evaporator, an indoor first heat exchanger, an indoor second heat exchanger, a first four-way reversing valve, and a second four-way reversing valve; the inlet end of the flash evaporator is connected to the outdoor heat exchanger; the first throttling device is disposed on the pipeline between the flash evaporator and the outdoor heat exchanger; the indoor first heat exchanger and the indoor second heat exchanger are connected in parallel and then connected to the flash evaporator through the second throttling device; the third throttling device is disposed on the pipeline in parallel between the indoor second heat exchanger and the indoor first heat exchanger.

[0005] The control method includes: determining whether the air conditioning system is currently in a target operating state; if it is determined that the air conditioning system is not currently in a target operating state, then determining the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device based on the detected operating parameters of the air conditioner, the preset flow correction coefficient of the throttling device, the preset compressor displacement, the preset target control parameters, and the predetermined fitting parameters; controlling the first throttling device to operate at the target opening degree of the first throttling device, controlling the second throttling device to operate at the target opening degree of the second throttling device, and controlling the third throttling device to operate at the target opening degree of the third throttling device.

[0006] Optionally, before determining whether the air conditioning system is currently in the target operating state, the method further includes: after the air conditioning system is turned on, determining the compressor frequency, outdoor fan speed, and / or indoor fan speed of the air conditioning system based on the outdoor ambient temperature, indoor ambient temperature, and indoor set temperature; determining the initial opening degree of the first throttling device, the second throttling device, and the third throttling device based on the current operating mode of the air conditioning system; and controlling the operation of the air conditioning system based on the determined compressor frequency, outdoor fan speed, and / or indoor fan speed and the determined initial opening degree of the first throttling device, the second throttling device, and the third throttling device.

[0007] Optionally, determining whether the air conditioning system is currently in the target operating state includes: determining the high-temperature suction superheat, low-temperature suction superheat, and / or target flash temperature of the compressor of the air conditioning system; and determining whether the air conditioning system is currently in the target operating state based on the high-temperature suction superheat, the low-temperature suction superheat, and / or the target flash temperature.

[0008] Optionally, determining whether the air conditioning system is currently in a target operating state based on the high-temperature suction superheat, the low-temperature suction superheat, and / or the target flash temperature includes: in cooling mode, determining whether the high-temperature suction superheat is greater than or equal to a first preset threshold and less than or equal to a second preset threshold, whether the low-temperature suction superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, and whether the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within a preset temperature difference range; if the high-temperature suction superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, the low-temperature suction superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, and the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within a preset temperature difference range, then the air conditioning system is determined to be in a target operating state; if the high-temperature suction superheat is less than the first preset threshold or greater than the second preset threshold, or the low-temperature suction superheat is less than the first preset threshold or greater than the second preset threshold, when If the absolute value of the temperature difference between the current flash temperature and the target flash temperature is not within the preset temperature difference range, then the air conditioning system is determined not to be in the target operating state; and / or, in heating mode, it is determined whether the high-temperature suction superheat or the low-temperature suction superheat is greater than or equal to a first preset threshold and less than or equal to a second preset threshold, and whether the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within the preset temperature difference range; if it is determined that the high-temperature suction superheat or the low-temperature suction superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, and the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within the preset temperature difference range, then the air conditioning system is determined to be in the target operating state; if it is determined that the high-temperature suction superheat or the low-temperature suction superheat is less than the first preset threshold, or the high-temperature suction superheat or the low-temperature suction superheat is greater than the second preset threshold, or the absolute value of the temperature difference between the current flash temperature and the target flash temperature is not within the preset temperature difference range, then the air conditioning system is determined not to be in the target operating state.

[0009] Optionally, the operating parameters of the air conditioner include at least one of the following: the mid-flow temperature of the first indoor heat exchanger, the mid-flow temperature of the second indoor heat exchanger, the high-temperature suction temperature, the low-temperature suction temperature, the mid-flow temperature of the outdoor heat exchanger, the outlet temperature of the outdoor heat exchanger, the flash temperature, the total inlet temperature of the indoor heat exchanger, and the current compressor frequency; the preset flow correction coefficient of the throttling device includes at least one of the following: the first flow correction coefficient of the first throttling device, the second flow correction coefficient of the second throttling device, and the third flow correction coefficient of the third throttling device; the preset compressor displacement includes: the high-temperature cylinder displacement of the compressor and / or the low-temperature cylinder displacement of the compressor; the preset target control parameters include: the target high-temperature suction superheat and / or the target low-temperature suction superheat; the pre-matched fitting parameters include: the high-temperature liquid pipe saturation temperature drop, the high-temperature suction pipe saturation temperature drop, the low-temperature suction pipe saturation temperature drop, the high-temperature cylinder volumetric efficiency of the compressor, and the low-temperature cylinder volumetric efficiency of the compressor.

[0010] Optionally, in cooling mode, the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device are determined based on the operating parameters of the air conditioner, the preset flow correction coefficient of the throttling device, the preset compressor displacement, the preset target control parameters, and the pre-matched fitting parameters. This includes: determining the flow rate of the first indoor heat exchanger based on the mid-flow temperature of the first indoor heat exchanger, the preset saturated temperature drop of the high-temperature suction pipe, the preset target high-temperature suction superheat, the preset high-temperature cylinder displacement of the compressor, the preset high-temperature cylinder volumetric efficiency of the compressor, and the current compressor frequency; determining the flow rate of the second indoor heat exchanger based on the mid-flow temperature of the second indoor heat exchanger, the preset saturated temperature drop of the low-temperature suction pipe, the target low-temperature suction superheat, the preset low-temperature cylinder displacement of the compressor, the preset low-temperature cylinder volumetric efficiency of the compressor, and the current compressor frequency; determining the refrigerant flow rate through the third throttling device based on the refrigerant flow rate of the second indoor heat exchanger; and determining the refrigerant flow rate through the second throttling device based on the refrigerant flow rate of the first indoor heat exchanger and the refrigerant flow rate through the third throttling device. The refrigerant flow rate is determined based on the refrigerant flow rate through the second throttling device and the flash dryness of the flash evaporator. The inlet and outlet pressure difference of the first throttling device is determined based on the mid-flow temperature of the outdoor heat exchanger and the target flash temperature. The inlet and outlet pressure difference of the second throttling device is determined based on the target flash temperature, the mid-flow temperature of the indoor first heat exchanger, and the saturation temperature drop of the high-temperature liquid pipe. The inlet and outlet pressure difference of the third throttling device is determined based on the mid-flow temperature of the indoor first heat exchanger and the mid-flow temperature of the indoor second heat exchanger. The inlet density of the first throttling device is determined based on the outlet temperature of the outdoor heat exchanger. The inlet density of the second throttling device is determined based on the target flash temperature. The inlet density of the third throttling device is determined based on the mid-flow temperature of the indoor first heat exchanger. The target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device are calculated based on the preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices.

[0011] Optionally, the flow rate of the first indoor heat exchanger is determined based on the midpoint temperature of the flow path of the first indoor heat exchanger, a predetermined saturation temperature drop of the high-temperature suction pipe, a preset target high-temperature suction superheat, a preset compressor high-temperature cylinder displacement, a predetermined compressor high-temperature cylinder volumetric efficiency, and the current compressor frequency. This includes: calculating the high-temperature suction saturation temperature based on the midpoint temperature of the flow path of the first indoor heat exchanger and the predetermined saturation temperature drop of the high-temperature suction pipe; determining the compressor high-temperature cylinder suction specific volume based on the calculated high-temperature suction saturation temperature and the target high-temperature suction superheat; and determining the compressor high-temperature cylinder suction specific volume based on the predetermined compressor high-temperature cylinder displacement, the predetermined compressor high-temperature cylinder volumetric efficiency, and the current compressor frequency. The flow rate of the indoor first heat exchanger is determined based on the specific volume of the compressor's high-temperature cylinder suction gas; and / or, the flow rate of the indoor second heat exchanger is determined based on the mid-flow path temperature of the indoor second heat exchanger, a predetermined saturation temperature drop of the low-temperature suction pipe, a target low-temperature suction superheat, a preset compressor low-temperature cylinder displacement, a predetermined compressor low-temperature cylinder volumetric efficiency, and the current compressor frequency, including: calculating the low-temperature suction saturation temperature based on the mid-flow path temperature of the indoor second heat exchanger and the predetermined saturation temperature drop of the low-temperature suction pipe; determining the specific volume of the compressor low-temperature cylinder suction gas based on the calculated low-temperature suction saturation temperature and the target low-temperature suction superheat; and determining the specific volume of the compressor low-temperature cylinder suction gas based on the predetermined compressor low-temperature cylinder displacement, the predetermined saturation temperature drop of the compressor's high-temperature cylinder suction gas, the predetermined compressor low-temperature cylinder volumetric efficiency, and the current compressor frequency. The flow rate of the second indoor heat exchanger is determined by the compressor's cryogenic cylinder volumetric efficiency and the current compressor frequency, along with the determined suction specific volume of the compressor's cryogenic cylinder; and / or, the refrigerant flow rate through the third throttling device is determined based on the refrigerant flow rate of the second indoor heat exchanger, including: the refrigerant flow rate through the third throttling device is equal to the refrigerant flow rate of the second indoor heat exchanger; the refrigerant flow rate through the second throttling device is determined based on the refrigerant flow rate of the first indoor heat exchanger and the refrigerant flow rate through the third throttling device, including: the refrigerant flow rate through the second throttling device is equal to the refrigerant flow rate of the first indoor heat exchanger and the refrigerant flow rate through the third throttling device. The sum of refrigerant flow rates; determining the refrigerant flow rate through the first throttling device based on the refrigerant flow rate through the second throttling device and the flash dryness of the flash evaporator, including: the refrigerant flow rate through the first throttling device is equal to the ratio of the difference between the refrigerant flow rate of the second throttling device and the product of 1 minus the sum of the parallel cylinder pumping liquid carry-over rate and 1 and the flash dryness of the flash evaporator; and / or, determining the inlet and outlet pressure difference of the first throttling device based on the temperature at the middle of the outdoor heat exchanger flow path and the target flash temperature, including: determining the inlet and outlet pressure difference of the first throttling device by fitting a correlation formula for the inlet and outlet pressure difference of the first throttling device under a preset cooling mode based on the temperature at the middle of the outdoor heat exchanger flow path and the target flash temperature;The inlet and outlet pressure difference of the second throttling device is determined based on the target flash temperature, the mid-flow temperature of the first heat exchanger, and the saturation temperature drop of the high-temperature liquid pipe. This includes: determining the inlet and outlet pressure difference of the second throttling device using a pre-set cooling mode and a fitted correlation equation based on the target flash temperature, the mid-flow temperature of the first heat exchanger, and the saturation temperature drop of the high-temperature liquid pipe; and the inlet and outlet pressure difference of the third throttling device is determined based on the mid-flow temperatures of the first and second heat exchangers. This includes: determining the inlet and outlet pressure difference of the third throttling device using the mid-flow temperatures of the first and second heat exchangers and a pre-set cooling mode. The inlet and outlet pressure difference of the third throttling device is determined by fitting a correlation equation; and / or, the inlet density of the first throttling device is determined based on the outlet temperature of the outdoor heat exchanger, including: determining the inlet density of the first throttling device using a correlation equation fitting a first throttling device under a preset cooling mode based on the outlet temperature of the outdoor heat exchanger; the inlet density of the second throttling device is determined based on the target flash temperature, including: determining the inlet density of the second throttling device using a correlation equation fitting a second throttling device under a preset cooling mode based on the target flash temperature; the inlet density of the third throttling device is determined based on the temperature at the middle of the flow path of the indoor first heat exchanger. The degree of opening includes: determining the inlet density of the third throttling device based on the temperature at the middle of the flow path of the first heat exchanger in the room, using a pre-set correlation formula fitting the inlet density of the third throttling device under the cooling mode; and / or, calculating the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device based on pre-set first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices, respectively, including: calculating the air flow rate of the first throttling device, the air flow rate of the second throttling device, and the air flow rate of the third throttling device based on pre-set first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet density of the first, second, and third throttling devices, respectively; and calculating the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device based on the air flow rates of the first, second, and third throttling devices, the target opening degree of the second throttling device, and the target opening degree of the third throttling device, respectively.

[0012] Optionally, in heating mode, the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device are determined based on the operating parameters of the air conditioner, the preset flow correction coefficient of the throttling device, the preset compressor displacement, the preset target control parameters, and the pre-matched fitting parameters. This includes: in heating mode, the opening degree of the third throttling device remains unchanged at an initially given fixed opening degree; the target opening degree of the first throttling device and the target opening degree of the second throttling device are determined based on the operating parameters of the air conditioner, the preset flow correction coefficient of the throttling device, the preset compressor displacement, the preset target control parameters, and the pre-matched fitting parameters. This includes: based on the high-temperature suction saturation temperature, the target high-temperature suction superheat, the preset compressor high-temperature cylinder displacement, the pre-determined compressor high-temperature cylinder volumetric efficiency, the preset compressor low-temperature cylinder displacement, the pre-determined compressor low-temperature cylinder volumetric efficiency, and the current compressor frequency. The following steps are taken: First, determine the flow rate of the outdoor heat exchanger; second, determine the refrigerant flow rate through the first throttling device based on the outdoor heat exchanger flow rate and the flash dryness of the flash evaporator; third, determine the inlet and outlet pressure difference of the first throttling device based on the midpoint temperature of the outdoor heat exchanger flow path and the target flash temperature; fourth, determine the inlet and outlet pressure difference of the second throttling device based on the target flash temperature, the midpoint temperature of the indoor first heat exchanger flow path, and the saturation temperature drop of the high-temperature liquid pipe; fifth, determine the inlet density of the first throttling device based on the target flash temperature; sixth, determine the inlet density of the second throttling device based on the total inlet temperature of the indoor heat exchanger; seventh, calculate the target opening degree of the first throttling device and the target opening degree of the second throttling device based on preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices, respectively.

[0013] Optionally, the outdoor heat exchanger flow rate is determined based on the high-temperature suction saturation temperature, the target high-temperature suction superheat, the preset compressor high-temperature cylinder displacement, the predetermined compressor high-temperature cylinder volumetric efficiency, the preset compressor low-temperature cylinder performance coefficient, and the current compressor frequency. This includes: determining the compressor high-temperature cylinder suction specific volume based on the high-temperature suction saturation temperature and the target high-temperature suction superheat; determining the outdoor heat exchanger flow rate based on the preset compressor high-temperature cylinder displacement, the predetermined compressor high-temperature cylinder volumetric efficiency, the preset compressor low-temperature cylinder displacement, the predetermined compressor low-temperature cylinder volumetric efficiency, the current compressor frequency, and the compressor high-temperature cylinder suction specific volume; and / or, determining the refrigerant flow rate through the first throttling device based on the outdoor heat exchanger flow rate. The refrigerant flow rate through the first throttling device is equal to the flow rate of the outdoor heat exchanger; the refrigerant flow rate through the second throttling device is determined based on the refrigerant flow rate through the first throttling device and the flash dryness of the flash evaporator, including: the refrigerant flow rate through the second throttling device is equal to the ratio of the difference between the refrigerant flow rate of the first throttling device and the product of 1 minus the sum of the parallel cylinder pumping liquid carry-over rate and 1 and the flash dryness of the flash evaporator; and / or, the inlet and outlet pressure difference of the first throttling device is determined based on the mid-flow temperature of the outdoor heat exchanger and the target flash temperature, including: the inlet and outlet pressure difference of the first throttling device is determined using a fitted correlation formula of the inlet and outlet pressure difference of the first throttling device under a preset heating mode, based on the mid-flow temperature of the outdoor heat exchanger and the target flash temperature. The outlet pressure difference; determining the inlet and outlet pressure difference of the second throttling device based on the target flash temperature, the temperature at the middle of the flow path of the first heat exchanger in the room, and the saturation temperature drop of the high-temperature liquid pipe, including: determining the inlet and outlet pressure difference of the second throttling device using a pre-set correlation formula for the inlet and outlet pressure difference under the heating mode based on the target flash temperature, the temperature at the middle of the flow path of the first heat exchanger in the room, and the saturation temperature drop of the high-temperature liquid pipe; and / or determining the inlet density of the first throttling device based on the target flash temperature, including: determining the inlet density of the first throttling device using a pre-set correlation formula for the inlet density of the first throttling device under the heating mode based on the target flash temperature; determining the inlet density of the second throttling device based on the total inlet temperature of the indoor heat exchanger, including: determining the inlet density of the second throttling device based on the total inlet temperature of the indoor heat exchanger using a pre-set correlation formula for the inlet density of the first throttling device under the heating mode based on the target flash temperature; and .... In the heating mode, the inlet density of the second throttling device is determined by fitting a correlation equation; and / or, based on preset first and second flow correction coefficients, refrigerant flow rates of the first and second throttling devices, inlet and outlet pressure differences of the first and second throttling devices, and inlet densities of the first and second throttling devices, the target opening degree of the first throttling device and the target opening degree of the second throttling device are calculated respectively, including: based on preset first and second flow correction coefficients, refrigerant flow rates of the first and second throttling devices, inlet and outlet pressure differences of the first and second throttling devices, and inlet densities of the first and second throttling devices, the air flow rate of the first throttling device and the air flow rate of the second throttling device are calculated respectively;Based on the airflow rates of the first and second throttling devices, the target opening degrees of the first and second throttling devices are calculated, respectively.

[0014] In another aspect, the present invention provides a control device for an air conditioning system, comprising: the air conditioning system including: a compressor, an outdoor heat exchanger, a first throttling device, a second throttling device, a third throttling device, a flash evaporator, an indoor first heat exchanger, an indoor second heat exchanger, a first four-way reversing valve, and a second four-way reversing valve; the control device including: a judgment unit for judging whether the air conditioning system is currently in a target operating state; a determination unit for determining, if the judgment unit judges that the air conditioning system is not currently in a target operating state, determining, based on detected operating parameters of the air conditioning system, a preset throttling device flow correction coefficient, a preset compressor displacement, preset target control parameters, and pre-determined fitting parameters, the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device; and a control unit for controlling the first throttling device to operate at the target opening degree of the first throttling device, controlling the second throttling device to operate at the target opening degree of the second throttling device, and controlling the third throttling device to operate at the target opening degree of the third throttling device.

[0015] Optionally, it further includes: an initial parameter determination unit, configured to, after the air conditioning system is turned on, before determining whether the air conditioning system is currently in the target operating state, determine the compressor frequency, outdoor fan speed and / or indoor fan speed of the air conditioning system based on the outdoor ambient temperature, indoor ambient temperature and indoor set temperature, and determine the initial opening degree of the first throttling device, the second throttling device and the third throttling device based on the current operating mode of the air conditioning system; the control unit is further configured to: control the operation of the air conditioning system based on the determined compressor frequency, outdoor fan speed and / or indoor fan speed and the determined initial opening degree of the first throttling device, the second throttling device and the third throttling device.

[0016] Optionally, the determination unit determines whether the air conditioning system is currently in the target operating state, including: determining the high-temperature suction superheat, low-temperature suction superheat, and / or target flash temperature of the compressor of the air conditioning system; and determining whether the air conditioning system is currently in the target operating state based on the high-temperature suction superheat, the low-temperature suction superheat, and / or the target flash temperature.

[0017] Optionally, the determination unit determines whether the air conditioning system is currently in the target operating state based on the high-temperature suction superheat, the low-temperature suction superheat, and / or the target flash temperature, including: in cooling mode, determining whether the high-temperature suction superheat is greater than or equal to a first preset threshold and less than or equal to a second preset threshold, whether the low-temperature suction superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, and whether the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within a preset temperature difference range; if the high-temperature suction superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, the low-temperature suction superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, and the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within the preset temperature difference range, then the air conditioning system is determined to be in the target operating state.

[0018] If the high-temperature intake superheat is determined to be less than a first preset threshold or greater than a second preset threshold, or the low-temperature intake superheat is determined to be less than a first preset threshold or greater than a second preset threshold, and the absolute value of the temperature difference between the current flash temperature and the target flash temperature is not within a preset temperature difference range, then the air conditioning system is determined not to be in the target operating state; and / or, in heating mode, it is determined whether the high-temperature intake superheat or the low-temperature intake superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, and whether the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within a preset temperature difference range; if determined... If the high-temperature intake superheat or the low-temperature intake superheat is greater than or equal to a first preset threshold and less than or equal to a second preset threshold, and the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within a preset temperature difference range, then the air conditioning system is determined to be in the target operating state. If the high-temperature intake superheat or the low-temperature intake superheat is less than the first preset threshold, or the high-temperature intake superheat or the low-temperature intake superheat is greater than the second preset threshold, or the absolute value of the temperature difference between the current flash temperature and the target flash temperature is not within a preset temperature difference range, then the air conditioning system is determined not to be in the target operating state.

[0019] Optionally, the operating parameters of the air conditioner include at least one of the following: the mid-flow temperature of the first indoor heat exchanger, the mid-flow temperature of the second indoor heat exchanger, the high-temperature suction temperature, the low-temperature suction temperature, the mid-flow temperature of the outdoor heat exchanger, the outdoor heat exchanger outlet temperature, the flash temperature, the total inlet temperature of the indoor heat exchanger, and the current compressor frequency f; the preset flow correction coefficient of the throttling device includes at least one of the following: the first flow correction coefficient of the first throttling device, the second flow correction coefficient of the second throttling device, and the third flow correction coefficient of the third throttling device; the preset compressor displacement includes: the high-temperature cylinder displacement of the compressor and / or the low-temperature cylinder displacement of the compressor; the preset target control parameters include: the target high-temperature suction superheat and / or the target low-temperature suction superheat; the pre-matched fitting parameters include at least one of the following: the high-temperature liquid pipe saturation temperature drop, the high-temperature suction pipe saturation temperature drop, the low-temperature suction pipe saturation temperature drop, the high-temperature cylinder volumetric efficiency of the compressor, and the low-temperature cylinder volumetric efficiency of the compressor.

[0020] Optionally, the determining unit, in cooling mode, determines the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device based on the operating parameters of the air conditioner, a preset throttling device flow correction coefficient, a preset compressor displacement, preset target control parameters, and pre-matched fitting parameters. This includes: a first heat exchanger flow determination unit, used to determine the target opening degree of the first heat exchanger flow path based on the temperature at the middle of the flow path, a preset high-temperature suction pipe saturation temperature drop, a preset target high-temperature suction superheat, a preset compressor high-temperature cylinder displacement, a preset compressor high-temperature cylinder volumetric efficiency, and... The current compressor frequency f determines the flow rate of the first indoor heat exchanger. The flow rate of the second indoor heat exchanger is determined based on the mid-flow temperature of the second indoor heat exchanger, the predetermined saturated temperature drop of the low-temperature suction pipe, the target low-temperature suction superheat, the preset compressor low-temperature cylinder displacement, the predetermined compressor low-temperature cylinder volumetric efficiency, and the current compressor frequency. A first refrigerant flow rate determination unit is used to determine the refrigerant flow rate through the third throttling device based on the refrigerant flow rate of the second indoor heat exchanger; and to determine the refrigerant flow rate through the second throttling device based on the refrigerant flow rate of the first indoor heat exchanger and the refrigerant flow rate through the third throttling device. Refrigerant flow rate; the refrigerant flow rate through the first throttling device is determined based on the refrigerant flow rate through the second throttling device and the flash dryness of the flasher; a first inlet / outlet pressure difference determination unit is used to determine the inlet / outlet pressure difference of the first throttling device based on the mid-flow temperature of the outdoor heat exchanger and the target flash temperature, to determine the inlet / outlet pressure difference of the second throttling device based on the target flash temperature, the mid-flow temperature of the indoor first heat exchanger and the saturation temperature drop of the high-temperature liquid pipe, and to determine the inlet / outlet pressure difference of the third throttling device based on the mid-flow temperature of the indoor first heat exchanger and the mid-flow temperature of the indoor second heat exchanger; a first inlet density determination unit is used to determine the inlet / outlet pressure difference of the third throttling device based on the outdoor heat exchanger... The outlet temperature determines the inlet density of the first throttling device; the target flash temperature determines the inlet density of the second throttling device; the temperature at the middle of the flow path of the first heat exchanger in the room determines the inlet density of the third throttling device; the first target opening calculation unit is used to calculate the target opening of the first throttling device, the target opening of the second throttling device, and the target opening of the third throttling device respectively based on the preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices.

[0021] Optionally, the first heat exchanger flow rate determination unit determines the flow rate of the indoor first heat exchanger based on the temperature at the middle of the flow path of the indoor first heat exchanger, a predetermined high-temperature suction pipe saturation temperature drop, a predetermined target high-temperature suction superheat, a predetermined compressor high-temperature cylinder displacement, a predetermined compressor high-temperature cylinder volumetric efficiency, and the current compressor frequency f. This includes: calculating the high-temperature suction saturation temperature based on the temperature at the middle of the flow path of the indoor first heat exchanger and the predetermined high-temperature suction pipe saturation temperature drop; determining the compressor high-temperature cylinder suction specific volume based on the calculated high-temperature suction saturation temperature and the target high-temperature suction superheat; and determining the compressor high-temperature cylinder suction specific volume based on the predetermined compressor high-temperature cylinder displacement, the predetermined compressor high-temperature cylinder volumetric efficiency, and the current compressor frequency f. The flow rate of the first heat exchanger in the room is determined by the specific volume of the high-temperature cylinder suction gas; and / or, the first heat exchanger flow rate determination unit determines the flow rate of the second heat exchanger in the room based on the mid-section temperature of the flow path of the second heat exchanger in the room, a predetermined saturation temperature drop of the low-temperature suction pipe, a target low-temperature suction superheat, a preset compressor low-temperature cylinder displacement, a predetermined compressor low-temperature cylinder volumetric efficiency, and the current compressor frequency, including: calculating the low-temperature suction saturation temperature based on the mid-section temperature of the flow path of the second heat exchanger in the room and the predetermined saturation temperature drop of the low-temperature suction pipe; determining the specific volume of the compressor low-temperature cylinder suction gas based on the calculated low-temperature suction saturation temperature and the target low-temperature suction superheat; and determining the specific volume of the compressor low-temperature cylinder suction gas based on the preset compressor low-temperature cylinder displacement, the predetermined compressor low-temperature cylinder volumetric efficiency, and the current compressor frequency. The compressor frequency f and the determined suction specific volume of the compressor's low-temperature cylinder are used to determine the flow rate of the second indoor heat exchanger; and / or, the first refrigerant flow rate determination unit determines the refrigerant flow rate through the third throttling device based on the refrigerant flow rate of the second indoor heat exchanger, including: the refrigerant flow rate through the third throttling device is equal to the refrigerant flow rate of the second indoor heat exchanger; the first refrigerant flow rate determination unit determines the refrigerant flow rate through the second throttling device based on the refrigerant flow rate of the first indoor heat exchanger and the refrigerant flow rate through the third throttling device, including: the refrigerant flow rate through the second throttling device is equal to the sum of the refrigerant flow rate of the first indoor heat exchanger and the refrigerant flow rate through the third throttling device; The first refrigerant flow rate determination unit determines the refrigerant flow rate through the first throttling device based on the refrigerant flow rate through the second throttling device and the flash dryness of the flash evaporator, including: the refrigerant flow rate through the first throttling device is equal to the ratio of the difference between the refrigerant flow rate of the second throttling device and the product of 1 minus the sum of the parallel cylinder pumping liquid carry-over rate and 1 and the flash dryness of the flash evaporator; and / or, the first inlet and outlet pressure difference determination unit determines the inlet and outlet pressure difference of the first throttling device based on the temperature at the middle of the outdoor heat exchanger flow path and the target flash temperature t, including: based on the temperature at the middle of the outdoor heat exchanger flow path and the target flash temperature, using a pre-set correlation formula to determine the inlet and outlet pressure difference of the first throttling device under a preset cooling mode;The first inlet / outlet pressure difference determination unit determines the inlet / outlet pressure difference of the second throttling device based on the target flash temperature, the temperature at the middle of the flow path of the first indoor heat exchanger, and the saturation temperature drop of the high-temperature liquid pipe. This includes: determining the inlet / outlet pressure difference of the second throttling device using a pre-set correlation formula fitted to the target flash temperature, the temperature at the middle of the flow path of the first indoor heat exchanger, and the saturation temperature drop of the high-temperature liquid pipe. The first inlet / outlet pressure difference determination unit also determines the inlet / outlet pressure difference of the third throttling device based on the temperatures at the middle of the flow paths of the first and second indoor heat exchangers. This includes: determining the inlet / outlet pressure difference of the third throttling device based on the temperatures at the middle of the flow paths of the first and second indoor heat exchangers, and using... The inlet and outlet pressure difference of the third throttling device is determined by fitting a correlation equation under a preset cooling mode; and / or, the first inlet density determination unit determines the inlet density of the first throttling device based on the outlet temperature of the outdoor heat exchanger, including: determining the inlet density of the first throttling device based on the outlet temperature of the outdoor heat exchanger using a fitting correlation equation under a preset cooling mode; the first inlet density determination unit determines the inlet density of the second throttling device based on the target flash temperature, including: determining the inlet density of the second throttling device based on the target flash temperature using a fitting correlation equation under a preset cooling mode; the first inlet density determination unit... The method for determining the inlet density of the third throttling device based on the midpoint temperature of the flow path of the first indoor heat exchanger includes: determining the inlet density of the third throttling device using a pre-set correlation formula for fitting the inlet density of the third throttling device under a preset cooling mode, based on the midpoint temperature of the flow path of the first indoor heat exchanger; and / or, the target opening determination unit, based on preset first, second, and third flow correction coefficients, refrigerant flow rates of the first, second, and third throttling devices, inlet and outlet pressure differences of the first, second, and third throttling devices, and inlet densities of the first, second, and third throttling devices, respectively calculates the target opening of the first throttling device, the target opening of the second throttling device, and the target opening of the third throttling device. The target opening degree includes: calculating the air flow rate of the first throttling device, the air flow rate of the second throttling device, and the air flow rate of the third throttling device based on preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet density of the first, second, and third throttling devices, respectively; and calculating the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device based on the air flow rates of the first, second, and third throttling devices, respectively.

[0022] Optionally, the determining unit, in heating mode, determines the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device based on the operating parameters of the air conditioner, a preset throttling device flow correction coefficient, a preset compressor displacement, preset target control parameters, and pre-matched fitting parameters. This includes: in heating mode, the opening degree of the third throttling device remains unchanged at an initially given fixed opening degree; and the target opening degree of the first throttling device and the target opening degree of the second throttling device are determined based on the operating parameters of the air conditioner, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and pre-matched fitting parameters. This includes: a second heat exchanger flow determination unit, used to determine the outdoor heat exchanger flow rate based on the high-temperature suction saturation temperature, the target high-temperature suction superheat, the preset compressor high-temperature cylinder displacement, the preset compressor high-temperature cylinder volumetric efficiency, the preset compressor low-temperature cylinder displacement, the preset compressor low-temperature cylinder volumetric efficiency, and the current compressor frequency; and a second cooling unit. The refrigerant flow rate determination unit is used to determine the refrigerant flow rate through the first throttling device based on the flow rate of the outdoor heat exchanger, and to determine the refrigerant flow rate through the second throttling device based on the refrigerant flow rate through the first throttling device and the flash dryness of the flash evaporator; the second inlet and outlet pressure difference determination unit is used to determine the inlet and outlet pressure difference of the first throttling device based on the mid-flow temperature of the outdoor heat exchanger and the target flash temperature, and to determine the inlet and outlet pressure difference of the second throttling device based on the target flash temperature, the mid-flow temperature of the indoor first heat exchanger, and the saturation temperature drop of the high-temperature liquid pipe; the second inlet density determination unit is used to determine the inlet density of the first throttling device based on the target flash temperature; and to determine the inlet density of the second throttling device based on the total inlet temperature of the indoor heat exchanger; the second target opening degree calculation unit is used to calculate the target opening degree of the first throttling device and the target opening degree of the second throttling device based on preset first and second flow rate correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices, respectively.

[0023] Optionally, the second heat exchanger flow rate determination unit determines the outdoor heat exchanger flow rate based on the high-temperature suction saturation temperature, the target high-temperature suction superheat, the preset compressor high-temperature cylinder displacement, the predetermined compressor high-temperature cylinder volumetric efficiency, the preset compressor low-temperature cylinder performance coefficient, and the current compressor frequency. This includes: determining the compressor high-temperature cylinder suction specific volume based on the high-temperature suction saturation temperature and the target high-temperature suction superheat; and determining the outdoor heat exchanger flow rate based on the preset compressor high-temperature cylinder displacement, the predetermined compressor high-temperature cylinder volumetric efficiency, the preset compressor low-temperature cylinder displacement, the predetermined compressor low-temperature cylinder volumetric efficiency, the current compressor frequency, and the compressor high-temperature cylinder suction specific volume. The refrigerant flow rate determination unit determines the refrigerant flow rate through the first throttling device based on the outdoor heat exchanger flow rate, including: the refrigerant flow rate through the first throttling device is equal to the outdoor heat exchanger flow rate; the second refrigerant flow rate determination unit determines the refrigerant flow rate through the second throttling device based on the refrigerant flow rate through the first throttling device and the flash dryness of the flash evaporator, including: the refrigerant flow rate through the second throttling device is equal to the ratio of the difference between the refrigerant flow rate of the first throttling device and the product of 1 minus the sum of the parallel cylinder pumping liquid carry-over rate and 1 and the flash dryness of the flash evaporator. The second inlet and outlet pressure difference determining unit determines the inlet and outlet pressure difference of the first throttling device based on the mid-flow temperature of the outdoor heat exchanger and the target flash temperature, including: determining the inlet and outlet pressure difference of the first throttling device using a pre-set correlation formula based on the mid-flow temperature of the outdoor heat exchanger and the target flash temperature; the second inlet and outlet pressure difference determining unit determines the inlet and outlet pressure difference of the second throttling device based on the target flash temperature, the mid-flow temperature of the indoor first heat exchanger and the saturation temperature drop of the high-temperature liquid pipe, including: determining the inlet and outlet pressure difference of the second throttling device using a pre-set correlation formula based on the mid-flow temperature of the outdoor heat exchanger and the target flash temperature, ... The inlet and outlet pressure difference of the second throttling device is determined by a fitting correlation formula under the heating mode; and / or, the second inlet density determination unit determines the inlet density of the first throttling device based on the target flash temperature, including: determining the inlet density of the first throttling device based on the target flash temperature using a preset fitting correlation formula under the heating mode; the second inlet density determination unit determines the inlet density of the second throttling device based on the total inlet temperature of the indoor heat exchanger, including: determining the inlet density of the second throttling device based on the total inlet temperature of the indoor heat exchanger using a preset fitting correlation formula under the heating mode;And / or, the second target opening determination unit calculates the target opening of the first throttling device and the target opening of the second throttling device based on preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices, respectively. This includes: calculating the air flow rate of the first throttling device and the air flow rate of the second throttling device based on preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices; and calculating the target opening of the first throttling device and the target opening of the second throttling device based on the air flow rates of the first and second throttling devices.

[0024] In another aspect, the present invention provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0025] In another aspect, the present invention provides an air conditioning system, including a processor, a memory, and a computer program stored in the memory that can run on the processor, wherein the processor executes the program to implement the steps of any of the methods described above.

[0026] In another aspect, the present invention provides an air conditioning system, including a control device for any of the aforementioned air conditioning systems.

[0027] According to the technical solution of this invention, for an air conditioning system with three throttling devices, the control of the three throttling devices is decoupled to improve system operating energy efficiency. The opening degree of all electronic expansion valves in the system is precisely calculated and adjusted. Since each sensor in the system is affected by the opening degree of each electronic expansion valve, this method prevents situations where a change in the opening degree of one electronic expansion valve causes changes in all sensors, requiring multiple feedback judgments, repeated adjustments to the electronic expansion valve opening, over-adjustment of the opening degrees of other electronic expansion valves, or large fluctuations in the opening degree control of the electronic expansion valves. This results in a longer time and slower speed for the compressor to reach a stable operating state after startup. Precise and rapid control of the system's status detection ensures that the air conditioning system is in an optimal state, achieving optimal energy saving and improving the accuracy of electronic expansion valve control.

[0028] During the operation of a dual-temperature system, there are multiple detection and control issues. When the coupling of various detections affects the performance of the air conditioning system, the technical solution of this invention processes the detections in association, which can reduce the complexity of system control. The electronic expansion valve opening is correlated and fitted with the system flow rate, thereby directly calculating the electronic expansion valve opening under the target parameters, accurately adjusting the flash temperature and multiple suction superheats, and reducing the system feedback calculation time. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 This is a schematic diagram of an embodiment of the control method for an air conditioning system provided by the present invention;

[0031] Figure 2 A schematic diagram of an air conditioning system according to the present invention is shown;

[0032] Figure 3 A control flowchart of a specific embodiment of the power-on phase according to the present invention is shown;

[0033] Figure 4 A flowchart illustrating a specific embodiment of the steps for determining the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device under the cooling mode of the present invention is shown.

[0034] Figure 5 A flowchart illustrating a specific embodiment of the steps for determining the flow rate of the first indoor heat exchanger under the refrigeration mode of the present invention is shown. The steps are: the temperature at the middle of the flow path of the first indoor heat exchanger, the pre-determined saturated temperature drop of the high-temperature suction pipe, the preset target high-temperature suction superheat, the preset high-temperature cylinder displacement of the compressor, the pre-determined volumetric efficiency of the high-temperature cylinder of the compressor, and the current compressor frequency.

[0035] Figure 6 A flowchart illustrating a specific embodiment of the steps for determining the flow rate of the indoor second heat exchanger under the refrigeration mode of the present invention is shown. The steps are: temperature at the middle of the flow path of the indoor second heat exchanger, a predetermined saturation temperature drop of the low-temperature suction line, target low-temperature suction superheat, preset compressor low-temperature cylinder displacement, predetermined compressor low-temperature cylinder volumetric efficiency, and current compressor frequency.

[0036] Figure 7 A flowchart illustrating the steps for calculating the target opening of the first throttling device, the target opening of the second throttling device, and the target opening of the third throttling device is shown.

[0037] Figure 8 A flowchart illustrating a specific embodiment of the steps for determining the target opening degree of the first throttling device and the target opening degree of the second throttling device under the heating mode of the present invention is shown.

[0038] Figure 9A flowchart illustrating a specific implementation of the steps for determining the flow rate of an outdoor heat exchanger based on the high-temperature suction saturation temperature, the target high-temperature suction superheat, the preset high-temperature cylinder displacement of the compressor, the predetermined high-temperature cylinder volumetric efficiency of the compressor, the preset low-temperature cylinder displacement of the compressor, the predetermined low-temperature cylinder volumetric efficiency of the compressor, and the current compressor frequency.

[0039] Figure 10 A flowchart illustrating the steps for calculating the target opening of the first throttling device and the target opening of the second throttling device is shown.

[0040] Figure 11 This is a schematic diagram of the throttling device control process in a cooling mode according to a specific embodiment of the present invention;

[0041] Figure 12 A flowchart illustrating the calculation of the opening degree of the throttling device (electronic expansion valve) under the refrigeration mode according to the present invention is shown;

[0042] Figure 13 This is a schematic diagram of the throttling device control process in heating mode according to a specific embodiment of the present invention.

[0043] Figure 14 A flowchart illustrating the calculation of the opening degree of the throttling device (electronic expansion valve) under the heating mode according to the present invention is shown;

[0044] Figure 15 This is a structural block diagram of an embodiment of the control device for an air conditioning system provided by the present invention;

[0045] Figure 16 A structural block diagram of a specific embodiment of the determining unit according to the present invention is shown;

[0046] Figure 17 A structural block diagram of another specific embodiment of the determining unit according to the present invention is shown;

[0047] The reference numerals in the attached figures are as follows:

[0048] 1 is the compressor, 2 is the outdoor heat exchanger, 3a is the first electronic expansion valve, 3b is the second electronic expansion valve, 3c is the third electronic expansion valve, 4 is the flash evaporator, 5a is the first high-temperature heat exchanger, 5b is the second low-temperature heat exchanger, 6a is the first four-way reversing valve, 6b is the second four-way reversing valve, 7 is the temperature sampling point in the system, and 7a is the temperature t in the middle of the flow path of the first indoor heat exchanger. e_h 7b represents the temperature t in the middle of the flow path of the second indoor heat exchanger. e_l 7c is the high-temperature intake temperature t_ suc_h 7d is the low-temperature intake temperature t_ suc_l7e is the exhaust temperature t_dis, 7f is the temperature at the middle of the flow path of the outdoor heat exchanger t_c, 7g is the outlet temperature of the outdoor heat exchanger t_c_o, and 7h is the flash temperature t_ ft 7i represents the total inlet temperature t_e_in of the indoor heat exchanger. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0050] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0051] The related technology features a high-efficiency air conditioning system with dual evaporation temperatures and parallel suction enthalpy enhancement. In cooling, this system achieves cascaded heat exchange at dual evaporation temperatures, improving system energy efficiency. Parallel suction compression reduces the evaporator inlet specific enthalpy, increasing the cooling capacity per unit mass and further enhancing system energy efficiency. During cooling operation, this system must control the outlet superheat of the high and low temperature evaporators or the corresponding compressor suction superheat, as well as the flash evaporator temperature or pressure, to achieve optimal operating conditions. During heating operation, it needs to simultaneously control the flash evaporator temperature and the compressor discharge superheat to achieve optimal operating conditions and compressor reliability. The strong coupling of the three electronic expansion valves in the air conditioning system makes operation and control complex and challenging.

[0052] This invention provides a control method for an air conditioning system, wherein the air conditioning system can specifically be an air conditioning system with dual evaporation temperatures and parallel extraction enthalpy enhancement.

[0053] Figure 2 A schematic diagram of an air conditioning system according to the present invention is shown. Figure 2As shown, the air conditioning system includes: a compressor 1, an outdoor heat exchanger 2, a first throttling device 3a, a second throttling device 3b, a third throttling device 3c, a flash evaporator 4, an indoor first heat exchanger 5a, an indoor second heat exchanger 5b, a first four-way reversing valve 6a, and a second four-way reversing valve 6b. The first throttling device 3a, the second throttling device 3b, and the third throttling device 3c can specifically be electronic expansion valves. The indoor first heat exchanger 5a is a high-temperature heat exchanger, also referred to as the first high-temperature heat exchanger 5a, and the indoor second heat exchanger 5b is a low-temperature heat exchanger, also referred to as the second low-temperature heat exchanger 5b.

[0054] The indoor first heat exchanger 5a is connected to the outdoor heat exchanger 2 via the second throttling device 3b, the flash evaporator 4, and the first throttling device 3a in sequence. The indoor second heat exchanger 5b is connected to the outdoor heat exchanger 2 via the third throttling device 3c, the second throttling device 3b, the flash evaporator 4, and the first throttling device 3a in sequence. The inlet end of the flash evaporator 4 is connected to the outdoor heat exchanger 2. The first throttling device 3a is installed on the pipeline between the flash evaporator 4 and the outdoor heat exchanger 2. The gas outlet end of the flash evaporator 4 is connected to the third suction port of the compressor. The indoor first heat exchanger 5a and the indoor second heat exchanger 5b are connected in parallel and then connected to the outlet end of the flash evaporator 4 via the second throttling device 3b. The third throttling device 3c is installed on the pipeline connecting the indoor second heat exchanger 5b and the indoor first heat exchanger 5a in parallel.

[0055] The first four-way reversing valve 6a has its D-pipe connected to the compressor's discharge port, its C-pipe connected to the outdoor heat exchanger 2, its S-pipe connected to the compressor's first suction port, and its E-pipe connected to the indoor first heat exchanger 5a. The second four-way reversing valve 6b has its D-pipe connected to the compressor's discharge port, its C-pipe connected to the outdoor heat exchanger 2, its S-pipe connected to the compressor's second suction port, and its E-pipe connected to the indoor second heat exchanger 5a.

[0056] In cooling mode, the indoor first heat exchanger 5a is connected to the outdoor heat exchanger 2 sequentially via the second throttling device 3b, the flash evaporator 4, and the first throttling device 3a. The indoor second heat exchanger 5b is connected to the outdoor heat exchanger 2 sequentially via the third throttling device 3c, the second throttling device 3b, the flash evaporator 4, and the first throttling device 3a. The indoor first heat exchanger 5a is connected to the first suction port of the compressor 1 via the E and S pipes of the first four-way reversing valve 6a. The indoor second heat exchanger 5b is connected to the second suction port of the compressor 1 via the E and S pipes of the second four-way reversing valve 6b. The outdoor heat exchanger 2 is connected to the exhaust port of the compressor 1 via the C and D pipes of the first four-way reversing valve 6a. The outdoor heat exchanger 2 is connected to the exhaust port of the compressor 1 via the C and D pipes of the second four-way reversing valve 6b.

[0057] In heating mode, the indoor first heat exchanger 5a is connected to the outdoor heat exchanger 2 via the second throttling device 3b, the flash evaporator 4, and the first throttling device 3a in sequence. The indoor second heat exchanger 5b is connected to the outdoor heat exchanger 2 via the third throttling device 3c, the second throttling device 3b, the flash evaporator 4, and the first throttling device 3a in sequence.

[0058] The outdoor heat exchanger 2 is connected to the first suction port of the compressor 1 via the C and S pipes of the first four-way reversing valve 6a, and to the second suction port of the compressor 1 via the C and S pipes of the second four-way reversing valve 6b. The indoor first heat exchanger 5a is connected to the exhaust port of the compressor 1 via the E and D pipes of the first four-way reversing valve 6a, and the indoor second heat exchanger 5b is connected to the exhaust port of the compressor 1 via the E and D pipes of the second four-way reversing valve 6b.

[0059] The indoor first heat exchanger 5a is equipped with a device to collect the temperature t at the middle of the flow path of the indoor first heat exchanger. e_h Sampling point 7a, and the indoor second heat exchanger 5b are equipped with a temperature collection device for the middle part of the flow path of the indoor second heat exchanger, t. e_l Sampling point 7b, the first suction pipe of compressor 1 is equipped with a device for collecting high-temperature suction temperature t_ suc_h Sampling point 7c, the second suction pipe of compressor 1 is equipped with a device for collecting low-temperature suction temperature t_ suc_l Sampling point 7d; sampling point 7e is set on the exhaust pipe of compressor 1 to collect the exhaust temperature t_dis; sampling point 7f is the temperature t_c in the middle of the flow path of the outdoor heat exchanger; sampling point 7g is set at the outlet of outdoor heat exchanger 2 to collect the outlet temperature t_c_o; and sampling point 7g is set at the outlet end of flash evaporator 4 to collect the flash temperature t_ ftThe sampling point 7h is provided on the pipeline connecting the indoor first heat exchanger 5a and the indoor second heat exchanger 5b in parallel with the second throttling device to collect the total inlet temperature t_e_in of the indoor heat exchanger.

[0060] Figure 1 This is a schematic diagram of an embodiment of the control method for an air conditioning system provided by the present invention.

[0061] like Figure 1 As shown, according to an embodiment of the present invention, the control method of the air conditioning system includes at least steps S130, S140, and S150. Preferably, the control method further includes steps S110 and S120.

[0062] Step S110: After the air conditioning system is turned on, determine the compressor frequency, outdoor fan speed and / or indoor fan speed of the air conditioning system according to the outdoor ambient temperature, indoor ambient temperature and indoor set temperature, and determine the initial opening degree of the first throttling device, the second throttling device and the third throttling device according to the current operating mode of the air conditioning system.

[0063] Step S120: Control the operation of the air conditioning system according to the determined compressor frequency of the air conditioning system, the speed of the outdoor fan and / or the speed of the indoor fan, and the determined initial opening degree of the first throttling device 3a, the second throttling device 3b and the third throttling device.

[0064] Specifically, if the air conditioner is currently operating in heating mode, a fixed opening degree is given to the third throttling device 3c as the initial opening degree, and the third throttling device 3c maintains this fixed opening degree during heating. The initial opening degrees of the first throttling device 3a and the second throttling device 3b are determined based on the compressor frequency, indoor ambient temperature, and outdoor ambient temperature. The initial opening degrees of the first throttling device 3a and the second throttling device 3b corresponding to different compressor frequencies, indoor ambient temperatures, and outdoor ambient temperatures can be determined in advance through experiments. If the air conditioner is currently operating in non-heating mode, the initial opening degrees of the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c are determined based on the compressor frequency, indoor ambient temperature, and outdoor ambient temperature. The initial opening degrees of the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c corresponding to different compressor frequencies, indoor ambient temperatures, and outdoor ambient temperatures can be determined in advance through experiments.

[0065] The first throttling device 3a, the second throttling device 3b, and the third throttling device 3c can specifically be electronic expansion valves. Figure 3 A control flowchart for the startup phase according to the present invention is shown. Figure 3The first throttling device 3a is the first electronic expansion valve EEV1, the second throttling device 3b is the second electronic expansion valve EEV2, and the third throttling device 3c is the third electronic expansion valve EEV3. For example... Figure 3 As shown, upon receiving a power-on signal, the first electronic expansion valve EEV1, the second electronic expansion valve EEV2, and the third electronic expansion valve EEV3 are reset. The signal is then analyzed to determine the current operating mode of the air conditioner. When the heating mode is activated, the third electronic expansion valve EEV3 is given a fixed opening, and the third electronic expansion valve EEV2 maintains a fixed opening during heating operation. Subsequently, the indoor and outdoor ambient temperatures are detected, and the initial openings of the first electronic expansion valve EEV1 and the second electronic expansion valve EEV2 are determined accordingly. When the non-heating mode is activated, the indoor and outdoor ambient temperatures are detected, and the initial openings of the first electronic expansion valve EEV1, the second electronic expansion valve EEV2, and the third electronic expansion valve EEV3 are determined accordingly.

[0066] When the air conditioner receives the start command, the compressor frequency, outdoor fan speed and / or indoor fan speed operate according to the preset values ​​of the indoor and outdoor ambient temperatures detected by the temperature sensors and the user-set temperature. The opening degree of the outdoor electronic expansion valve (first electronic expansion valve and second electronic expansion valve) and the indoor electronic expansion valve (third electronic expansion valve) is calculated based on the temperature detected by the temperature sensors.

[0067] Figure 3 A control flowchart of a specific embodiment of the power-on phase according to the present invention is shown. Figure 3 As shown, upon receiving the power-on signal, the first electronic expansion valve EEV1, the second electronic expansion valve EEV2, and the third electronic expansion valve EEV3 are reset and the signal is judged. When the user turns on the heating mode, the third electronic expansion valve EEV3 is given a fixed opening (the third electronic expansion valve EEV3 maintains this fixed opening during heating operation). Then, the indoor and outdoor ambient temperatures are detected, and the initial openings of the first electronic expansion valve EEV1 and the second electronic expansion valve EEV2 are given. When the user turns on the non-heating mode, the indoor and outdoor ambient temperatures are detected, and the initial openings of the first electronic expansion valve EEV1, the second electronic expansion valve EEV2, and the third electronic expansion valve EEV3 are given.

[0068] Step S130: Determine whether the air conditioning system is currently in the target operating state.

[0069] Specifically, the high-temperature suction superheat sh of the compressor in the air conditioning system is determined. suc_h Low temperature intake superheat sh suc_l and / or target flash temperature t ft_target According to the aforementioned high-temperature intake superheat sh suc_h The low-temperature intake superheat sh suc_lAnd / or the target flash temperature t ft_target Determine whether the air conditioning system is currently in the target operating state.

[0070] More specifically, in cooling mode, the high-temperature suction superheat sh of the compressor of the air conditioning system is calculated. suc_h and temperature of intake superheat sh suc_l And calculate the target flash temperature t ft_target According to the aforementioned high-temperature intake superheat sh suc_h The low-temperature intake superheat sh suc_l and the target flash temperature t ft_target Determine whether the air conditioning system is currently in the target operating state, wherein the superheat sh suc_h (l) = intake temperature t suc_h (l) - Intake saturation temperature t suc_h(l)_sat That is, the high-temperature intake superheat sh suc_h =High-temperature intake temperature t suc_h -High-temperature intake saturation temperature t suc_h_sat Low temperature intake superheat sh suc_l =Low-temperature intake temperature t suc_l -Low-temperature intake saturation temperature t suc_l_sat .

[0071] Determine the high-temperature intake superheat sh suc_h Whether the low-temperature intake superheat sh is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b. suc_l Whether it is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b, and the current flash temperature t. ft With the target flash temperature t ft_target The absolute value of the temperature difference |t ft -t ft_target |Whether it is within the preset temperature difference range (specifically, a temperature difference range of 0℃ to C), if the high-temperature intake superheat sh is determined suc_h The low-temperature intake superheat sh is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b. suc_l The current flash temperature t is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b. ft With the target flash temperature t ft_target The absolute value of the temperature difference |t ft -t ft_target If the temperature difference is within a preset range (specifically, a temperature difference range of 0℃ to °C), the air conditioning system is determined to be in the target operating state. That is, when the compressor's high-temperature suction superheat a ≤ sh suc_h ≤b, Low-temperature intake superheat a≤sh suc_l ≤b, and flash temperature tft Differing from the target flash temperature t ft_target by (the absolute value of the temperature difference |t ft -t ft_target |) within the range of 0 to c, it is determined that the air-conditioning system is in the target operating state. a < b, the value range of a can be 1°C to 5°C, the preferred value is 3°C, the value range of b can be 2°C to 6°C, the preferred value is 4°C, 0°C < c < 3°C, and the preferred value is 1°C.

[0072] If it is determined that the high-temperature suction superheat sh suc_h is less than the first preset threshold a, or greater than the second preset threshold b, or the low-temperature suction superheat sh suc_l is less than the first preset threshold a, or greater than the second preset threshold b, and the current flash temperature t ft differs from the target flash temperature t ft_target by an absolute value of the temperature difference |t ft -t ft_target | not within the preset temperature difference range, it is determined that the air-conditioning system is not in the target operating state; that is, when the high-temperature suction superheat sh of the compressor suc_h < a, or sh suc_h > b, or the low-temperature suction superheat sh suc_l < a, or sh suc_l > b, or the flash temperature t ft differs from the target flash temperature t ft_target by an absolute value of the difference |t ft -t ft_target | > c, it is determined that the air-conditioning system is not in the target operating state.

[0073] In the heating mode, calculate the high-temperature suction superheat sh of the compressor of the air-conditioning system suc_h or the low-temperature suction superheat sh suc_l , and calculate the target flash temperature t ft_target , and determine whether the air-conditioning system is currently in the target operating state according to the high-temperature suction superheat sh suc_h or the low-temperature suction superheat sh suc_l , and according to the target flash temperature t ft_target , where the superheat sh suc_h (l) = suction temperature t suc_h (l) - suction saturation temperature t suc_h(l)_sat ; that is, the high-temperature suction superheat sh suc_h = high-temperature suction temperature t suc_h - high-temperature suction saturation temperature t suc_h_sat , the low-temperature suction superheat sh suc_l = low-temperature suction temperature t suc_l - low-temperature suction saturation temperature tsuc_l_sat . In the heating mode, it is a single-temperature system, and the high-temperature suction superheat sh suc_h is the same as the low-temperature suction superheat. Therefore, in the above conditions, only one of them needs to be calculated.

[0074] Judge whether the high-temperature suction superheat sh suc_h or the low-temperature suction superheat sh suc_l is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b, and the absolute value of the temperature difference between the current flashing temperature t ft and the target flashing temperature t ft_target , |t ft -t ft_target | is within the preset temperature difference range (specifically, the temperature difference range of 0°C to c). If it is judged that the high-temperature suction superheat sh suc_h or the low-temperature suction superheat sh suc_l is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b, and the absolute value of the temperature difference between the current flashing temperature t ft and the target flashing temperature t ft_target , |t ft -t ft_target | is within the preset temperature difference range, then it is judged that the air-conditioning system is in the target operating state. That is, when the high-temperature suction superheat sh of the compressor suc_h or the low-temperature suction superheat sh suc_l satisfies a ≤ sh suc_h [[ID=३६]](sh suc_l ) ≤ b, and the flashing temperature t ft differs from the target flashing temperature t ft_target by (the absolute value of the temperature difference |t ft -t ft_target |) within the range of 0 to c, it is determined that the air-conditioning system is in the target operating state. a < b, and the value range of a or b can be 1°C to 3°C, with a preferred value of 2°C, 0°C < c < 3°C, and a preferred value of 1°C. <00DONG1392>... If it is judged that the high-temperature suction superheat sh suc_h or the low-temperature suction superheat sh suc_l is less than the first preset threshold a, or the high-temperature suction superheat sh suc_h or the low-temperature suction superheat sh suc_l is greater than the second preset threshold b, or the absolute value of the temperature difference between the current flashing temperature t ft and the target flashing temperature t ft_target , |t ft -t ft_target | is not within the preset temperature difference range, it is judged that the air-conditioning system is not in the target operating state; that is, when the high-temperature suction superheat sh of the compressorsuc_h Or low temperature intake superheat sh suc_l Satisfy sh suc_h (sh suc_l ) < a, or sh suc_h (sh suc_l )>b, or flash temperature t ft With the target flash temperature t ft_target Phase difference (absolute value of temperature difference |t) ft -t ft_target When |)>c, it is determined that the air conditioning system is not in the target operating state.

[0076] Step S140: If it is determined that the air conditioning system is not currently in the target operating state, then the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device are determined based on the detected operating parameters of the air conditioner, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and the predetermined fitting parameters.

[0077] Specifically, if it is determined that the air conditioning system is currently in the target operating state, the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c maintain their current opening degrees. If it is determined that the air conditioning system is not currently in the target operating state, the target opening degrees of the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c are determined based on the air conditioning operating parameters, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and the pre-determined fitting parameters.

[0078] The calculation of the throttling device opening degree in this invention requires the use of detected values, preset values, and fitted values. The detected values ​​are the detected operating parameters of the air conditioner, which may specifically include: the temperature t in the middle of the flow path of the first indoor heat exchanger. e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l High-temperature intake temperature t suc_h Low-temperature intake temperature t suc_l outdoor heat exchanger flow path midpoint temperature tc, outdoor heat exchanger outlet temperature tc_o, flash temperature t ftThe total inlet temperature of the indoor heat exchanger is te_in; the preset values ​​may specifically include: preset throttling device flow correction coefficients, preset compressor displacement, and preset target control parameters. The preset throttling device flow correction coefficients include the first flow correction coefficient kc1 of the first throttling device 3a, the second flow correction coefficient kc2 of the second throttling device 3b, and the third flow correction coefficient kc3 of the third throttling device 3c. For example, if the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c are all electronic expansion valves, i.e., a first electronic expansion valve, a second electronic expansion valve, and a third electronic expansion valve, then the preset throttling device flow correction coefficients include the first electronic expansion valve flow correction coefficient kc1, the second electronic expansion valve flow correction coefficient kc2, and the third electronic expansion valve flow correction coefficient kc3. The preset compressor displacement may specifically include the compressor high-temperature cylinder displacement Vrev_h and the compressor low-temperature cylinder displacement Vrev_l. The high-temperature cylinder refers to the cylinder corresponding to the compressor suction port connected to the first heat exchanger in the room, and the low-temperature cylinder refers to the cylinder corresponding to the compressor suction port connected to the second heat exchanger in the room. The preset target control parameters may specifically include the target high-temperature suction superheat sh. suc_h_target Target low-temperature intake superheat sh suc_l_target .

[0079] The parameters that need to be fitted during prototype matching include: the saturation temperature drop dt of the high-temperature liquid pipe. sat_ll High-temperature intake pipe saturation temperature drop dt sat_suc_h Low-temperature intake pipe saturation temperature drop dt sat_suc_l The volumetric efficiency of the compressor's high-temperature cylinder is y_h, and the volumetric efficiency of the compressor's low-temperature cylinder is y_l. The opening degrees of the first, second, and third throttling devices (e.g., electronic expansion valves) are Pulse1 = f(Va_o_1), Pulse2 = f(Va_o_2), and Pulse3 = f(Va_o_3). The saturated temperature drop dt of the high-temperature liquid line is also considered. sat_ll = a*f*f+b*f+c.

[0080] In cooling mode, the first throttling device (e.g., an electronic expansion valve) controls the flow with the flash temperature as the target. The target flash temperature can be calculated using a fitted correlation, i.e., t ft_target =f(tc_o,t suc_h_sat ,t suc_l_sat ,f),t ft_target =(0.5*tc_o+0.25*t) suc_h_sat +0.25*t suc_l_sat +a*f+c), where a and c are fitting coefficients, and t is the high-temperature evaporation temperature (high-temperature absorption saturation temperature). suc_h_sat =Temperature t in the middle of the flow path of the first heat exchanger in the room e_h-Saturation temperature drop dt of high-temperature intake line sat_suc_h High-temperature intake pipe saturation temperature drop dt sat_suc_h =f(f); Low-temperature evaporation temperature (low-temperature absorption saturation temperature) t suc_l_sat =Temperature t in the middle of the flow path of the second heat exchanger in the room e_l - Saturation temperature drop dt of low-temperature intake line sat_suc_l Low-temperature intake pipe saturation temperature drop dt sat_suc_l =f(f); f(f) is obtained by fitting experimental data. The outdoor heat exchanger outlet temperature tc_o and the indoor first heat exchanger flow path midpoint temperature t e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l The temperature is detected by a temperature sensing bulb. In cooling mode, the second throttling device (e.g., an electronic expansion valve) and the third throttling device (e.g., an electronic expansion valve) control the high-temperature suction superheat and low-temperature suction superheat as targets, with the target high-temperature suction superheat sh... suc_h_target Target low-temperature intake superheat sh suc_l_target The value is given based on the experimental conditions, and is generally taken as 1 to 6℃.

[0081] Figure 4 The diagram illustrates a specific embodiment of the steps for determining the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device under the cooling mode of the present invention.

[0082] like Figure 4 As shown, in one specific embodiment, in cooling mode, the step of determining the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device according to the operating parameters of the air conditioner, the preset flow correction coefficient of the throttling device, the preset compressor displacement, the preset target control parameters, and the pre-matched fitting parameters includes the following steps S141 to S145.

[0083] Step S141: Determine the flow rate of the first heat exchanger in the room based on the temperature at the middle of the flow path of the first heat exchanger in the room, the predetermined saturation temperature drop of the high-temperature suction pipe, the predetermined target high-temperature suction superheat, the predetermined high-temperature cylinder displacement of the compressor, the predetermined volumetric efficiency of the high-temperature cylinder of the compressor, and the current compressor frequency. Determine the flow rate of the second heat exchanger in the room based on the temperature at the middle of the flow path of the second heat exchanger in the room, the predetermined saturation temperature drop of the low-temperature suction pipe, the target low-temperature suction superheat, the predetermined low-temperature cylinder displacement of the compressor, the predetermined volumetric efficiency of the low-temperature cylinder of the compressor, and the current compressor frequency.

[0084] Figure 5The diagram illustrates a specific embodiment of the steps for determining the flow rate of the first indoor heat exchanger under the cooling mode of the present invention, based on a pre-determined high-temperature suction pipe saturation temperature drop at the midpoint of the flow path of the first indoor heat exchanger, a pre-set target high-temperature suction superheat, a pre-set compressor high-temperature cylinder displacement, a pre-determined compressor high-temperature cylinder volumetric efficiency, and the current compressor frequency.

[0085] like Figure 5 As shown, step S141 includes steps S1411 to S1413.

[0086] Step S1411, based on the temperature t at the middle of the flow path of the first heat exchanger in the room e_h The predetermined saturation temperature drop dt of the high-temperature intake pipeline sat_suc_h Calculate the high-temperature intake saturation temperature t suc_h_sat .

[0087] Wherein, the high-temperature intake saturation temperature t suc_h_sat The temperature t in the middle of the flow path of the first heat exchanger in the room is equal to the temperature of the middle of the flow path. e_h The saturation temperature drop dt of the high-temperature intake pipeline sat_suc_h The difference; the saturation temperature drop dt of the high-temperature intake pipeline. sat_suc_h Related to the compressor frequency f, for example, it can be: dt sat_suc_h = a*f*f+b*f+c, where a, b and c are fitting coefficients. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlation formulas.

[0088] Step S1412, based on the calculated high-temperature intake saturation temperature t suc_h_sat and the preset target high-temperature intake superheat sh suc_h_target Determine the suction specific volume v of the high-temperature cylinder of the compressor suc_h .

[0089] Among them, the suction specific volume v of the high-temperature cylinder of the compressor suc_h With high-temperature intake saturation temperature t suc_h_sat and target high-temperature intake superheat sh suc_h_target Related, v suc_h =f(t) suc_h_sat sh suc_h_target For example, it could be: v suc_h ==(g+h*t) suc_h_sat +a*sh suc_h_target )*(b*t suc_h_sat *t suc_h_sat +c*t suc_h_sat +d), where a, b, c, d, g, and h are fitting coefficients related to refrigerant properties. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations; target high-temperature suction superheat shsuc_h_target The compressor high-temperature cylinder displacement Vrev_h is a preset value; the compressor high-temperature cylinder volumetric efficiency y_h is related to the outdoor heat exchanger flow path midpoint temperature tc and the indoor first heat exchanger flow path midpoint temperature t e_h Related to the compressor frequency f, y_h=a*tc+b*t e_h +c*f+d, where a, b, c and d are fitting coefficients. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations.

[0090] Step S1413: Based on the preset compressor high-temperature cylinder displacement Vrev_h, the predetermined compressor high-temperature cylinder volumetric efficiency y_h, and the current compressor frequency f, and the determined compressor high-temperature cylinder suction specific volume v... suc_h Determine the flow rate M of the first heat exchanger in the room. e_h .

[0091] Wherein, the flow rate M of the first indoor heat exchanger e_h The product of the preset compressor high-temperature cylinder displacement Vrev_h, the predetermined compressor high-temperature cylinder volumetric efficiency y_h, the current compressor frequency f, and the compressor high-temperature cylinder suction specific volume v is equal to the product of the preset compressor high-temperature cylinder displacement Vrev_h, the preset compressor high-temperature cylinder volumetric efficiency y_h, the current compressor frequency f, and the current compressor high-temperature cylinder suction specific volume v. suc_h The ratio; that is, M e_h =Vrev_h*y_h*f / v suc_h .

[0092] Figure 6 The diagram illustrates a specific embodiment of the steps for determining the flow rate of the indoor second heat exchanger under the refrigeration mode of the present invention, based on the temperature at the middle of the flow path of the indoor second heat exchanger, a predetermined saturation temperature drop of the low-temperature suction line, a target low-temperature suction superheat, a preset compressor low-temperature cylinder displacement, a predetermined compressor low-temperature cylinder volumetric efficiency, and the current compressor frequency.

[0093] like Figure 6 As shown, step S141 includes steps S1414 to S1416.

[0094] Step S1414, based on the temperature t in the middle of the flow path of the second indoor heat exchanger. e_l Compared with the predetermined saturation temperature drop dt of the cryogenic intake line sat_suc_l Calculate the low-temperature intake saturation temperature t suc_l_sat .

[0095] Among them, the low-temperature intake saturation temperature t suc_l_sat Equal to the temperature t in the middle of the flow path of the second heat exchanger in the room e_l With low temperature intake line saturation temperature drop dt sat_suc_l The difference; saturation temperature drop dt of the low-temperature intake line sat_suc_l Related to the compressor frequency f, for example, it can be: dtsat_suc_l = a*f*f+b*f+c, where a, b and c are fitting coefficients. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlation formulas.

[0096] Step S1415, based on the calculated low-temperature intake saturation temperature t suc_l_sat and target low temperature intake superheat sh suc_l_target Determine the specific volume v of the compressor's cryogenic cylinder intake. suc_l .

[0097] Among them, the specific volume v of the compressor's cryogenic cylinder intake suc_l With low-temperature intake saturation temperature t suc_l_sat and target low-temperature intake superheat sh suc_l_target Related, that is, v suc_l =f(t) suc_l_sat sh suc_l_target For example, v suc_l =(g+h*t) suc_l_sat +a*sh suc_l_target )*(b*t suc_l_sat *t suc_l_sat +c*t suc_l_sat +d), where a, b, c, d, g, and h are fitting coefficients related to refrigerant properties. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations; target low-temperature suction superheat sh suc_l_target This is the preset value. Target low-temperature intake superheat sh suc_l_target The compressor's cryogenic cylinder displacement Vrev_l is a preset value; the compressor's cryogenic cylinder volumetric efficiency y_l is related to the outdoor heat exchanger's mid-flow path temperature tc and the indoor second heat exchanger's mid-flow path temperature t e_l Related to the compressor frequency f, y_l=a*tc+b*t e_l +c*f+d, where a, b, c and d are fitting coefficients. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations.

[0098] Step S1416: Based on the preset compressor cryogenic cylinder displacement Vrev_l, the predetermined compressor cryogenic cylinder volumetric efficiency y_l, and the current compressor frequency f, and the determined compressor cryogenic cylinder suction specific volume v... suc_l Determine the flow rate M of the second heat exchanger in the room. e_l .

[0099] Wherein, the flow rate M of the second indoor heat exchanger e_l The product of the preset compressor cryogenic cylinder displacement Vrev_l, the predetermined compressor cryogenic cylinder volumetric efficiency y_l, multiplied by the current compressor frequency f, and the compressor cryogenic cylinder suction specific volume v is equal to the product of the preset compressor cryogenic cylinder displacement Vrev_l, the preset compressor cryogenic cylinder volumetric efficiency y_l, the current compressor frequency f, and the current compressor frequency f. suc_l The ratio; that is, Me_l =Vrev_l*y_l*f / v suc_l .

[0100] Step S142: Determine the refrigerant flow rate through the third throttling device based on the refrigerant flow rate of the second indoor heat exchanger; determine the refrigerant flow rate through the second throttling device based on the refrigerant flow rate of the first indoor heat exchanger and the refrigerant flow rate through the third throttling device; determine the refrigerant flow rate through the second throttling device based on the refrigerant flow rate through the second throttling device and the flash dryness x of the flash evaporator. ft Determine the refrigerant flow rate through the first throttling device.

[0101] Specifically, based on the refrigerant flow rate M of the second indoor heat exchanger e_l Determine the refrigerant flow rate M through the third throttling device. r_3 The refrigerant flow rate M flowing through the third throttling device r_3 Equal to the refrigerant flow rate M of the second indoor heat exchanger e_l That is, M r_3 =M e_l According to the refrigerant flow rate M of the first indoor heat exchanger. e_h The refrigerant flow rate M flowing through the third throttling device r_3 Determine the refrigerant flow rate M through the second throttling device. r_2 The refrigerant flow rate M flowing through the second throttling device is... r_2 Equal to the refrigerant flow rate M of the first indoor heat exchanger e_h The refrigerant flow rate M flowing through the third throttling device r_3 The sum; that is, M r_2 =M r_3 +M e_h =Vrev_l*y_l*f / v suc_l +Vrev_h*y_h*f / v suc_h According to the refrigerant flow rate M flowing through the second throttling device r_2 Flash dryness of flash generator x ft Determine the refrigerant flow rate M through the first throttling device. r_1 Wherein, the refrigerant flow rate M flowing through the first throttling device r_1 Equal to the refrigerant flow rate M of the second throttling device r_2 The ratio of 1 to the product of the sum of the parallel cylinder pumping liquid carry-over rate and 1, and the flash dryness of the flash evaporator; that is, the refrigerant flow rate M through the first throttling device. r_1 =M r_2 / (1-(1+E)x ft ).

[0102] Where E is the parallel cylinder pumping liquid carry-over rate (the ratio of liquid mass flow rate to gas mass flow rate), with a value of 0, x ft For flash dryness, x ft =(h c_o -h f ) / h fg hc_o represents the specific enthalpy at the outlet of the outdoor heat exchanger, the cold outlet specific enthalpy is approximately equal to the saturated liquid specific enthalpy corresponding to the cold outlet temperature, hf represents the flash saturated liquid specific enthalpy, and hfg represents the flash latent heat of phase change. Given that the refrigerant used in the system is known, the correlation between refrigerant temperature and refrigerant specific enthalpies (outdoor heat exchanger outlet specific enthalpy hc_o, flash saturated liquid specific enthalpy hf, and flash latent heat of phase change hfg) can be fitted using refrigerant property software (e.g., NIST).

[0103] Taking R410A as an example, within the temperature range of 0–35℃, the fitting formula for the saturated liquid enthalpy (kJ / kg) of R410A is: h = 0.0073*t*t + 1.3492*t + 201.01; the fitting formula for the latent heat of phase change (kJ / kg) of R410A is: h fg = -0.0184*t*t - 0.7771*t + 218.79. Therefore, the flow rate of the first throttling device (e.g., an electronic expansion valve) can be expressed as...

[0104] Step S143: Determine the inlet and outlet pressure difference of the first throttling device based on the mid-flow temperature of the outdoor heat exchanger and the target flash temperature; determine the inlet and outlet pressure difference of the second throttling device based on the target flash temperature, the mid-flow temperature of the indoor first heat exchanger and the saturation temperature drop of the high-temperature liquid pipe; and determine the inlet and outlet pressure difference of the third throttling device based on the mid-flow temperature of the indoor first heat exchanger and the mid-flow temperature of the indoor second heat exchanger.

[0105] When the refrigerant used is known, the correlation between the saturated vapor pressure of the refrigerant and the corresponding saturation temperature, P = f(t), can be fitted using refrigerant property software (such as NIST).

[0106] The fitted correlation formula for the refrigerant saturated vapor pressure can be expressed as the sum of the product of a preset coefficient and the corresponding saturation temperature *t*, multiplied by the product of the corresponding saturation temperature *t*, and the product of the first preset constant and the refrigerant temperature *t*, plus the second preset constant. The pressure difference between the inlet and outlet of the throttling device can be expressed as the sum of the preset coefficient and the sum of the saturation temperatures corresponding to the inlet and outlet of the throttling device, multiplied by the first preset constant, and then by the difference between the saturation temperatures corresponding to the inlet and outlet of the throttling device. For example, taking refrigerant R410A as an example, in the range of 0–35℃, the fitted formula for the saturated vapor pressure (Pa) of R410A is: p = 494.8 * t * t + 20438 * t + 826796. Therefore, the pressure difference between the valve inlet and outlet can be expressed as Δp. r=[494.8(t)] ri +t ro )+20438](t ri -t ro ), where tri and tro are the saturation temperatures corresponding to the inlet and outlet of the electronic expansion valve, respectively.

[0107] In one specific implementation, based on the temperature tc at the middle of the flow path of the outdoor heat exchanger and the target flash temperature t ft_target The pressure difference Δp between the inlet and outlet of the first throttling device (e.g., the first electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the first throttling device under a preset cooling mode. r1 .

[0108] Specifically, the fitting correlation of the inlet and outlet pressure difference of the first throttling device under the preset refrigeration mode can be expressed as:

[0109] △p r1 =[a1(tc+t ft_target )+b1](tc-t ft_target );

[0110] Wherein, a1 and b1 are obtained through fitting (e.g., fitting using refrigerant property software NIST). Taking refrigerant R410A as an example, Δp r1 =[494.8((tc+t ft_target )+20438](tc-t ft_target ).

[0111] In one specific implementation, based on the target flash temperature t ft_target Temperature t in the middle of the flow path of the first heat exchanger in the room e_h and the saturation temperature drop dt of the high-temperature liquid pipe sat_ll The pressure difference Δp between the inlet and outlet of the second throttling device (e.g., the second electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the second throttling device under a preset cooling mode. r2 .

[0112] Specifically, the fitting correlation of the inlet and outlet pressure difference of the first throttling device under the preset refrigeration mode can be expressed as:

[0113] △p r2 =[a1(t ft_target +t e_h +dt sat_ll )+b1](t ft_target -t e_h -dt sat_ll );

[0114] Wherein, a1 and b1 are obtained through fitting (e.g., fitting using refrigerant property software NIST). Taking refrigerant R410A as an example, Δpr2 =[494.8(t)] ft_target +t e_h +dt sat_ll )+20438](t ft_target -t e_h -dt sat_ll ).

[0115] In one specific implementation, based on the temperature t at the middle of the flow path of the first heat exchanger indoors... e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l The pressure difference Δp between the inlet and outlet of the third throttling device (e.g., the third electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the third throttling device under the preset cooling mode. r3 .

[0116] Specifically, the fitting correlation of the inlet and outlet pressure difference of the third throttling device under the preset cooling mode can be expressed as:

[0117] △p r3 =[a1(t e_h +t e_l )+b1](t e_h -t e_l );

[0118] Wherein, a1 and b1 are obtained through fitting (e.g., fitting using refrigerant property software NIST). Taking refrigerant R410A as an example, Δp r3 =[494.8(t)] e_h +t e_l )+20438](t e_h -t e_l ).

[0119] Step S144: Determine the inlet density of the first throttling device based on the outlet temperature of the outdoor heat exchanger; determine the inlet density of the second throttling device based on the target flash temperature; determine the inlet density of the third throttling device based on the temperature in the middle of the flow path of the indoor first heat exchanger.

[0120] In one specific implementation, the inlet density ρ of the first throttling device is determined based on the outdoor heat exchanger outlet temperature tc_o. r1 Specifically, this includes: determining the inlet density ρ of the first throttling device based on the outdoor heat exchanger outlet temperature tc_o, using a pre-set correlation formula fitting the inlet density of the first throttling device under the preset cooling mode. r1 ;

[0121] Specifically, the correlation formula for fitting the density of the first throttling device inlet (refrigerant) under the preset refrigeration mode can be expressed as:

[0122] ρ r1= -a2*tc_o*tc_o-b2*tc_o+d;

[0123] Among them, a2, b2, and d are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r1 =-0.0513*tc_o*tc_o-2.6726*tc_o+1162.

[0124] In one specific implementation, based on the target flash temperature t ft_target Determine the inlet density ρ of the second throttling device r2 Specifically, this can include: based on the target flash temperature t ft_target The inlet density ρ of the second throttling device is determined by fitting a correlation equation to the inlet density of the second throttling device under a preset cooling mode. r2 ;

[0125] Specifically, the correlation formula for fitting the density of the refrigerant at the inlet of the second throttling device under the preset refrigeration mode can be expressed as:

[0126] ρ r2 =-a2*t ft_target *t ft_target -b2*t ft_target +d

[0127] Among them, a2, b2, and d are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r2 =-0.0513*t ft_target *t ft_target -2.6726*t ft_target +1162.

[0128] In one specific implementation, based on the temperature t at the middle of the flow path of the first heat exchanger indoors... e_h Determine the inlet density ρ of the third throttling device r3 Specifically, this may include: based on the temperature t in the middle of the flow path of the first heat exchanger indoors. e_h The inlet density ρ of the third throttling device is determined by fitting a correlation equation based on the inlet density of the third throttling device under a preset cooling mode. r3 ;

[0129] Specifically, the correlation formula for fitting the density of the refrigerant at the inlet of the third throttling device under the preset refrigeration mode can be expressed as:

[0130] ρ r3 =-a2*t e_h *t e_h -b2*t e_h +d

[0131] Among them, a2, b2, and d are obtained by fitting refrigerant property data (e.g., by fitting with refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r3 =-0.0513*t e_h *t e_h -2.6726*t e_h +1162.

[0132] Step S145: Based on the preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices, the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device are calculated respectively.

[0133] Figure 7 A flowchart illustrating the steps for calculating the target opening degrees of the first throttling device, the second throttling device, and the third throttling device is shown. Figure 7 As shown, step S145 further includes steps S1451 and S1452.

[0134] Step S1451: Based on the preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices, calculate the air flow rate V of the first throttling device. a_o_1 The air flow rate V of the second throttling device a_o_2 and the air flow rate V of the third throttling device a_o_3 ;

[0135] Specifically, based on the preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices, the air flow rate V of the first throttling device is calculated using the correlation formula between the air flow rate of the throttling device (e.g., an electronic expansion valve) and the refrigerant flow rate in cooling mode. a_o_1 The air flow rate V of the second throttling device a_o_2 and the air flow rate V of the third throttling device a_o_3 .

[0136] The relationship between airflow and refrigerant flow rate for a throttling device (e.g., an electronic expansion valve) with an inlet gauge pressure of 0.1 MPa (ambient temperature 22–28°C, atmospheric pressure 101.325 kPa) is as follows:

[0137]

[0138] Where Va_o is the air flow rate of the throttling device (e.g., an electronic expansion valve), L / min; kc is the flow correction coefficient, which can be obtained experimentally; Mr is the refrigerant mass flow rate of the valve body of the throttling device, g / min; Δpr is the difference between the inlet and outlet pressures of the valve body of the throttling device, Pa; ρr_i is the inlet (refrigerant) density, the relationship between the refrigerant property software NIST and temperature, kg / m3. Taking R410A as an example, in the range of 0~35℃, the fitting formula for the saturated density (kg / m3) of R410A is: ρ=-0.0513*t*t-2.6726*t+1162, where the inlet temperature of the first electronic expansion valve is the outlet temperature tc_o of the outdoor heat exchanger; and the inlet temperature of the second electronic expansion valve is the target flash temperature t. ft_target The inlet temperature of the third electronic expansion valve is the tube temperature of the first heat exchanger in the room. e_h .

[0139] Based on the above correlation between air flow rate and refrigerant flow rate of the throttling device, the correlation between air flow rate and refrigerant flow rate of the first, second, and third throttling devices can be obtained respectively.

[0140] According to the preset first flow correction coefficient kc1 of the first throttling device, the refrigerant flow rate M flowing through the first throttling device r_1 The inlet and outlet pressure difference Δp of the first throttling device r1 and the inlet density ρ of the first throttling device r1 The air flow rate V of the first throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the first throttling device. a_o_1 .

[0141] Based on the above-mentioned relationship between the air flow rate and refrigerant flow rate of the throttling device, the air flow rate V of the first throttling device (e.g., the first electronic expansion valve) can be obtained. a_o_1 Relationship with refrigerant flow rate:

[0142] V a_o_1 =k c1 M r_1 / (ρ r1 *△p r1 ^0.5 )

[0143] According to the preset second flow correction coefficient kc2 of the second throttling device, the refrigerant flow rate M flowing through the second throttling device r_2 The inlet and outlet pressure difference Δp of the second throttling device r2 and the inlet density ρ of the second throttling device r2The air flow rate V of the second throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the second throttling device. a_o_2 .

[0144] Based on the above correlation between the airflow rate and refrigerant flow rate of the throttling device, the airflow rate V of the second throttling device (e.g., the second electronic expansion valve) can be obtained. a_o_2 Relationship with refrigerant flow rate:

[0145] V a_o_2 =k c2 M r_2 / (ρ r2 *△p r2 ^0.5 )

[0146] Based on the preset third flow correction coefficient kc3 of the third throttling device, and the refrigerant flow rate M flowing through the third throttling device... r_3 The inlet and outlet pressure difference Δp of the third throttling device r3 and the inlet density ρ of the third throttling device r3 The air flow rate V of the third throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the third throttling device. a_o_3 ;

[0147] Based on the above correlation between the airflow rate and refrigerant flow rate of the throttling device, the airflow rate V of the third throttling device (e.g., the third electronic expansion valve) can be obtained. a_o_3 Relationship with refrigerant flow rate:

[0148] V a_o_3 =k c3 M r_3 / (ρ r3 *△p r3 ^0.5 )

[0149] Step S1452, based on the air flow rate V of the first throttling device a_o_1 The air flow rate V of the second throttling device a_o_2 and the air flow rate V of the third throttling device a_o_3 The target opening Pulse1 of the first throttling device, the target opening Pulse2 of the second throttling device, and the target opening Pulse3 of the third throttling device are calculated respectively.

[0150] Specifically, based on the air flow rate V of the first throttling device a_o_1 The air flow rate V of the second throttling device a_o_2 and the air flow rate V of the third throttling device a_o_3 Using the preset throttling device opening and the throttling device airflow Va_o The target opening Pulse1 of the first throttling device, the target opening Pulse2 of the second throttling device, and the target opening Pulse3 of the third throttling device are obtained respectively using the correlation formula.

[0151] The target opening of the throttling device, Pulse, is related to the airflow rate, V, of the throttling device. a_o The correlation can be expressed as:

[0152] Pulse = (-C1 + (C1^2 - 4 * C2 * (C0 - V)) a_o ))^0.5) / (2*C2), then we can get:

[0153] The target opening degree Pulse1 of the first throttling device and the air flow rate V of the first throttling device a_o_1 The correlation can be expressed as:

[0154] Pulse1 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_1 )) ^0.5 ) / (2*C2)

[0155] The target opening degree Pulse2 of the second throttling device and the air flow rate V of the second throttling device a_o_2 The correlation can be expressed as:

[0156] Pulse2 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_2 )) ^0.5 ) / (2*C2)

[0157] The target opening degree Pulse3 of the third throttling device and the air flow rate V of the third throttling device a_o_3 The correlation can be expressed as:

[0158] Pulse3 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_3 )) ^0.5 ) / (2*C2).

[0159] In heating mode, the opening degree of the third throttling device remains unchanged at the initially given fixed opening degree. Based on the operating parameters of the air conditioner, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and the pre-matched fitting parameters, the target opening degree of the first throttling device and the target opening degree of the second throttling device are determined.

[0160] Specifically, in heating mode, the third throttling device 3c (e.g., an electronic expansion valve) maintains a fixed opening. The first throttling device (e.g., an electronic expansion valve) controls the target parameter as the high-temperature suction superheat, the target high-temperature suction superheat sh. suc_h_target The value is given based on experimental conditions, and is generally taken as 1-3℃. The second throttling device (e.g., an electronic expansion valve) controls the flash temperature as the target, which can be calculated using a fitted correlation, i.e., t ft_target = (0.5*te_in+0.5*t) suc_h_sat +a*f+c), where a and c are fitting coefficients. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations.

[0161] The inlet pressure of the first throttling device (e.g., an electronic expansion valve) is the saturation pressure corresponding to the flash temperature, pr_i_1 = f(t). ft_target The outlet pressure is the saturation pressure pr_o_1 = f(tc) corresponding to the temperature at the middle of the flow path of the outdoor heat exchanger; the inlet pressure of the second throttling device (e.g., an electronic expansion valve) is the difference between the temperature of the tubes of the first indoor heat exchanger and the saturation temperature drop from the heat exchanger to the valve body inlet pr_i_2 = f(tc). e_h -dt sat_ll The outlet pressure is the saturation pressure corresponding to the flash temperature, pr_o_2 = f(t). ft_target The differential pressure calculation is the same as in the cooling mode.

[0162] Figure 8 A flowchart illustrating a specific embodiment of the steps for determining the target opening degree of the first throttling device and the target opening degree of the second throttling device under the heating mode of the present invention is shown.

[0163] like Figure 8 As shown, in heating mode, the third throttling device maintains a given fixed opening degree. The steps of determining the target opening degree of the first throttling device and the target opening degree of the second throttling device according to the operating parameters of the air conditioner, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and the pre-matched fitting parameters include the following steps S146 to S149.

[0164] Step S146, based on the high-temperature intake saturation temperature t suc_h_sat Target high-temperature intake superheat sh suc_h_target The preset compressor high-temperature cylinder displacement Vrev_h, the preset compressor high-temperature cylinder volumetric efficiency y_h, the preset compressor low-temperature cylinder displacement Vrev_l, the preset compressor low-temperature cylinder volumetric efficiency y_l, the current compressor frequency f, and the outdoor heat exchanger flow rate Mc are determined.

[0165] Figure 9 A flowchart illustrating a specific implementation of the steps for determining the flow rate of an outdoor heat exchanger based on the high-temperature suction saturation temperature, the target high-temperature suction superheat, the preset high-temperature cylinder displacement of the compressor, the predetermined high-temperature cylinder volumetric efficiency of the compressor, the preset low-temperature cylinder displacement of the compressor, the predetermined low-temperature cylinder volumetric efficiency of the compressor, and the current compressor frequency.

[0166] like Figure 9 As shown, step S146 includes steps S1461 to S1462.

[0167] Step S1461, based on the high-temperature intake saturation temperature t suc_h_sat and target high-temperature intake superheat sh suc_h_target Determine the suction specific volume v of the high-temperature cylinder of the compressor suc_h .

[0168] Among them, the suction specific volume v of the high-temperature cylinder of the compressor suc_h With high-temperature intake saturation temperature t suc_h_sat and target high-temperature intake superheat sh suc_h_target Related, that is, v suc_h =f(t) suc_h_sat sh suc_h_target ), v suc_h ==(g+h*t) suc_h_sat +a*sh suc_h_target )*(b*t suc_h_sat *t suc_h_sat +c*t suc_h_sat +d), where a, b, c, d, g, and h are fitting coefficients related to refrigerant properties. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations; target high-temperature suction superheat sh suc_h_target This is the default value.

[0169] Step S1462: Based on the preset compressor high-temperature cylinder displacement Vrev_h, the predetermined compressor high-temperature cylinder volumetric efficiency y_h, the preset compressor low-temperature cylinder displacement Vrev_l, the predetermined compressor low-temperature cylinder volumetric efficiency y_l, the current compressor frequency, and the compressor high-temperature cylinder suction specific volume v... suc_h Determine the flow rate Mc of the outdoor heat exchanger.

[0170] Wherein, the outdoor heat exchanger flow rate Mc is equal to the product of the compressor high-temperature cylinder displacement Vrev_h and the predetermined compressor high-temperature cylinder volumetric efficiency y_h, multiplied by the sum of the products of the compressor low-temperature cylinder displacement Vrev_l and the predetermined compressor low-temperature cylinder volumetric efficiency y_l, multiplied by the current compressor frequency f, and the compressor high-temperature cylinder suction specific volume v. suc_h The ratio, i.e., Mc = (Vrev_h*y_h + Vrev_l*y_l)*f / vsuc_h .

[0171] Step S147: Determine the refrigerant flow rate M flowing through the first throttling device based on the outdoor heat exchanger flow rate. r_1 ,

[0172] According to the refrigerant flow rate M through the first throttling device r_1 and the flash dryness x of the flash generator ft Determine the refrigerant flow rate M through the second throttling device. r_2 ;

[0173] Specifically, the refrigerant flow rate M flowing through the first throttling device is determined based on the flow rate of the outdoor heat exchanger. r_1 Wherein, the refrigerant flow rate M flowing through the first throttling device r_1 The flow rate Mc of the outdoor heat exchanger is equal to the flow rate M of the refrigerant flowing through the first throttling device. r_1 and the flash dryness x of the flash generator ft Determine the refrigerant flow rate M through the second throttling device. r_2 Wherein, the refrigerant flow rate through the second throttling device is equal to the ratio of the refrigerant flow rate of the first throttling device to the product of 1 minus the sum of the parallel cylinder pumping liquid carry-over rate and 1, and the flash dryness of the flasher; that is, the refrigerant flow rate M through the second throttling device. r_2 =M r_1 / (1-(1+E)x ft );

[0174] Where E is the parallel cylinder pumping liquid carry-over rate (the ratio of liquid mass flow rate to gas mass flow rate), with a value of 0, x ft For flash dryness, x ft =(h e_in -h f ) / h fg Let he_in be the specific enthalpy at the outlet of the indoor heat exchanger, hf be the flash saturated liquid specific enthalpy, and hfg be the flash latent heat of phase change. Given that the refrigerant used in the system is known, the correlation between refrigerant temperature and refrigerant specific enthalpies (outdoor heat exchanger outlet specific enthalpy hc_o, flash saturated liquid specific enthalpy hf, and flash latent heat of phase change hfg) can be fitted using refrigerant property software (e.g., NIST).

[0175] Taking R410A as an example, within the temperature range of 0–35℃, the fitting formula for the saturated liquid enthalpy (kJ / kg) of R410A is: h = 0.0073*t*t + 1.3492*t + 201.01; the fitting formula for the latent heat of phase change (kJ / kg) of R410A is: h fg= -0.0184*t*t - 0.7771*t + 218.79. Therefore, the flow rate of the first throttling device (e.g., an electronic expansion valve) can be expressed as...

[0176] Step S148, based on the temperature tc at the middle of the flow path of the outdoor heat exchanger and the target flash temperature t ft_target Determine the pressure difference Δp between the inlet and outlet of the first throttling device. r1 According to the target flash temperature t ft_target Temperature t in the middle of the flow path of the first heat exchanger in the room e_h and the saturation temperature drop dt of the high-temperature liquid pipe sat_ll The pressure difference Δp between the inlet and outlet of the second throttling device is determined by fitting a correlation equation under the preset heating mode. r2 According to the target flash temperature t ft_target Determine the inlet density ρ of the first throttling device r1 Based on the total inlet temperature t of the indoor heat exchanger e_in Determine the inlet density ρ of the second throttling device r2 .

[0177] In one specific implementation, based on the temperature tc at the middle of the flow path of the outdoor heat exchanger and the target flash temperature t ft_target Determine the pressure difference Δp between the inlet and outlet of the first throttling device. r1 Specifically, this includes, based on the temperature tc at the center of the outdoor heat exchanger flow path and the target flash temperature t ft_target The pressure difference Δp between the inlet and outlet of the first throttling device (e.g., the first electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the first throttling device under a preset heating mode. r1 .

[0178] Specifically, the fitting correlation of the inlet and outlet pressure difference of the first throttling device under the preset heating mode can be expressed as:

[0179] △p r1 =[a1(t ft_target +t c )+b1](t ft_target -t c );

[0180] Wherein, a1 and b1 are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example, Δp r1 =[494.8(t)] ft_target +t c )+20438](t ft_target -t c );

[0181] In one specific implementation, based on the target flash temperature tft_target Temperature t in the middle of the flow path of the first heat exchanger in the room e_h and the saturation temperature drop dt of the high-temperature liquid pipe sat_ll Determine the pressure difference Δp between the inlet and outlet of the second throttling device. r2 Specifically, this includes: based on the target flash temperature t ft_target Temperature t in the middle of the flow path of the first heat exchanger in the room e_h and the saturation temperature drop dt of the high-temperature liquid pipe sat_ll The pressure difference Δp between the inlet and outlet of the second throttling device (e.g., the second electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the second throttling device under a preset heating mode. r2 ;

[0182] Specifically, the fitting correlation of the inlet and outlet pressure difference of the second throttling device under the preset heating mode can be expressed as:

[0183] △p r2 =[494.8(t)] e_h -dt sat_ll +t ft_target )+20438](t e_h -dt sat_ll -t ft_target );

[0184] Among them, a1 and b1 are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example,

[0185] △p r2 =[494.8(t)] e_h -dt sat_ll +t ft_target )+20438](t e_h -dt sat_ll -t ft_target ).

[0186] In one specific implementation, based on the target flash temperature t ft_target Determine the inlet density ρ of the first throttling device r1 Specifically, this can include: based on the target flash temperature t ft_target The inlet density ρ of the first throttling device is determined by fitting a correlation equation to the inlet density of the first throttling device under a preset heating mode. r1 ;

[0187] Specifically, the density fitting correlation of the inlet (refrigerant) of the first throttling device under the preset heating mode can be expressed as:

[0188] ρ r1 =-a2*t ft_target *t ft_target -b2*tft_target +d;

[0189] Among them, a2, b2, and d are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r1 =-0.0513*t ft_target *t ft_target -2.6726*t ft_target +1162.

[0190] In one specific implementation, based on the total inlet temperature t of the indoor heat exchanger e_in Determine the inlet density ρ of the second throttling device r2 Specifically, this may include: based on the total inlet temperature t of the indoor heat exchanger e_in The inlet density ρ of the second throttling device is determined by fitting a correlation equation to the inlet density of the second throttling device under a preset heating mode. r2 ;

[0191] Specifically, the correlation formula for the density fitting of the inlet (refrigerant) of the second throttling device under the preset heating mode can be expressed as:

[0192] ρ r2 =-a2*te_in*te_in-b2*te_in+d;

[0193] Among them, a2, b2, and d are obtained through fitting (e.g., fitting using refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r2 =-0.0513*te_in*te_in-2.6726*te_in+1162.

[0194] Step S149: Based on the preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices, the target opening degree Pulse1 of the first throttling device and the target opening degree Pulse2 of the second throttling device are calculated respectively.

[0195] Figure 10 A flowchart illustrating the steps for calculating the target opening degrees of the first and second throttling devices is shown. Figure 10 As shown, step S149 further includes steps S1491 and S1492.

[0196] Step S1491: Based on the preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices, calculate the air flow rate V of the first throttling device. a_o_1 and the air flow rate V of the second throttling device a_o_2 .

[0197] Specifically, based on the preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices, the air flow rate V of the first throttling device is calculated using the correlation formula between the air flow rate of the throttling device (e.g., an electronic expansion valve) and the refrigerant flow rate in heating mode. a_o_1 and the air flow rate V of the second throttling device a_o_2 .

[0198] The relationship between airflow and refrigerant flow rate for a throttling device (e.g., an electronic expansion valve) with an inlet gauge pressure of 0.1 MPa (ambient temperature 22–28°C, atmospheric pressure 101.325 kPa) is as follows:

[0199]

[0200] Where Va_o is the air flow rate of the electronic expansion valve, L / min; kc is the flow correction coefficient, which can be obtained experimentally; Mr is the refrigerant mass flow rate of the valve body, g / min; Δpr is the difference between the inlet and outlet pressures of the valve body, Pa; ρr_i is the inlet refrigerant density, the relationship between the refrigerant property software NIST and temperature, kg / m3; and the inlet temperature of the first electronic expansion valve is the target flash temperature t. ft_target The inlet temperature of the second electronic expansion valve is the inlet temperature of the indoor heat exchanger, te_in.

[0201] Based on the above correlation between air flow rate and refrigerant flow rate of the throttling device, the correlation between air flow rate and refrigerant flow rate of the first and second throttling devices can be obtained respectively.

[0202] According to the preset first flow correction coefficient kc1 of the first throttling device, the refrigerant flow rate M flowing through the first throttling device r_1 The inlet and outlet pressure difference Δp of the first throttling device r1 and the inlet density ρ of the first throttling device r1 The air flow rate V of the first throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the first throttling device. a_o_1 ;

[0203] Based on the above-mentioned relationship between the air flow rate and refrigerant flow rate of the throttling device, the air flow rate V of the first throttling device (e.g., the first electronic expansion valve) can be obtained. a_o_1 Relationship with refrigerant flow rate:

[0204] V a_o_1 =k c1 M r_1 / (ρ r1 *△p r1 ^0.5 )

[0205] According to the preset second flow correction coefficient kc2 of the second throttling device, the refrigerant flow rate M flowing through the second throttling device r_2 The inlet and outlet pressure difference Δp of the second throttling device r2 and the inlet density ρ of the second throttling device r2 The air flow rate V of the second throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the second throttling device. a_o_2 .

[0206] Based on the above correlation between the airflow rate and refrigerant flow rate of the throttling device, the airflow rate V of the second throttling device (e.g., the second electronic expansion valve) can be obtained. a_o_2 Relationship with refrigerant flow rate:

[0207] V a_o_2 =k c2 M r_2 / (ρ r2 *△p r2 ^0.5 ).

[0208] Step S1492, based on the air flow rate V of the first throttling device a_o_1 and the air flow rate V of the second throttling device a_o_2 The target opening Pulse1 of the first throttling device and the target opening Pulse2 of the second throttling device are calculated respectively.

[0209] Specifically, based on the air flow rate V of the first throttling device a_o_1 and the air flow rate V of the second throttling device a_o_2 Using the pre-defined relationship between the opening degree of the throttling device and the air flow rate of the throttling device under the heating mode, the target opening degree Pulse1 of the first throttling device and the target opening degree Pulse2 of the second throttling device are obtained respectively.

[0210] The target opening of the throttling device, Pulse, is related to the airflow rate, V, of the throttling device. a_o The correlation can be expressed as:

[0211] Pulse = (-C1 + (C1^2 - 4 * C2 * (C0 - V)) a_o ))^0.5) / (2*C2), then we can get:

[0212] The target opening degree Pulse1 of the first throttling device and the air flow rate V of the first throttling device a_o_1 The correlation can be expressed as:

[0213] Pulse1 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_1 )) ^0.5 ) / (2*C2)

[0214] The target opening degree Pulse2 of the second throttling device and the air flow rate V of the second throttling device a_o_2 The correlation can be expressed as:

[0215] Pulse2 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_2 )) ^0.5 ) / (2*C2).

[0216] Step S150: Control the first throttling device to operate at the target opening degree of the first throttling device, control the second throttling device to operate at the target opening degree of the second throttling device, and control the third throttling device to operate at the target opening degree of the third throttling device.

[0217] Specifically, the target opening degree Pulse1 of the first throttling device, the target opening degree Pulse2 of the second throttling device, and the target opening degree Pulse3 of the third throttling device are obtained. The first throttling device 3a is controlled to operate at the target opening degree of the first throttling device 3a, the second throttling device 3b is controlled to operate at the target opening degree of the second throttling device 3b, and the third throttling device 3c is controlled to operate at the target opening degree of the third throttling device 3c).

[0218] To clearly illustrate the technical solution of the present invention, the execution flow of the control method for the air conditioning system provided by the present invention will be described below with reference to several specific embodiments.

[0219] Figure 11 This is a schematic diagram of the throttling device control flow in a cooling mode according to a specific embodiment of the present invention. Figure 11 As shown:

[0220] S11. The air conditioning system is switched to cooling mode.

[0221] S12. Detect compressor operating status: frequency f;

[0222] S13. Temperature of each component in the detection system: Temperature t at the middle of the flow path of the indoor first heat exchanger. e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l High-temperature intake temperature t suc_h Low-temperature intake temperature t suc_l outdoor heat exchanger flow path midpoint temperature tc, outdoor heat exchanger outlet temperature tc_o, flash temperature t ft ;

[0223] S14. Calculate the high-temperature suction superheat sh of the compressor. suc_h Low temperature intake superheat sh suc_l and target flash temperature t ft_target Among them, the superheat sh suc_h (l) = intake temperature t suc_h (l) - Intake saturation temperature t suc_h(l)_sat That is, the high-temperature intake superheat sh suc_h =High-temperature intake temperature t suc_h -High-temperature intake saturation temperature t suc_h_sat Low temperature intake superheat sh suc_l =Low-temperature intake temperature t suc_l -Low-temperature intake saturation temperature t suc_l_sat ;

[0224] S15. Determine the system's operating status. When the compressor's high-temperature suction superheat a ≤ sh suc_h ≤b, Low-temperature intake superheat a≤sh suc_l ≤b, and flash temperature t ft With the target flash temperature t ft_target Phase difference (absolute value of temperature difference |t) ft -t ft_target |) When the temperature is within the range of 0 to c, the air conditioning system is determined to be in the target operating state, a < b, the value of a can be 1℃ to 5℃, the preferred value is 3℃, the value of b can be 2℃ to 6℃, the preferred value is 4℃, c > 0, the preferred value is 0.5℃;

[0225] S16. If the air conditioning system is determined to be in the target operating state, keep the opening of the first, second and third throttling devices (e.g., the first, second and third electronic expansion valves) unchanged, and the operating time Δt1, return to step S12). The value of Δt1 can be 0 minutes to 10 minutes, with a preferred value of 5 minutes.

[0226] S17. When the compressor's high-temperature suction superheat sh suc_h <a, or sh suc_h >b, or low-temperature intake superheat sh suc_l <a, or sh suc_l >b, or flash temperature tft With the target flash temperature t ft_target The absolute value of the difference |t ft -t ft_target When |>c, it is determined that the air conditioning system is not in the target operating state, and the inlet and outlet detection of the electronic expansion valve is calculated;

[0227] Calculate the refrigerant flow rate M of the first heat exchanger in the room. e_h , Refrigerant flow rate M of the second indoor heat exchanger e_l The inlet and outlet pressure difference Δp of the first electronic expansion valve, the second electronic expansion valve, and the third electronic expansion valve r1 , △p r2 , △p r3 ;

[0228] S18. Calculate the refrigerant flow rate M through the second electronic expansion valve EEV2. r_2 ;

[0229] S19. Calculate the refrigerant flow rate M through the first electronic expansion valve EEV1. r_1 ;

[0230] S20. Calculate and adjust the opening degrees of the first electronic expansion valve B1, the second electronic expansion valve B2, and the third electronic expansion valve B3.

[0231] After adjusting the opening, the running time is △t2, and the process returns to step S12). The value of △t2 can range from 0 minutes to 5 minutes, with a preferred value of 2.5 minutes.

[0232] Figure 12 A flowchart illustrating the calculation of the opening degree of the throttling device (electronic expansion valve) under the refrigeration mode according to the present invention is shown;

[0233] like Figure 12 As shown, the measured parameter is the temperature t at the middle of the flow path of the first heat exchanger in the room. e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l High-temperature intake temperature t suc_h Low-temperature intake temperature t suc_l outdoor heat exchanger flow path midpoint temperature tc, outdoor heat exchanger outlet temperature tc_o, flash temperature t ft The total inlet temperature of the indoor heat exchanger is te_in; preset parameters: flow correction coefficients for the first electronic expansion valve (kc1), the second electronic expansion valve (kc2), and the third electronic expansion valve (kc3); compressor high-temperature cylinder displacement (Vrev_h); compressor low-temperature cylinder displacement (Vrev_l). The high-temperature liquid pipe saturation temperature drop (dt) is calculated sequentially according to the predetermined fitting correlation. sat_ll saturation temperature drop dt of high-temperature intake pipeline sat_suc_h dt of low-temperature intake piping saturation temperaturesat_suc_l Calculate the high-temperature cylinder volumetric efficiency y_h and the low-temperature cylinder volumetric efficiency y_l of the compressor; calculate the high-temperature suction saturation temperature t. suc_h_sat =t e_h -dt sat_suc_h Low-temperature intake saturation temperature t suc_l_sat =t e_l -dt sat_suc_l ; Calculate the specific volume v of the high-temperature cylinder intake of the compressor suc_h The specific volume of the intake gas of the compressor's cryogenic cylinder is v suc_l And calculate the target flash temperature t ft_target Calculate the pressure difference Δp between the inlet and outlet of the first electronic expansion valve. r1 and inlet density ρ r1 Calculate the pressure difference Δp between the inlet and outlet of the second electronic expansion valve. r2 and inlet density ρ r2 Calculate the pressure difference Δp between the inlet and outlet of the third electronic expansion valve. r3 and inlet density ρ r3 .

[0234] Calculate the refrigerant flow rate M of the second indoor heat exchanger. e_l The refrigerant flow rate M flowing through the third electronic expansion valve r_3 Equal to the refrigerant flow rate M of the second indoor heat exchanger e_l Calculate the refrigerant flow rate M of the first heat exchanger in the room. e_h The refrigerant flow rate M flowing through the second electronic expansion valve r_2 Equal to the refrigerant flow rate M of the first indoor heat exchanger e_h The refrigerant flow rate M flowing through the third electronic expansion valve r_3 The sum of these values ​​is used to calculate the flash dryness x of the flash generator. ft x ft =(h c_o -h f ) / h fg According to flash dryness x ft Calculate the refrigerant flow rate M through the first electronic expansion valve r_1 M r_1 =M r_2 / (1-(1+E)x ft ).

[0235] Calculate the air flow rate V of the first electronic expansion valve respectively. a_o_1 The air flow rate V of the second electronic expansion valve a_o_2 and the air flow rate V of the third electronic expansion valve a_o_3。根据 Air flow rate V of the first electronic expansion valve a_o_1 The air flow rate V of the second electronic expansion valve a_o_2 and the air flow rate V of the third electronic expansion valve a_o_3The target opening Pulse1 of the first throttling device, the target opening Pulse2 of the second throttling device, and the target opening Pulse3 of the third throttling device are calculated respectively.

[0236] Figure 13 This is a schematic diagram of the throttling device control flow in heating mode according to a specific embodiment of the present invention. Figure 13 As shown:

[0237] S21. The air conditioning system is turned on in heating mode;

[0238] S22. Detect compressor operating status: frequency f;

[0239] S23. Temperature of each component in the detection system: Temperature t at the middle of the flow path of the first indoor heat exchanger. e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l High-temperature intake temperature t suc_h Low-temperature intake temperature t suc_l outdoor heat exchanger flow path midpoint temperature tc, outdoor heat exchanger outlet temperature tc_o, flash temperature t ft The inlet temperature of the indoor heat exchanger is te_in;

[0240] S24. Calculate the compressor suction superheat sh suc_h Or sh suc_l In heating mode, it is a single-temperature system with the same superheat for both intake gases, and the target flash temperature t. ft_target ;

[0241] S25. Determine the operating status of the air conditioning system. When the compressor's high-temperature suction superheat sh suc_h Or low temperature intake superheat sh suc_l Satisfying a≤sh suc_h (sh suc_l )≤b, and flash temperaturet ft With the target flash temperature t ft_target Phase difference (absolute value of temperature difference |t) ft -t ft_target |) When the temperature is within the range of 0 to c, the air conditioning system is determined to be in the target operating state, a < b, the value of a can be 1℃ to 5℃, the preferred value is 3℃, the value of b can be 2℃ to 6℃, the preferred value is 4℃, c > 0, the preferred value is 0.5℃;

[0242] S26. If the air conditioning system is determined to be in the target state, keep the opening of the first, second, and third throttling devices (e.g., the first, second, and third electronic expansion valves) unchanged, and the running time Δt1. Return to step S22. The value range of Δt1 is 0 minutes to 10 minutes, with a preferred value of 5 minutes.

[0243] S27. When the compressor's high-temperature suction superheat sh suc_h Or low temperature intake superheat sh suc_l Satisfy sh suc_h (sh suc_l ) < a, or sh suc_h (sh suc_l )>b, or flash temperature t ft With the target flash temperature t ft_target Phase difference (absolute value of temperature difference |t) ft -t ft_target When |)>c, it is determined that the air conditioning system is not in the target operating state, and the refrigerant flow state of the system is calculated;

[0244] Calculate the outdoor heat exchanger flow rate Mc, and the inlet and outlet pressure difference Δp of the first and second electronic expansion valves. r1 , △p r2 ;

[0245] S28. Calculate the refrigerant flow rate M through the second electronic expansion valve EEV2. r_2 ;

[0246] S29. Calculate and adjust the opening B1 of the first electronic expansion valve and the opening B2 of the second electronic expansion valve. After adjusting the opening, the running time Δt2 is returned to step S22. The value of Δt2 can be 0 minutes to 5 minutes, with a preferred value of 2.5 minutes.

[0247] Figure 14 A flowchart illustrating the calculation of the opening degree of the throttling device (electronic expansion valve) under the heating mode according to the present invention is shown;

[0248] like Figure 14 As shown, the measured parameter is the temperature t at the middle of the flow path of the first heat exchanger in the room. e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l High-temperature intake temperature t suc_h Low-temperature intake temperature t suc_l outdoor heat exchanger flow path midpoint temperature tc, outdoor heat exchanger outlet temperature tc_o, flash temperature t ft The total inlet temperature of the indoor heat exchanger is te_in; preset parameters: flow correction coefficients for the first electronic expansion valve (kc1), the second electronic expansion valve (kc2), and the third electronic expansion valve (kc3); compressor high-temperature cylinder displacement Vrev_h; compressor low-temperature cylinder displacement Vrev_l. The saturated temperature drop dt of the high-temperature liquid pipe is obtained. sat_ll saturation temperature drop dt of high-temperature intake pipeline sat_suc_h Fitting correlations for frequencies; calculating the high-temperature intake saturation temperature t. suc_h_sat =t e_h -dtsat_suc_h Calculate the high-temperature cylinder suction specific volume v of the compressor. suc_h And calculate the target flash temperature t ft_target Calculate the pressure difference Δp between the inlet and outlet of the first electronic expansion valve. r1 and inlet density ρ r1 Calculate the pressure difference Δp between the inlet and outlet of the second electronic expansion valve. r2 and inlet density ρ r2 Calculate the flow rate of the outdoor heat exchanger and the refrigerant flow rate M through the first throttling device. r_1 The refrigerant flow rate Mc is equal to the outdoor heat exchanger flow rate. The refrigerant flow rate M flowing through the first electronic expansion valve is calculated. r_1 Calculate the flash dryness x of the flash evaporator ft x ft =(h c_o -h f ) / h fg According to flash dryness x ft and the refrigerant flow rate M flowing through the first electronic expansion valve r_1 Calculate the refrigerant flow rate M through the second electronic expansion valve. r_2 M r_2 =M r_1 / (1-(1+E)x ft ).

[0249] Calculate the air flow rate V of the first electronic expansion valve respectively. a_o_1 The air flow rate V of the second electronic expansion valve a_o_2 According to the air flow rate V of the first electronic expansion valve a_o_1 The air flow rate V of the second electronic expansion valve a_o_2 The target opening degree Pulse1 of the first throttling device and the target opening degree Pulse2 of the second throttling device are calculated respectively.

[0250] Figure 15 This is a structural block diagram of an embodiment of the control device for an air conditioning system provided by the present invention. Figure 15 As shown, the control device 100 of the air conditioning system includes: a judgment unit 110, a determination unit 120 and a control unit 130.

[0251] Preferably, the device 100 further includes an initial parameter determination unit (not shown).

[0252] The initial parameter determination unit is used to determine the compressor frequency, outdoor fan speed, and / or indoor fan speed of the air conditioning system based on the outdoor ambient temperature, indoor ambient temperature, and indoor set temperature after the air conditioning system is turned on, and before determining whether the air conditioning system is currently in the target operating state. It also determines the initial opening degree of the first throttling device, the second throttling device, and the third throttling device based on the current operating mode of the air conditioning system. The control unit 130 is used to control the operation of the air conditioning system based on the determined compressor frequency, outdoor fan speed, and / or indoor fan speed, and the determined initial opening degree of the first throttling device, the second throttling device, and the third throttling device.

[0253] Specifically, if the air conditioner is currently operating in heating mode, a fixed opening degree is given to the third throttling device 3c as the initial opening degree, and the third throttling device 3c maintains this fixed opening degree during heating. The initial opening degrees of the first throttling device 3a and the second throttling device 3b are determined based on the compressor frequency, indoor ambient temperature, and outdoor ambient temperature. The initial opening degrees of the first throttling device 3a and the second throttling device 3b corresponding to different compressor frequencies, indoor ambient temperatures, and outdoor ambient temperatures can be determined in advance through experiments. If the air conditioner is currently operating in non-heating mode, the initial opening degrees of the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c are determined based on the compressor frequency, indoor ambient temperature, and outdoor ambient temperature. The initial opening degrees of the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c corresponding to different compressor frequencies, indoor ambient temperatures, and outdoor ambient temperatures can be determined in advance through experiments.

[0254] The first throttling device 3a, the second throttling device 3b, and the third throttling device 3c can specifically be electronic expansion valves. Figure 3 A control flowchart for the startup phase according to the present invention is shown. Figure 3 The first throttling device 3a is the first electronic expansion valve EEV1, the second throttling device 3b is the second electronic expansion valve EEV2, and the third throttling device 3c is the third electronic expansion valve EEV3. For example... Figure 3As shown, upon receiving a power-on signal, the first electronic expansion valve EEV1, the second electronic expansion valve EEV2, and the third electronic expansion valve EEV3 are reset. The signal is then analyzed to determine the current operating mode of the air conditioner. When the heating mode is activated, the third electronic expansion valve EEV3 is given a fixed opening, and the third electronic expansion valve EEV2 maintains a fixed opening during heating operation. Subsequently, the indoor and outdoor ambient temperatures are detected, and the initial openings of the first electronic expansion valve EEV1 and the second electronic expansion valve EEV2 are determined accordingly. When the non-heating mode is activated, the indoor and outdoor ambient temperatures are detected, and the initial openings of the first electronic expansion valve EEV1, the second electronic expansion valve EEV2, and the third electronic expansion valve EEV3 are determined accordingly.

[0255] When the air conditioner receives the start command, the compressor frequency, outdoor fan speed and / or indoor fan speed operate according to the preset values ​​of the indoor and outdoor ambient temperatures detected by the temperature sensors and the user-set temperature. The opening degree of the outdoor electronic expansion valve (first electronic expansion valve and second electronic expansion valve) and the indoor electronic expansion valve (third electronic expansion valve) is calculated based on the temperature detected by the temperature sensors.

[0256] Figure 3 A control flowchart of a specific embodiment of the power-on phase according to the present invention is shown. Figure 3 As shown, upon receiving the power-on signal, the first electronic expansion valve EEV1, the second electronic expansion valve EEV2, and the third electronic expansion valve EEV3 are reset and the signal is judged. When the user turns on the heating mode, the third electronic expansion valve EEV3 is given a fixed opening (the third electronic expansion valve EEV3 maintains this fixed opening during heating operation). Then, the indoor and outdoor ambient temperatures are detected, and the initial openings of the first electronic expansion valve EEV1 and the second electronic expansion valve EEV2 are given. When the user turns on the non-heating mode, the indoor and outdoor ambient temperatures are detected, and the initial openings of the first electronic expansion valve EEV1, the second electronic expansion valve EEV2, and the third electronic expansion valve EEV3 are given.

[0257] The judgment unit 110 is used to determine whether the air conditioning system is currently in the target operating state.

[0258] Specifically, the judgment unit 110 determines the high-temperature suction superheat, low-temperature suction superheat, and / or target flash temperature of the compressor of the air conditioning system; and determines whether the air conditioning system is currently in the target operating state based on the high-temperature suction superheat, the low-temperature suction superheat, and / or the target flash temperature.

[0259] More specifically, in cooling mode, the high-temperature suction superheat sh of the compressor of the air conditioning system is calculated. suc_h and temperature of intake superheat sh suc_l And calculate the target flash temperature tft_target According to the aforementioned high-temperature intake superheat sh suc_h The low-temperature intake superheat sh suc_l and the target flash temperature t ft_target Determine whether the air conditioning system is currently in the target operating state, wherein the superheat sh suc_h (l) = intake temperature t suc_h (l) - Intake saturation temperature t suc_h(l)_sat That is, the high-temperature intake superheat sh suc_h =High-temperature intake temperature t suc_h -High-temperature intake saturation temperature t suc_h_sat Low temperature intake superheat sh suc_l =Low-temperature intake temperature t suc_l -Low-temperature intake saturation temperature t suc_l_sat .

[0260] In cooling mode, the judgment unit 110 determines the high-temperature intake superheat sh. suc_h Whether the low-temperature intake superheat sh is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b. suc_l Whether it is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b, and the current flash temperature t. ft With the target flash temperature t ft_target The absolute value of the temperature difference |t ft -t ft_target |Whether it is within the preset temperature difference range (specifically, a temperature difference range of 0℃ to C), if the high-temperature intake superheat sh is determined suc_h The low-temperature intake superheat sh is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b. suc_l The current flash temperature t is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b. ft With the target flash temperature t ft_target The absolute value of the temperature difference |t ft -t ft_target If the temperature difference is within a preset range (specifically, a temperature difference range of 0℃ to °C), the air conditioning system is determined to be in the target operating state. That is, when the compressor's high-temperature suction superheat a ≤ sh suc_h ≤b, Low-temperature intake superheat a≤sh suc_l ≤b, and flash temperature t ft With the target flash temperature t ft_target Phase difference (absolute value of temperature difference |t) ft -t ft_targetWhen it is within the range of 0 to c, it is determined that the air-conditioning system is in the target operating state, a < b, the value range of a can be 1°C to 5°C, the preferred value is 3°C, the value range of b can be 2°C to 6°C, the preferred value is 4°C, 0°C < c < 3°C, and the preferred value is 1°C.

[0261] If it is determined that the high-temperature suction superheat sh suc_h is less than the first preset threshold value a, or greater than the second preset threshold value b, or the low-temperature suction superheat sh suc_l is less than the first preset threshold value a, or greater than the second preset threshold value b, and the current flash temperature t ft and the target flash temperature t ft_target The absolute value of the temperature difference |t ft -t ft_target | is not within the preset temperature difference range, then it is determined that the air-conditioning system is not in the target operating state; that is, when the high-temperature suction superheat sh of the compressor suc_h < a, or sh suc_h > b, or the low-temperature suction superheat sh suc_l < a, or sh suc_l > b, or the flash temperature t ft and the target flash temperature t ft_target The absolute value of the difference |t ft -t ft_target | > c, it is determined that the air-conditioning system is not in the target operating state.

[0262] In the heating mode, calculate the high-temperature suction superheat sh of the compressor of the air-conditioning system suc_h or the low-temperature suction superheat sh suc_l , and calculate the target flash temperature t ft_target , according to the high-temperature suction superheat sh suc_h or the low-temperature suction superheat sh suc_l , and according to the target flash temperature t ft_target judge whether the air-conditioning system is currently in the target operating state, where the superheat sh suc_h (l) = suction temperature t suc_h (l) - suction saturation temperature t suc_h(l)_sat ; that is, the high-temperature suction superheat sh suc_h = high-temperature suction temperature t suc_h - high-temperature suction saturation temperature t suc_h_sat , the low-temperature suction superheat sh suc_l = low-temperature suction temperature t suc_l - low-temperature suction saturation temperature t suc_l_sat . In the heating mode, it is a single-temperature system, and the high-temperature suction superheat sh suc_hIt is the same as the low-temperature suction superheat degree. Therefore, in the above conditions, only one of them needs to be calculated.

[0263] In the heating mode, the judgment unit 110 judges the high-temperature suction superheat degree sh suc_h or the low-temperature suction superheat degree sh suc_l whether it is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b, and the current flashing temperature t ft and the target flashing temperature t ft_target the absolute value of the temperature difference |t ft -t ft_target | is within the preset temperature difference range (specifically, the temperature difference range of 0°C to c). If it is judged that the high-temperature suction superheat degree sh suc_h or the low-temperature suction superheat degree sh suc_l is greater than or equal to the first preset threshold a and less than or equal to the second preset threshold b, and the current flashing temperature t ft and the target flashing temperature t ft_target the absolute value of the temperature difference |t ft -t ft_target | is within the preset temperature difference range, then it is judged that the air-conditioning system is in the target operating state. That is, when the high-temperature suction superheat degree sh of the compressor suc_h or the low-temperature suction superheat degree sh suc_l satisfies a ≤ sh suc_h (sh suc_l ) ≤ b, and the flashing temperature t ft and the target flashing temperature t ft_target differ by (the absolute value of the temperature difference |t ft -t ft_target |) within the range of 0 to c, it is determined that the air-conditioning system is in the target operating state. a < b, and the value range of a or b can be 1°C to 3°C, the preferred value is 2°C, 0°C < c < 3°C, and the preferred value is 1°C.

[0264] If it is judged that the high-temperature suction superheat degree sh suc_h or the low-temperature suction superheat degree sh suc_l is less than the first preset threshold a, or the high-temperature suction superheat degree sh suc_h or the low-temperature suction superheat degree sh suc_l is greater than the second preset threshold b, or the absolute value of the temperature difference between the current flashing temperature t ft and the target flashing temperature t ft_target |t ft -t ft_target | is not within the preset temperature difference range, it is judged that the air-conditioning system is not in the target operating state; that is, when the high-temperature suction superheat degree sh of the compressor suc_h or the low-temperature suction superheat degree sh suc_lSatisfy sh suc_h (sh suc_l ) < a, or sh suc_h (sh suc_l )>b, or flash temperature t ft With the target flash temperature t ft_target Phase difference (absolute value of temperature difference |t) ft -t ft_target When |)>c, it is determined that the air conditioning system is not in the target operating state.

[0265] The determining unit 120 is used to determine the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device based on the detected operating parameters of the air conditioner, the preset flow correction coefficient of the throttling device, the preset compressor displacement, the preset target control parameters, and the pre-determined fitting parameters if the determining unit 110 determines that the air conditioning system is not currently in the target operating state.

[0266] Specifically, if the judgment unit 110 determines that the air conditioning system is currently in the target operating state, the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c maintain their current opening degrees. If the judgment unit 110 determines that the air conditioning system is not currently in the target operating state, the target opening degrees of the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c are determined based on the air conditioning operating parameters, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and the pre-determined fitting parameters.

[0267] The calculation of the throttling device opening degree in this invention requires the use of detected values, preset values, and fitted values. The detected values ​​are the detected operating parameters of the air conditioner, which may specifically include: the temperature t in the middle of the flow path of the first indoor heat exchanger. e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l High-temperature intake temperature t suc_h Low-temperature intake temperature t suc_l outdoor heat exchanger flow path midpoint temperature tc, outdoor heat exchanger outlet temperature tc_o, flash temperature t ftThe total inlet temperature of the indoor heat exchanger is te_in; the preset values ​​may specifically include: preset throttling device flow correction coefficients, preset compressor displacement, and preset target control parameters. The preset throttling device flow correction coefficients include the first flow correction coefficient kc1 of the first throttling device 3a, the second flow correction coefficient kc2 of the second throttling device 3b, and the third flow correction coefficient kc3 of the third throttling device 3c. For example, if the first throttling device 3a, the second throttling device 3b, and the third throttling device 3c are all electronic expansion valves, i.e., a first electronic expansion valve, a second electronic expansion valve, and a third electronic expansion valve, then the preset throttling device flow correction coefficients include the first electronic expansion valve flow correction coefficient kc1, the second electronic expansion valve flow correction coefficient kc2, and the third electronic expansion valve flow correction coefficient kc3. The preset compressor displacement may specifically include the compressor high-temperature cylinder displacement Vrev_h and the compressor low-temperature cylinder displacement Vrev_l. The high-temperature cylinder refers to the cylinder corresponding to the compressor suction port connected to the first heat exchanger in the room, and the low-temperature cylinder refers to the cylinder corresponding to the compressor suction port connected to the second heat exchanger in the room. The preset target control parameters may specifically include the target high-temperature suction superheat sh. suc_h_target Target low-temperature intake superheat sh suc_l_target .

[0268] The parameters that need to be fitted during prototype matching include: the saturation temperature drop dt of the high-temperature liquid pipe. sat_ll High-temperature intake pipe saturation temperature drop dt sat_suc_h Low-temperature intake pipe saturation temperature drop dt sat_suc_l The volumetric efficiency of the compressor's high-temperature cylinder is y_h, and the volumetric efficiency of the compressor's low-temperature cylinder is y_l. The opening degrees of the first, second, and third throttling devices (e.g., electronic expansion valves) are Pulse1 = f(Va_o_1), Pulse2 = f(Va_o_2), and Pulse3 = f(Va_o_3). The saturated temperature drop dt of the high-temperature liquid line is also considered. sat_ll = a*f*f+b*f+c.

[0269] In cooling mode, the first throttling device (e.g., an electronic expansion valve) controls the flow with the flash temperature as the target. The target flash temperature can be calculated using a fitted correlation, i.e., t ft_target =f(tc_o,t suc_h_sat ,t suc_l_sat ,f),t ft_target =(0.5*tc_o+0.25*t) suc_h_sat +0.25*t suc_l_sat +a*f+c), where a and c are fitting coefficients, and t is the high-temperature evaporation temperature (high-temperature absorption saturation temperature). suc_h_sat =Temperature t in the middle of the flow path of the first heat exchanger in the room e_h-Saturation temperature drop dt of high-temperature intake line sat_suc_h High-temperature intake pipe saturation temperature drop dt sat_suc_h =f(f); Low-temperature evaporation temperature (low-temperature absorption saturation temperature) t suc_l_sat =Temperature t in the middle of the flow path of the second heat exchanger in the room e_l - Saturation temperature drop dt of low-temperature intake line sat_suc_l Low-temperature intake pipe saturation temperature drop dt sat_suc_l =f(f); f(f) is obtained by fitting experimental data. The outdoor heat exchanger outlet temperature tc_o and the indoor first heat exchanger flow path midpoint temperature t e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l The temperature is detected by a temperature sensing bulb. In cooling mode, the second throttling device (e.g., an electronic expansion valve) and the third throttling device (e.g., an electronic expansion valve) control the high-temperature suction superheat and low-temperature suction superheat as targets, with the target high-temperature suction superheat sh... suc_h_target Target low-temperature intake superheat sh suc_l_target The value is given based on the experimental conditions, and is generally taken as 1 to 6℃.

[0270] Figure 16 A structural block diagram of a specific embodiment of the determining unit according to the present invention is shown. Figure 16 As shown, in one specific embodiment, the determining unit 120, in cooling mode, when determining the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device based on the operating parameters of the air conditioner, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and the pre-matched fitting parameters, may include a first heat exchanger flow determination unit 121, a first refrigerant flow determination unit 122, a first inlet and outlet pressure difference determination unit 123, a first inlet density determination unit 124, and a first target opening degree calculation unit 125.

[0271] The first heat exchanger flow rate determination unit 121 is used to determine the flow rate based on the temperature t in the middle of the flow path of the first heat exchanger in the room. e_h The pre-determined saturation temperature drop dt of the high-temperature intake pipeline sat_suc_h The preset target high-temperature intake superheat (sh) suc_h_target The flow rate M of the first heat exchanger in the room is determined by the preset compressor high-temperature cylinder displacement Vrev_h, the predetermined compressor high-temperature cylinder volumetric efficiency y_h, and the current compressor frequency f. e_h According to the temperature t in the middle of the flow path of the second heat exchanger in the room e_l The pre-determined saturation temperature drop dt of the low-temperature intake pipeline sat_suc_l Target low-temperature intake superheat sh suc_l_targetThe flow rate M of the second indoor heat exchanger is determined by the preset compressor low-temperature cylinder displacement Vrev_l, the predetermined compressor low-temperature cylinder volumetric efficiency y_l, and the current compressor frequency f. e_l .

[0272] In one specific embodiment, the first heat exchanger flow determination unit 121, in cooling mode, determines the saturated temperature drop dt of the high-temperature suction pipe based on the temperature at the middle of the flow path of the first heat exchanger in the room. sat_suc_h The preset target high-temperature suction superheat, preset compressor high-temperature cylinder displacement Vrev_h, predetermined compressor high-temperature cylinder volumetric efficiency y_h, and current compressor frequency f determine the indoor first heat exchanger, including: based on the temperature t in the middle of the flow path of the indoor first heat exchanger. e_h The predetermined saturation temperature drop dt of the high-temperature intake pipeline sat_suc_h Calculate the high-temperature intake saturation temperature t suc_h_sat Wherein, the high-temperature intake saturation temperature t suc_h_sat The temperature t in the middle of the flow path of the first heat exchanger in the room is equal to the temperature of the middle of the flow path. e_h The saturation temperature drop dt of the high-temperature intake pipeline sat_suc_h The difference; the saturation temperature drop dt of the high-temperature intake pipeline. sat_suc_h Related to the compressor frequency f, for example, it can be dt sat_suc_h = a*f*f + b*f + c, where a, b, and c are fitting coefficients; based on the calculated high-temperature intake saturation temperature t suc_h_sat and the preset target high-temperature intake superheat sh suc_h_target Determine the suction specific volume v of the high-temperature cylinder of the compressor suc_h Among them, the specific volume v of the high-temperature cylinder suction of the compressor. suc_h With high-temperature intake saturation temperature t suc_h_sat and target high-temperature intake superheat sh suc_h_target Related, v suc_h ==(g+h*t) suc_h_sat +a*sh suc_h_target )*(b*t suc_h_sat *t suc_h_sat +c*t suc_h_sat +d), where a, b, c, d, g, and h are fitting coefficients related to refrigerant properties. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations; target high-temperature suction superheat sh suc_h_target The compressor high-temperature cylinder displacement Vrev_h is a preset value; the compressor high-temperature cylinder volumetric efficiency y_h is related to the outdoor heat exchanger flow path midpoint temperature tc and the indoor first heat exchanger flow path midpoint temperature t e_h Related to the compressor frequency f, y_h=a*tc+b*t e_h+c*f+d, where a, b, c, and d are fitting coefficients. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlation formulas. Based on the preset compressor high-temperature cylinder displacement Vrev_h, the predetermined compressor high-temperature cylinder volumetric efficiency y_h, and the current compressor frequency f, and the determined compressor high-temperature cylinder suction specific volume v... suc_h Determine the flow rate M of the first heat exchanger in the room. e_h Wherein, the flow rate M of the first indoor heat exchanger e_h The product of the preset compressor high-temperature cylinder displacement Vrev_h, the predetermined compressor high-temperature cylinder volumetric efficiency y_h, the current compressor frequency f, and the compressor high-temperature cylinder suction specific volume v is equal to the product of the preset compressor high-temperature cylinder displacement Vrev_h, the preset compressor high-temperature cylinder volumetric efficiency y_h, the current compressor frequency f, and the current compressor high-temperature cylinder suction specific volume v. suc_h The ratio; that is, M e_h =Vrev_h*y_h*f / v suc_h .

[0273] The first heat exchanger flow determination unit 121 determines the saturated temperature drop dt of the high-temperature suction pipe based on the pre-determined temperature in the middle of the flow path of the first heat exchanger in the room. sat_suc_h The preset target high-temperature intake superheat, the preset compressor high-temperature cylinder displacement Vrev_h, the predetermined compressor high-temperature cylinder volumetric efficiency y_h, and the current compressor frequency f determine the flow rate of the first heat exchanger in the room. You can also refer to steps S1411 to S1413 in step S141.

[0274] In one specific embodiment, the first heat exchanger flow rate determination unit 121 determines the flow rate of the indoor second heat exchanger in cooling mode based on the midpoint temperature of the indoor second heat exchanger flow path, a pre-determined saturated temperature drop of the low-temperature suction pipe, a target low-temperature suction superheat, a pre-determined compressor low-temperature cylinder displacement Vrev_l, a pre-determined compressor low-temperature cylinder volumetric efficiency y_l, and the current compressor frequency f. This includes: determining the flow rate of the indoor second heat exchanger based on the midpoint temperature t of the indoor second heat exchanger flow path. e_l Compared with the predetermined saturation temperature drop dt of the cryogenic intake line sat_suc_l Calculate the low-temperature intake saturation temperature t suc_l_sat Among them, the low-temperature intake saturation temperature t suc_l_sat Equal to the temperature t in the middle of the flow path of the second heat exchanger in the room e_l With low temperature intake line saturation temperature drop dt sat_suc_l The difference; saturation temperature drop dt of the low-temperature intake line sat_suc_l Related to the compressor frequency f, for example, it can be d tsat_suc_l = a*f*f + b*f + c, where a, b, and c are fitting coefficients; based on the calculated low-temperature intake saturation temperature t suc_l_sat and target low temperature intake superheat sh suc_l_target Determine the specific volume v of the compressor's cryogenic cylinder intake. suc_l Among them, the specific volume v of the compressor's cryogenic cylinder suction is...suc_l With low-temperature intake saturation temperature t suc_l_sat and target low-temperature intake superheat sh suc_l_target Related, that is, v suc_l =f(t) suc_l_sat sh suc_l_target For example, it could be: v suc_l =(g+h*t) suc_l_sat +a*sh suc_l_target )*(b*t suc_l_sat *t suc_l_sat +c*t suc_l_sat +d), where a, b, c, d, g, and h are fitting coefficients related to refrigerant properties. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations; target low-temperature suction superheat sh suc_l_target The compressor's cryogenic cylinder displacement Vrev_l is a preset value; the compressor's cryogenic cylinder volumetric efficiency y_l is related to the outdoor heat exchanger's mid-flow path temperature tc and the indoor second heat exchanger's mid-flow path temperature t e_l Related to the compressor frequency f, y_l=a*tc+b*t e_l +c*f+d, where a, b, c, and d are fitting coefficients. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlation equations. Based on the preset compressor cryogenic cylinder displacement Vrev_l, the predetermined compressor cryogenic cylinder volumetric efficiency y_l, and the current compressor frequency f, and the determined compressor cryogenic cylinder suction specific volume v... suc_l Determine the flow rate M of the second heat exchanger in the room. e_l The flow rate M of the second indoor heat exchanger is... e_l The product of the preset compressor cryogenic cylinder displacement Vrev_l, the predetermined compressor cryogenic cylinder volumetric efficiency y_l, the current compressor frequency f, and the compressor cryogenic cylinder suction specific volume v is equal to the product of the preset compressor cryogenic cylinder displacement Vrev_l, the preset compressor cryogenic cylinder volumetric efficiency y_l, the current compressor frequency f, and the current compressor cryogenic cylinder suction specific volume v. suc_l The ratio; that is, M e_l =Vrev_l*y_l*f / v suc_l The first heat exchanger flow determination unit 121 determines the flow rate of the second heat exchanger in cooling mode based on the temperature at the middle of the flow path of the second heat exchanger, the predetermined saturation temperature drop of the low-temperature suction pipe, the target low-temperature suction superheat, the preset compressor low-temperature cylinder displacement Vrev_l, the predetermined compressor low-temperature cylinder volumetric efficiency y_l, and the current compressor frequency f. It can also refer to steps S1414 to S1416 in step S141.

[0275] The first and second refrigerant flow rate determination unit 122 is used to determine the refrigerant flow rate M of the indoor second heat exchanger. e_l Determine the refrigerant flow rate M through the third throttling device. r_3According to the refrigerant flow rate M of the first indoor heat exchanger e_h The refrigerant flow rate M flowing through the third throttling device r_3 Determine the refrigerant flow rate M through the second throttling device. r_2 According to the refrigerant flow rate M flowing through the second throttling device r_2 Flash dryness of flash generator x ft Determine the refrigerant flow rate M through the first throttling device. r_1 .

[0276] Specifically, based on the refrigerant flow rate M of the second indoor heat exchanger e_l Determine the refrigerant flow rate M through the third throttling device. r_3 The refrigerant flow rate M flowing through the third throttling device r_3 Equal to the refrigerant flow rate M of the second indoor heat exchanger e_l That is, M r_3 =M e_l According to the refrigerant flow rate M of the first indoor heat exchanger. e_h The refrigerant flow rate M flowing through the third throttling device r_3 Determine the refrigerant flow rate M through the second throttling device. r_2 The refrigerant flow rate M flowing through the second throttling device is... r_2 Equal to the refrigerant flow rate M of the first indoor heat exchanger e_h The refrigerant flow rate M flowing through the third throttling device r_3 The sum; that is, M r_2 =M r_3 +M e_h =Vrev_l*y_l*f / v suc_l +Vrev_h*y_h*f / v suc_h According to the refrigerant flow rate M flowing through the second throttling device r_2 Flash dryness of flash generator x ft Determine the refrigerant flow rate M through the first throttling device. r_1 Wherein, the refrigerant flow rate M flowing through the first throttling device r_1 Equal to the refrigerant flow rate M of the second throttling device r_2 The ratio of 1 to the product of the sum of the parallel cylinder pumping liquid carry-over rate and 1, and the flash dryness of the flash evaporator; that is, the refrigerant flow rate M through the first throttling device. r_1 =M r_2 / (1-(1+E)x ft ).

[0277] Where E is the parallel cylinder pumping liquid carry-over rate (the ratio of liquid mass flow rate to gas mass flow rate), with a value of 0, x ftFor flash dryness, x ft =(h c_o -h f ) / h fg hc_o represents the specific enthalpy at the outlet of the outdoor heat exchanger, the cold outlet specific enthalpy is approximately equal to the saturated liquid specific enthalpy corresponding to the cold outlet temperature, hf represents the flash saturated liquid specific enthalpy, and hfg represents the flash latent heat of phase change. Given that the refrigerant used in the system is known, the correlation between refrigerant temperature and refrigerant specific enthalpies (outdoor heat exchanger outlet specific enthalpy hc_o, flash saturated liquid specific enthalpy hf, and flash latent heat of phase change hfg) can be fitted using refrigerant property software (e.g., NIST).

[0278] Taking R410A as an example, within the temperature range of 0–35℃, the fitting formula for the saturated liquid enthalpy (kJ / kg) of R410A is: h = 0.0073*t*t + 1.3492*t + 201.01; the fitting formula for the latent heat of phase change (kJ / kg) of R410A is: h fg = -0.0184*t*t - 0.7771*t + 218.79. Therefore, the flow rate of the first throttling device (e.g., an electronic expansion valve) can be expressed as...

[0279] The first inlet / outlet pressure difference determination unit 123 is used to determine the pressure difference based on the temperature tc in the middle of the flow path of the outdoor heat exchanger and the target flash temperature t. ft_target Determine the pressure difference Δp between the inlet and outlet of the first throttling device. r1 According to the target flash temperature t ft_target Temperature t in the middle of the flow path of the first heat exchanger in the room e_h and the saturation temperature drop dt of the high-temperature liquid pipe sat_ll Determine the pressure difference Δp between the inlet and outlet of the second throttling device. r2 And based on the temperature t in the middle of the flow path of the first heat exchanger in the room e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l Determine the pressure difference Δp between the inlet and outlet of the third throttling device. r3 .

[0280] In one specific embodiment, the first inlet and outlet pressure difference determination unit 123 determines the temperature tc at the middle of the flow path of the outdoor heat exchanger and the target flash temperature t based on these parameters. ft_target The pressure difference Δp between the inlet and outlet of the first throttling device (e.g., the first electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the first throttling device under a preset cooling mode. r1 .

[0281] Specifically, the fitting correlation of the inlet and outlet pressure difference of the first throttling device under the preset refrigeration mode can be expressed as:

[0282] △p r1 =[a1(tc+t ft_target )+b1](tc-tft_target );

[0283] Wherein, a1 and b1 are obtained through fitting (e.g., fitting using refrigerant property software NIST). Taking refrigerant R410A as an example, Δp r1 =[494.8((tc+t ft_target )+20438](tc-t ft_target ).

[0284] In one specific embodiment, the first inlet and outlet pressure difference determination unit 123 determines the target flash temperature t based on the target flash temperature t. ft_target Temperature t in the middle of the flow path of the first heat exchanger in the room e_h and the saturation temperature drop dt of the high-temperature liquid pipe sat_ll The pressure difference Δp between the inlet and outlet of the second throttling device (e.g., the second electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the second throttling device under a preset cooling mode. r2 .

[0285] Specifically, the fitting correlation of the inlet and outlet pressure difference of the second throttling device under the preset cooling mode can be expressed as:

[0286] △p r2 =[a1(t ft_target +t e_h +dt sat_ll )+b1](t ft_target -t e_h -dt sat_ll );

[0287] Wherein, a1 and b1 are obtained through fitting (e.g., fitting using refrigerant property software NIST). Taking refrigerant R410A as an example, Δp r2 =[494.8(t)] ft_target +t e_h +dt sat_ll )+20438](t ft_target -t e_h -dt sat_ll ).

[0288] In one specific embodiment, the first inlet / outlet pressure difference determination unit 123 determines the temperature t at the middle of the flow path of the first indoor heat exchanger based on the temperature t. e_h Temperature t in the middle of the flow path of the second heat exchanger in the room e_l The pressure difference Δp between the inlet and outlet of the third throttling device (e.g., the third electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the third throttling device under the preset cooling mode. r3 .

[0289] Specifically, the fitting correlation of the inlet and outlet pressure difference of the third throttling device under the preset cooling mode can be expressed as:

[0290] △p r3 =[a1(t e_h +t e_l )+b1](t e_h -t e_l );

[0291] Wherein, a1 and b1 are obtained through fitting (e.g., fitting using refrigerant property software NIST). Taking refrigerant R410A as an example, Δp r3 =[494.8(t)] e_h +t e_l )+20438](t e_h -t e_l ).

[0292] The first inlet density determination unit 124 is used to determine the inlet density ρ of the first throttling device based on the outdoor heat exchanger outlet temperature tc_o. r1 According to the target flash temperature t ft_target Determine the inlet density ρ of the second throttling device r2 According to the temperature t in the middle of the flow path of the first heat exchanger in the room e_h Determine the inlet density ρ of the third throttling device r3 .

[0293] In one specific embodiment, the first inlet density determining unit 124 determines the first throttling device inlet density ρ based on the outdoor heat exchanger outlet temperature tc_o. r1 Specifically, this includes: determining the inlet density ρ of the first throttling device based on the outdoor heat exchanger outlet temperature tc_o, using a pre-set correlation formula fitting the inlet density of the first throttling device under the preset cooling mode. r1 ;

[0294] Specifically, the correlation formula for fitting the density of the first throttling device inlet (refrigerant) under the preset refrigeration mode can be expressed as:

[0295] ρ r1 = -a2*tc_o*tc_o-b2*tc_o+d;

[0296] Among them, a2, b2, and d are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r1 =-0.0513*tc_o*tc_o-2.6726*tc_o+1162.

[0297] In one specific embodiment, the first inlet density determination unit 124 determines the density based on the target flash temperature t. ft_target Determine the inlet density ρ of the second throttling device r2 Specifically, this can include: based on the target flash temperature tft_target The inlet density ρ of the second throttling device is determined by fitting a correlation equation to the inlet density of the second throttling device under a preset cooling mode. r2 ;

[0298] Specifically, the correlation formula for fitting the density of the refrigerant at the inlet of the second throttling device under the preset refrigeration mode can be expressed as:

[0299] ρ r2 =-a2*t ft_target *t ft_target -b2*t ft_target +d

[0300] Among them, a2, b2, and d are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r2 =-0.0513*t ft_target *t ft_target -2.6726*t ft_target +1162.

[0301] In one specific embodiment, the first inlet density determination unit 124 determines the density based on the temperature t at the middle of the flow path of the first heat exchanger in the room. e_h Determine the inlet density ρ of the third throttling device r3 Specifically, this may include: based on the temperature t in the middle of the flow path of the first heat exchanger indoors. e_h The inlet density ρ of the third throttling device is determined by fitting a correlation equation based on the inlet density of the third throttling device under a preset cooling mode. r3 ;

[0302] Specifically, the correlation formula for fitting the density of the refrigerant at the inlet of the third throttling device under the preset refrigeration mode can be expressed as:

[0303] ρ r3 =-a2*t e_h *t e_h -b2*t e_h +d

[0304] Among them, a2, b2, and d are obtained by fitting refrigerant property data (e.g., by fitting with refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r3 =-0.0513*t e_h *t e_h -2.6726*t e_h +1162.

[0305] The first target opening calculation unit 125 is used to calculate the target opening of the first throttling device, the target opening of the second throttling device, and the target opening of the third throttling device based on the preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices, respectively.

[0306] Specifically, the first target opening calculation unit 125 first calculates the air flow rate V of the first throttling device based on the preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices. a_o_1 The air flow rate V of the second throttling device a_o_2 and the air flow rate V of the third throttling device a_o_3 Then, based on the airflow V of the first throttling device a_o_1 The air flow rate V of the second throttling device a_o_2 and the air flow rate V of the third throttling device a_o_3 The target opening Pulse1 of the first throttling device, the target opening Pulse2 of the second throttling device, and the target opening Pulse3 of the third throttling device are calculated respectively.

[0307] Specifically, the first target opening calculation unit 125 calculates the air flow rate V of the first throttling device based on preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet density of the first, second, and third throttling devices, using the correlation formula between the air flow rate and refrigerant flow rate of the throttling device (e.g., an electronic expansion valve) in cooling mode. a_o_1 The air flow rate V of the second throttling device a_o_2 and the air flow rate V of the third throttling device a_o_3 .

[0308] The relationship between airflow and refrigerant flow rate for a throttling device (e.g., an electronic expansion valve) with an inlet gauge pressure of 0.1 MPa (ambient temperature 22–28°C, atmospheric pressure 101.325 kPa) is as follows:

[0309]

[0310] Where Va_o is the air flow rate of the throttling device (e.g., an electronic expansion valve), L / min; kc is the flow correction coefficient, which can be obtained experimentally; Mr is the refrigerant mass flow rate of the valve body of the throttling device, g / min; Δpr is the difference between the inlet and outlet pressures of the valve body of the throttling device, Pa; ρr_i is the inlet (refrigerant) density, the relationship between the refrigerant property software NIST and temperature, kg / m3. Taking R410A as an example, in the range of 0~35℃, the fitting formula for the saturated density (kg / m3) of R410A is: ρ=-0.0513*t*t-2.6726*t+1162, where the inlet temperature of the first electronic expansion valve is the outlet temperature tc_o of the outdoor heat exchanger; and the inlet temperature of the second electronic expansion valve is the target flash temperature t. ft_target The inlet temperature of the third electronic expansion valve is the tube temperature of the first heat exchanger in the room. e_h .

[0311] Based on the above correlation between air flow rate and refrigerant flow rate of the throttling device, the correlation between air flow rate and refrigerant flow rate of the first, second, and third throttling devices can be obtained respectively.

[0312] According to the preset first flow correction coefficient kc1 of the first throttling device, the refrigerant flow rate M flowing through the first throttling device r_1 The inlet and outlet pressure difference Δp of the first throttling device r1 and the inlet density ρ of the first throttling device r1 The air flow rate V of the first throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the first throttling device. a_o_1 .

[0313] Based on the above-mentioned relationship between the air flow rate and refrigerant flow rate of the throttling device, the air flow rate V of the first throttling device (e.g., the first electronic expansion valve) can be obtained. a_o_1 Relationship with refrigerant flow rate:

[0314] V a_o_1 =k c1 M r_1 / (ρ r1 *△p r1 ^0.5 )

[0315] According to the preset second flow correction coefficient kc2 of the second throttling device, the refrigerant flow rate M flowing through the second throttling device r_2 The inlet and outlet pressure difference Δp of the second throttling device r2 and the inlet density ρ of the second throttling device r2 The air flow rate V of the second throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the second throttling device. a_o_2 .

[0316] Based on the above correlation between the airflow rate and refrigerant flow rate of the throttling device, the airflow rate V of the second throttling device (e.g., the second electronic expansion valve) can be obtained. a_o_2 Relationship with refrigerant flow rate:

[0317] V a_o_2 =k c2 M r_2 / (ρ r2 *△p r2 ^0.5 )

[0318] Based on the preset third flow correction coefficient kc3 of the third throttling device, and the refrigerant flow rate M flowing through the third throttling device... r_3 The inlet and outlet pressure difference Δp of the third throttling device r3 and the inlet density ρ of the third throttling device r3 The air flow rate V of the third throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the third throttling device. a_o_3 ;

[0319] Based on the above correlation between the airflow rate and refrigerant flow rate of the throttling device, the airflow rate V of the third throttling device (e.g., the third electronic expansion valve) can be obtained. a_o_3 Relationship with refrigerant flow rate:

[0320] V a_o_3 =k c3 M r_3 / (ρ r3 *△p r3 ^0.5 )

[0321] After the first target opening calculation unit 125 calculates the target opening Pulse1 of the first throttling device, the target opening Pulse2 of the second throttling device, and the target opening Pulse3 of the third throttling device, it calculates the air flow rate V of the first throttling device. a_o_1 The air flow rate V of the second throttling device a_o_2 and the air flow rate V of the third throttling device a_o_3 Using the preset throttling device opening and the throttling device airflow V a_o The target opening Pulse1 of the first throttling device, the target opening Pulse2 of the second throttling device, and the target opening Pulse3 of the third throttling device are obtained respectively using the correlation formula.

[0322] The target opening of the throttling device, Pulse, is related to the airflow rate, V, of the throttling device. a_o The correlation can be expressed as:

[0323] Pulse = (-C1 + (C1^2 - 4 * C2 * (C0 - V)) a_o ))^0.5) / (2*C2), then we can get:

[0324] The target opening degree Pulse1 of the first throttling device and the air flow rate V of the first throttling device a_o_1 The correlation can be expressed as:

[0325] Pulse1 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_1 )) ^0.5 ) / (2*C2)

[0326] The target opening degree Pulse2 of the second throttling device and the air flow rate V of the second throttling device a_o_2 The correlation can be expressed as:

[0327] Pulse2 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_2 )) ^0.5 ) / (2*C2)

[0328] The target opening degree Pulse3 of the third throttling device and the air flow rate V of the third throttling device a_o_3 The correlation can be expressed as:

[0329] Pulse3 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_3 )) ^0.5 ) / (2*C2).

[0330] In heating mode, the opening degree of the third throttling device remains unchanged at the initially given fixed opening degree. The determining unit 120 determines the target opening degree of the first throttling device and the target opening degree of the second throttling device based on the operating parameters of the air conditioner, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and the pre-matched fitting parameters.

[0331] Specifically, in heating mode, the third throttling device 3c (e.g., an electronic expansion valve) maintains a fixed opening. The first throttling device (e.g., an electronic expansion valve) controls the target parameter as the high-temperature suction superheat, the target high-temperature suction superheat sh. suc_h_target The value is given based on experimental conditions, and is generally taken as 1-3℃. The second throttling device (e.g., an electronic expansion valve) controls the flash temperature as the target, which can be calculated using a fitted correlation, i.e., t ft_target = (0.5*te_in+0.5*t) suc_h_sat+a*f+c), where a and c are fitting coefficients. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations.

[0332] The inlet pressure of the first throttling device (e.g., an electronic expansion valve) is the saturation pressure corresponding to the flash temperature, pr_i_1 = f(t). ft_target The outlet pressure is the saturation pressure pr_o_1 = f(tc) corresponding to the temperature at the middle of the flow path of the outdoor heat exchanger; the inlet pressure of the second throttling device (e.g., an electronic expansion valve) is the difference between the temperature of the tubes of the first indoor heat exchanger and the saturation temperature drop from the heat exchanger to the valve body inlet pr_i_2 = f(tc). e_h -dt sat_ll The outlet pressure is the saturation pressure corresponding to the flash temperature, pr_o_2 = f(t). ft_target The differential pressure calculation is the same as in the cooling mode.

[0333] Figure 17 A structural block diagram of another specific embodiment of the determining unit according to the present invention is shown. For example... Figure 17 As shown, in heating mode, the third throttling device maintains a given fixed opening degree. When determining the target opening degree of the first throttling device and the target opening degree of the second throttling device based on the operating parameters of the air conditioner, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and the pre-matched fitting parameters, the determining unit 120 may include a second heat exchanger flow determination unit 126, a second refrigerant flow determination unit 127, a second inlet and outlet pressure difference determination unit 128, a second inlet density determination unit 129, and a second target opening degree calculation unit 1210.

[0334] The second heat exchanger flow rate determination unit 126 is used to determine the flow rate based on the high-temperature suction saturation temperature t. suc_h_sat Target high-temperature intake superheat sh suc_h_target The preset compressor high-temperature cylinder displacement Vrev_h, the preset compressor high-temperature cylinder volumetric efficiency y_h, the preset compressor low-temperature cylinder displacement Vrev_l, the preset compressor low-temperature cylinder volumetric efficiency y_l, and the current compressor frequency are used to determine the outdoor heat exchanger flow rate Mc.

[0335] In one specific embodiment, the second heat exchanger flow rate determination unit 126 first determines the flow rate based on the high-temperature suction saturation temperature t. suc_h_sat and target high-temperature intake superheat sh suc_h_target Determine the suction specific volume v of the high-temperature cylinder of the compressor suc_h Among them, the specific volume v of the high-temperature cylinder suction of the compressor. suc_h With high-temperature intake saturation temperature t suc_h_sat and target high-temperature intake superheat sh suc_h_target Related, that is, v suc_h=f(t) suc_h_sat sh suc_h_target ), v suc_h ==(g+h*t) suc_h_sat +a*sh suc_h_target )*(b*t suc_h_sat *t suc_h_sat +c*t suc_h_sat +d), where a, b, c, d, g, and h are fitting coefficients related to refrigerant properties. In this invention, the values ​​of the same (identified) fitting coefficients are different in different fitting correlations; target high-temperature suction superheat sh suc_h_target These are preset values. Then, based on the preset compressor high-temperature cylinder displacement Vrev_h, the predetermined compressor high-temperature cylinder volumetric efficiency y_h, the preset compressor low-temperature cylinder displacement Vrev_l, the predetermined compressor low-temperature cylinder volumetric efficiency y_l, the current compressor frequency, and the compressor high-temperature cylinder suction specific volume v... suc_h Determine the outdoor heat exchanger flow rate Mc. The outdoor heat exchanger flow rate Mc is equal to the sum of the product of the compressor high-temperature cylinder displacement Vrev_h and the predetermined compressor high-temperature cylinder volumetric efficiency y_h, and the product of the compressor low-temperature cylinder displacement Vrev_l and the predetermined compressor low-temperature cylinder volumetric efficiency y_l, multiplied by the current compressor frequency f, and the compressor high-temperature cylinder suction specific volume v. suc_h The ratio, i.e., Mc = (Vrev_h*y_h + Vrev_l*y_l)*f / v suc_h The second heat exchanger flow rate determination unit 126 is based on the high-temperature suction saturation temperature t. suc_h_sat Target high-temperature intake superheat sh suc_h_target The preset compressor high-temperature cylinder displacement Vrev_h, the predetermined compressor high-temperature cylinder volumetric efficiency y_h, the preset compressor low-temperature cylinder displacement Vrev_l, the predetermined compressor low-temperature cylinder volumetric efficiency y_l, and the current compressor frequency are used to determine the outdoor heat exchanger flow rate Mc. Steps S1461 to S1462 in the aforementioned steps S146 can also be referred to.

[0336] The second refrigerant flow rate determination unit 127 is used to determine the refrigerant flow rate M flowing through the first throttling device based on the flow rate of the outdoor heat exchanger. r_1 According to the refrigerant flow rate M flowing through the first throttling device r_1 and the flash dryness x of the flash generator ft Determine the refrigerant flow rate M through the second throttling device. r_2 .

[0337] Specifically, the refrigerant flow rate M flowing through the first throttling device is determined based on the flow rate of the outdoor heat exchanger. r_1 Wherein, the refrigerant flow rate M flowing through the first throttling device r_1The flow rate Mc of the outdoor heat exchanger is equal to the flow rate M of the refrigerant flowing through the first throttling device. r_1 and the flash dryness x of the flash generator ft Determine the refrigerant flow rate M through the second throttling device. r_2 Wherein, the refrigerant flow rate through the second throttling device is equal to the ratio of the refrigerant flow rate of the first throttling device to the product of 1 minus the sum of the parallel cylinder pumping liquid carry-over rate and 1 and the flash dryness of the flasher, that is, the refrigerant flow rate M through the second throttling device. r_2 =M r_1 / (1-(1+E)x ft );

[0338] Where E is the parallel cylinder pumping liquid carry-over rate (the ratio of liquid mass flow rate to gas mass flow rate), with a value of 0, x ft For flash dryness, x ft =(h e_in -h f ) / h fg Let he_in be the specific enthalpy at the outlet of the indoor heat exchanger, hf be the flash saturated liquid specific enthalpy, and hfg be the flash latent heat of phase change. Given that the refrigerant used in the system is known, the correlation between refrigerant temperature and refrigerant specific enthalpies (outdoor heat exchanger outlet specific enthalpy hc_o, flash saturated liquid specific enthalpy hf, and flash latent heat of phase change hfg) can be fitted using refrigerant property software (e.g., NIST).

[0339] Taking R410A as an example, within the temperature range of 0–35℃, the fitting formula for the saturated liquid enthalpy (kJ / kg) of R410A is: h = 0.0073*t*t + 1.3492*t + 201.01; the fitting formula for the latent heat of phase change (kJ / kg) of R410A is: h fg = -0.0184*t*t - 0.7771*t + 218.79. Therefore, the flow rate of the first throttling device (e.g., an electronic expansion valve) can be expressed as...

[0340] The second inlet and outlet pressure difference determination unit 128 is used to determine the pressure difference based on the temperature tc in the middle of the flow path of the outdoor heat exchanger and the target flash temperature t. ft_target Determine the pressure difference Δp between the inlet and outlet of the first throttling device. r1 According to the target flash temperature t ft_target Temperature t in the middle of the flow path of the first heat exchanger in the room e_h and the saturation temperature drop dt of the high-temperature liquid pipe sat_ll The pressure difference Δp between the inlet and outlet of the second throttling device is determined by fitting a correlation equation under the preset heating mode. r2 .

[0341] In one specific embodiment, the second inlet and outlet pressure difference determination unit 128 determines the pressure difference based on the temperature tc at the middle of the flow path of the outdoor heat exchanger and the target flash temperature t. ft_target Determine the pressure difference Δp between the inlet and outlet of the first throttling device. r1 Specifically, this includes, based on the temperature tc at the center of the outdoor heat exchanger flow path and the target flash temperature t ft_target The pressure difference Δp between the inlet and outlet of the first throttling device (e.g., the first electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the first throttling device under a preset heating mode. r1 .

[0342] Specifically, the fitting correlation of the inlet and outlet pressure difference of the first throttling device under the preset heating mode can be expressed as:

[0343] △p r1 =[a1(t ft_target +t c )+b1](t ft_target -t c );

[0344] Wherein, a1 and b1 are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example, Δp r1 =[494.8(t)] ft_target +t c )+20438](t ft_target -t c );

[0345] In one specific embodiment, the second inlet and outlet pressure difference determination unit 128 determines the target flash temperature t based on the target flash temperature t. ft_target Temperature t in the middle of the flow path of the first heat exchanger in the room e_h and the saturation temperature drop dt of the high-temperature liquid pipe sat_ll Determine the pressure difference Δp between the inlet and outlet of the second throttling device. r2 Specifically, this includes: based on the target flash temperature t ft_target Temperature t in the middle of the flow path of the first heat exchanger in the room e_h and the saturation temperature drop dt of the high-temperature liquid pipe sat_ll The pressure difference Δp between the inlet and outlet of the second throttling device (e.g., the second electronic expansion valve) is determined by fitting a correlation equation based on the pressure difference between the inlet and outlet of the second throttling device under a preset heating mode. r2 ;

[0346] Specifically, the fitting correlation of the inlet and outlet pressure difference of the second throttling device under the preset heating mode can be expressed as:

[0347] △p r2 =[494.8(t)] e_h -dt sat_ll +t ft_target)+20438](t e_h -dt sat_ll -t ft_target );

[0348] Among them, a1 and b1 are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example,

[0349] △p r2 =[494.8(t)] e_h -dt sat_ll +t ft_target )+20438](t e_h -dt sat_ll -t ft_target ).

[0350] The second inlet density determination unit 129 is used to determine the density based on the target flash temperature t. ft_target Determine the inlet density ρ of the first throttling device r1 Based on the total inlet temperature t of the indoor heat exchanger e_in Determine the inlet density ρ of the second throttling device r2 .

[0351] In one specific embodiment, the second inlet density determination unit 129 determines the density based on the target flash temperature t. ft_target Determine the inlet density ρ of the first throttling device r1 Specifically, this can include: based on the target flash temperature t ft_target The inlet density ρ of the first throttling device is determined by fitting a correlation equation to the inlet density of the first throttling device under a preset heating mode. r1 ;

[0352] Specifically, the density fitting correlation of the inlet (refrigerant) of the first throttling device under the preset heating mode can be expressed as:

[0353] ρ r1 =-a2*t ft_target *t ft_target -b2t ft_target +d;

[0354] Among them, a2, b2, and d are obtained by fitting refrigerant property data (e.g., by fitting refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r1 =-0.0513*t ft_target *t ft_target -2.6726t ft_target +1162.

[0355] In one specific embodiment, the second inlet density determination unit 129 determines the density based on the total inlet temperature t of the indoor heat exchanger.e_in Determine the inlet density ρ of the second throttling device r2 Specifically, this may include: based on the total inlet temperature t of the indoor heat exchanger e_in The inlet density ρ of the second throttling device is determined by fitting a correlation equation to the inlet density of the second throttling device under a preset heating mode. r2 ;

[0356] Specifically, the correlation formula for the density fitting of the inlet (refrigerant) of the second throttling device under the preset heating mode can be expressed as:

[0357] ρ r2 =-a2*te_in*te_in-b2te_in+d;

[0358] Among them, a2, b2, and d are obtained through fitting (e.g., fitting using refrigerant property software NIST). Taking refrigerant R410A as an example, ρ r2 =-0.0513*te_in*te_in-2.6726te_in+1162.

[0359] The second target opening calculation unit 1210 is used to calculate the target opening Pulse1 of the first throttling device and the target opening Pulse2 of the second throttling device based on the preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices.

[0360] Specifically, the second target opening calculation unit 1210 first calculates the air flow rate V of the first throttling device based on the preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices. a_o_1 and the air flow rate V of the second throttling device a_o_2 Then, based on the airflow V of the first throttling device a_o_1 and the air flow rate V of the second throttling device a_o_2 The target opening Pulse1 of the first throttling device and the target opening Pulse2 of the second throttling device are calculated respectively.

[0361] In one specific embodiment, the second target opening calculation unit 1210 calculates the air flow rate V of the first throttling device based on preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet density of the first and second throttling devices, using the correlation formula between the air flow rate of the throttling device (e.g., an electronic expansion valve) and the refrigerant flow rate in heating mode.a_o_1 and the air flow rate V of the second throttling device a_o_2 .

[0362] The relationship between airflow and refrigerant flow rate for a throttling device (e.g., an electronic expansion valve) with an inlet gauge pressure of 0.1 MPa (ambient temperature 22–28°C, atmospheric pressure 101.325 kPa) is as follows:

[0363]

[0364] Where Va_o is the air flow rate of the electronic expansion valve, L / min; kc is the flow correction coefficient, which can be obtained experimentally; Mr is the refrigerant mass flow rate of the valve body, g / min; Δpr is the difference between the inlet and outlet pressures of the valve body, Pa; ρr_i is the inlet refrigerant density, the relationship between the refrigerant property software NIST and temperature, kg / m3; and the inlet temperature of the first electronic expansion valve is the target flash temperature t. ft_target The inlet temperature of the second electronic expansion valve is the inlet temperature of the indoor heat exchanger, te_in.

[0365] Based on the above correlation between air flow rate and refrigerant flow rate of the throttling device, the correlation between air flow rate and refrigerant flow rate of the first and second throttling devices can be obtained respectively.

[0366] According to the preset first flow correction coefficient kc1 of the first throttling device, the refrigerant flow rate M flowing through the first throttling device r_1 The inlet and outlet pressure difference Δp of the first throttling device r1 and the inlet density ρ of the first throttling device r1 The air flow rate V of the first throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the first throttling device. a_o_1 ;

[0367] Based on the above-mentioned relationship between the air flow rate and refrigerant flow rate of the throttling device, the air flow rate V of the first throttling device (e.g., the first electronic expansion valve) can be obtained. a_o_1 Relationship with refrigerant flow rate:

[0368] V a_o_1 =k c1 M r_1 / (ρ r1 *△p r1 ^0.5 )

[0369] According to the preset second flow correction coefficient kc2 of the second throttling device, the refrigerant flow rate M flowing through the second throttling device r_2 The inlet and outlet pressure difference Δp of the second throttling device r2 and the inlet density ρ of the second throttling device r2The air flow rate V of the second throttling device is calculated using the correlation between the air flow rate and the refrigerant flow rate of the second throttling device. a_o_2 .

[0370] Based on the above correlation between the airflow rate and refrigerant flow rate of the throttling device, the airflow rate V of the second throttling device (e.g., the second electronic expansion valve) can be obtained. a_o_2 Relationship with refrigerant flow rate:

[0371] V a_o_2 =k c2 M r_2 / (ρ r2 *△p r2 ^0.5 ).

[0372] The second target opening calculation unit 1210 calculates the airflow rate V of the first throttling device based on the target opening degree calculation unit 1210. a_o_1 and the air flow rate V of the second throttling device a_o_2 The target opening Pulse1 of the first throttling device and the target opening Pulse2 of the second throttling device are calculated respectively.

[0373] In one specific embodiment, the second target opening calculation unit 1210 calculates the airflow rate V of the first throttling device. a_o_1 and the air flow rate V of the second throttling device a_o_2 Using the pre-defined relationship between the opening degree of the throttling device and the air flow rate of the throttling device under the heating mode, the target opening degree Pulse1 of the first throttling device and the target opening degree Pulse2 of the second throttling device are obtained respectively.

[0374] The target opening of the throttling device, Pulse, is related to the airflow rate, V, of the throttling device. a_o The correlation can be expressed as:

[0375] Pulse = (-C1 + (C1^2 - 4 * C2 * (C0 - V)) a_o ))^0.5) / (2*C2), then we can get:

[0376] The target opening degree Pulse1 of the first throttling device and the air flow rate V of the first throttling device a_o_1 The correlation can be expressed as:

[0377] Pulse1 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_1 )) ^0.5 ) / (2*C2)

[0378] The target opening degree Pulse2 of the second throttling device and the air flow rate V of the second throttling devicea_o_2 The correlation can be expressed as:

[0379] Pulse2 = (-C1 + (C1) ^2 -4*C2*(C0-V a_o_2 )) ^0.5 ) / (2*C2).

[0380] The control unit 130 is used to control the first throttling device to operate at the target opening degree of the first throttling device, control the second throttling device to operate at the target opening degree of the second throttling device, and control the third throttling device to operate at the target opening degree of the third throttling device.

[0381] Specifically, the target opening degree Pulse1 of the first throttling device, the target opening degree Pulse2 of the second throttling device, and the target opening degree Pulse3 of the third throttling device are obtained. The control unit 130 controls the first throttling device 3a to operate at the target opening degree of the first throttling device 3a, controls the second throttling device 3b to operate at the target opening degree of the second throttling device 3b, and controls the third throttling device 3c to operate at the target opening degree of the third throttling device 3c.

[0382] The present invention also provides a storage medium corresponding to the control method of the air conditioning system, wherein a computer program is stored thereon, and when the program is executed by a processor, the steps of any of the aforementioned methods are implemented.

[0383] The present invention also provides an air conditioning system corresponding to the control method of the air conditioning system, including a processor, a memory, and a computer program stored in the memory that can run on the processor, wherein the processor executes the program to implement the steps of any of the aforementioned methods.

[0384] The present invention also provides an air conditioning system corresponding to the control device of the air conditioning system, including any of the control devices described above.

[0385] Accordingly, the solution provided by this invention decouples the control of three throttling devices in an air conditioning system with three throttling devices, thereby improving system operating energy efficiency. It precisely calculates and adjusts the opening degree of all electronic expansion valves in the system. Since each sensor in the system is affected by the opening degree of each electronic expansion valve, this solution prevents situations where a change in the opening degree of one electronic expansion valve causes changes in all sensors, requiring multiple feedback judgments, repeated adjustments to the electronic expansion valve opening, over-adjustment of other electronic expansion valve openings, or large fluctuations in the opening degree control of the electronic expansion valves. This results in a longer time and slower speed for the compressor to reach a stable operating state after startup. Precise and rapid control of the system's status detection ensures that the air conditioning system is in an optimal state, achieving optimal energy saving and improving the accuracy of electronic expansion valve control.

[0386] During the operation of a dual-temperature system, there are multiple detection and control issues. When the coupling of various detections affects the performance of the air conditioning system, the technical solution of this invention processes the detections in association, which can reduce the complexity of system control. The electronic expansion valve opening is correlated and fitted with the system flow rate, thereby directly calculating the electronic expansion valve opening under the target parameters, accurately adjusting the flash temperature and multiple suction superheats, and reducing the system feedback calculation time.

[0387] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored as one or more instructions or codes on or transmitted via a computer-readable medium. Other examples and embodiments are within the scope and spirit of this invention and the appended claims. For example, due to the nature of software, the functions described above can be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Furthermore, the functional units can be integrated into a single processing unit, or each unit can exist physically separately, or two or more units can be integrated into a single unit.

[0388] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0389] The units described as separate components may or may not be physically separate. Similarly, the components of the control device may or may not be physical units; they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0390] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to related technologies, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0391] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A control method of an air conditioning system, characterized by, include: The air conditioning system includes: a compressor, an outdoor heat exchanger, a first throttling device, a second throttling device, a third throttling device, a flash evaporator, an indoor first heat exchanger, an indoor second heat exchanger, a first four-way reversing valve, and a second four-way reversing valve; the inlet end of the flash evaporator is connected to the outdoor heat exchanger, the first throttling device is installed on the pipeline between the flash evaporator and the outdoor heat exchanger, the indoor first heat exchanger and the indoor second heat exchanger are connected in parallel and then connected to the flash evaporator through the second throttling device, and the third throttling device is installed on the pipeline in parallel between the indoor second heat exchanger and the indoor first heat exchanger; The control method includes: Determining whether the air conditioning system is currently in the target operating state includes: determining the high-temperature suction superheat, low-temperature suction superheat, and / or target flash temperature of the compressor of the air conditioning system; and determining whether the air conditioning system is currently in the target operating state based on the high-temperature suction superheat, the low-temperature suction superheat, and / or the target flash temperature. If it is determined that the air conditioning system is not currently in the target operating state, then the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device are determined based on the detected operating parameters of the air conditioner, the preset throttling device flow correction coefficient, the preset compressor displacement, the preset target control parameters, and the pre-determined fitting parameters. The first throttling device is controlled to operate at its target opening degree, the second throttling device is controlled to operate at its target opening degree, and the third throttling device is controlled to operate at its target opening degree. The operating parameters of the air conditioner include at least one of the following: the temperature at the center of the flow path of the first indoor heat exchanger, the temperature at the center of the flow path of the second indoor heat exchanger, the high-temperature suction temperature, the low-temperature suction temperature, the temperature at the center of the flow path of the outdoor heat exchanger, the outlet temperature of the outdoor heat exchanger, the flash temperature, the total inlet temperature of the indoor heat exchanger, and the current compressor frequency; the preset target control parameters include: the target high-temperature suction superheat and / or the target low-temperature suction superheat; the predetermined fitting parameters include: the high-temperature liquid pipe saturation temperature drop, the high-temperature suction pipe saturation temperature drop, the low-temperature suction pipe saturation temperature drop, the compressor high-temperature cylinder volumetric efficiency, and the compressor low-temperature cylinder volumetric efficiency.

2. The method of claim 1, wherein, Before determining whether the air conditioning system is currently in the target operating state, the method further includes: After the air conditioning system is turned on, the compressor frequency, outdoor fan speed and / or indoor fan speed of the air conditioning system are determined according to the outdoor ambient temperature, indoor ambient temperature and indoor set temperature, and the initial opening degree of the first throttling device, the second throttling device and the third throttling device are determined according to the current operating mode of the air conditioning system. The operation of the air conditioning system is controlled based on the determined compressor frequency, outdoor fan speed and / or indoor fan speed, and the determined initial opening degree of the first throttling device, the second throttling device and the third throttling device.

3. The method of claim 1, wherein, Determining whether the air conditioning system is currently in the target operating state based on the high-temperature intake superheat, the low-temperature intake superheat, and / or the target flash temperature includes: In cooling mode, it is determined whether the high-temperature intake superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, whether the low-temperature intake superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, and whether the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within the preset temperature difference range. If it is determined that the high-temperature intake superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, the low-temperature intake superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, and the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within the preset temperature difference range, then it is determined that the air conditioning system is in the target operating state. If it is determined that the high-temperature intake superheat is less than the first preset threshold or greater than the second preset threshold, or the low-temperature intake superheat is less than the first preset threshold or greater than the second preset threshold, and the absolute value of the temperature difference between the current flash temperature and the target flash temperature is not within the preset temperature difference range, then it is determined that the air conditioning system is not in the target operating state. And / or, In heating mode, it is determined whether the high-temperature intake superheat or the low-temperature intake superheat is greater than or equal to a first preset threshold and less than or equal to a second preset threshold, and whether the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within the preset temperature difference range. If the high-temperature intake superheat or the low-temperature intake superheat is greater than or equal to the first preset threshold and less than or equal to the second preset threshold, and the absolute value of the temperature difference between the current flash temperature and the target flash temperature is within the preset temperature difference range, then the air conditioning system is determined to be in the target operating state. If the high-temperature intake superheat or the low-temperature intake superheat is less than a first preset threshold, or the high-temperature intake superheat or the low-temperature intake superheat is greater than a second preset threshold, or the absolute value of the temperature difference between the current flash temperature and the target flash temperature is not within the preset temperature difference range, then the air conditioning system is determined not to be in the target operating state.

4. The method according to any one of claims 1-3, characterized in that, The preset flow correction coefficient for the throttling device includes at least one of the following: the first flow correction coefficient of the first throttling device, the second flow correction coefficient of the second throttling device, and the third flow correction coefficient of the third throttling device; The preset compressor displacement includes: the high-temperature cylinder displacement of the compressor and / or the low-temperature cylinder displacement of the compressor.

5. The method according to claim 4, characterized in that, In cooling mode, based on the air conditioner's operating parameters, a preset throttling device flow correction coefficient, a preset compressor displacement, preset target control parameters, and pre-determined fitting parameters, the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device are determined, including: The flow rate of the first heat exchanger is determined based on the temperature at the middle of the flow path of the first heat exchanger, the predetermined saturation temperature drop of the high-temperature suction pipe, the predetermined target high-temperature suction superheat, the predetermined high-temperature cylinder displacement of the compressor, the predetermined high-temperature cylinder volumetric efficiency of the compressor, and the current compressor frequency. The flow rate of the second heat exchanger is determined based on the temperature at the middle of the flow path of the second heat exchanger, the predetermined saturation temperature drop of the low-temperature suction pipe, the target low-temperature suction superheat, the predetermined low-temperature cylinder displacement of the compressor, the predetermined low-temperature cylinder volumetric efficiency of the compressor, and the current compressor frequency. The refrigerant flow rate through the third throttling device is determined based on the refrigerant flow rate through the second indoor heat exchanger; the refrigerant flow rate through the second throttling device is determined based on the refrigerant flow rate through the first indoor heat exchanger and the refrigerant flow rate through the third throttling device; the refrigerant flow rate through the first throttling device is determined based on the refrigerant flow rate through the second throttling device and the flash dryness of the flash evaporator. The inlet and outlet pressure difference of the first throttling device is determined based on the temperature in the middle of the flow path of the outdoor heat exchanger and the target flash temperature. The inlet and outlet pressure difference of the second throttling device is determined based on the target flash temperature, the temperature in the middle of the flow path of the indoor first heat exchanger and the saturation temperature drop of the high-temperature liquid pipe. The inlet and outlet pressure difference of the third throttling device is determined based on the temperature in the middle of the flow path of the indoor first heat exchanger and the temperature in the middle of the flow path of the indoor second heat exchanger. The inlet density of the first throttling device is determined based on the outlet temperature of the outdoor heat exchanger; the inlet density of the second throttling device is determined based on the target flash temperature; and the inlet density of the third throttling device is determined based on the temperature in the middle of the flow path of the indoor first heat exchanger. Based on the preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices, the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device are calculated respectively.

6. The method according to claim 5, characterized in that, The flow rate of the first indoor heat exchanger is determined based on the temperature at the midpoint of the flow path of the first indoor heat exchanger, the predetermined saturation temperature drop of the high-temperature suction pipe, the predetermined target high-temperature suction superheat, the predetermined high-temperature cylinder displacement of the compressor, the predetermined high-temperature cylinder volumetric efficiency of the compressor, and the current compressor frequency. This includes: The high-temperature intake saturation temperature is calculated based on the temperature at the middle of the flow path of the first heat exchanger in the room and the predetermined saturation temperature drop of the high-temperature intake pipe. The specific volume of the compressor's high-temperature cylinder intake is determined based on the calculated high-temperature intake saturation temperature and the target high-temperature intake superheat. The flow rate of the first heat exchanger in the room is determined based on the preset compressor high-temperature cylinder displacement, the predetermined compressor high-temperature cylinder volumetric efficiency, the current compressor frequency, and the determined compressor high-temperature cylinder suction specific volume. And / or, The flow rate of the indoor second heat exchanger is determined based on the temperature at the middle of the flow path of the indoor second heat exchanger, the predetermined saturation temperature drop of the low-temperature suction line, the target low-temperature suction superheat, the preset compressor low-temperature cylinder displacement, the predetermined compressor low-temperature cylinder volumetric efficiency, and the current compressor frequency. This includes: The low-temperature suction saturation temperature is calculated based on the temperature in the middle of the flow path of the second heat exchanger in the room and the predetermined saturation temperature drop of the low-temperature suction pipe. The specific volume of the compressor's cryogenic cylinder intake is determined based on the calculated cryogenic intake saturation temperature and the target cryogenic intake superheat. The flow rate of the second heat exchanger in the room is determined based on the preset compressor low-temperature cylinder displacement, the predetermined compressor low-temperature cylinder volumetric efficiency, the current compressor frequency, and the determined compressor low-temperature cylinder suction specific volume. And / or, Determining the refrigerant flow rate through the third throttling device based on the refrigerant flow rate of the second indoor heat exchanger includes: The refrigerant flow rate through the third throttling device is equal to the refrigerant flow rate through the indoor second heat exchanger; Determining the refrigerant flow rate through the second throttling device based on the refrigerant flow rate of the first indoor heat exchanger and the refrigerant flow rate through the third throttling device includes: The refrigerant flow rate through the second throttling device is equal to the sum of the refrigerant flow rate through the first indoor heat exchanger and the refrigerant flow rate through the third throttling device; Determining the refrigerant flow rate through the first throttling device based on the refrigerant flow rate through the second throttling device and the flash dryness of the flash evaporator includes: The refrigerant flow rate through the first throttling device is equal to the ratio of the difference between the refrigerant flow rate of the second throttling device and the product of 1 minus the sum of the parallel cylinder pumping liquid carry-over rate and 1 and the flash dryness of the flash evaporator. And / or, The pressure difference between the inlet and outlet of the first throttling device is determined based on the temperature at the midpoint of the flow path of the outdoor heat exchanger and the target flash temperature, including: Based on the temperature in the middle of the flow path of the outdoor heat exchanger and the target flash temperature, the inlet and outlet pressure difference of the first throttling device is determined by fitting a correlation equation under the preset cooling mode. The inlet and outlet pressure difference of the second throttling device is determined based on the target flash temperature, the temperature in the middle of the flow path of the first heat exchanger in the room, and the saturation temperature drop of the high-temperature liquid pipe, including: Based on the target flash temperature, the temperature in the middle of the flow path of the first heat exchanger in the room, and the saturation temperature drop of the high-temperature liquid pipe, the inlet and outlet pressure difference of the second throttling device is determined by fitting the correlation equation of the inlet and outlet pressure difference of the second throttling device under the preset refrigeration mode. The inlet and outlet pressure difference of the third throttling device is determined based on the midpoint temperatures of the flow paths of the first and second indoor heat exchangers, including: The inlet and outlet pressure difference of the third throttling device is determined based on the midpoint temperature of the flow path of the first heat exchanger and the midpoint temperature of the flow path of the second heat exchanger in the room, and by fitting the correlation equation of the inlet and outlet pressure difference of the third throttling device under the preset cooling mode. And / or, The inlet density of the first throttling device is determined based on the outlet temperature of the outdoor heat exchanger, including: Based on the outdoor heat exchanger outlet temperature, the inlet density of the first throttling device is determined using a pre-set correlation formula fitting the inlet density of the first throttling device under the preset cooling mode. Determining the inlet density of the second throttling device based on the target flash temperature includes: Based on the target flash temperature, the inlet density of the second throttling device is determined by fitting a correlation equation to the inlet density of the second throttling device under a preset cooling mode. The inlet density of the third throttling device is determined based on the temperature at the middle of the flow path of the first heat exchanger in the room, including: Based on the temperature in the middle of the flow path of the first heat exchanger in the room, the inlet density of the third throttling device is determined by fitting the correlation equation of the inlet density of the third throttling device under the preset cooling mode. And / or, Based on preset first, second, and third flow correction coefficients, refrigerant flow rates of the first, second, and third throttling devices, inlet and outlet pressure differences of the first, second, and third throttling devices, and inlet densities of the first, second, and third throttling devices, the target opening degrees of the first throttling device, the second throttling device, and the third throttling device are calculated respectively, including: Based on the preset first, second, and third flow correction coefficients, the refrigerant flow rates of the first, second, and third throttling devices, the inlet and outlet pressure differences of the first, second, and third throttling devices, and the inlet densities of the first, second, and third throttling devices, the air flow rates of the first throttling device, the second throttling device, and the third throttling device are calculated respectively. Based on the air flow rates of the first throttling device, the second throttling device, and the third throttling device, the target opening degrees of the first throttling device, the second throttling device, and the third throttling device are calculated respectively.

7. The method according to claim 4, characterized in that, In heating mode, based on the air conditioner's operating parameters, a preset throttling device flow correction coefficient, a preset compressor displacement, preset target control parameters, and pre-determined fitting parameters, the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device are determined, including: In heating mode, the opening degree of the third throttling device remains unchanged at an initially given fixed opening degree. Based on the air conditioner's operating parameters, a preset throttling device flow correction coefficient, a preset compressor displacement, preset target control parameters, and pre-determined fitting parameters, the target opening degrees of the first and second throttling devices are determined, including: The outdoor heat exchanger flow rate is determined based on the high-temperature suction saturation temperature, the target high-temperature suction superheat, the preset high-temperature cylinder displacement of the compressor, the predetermined high-temperature cylinder volumetric efficiency of the compressor, the preset low-temperature cylinder displacement of the compressor, the predetermined low-temperature cylinder volumetric efficiency of the compressor, and the current compressor frequency. The refrigerant flow rate through the first throttling device is determined based on the flow rate of the outdoor heat exchanger, and the refrigerant flow rate through the second throttling device is determined based on the refrigerant flow rate through the first throttling device and the flash dryness of the flash evaporator. The inlet and outlet pressure difference of the first throttling device is determined based on the temperature at the middle of the flow path of the outdoor heat exchanger and the target flash temperature. The inlet and outlet pressure difference of the second throttling device is determined based on the target flash temperature, the temperature at the middle of the flow path of the indoor first heat exchanger, and the saturation temperature drop of the high-temperature liquid pipe. The inlet density of the first throttling device is determined based on the target flash temperature. The inlet density of the second throttling device is determined based on the total inlet temperature of the indoor heat exchanger. Based on the preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices, the target opening degree of the first throttling device and the target opening degree of the second throttling device are calculated respectively.

8. The method according to claim 7, characterized in that, Based on the high-temperature suction saturation temperature, target high-temperature suction superheat, preset compressor high-temperature cylinder displacement, predetermined compressor high-temperature cylinder volumetric efficiency, preset compressor low-temperature cylinder performance coefficient, and current compressor frequency, determine the outdoor heat exchanger flow rate, including: The specific volume of the compressor's high-temperature cylinder intake is determined based on the high-temperature intake saturation temperature and the target high-temperature intake superheat. The outdoor heat exchanger flow rate is determined based on the preset compressor high-temperature cylinder displacement, the predetermined compressor high-temperature cylinder volumetric efficiency, the preset compressor low-temperature cylinder displacement, the predetermined compressor low-temperature cylinder volumetric efficiency, the current compressor frequency, and the suction specific volume of the compressor high-temperature cylinder. And / or, Determining the refrigerant flow rate through the first throttling device based on the outdoor heat exchanger flow rate includes: The refrigerant flow rate through the first throttling device is equal to the flow rate of the outdoor heat exchanger; Determining the refrigerant flow rate through the second throttling device based on the refrigerant flow rate through the first throttling device and the flash dryness of the flash evaporator includes: The refrigerant flow rate through the second throttling device is equal to the ratio of the product of the refrigerant flow rate of the first throttling device and 1 minus the sum of the parallel cylinder pumping liquid carry-over rate and 1, and the flash dryness of the flash evaporator. And / or, Based on the temperature at the midpoint of the outdoor heat exchanger flow path and the target flash temperature, determine the inlet and outlet pressure difference of the first throttling device, including: Based on the temperature in the middle of the flow path of the outdoor heat exchanger and the target flash temperature, the inlet and outlet pressure difference of the first throttling device is determined by fitting a correlation equation under the preset heating mode. Based on the target flash temperature, the temperature in the middle of the flow path of the first heat exchanger in the room, and the saturation temperature drop of the high-temperature liquid pipe, determine the inlet and outlet pressure difference of the second throttling device, including: Based on the target flash temperature, the temperature in the middle of the flow path of the first heat exchanger in the room, and the saturation temperature drop of the high-temperature liquid pipe, the inlet and outlet pressure difference of the second throttling device is determined by fitting the correlation equation of the inlet and outlet pressure difference of the second throttling device under the preset heating mode. And / or, Determining the inlet density of the first throttling device based on the target flash temperature includes: determining the inlet density of the first throttling device based on the target flash temperature using a correlation fitting formula of the inlet density of the first throttling device under a preset heating mode; The method for determining the inlet density of the second throttling device based on the total inlet temperature of the indoor heat exchanger includes: determining the inlet density of the second throttling device based on the total inlet temperature of the indoor heat exchanger by fitting a correlation equation of the inlet density of the second throttling device under a preset heating mode. And / or, Based on preset first and second flow correction coefficients, refrigerant flow rates of the first and second throttling devices, inlet and outlet pressure differences of the first and second throttling devices, and inlet densities of the first and second throttling devices, the target opening degrees of the first throttling device and the second throttling device are calculated respectively, including: Based on the preset first and second flow correction coefficients, the refrigerant flow rates of the first and second throttling devices, the inlet and outlet pressure differences of the first and second throttling devices, and the inlet densities of the first and second throttling devices, the air flow rates of the first throttling device and the second throttling device are calculated respectively. Based on the air flow rates of the first throttling device and the second throttling device, the target opening degree of the first throttling device and the target opening degree of the second throttling device are calculated respectively.

9. A control device of an air conditioning system, characterized by comprising: include: The air conditioning system includes: a compressor, an outdoor heat exchanger, a first throttling device, a second throttling device, a third throttling device, a flash evaporator, an indoor first heat exchanger, an indoor second heat exchanger, a first four-way reversing valve, and a second four-way reversing valve; the inlet end of the flash evaporator is connected to the outdoor heat exchanger; the first throttling device is installed on the pipeline between the flash evaporator and the outdoor heat exchanger; the indoor first heat exchanger and the indoor second heat exchanger are connected in parallel and then connected to the flash evaporator through the second throttling device; the third throttling device is installed on the pipeline connecting the indoor second heat exchanger and the indoor first heat exchanger in parallel; the control device includes: The judgment unit is used to determine whether the air conditioning system is currently in the target operating state, including: determining the high-temperature suction superheat, low-temperature suction superheat and / or target flash temperature of the compressor of the air conditioning system; and determining whether the air conditioning system is currently in the target operating state based on the high-temperature suction superheat, the low-temperature suction superheat and / or the target flash temperature. The determining unit is configured to, if the judging unit determines that the air conditioning system is not currently in the target operating state, determine the target opening degree of the first throttling device, the target opening degree of the second throttling device, and the target opening degree of the third throttling device based on the detected operating parameters of the air conditioning system, the preset flow correction coefficient of the throttling device, the preset compressor displacement, the preset target control parameters, and the pre-determined fitting parameters. The control unit is used to control the first throttling device to operate at the target opening degree of the first throttling device, control the second throttling device to operate at the target opening degree of the second throttling device, and control the third throttling device to operate at the target opening degree of the third throttling device. The operating parameters of the air conditioner include at least one of the following: the temperature at the center of the flow path of the first indoor heat exchanger, the temperature at the center of the flow path of the second indoor heat exchanger, the high-temperature suction temperature, the low-temperature suction temperature, the temperature at the center of the flow path of the outdoor heat exchanger, the outlet temperature of the outdoor heat exchanger, the flash temperature, the total inlet temperature of the indoor heat exchanger, and the current compressor frequency; the preset target control parameters include: the target high-temperature suction superheat and / or the target low-temperature suction superheat; the predetermined fitting parameters include: the high-temperature liquid pipe saturation temperature drop, the high-temperature suction pipe saturation temperature drop, the low-temperature suction pipe saturation temperature drop, the compressor high-temperature cylinder volumetric efficiency, and the compressor low-temperature cylinder volumetric efficiency.

10. A storage medium, characterized by It stores a computer program that, when executed by a processor, implements the steps of the method according to any one of claims 1-8.

11. An air conditioning system, characterized in that, It includes a processor, a memory, and a computer program stored in the memory that can run on the processor, wherein the processor executes the program to implement the steps of any of the methods of claims 1-8, or includes the control device as described in claim 9.

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