A control method and device of an air conditioning system, the air conditioning system and a storage medium

Abstract

The application discloses a kind of control method, device, air conditioning system and storage medium of air conditioning system, first electronic expansion valve is arranged between first heat exchanger and flash vessel in air conditioning system, second electronic expansion valve is arranged between second heat exchanger and flash vessel;The method comprises: in refrigeration mode or heating mode, obtain the operating parameter of air conditioning system, recorded as first parameter;According to first parameter and pre-design calculation method, the opening of first electronic expansion valve and second electronic expansion valve is controlled;After setting time, the operating parameter of air conditioning system is obtained again, recorded as second parameter;According to the operating mode of air conditioning system, second parameter and pre-design calculation method, the opening of first electronic expansion valve and second electronic expansion valve is controlled respectively.The scheme, by different control logic respectively to two electronic expansion valves are controlled, the decoupling of electronic expansion valve is realized, the complexity of control is reduced, and the reliability of air conditioning system operation is improved.

Description

Technical Field

[0001] This invention belongs to the field of air conditioning technology, specifically relating to a control method, device, air conditioning system, and storage medium for an air conditioning system, and particularly to a control method, device, air conditioning system, and storage medium for decoupling an electronic expansion valve in an air conditioning system. Background Technology

[0002] Electronic expansion valves are widely used in heat pump air conditioning systems due to their wide adjustment range, high adjustment accuracy, and fast response speed. Existing electronic expansion valve control strategies in heat pump air conditioning systems typically rely on feedback adjustment based on compressor suction or exhaust superheat. This method is mainly suitable for conventional single-stage systems with a single electronic expansion valve. When multiple electronic expansion valves are coupled in the system, conventional control strategies become inapplicable.

[0003] The relevant scheme uses a parallel compression system to reduce the enthalpy at the evaporator inlet and increase the cooling capacity per unit mass by using a parallel supplementary gas compressor. However, the two electronic expansion valves in this system are strongly coupled, which makes the system operation and control complex and difficult.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a control method, device, air conditioning system, and storage medium for an air conditioning system, in order to solve the problem that the strong coupling between the two electronic expansion valves in the parallel compression system in related solutions leads to complex and difficult system operation control. The invention achieves the decoupling of the electronic expansion valves by controlling the two electronic expansion valves separately according to different control logics through a preset calculation method, thereby reducing the complexity of air conditioning system control and improving the reliability of air conditioning system operation.

[0006] This invention provides a control method for an air conditioning system, the air conditioning system comprising: a parallel compressor, a four-way valve, a first heat exchanger, a second heat exchanger, a first electronic expansion valve, a second electronic expansion valve, and a flash evaporator; the parallel compressor includes a compressor main cylinder and a compressor auxiliary cylinder; the four-way valve is connected to the outlet of the parallel compressor, the first heat exchanger, the inlet of the compressor main cylinder, and the second heat exchanger respectively; the first heat exchanger is connected to the first electronic expansion valve; the first electronic expansion valve is connected to the flash evaporator; one end of the outlet of the flash evaporator is connected to the second electronic expansion valve, and the other end is connected to the compressor. The auxiliary cylinder inlet is connected; the second electronic expansion valve is connected to the second heat exchanger; the method includes: when the air conditioning system is operating in cooling mode or heating mode, acquiring the operating parameters of the air conditioning system and recording them as first parameters; controlling the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve according to the first parameters and a preset calculation method; then, after a set time, acquiring the operating parameters of the air conditioning system again and recording them as second parameters; controlling the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve according to the operating mode of the air conditioning system, the second parameters, and the preset calculation method.

[0007] In some embodiments, the first parameter and the second parameter include: the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, the inlet temperature of the second heat exchanger, and the outlet temperature of the first heat exchanger; the preset calculation method includes: in refrigeration mode, calculating the suction dryness fraction of the parallel compressor based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the outlet temperature of the first heat exchanger; based on the magnitude of the suction dryness fraction of the parallel compressor, Calculate the refrigerant flow rate of the second heat exchanger; based on the refrigerant flow rate of the second heat exchanger, calculate the opening values ​​of the first electronic expansion valve and the second electronic expansion valve respectively; and / or, in heating mode, calculate the suction dryness of the parallel compressor based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the inlet temperature of the second heat exchanger; calculate the refrigerant flow rate of the first heat exchanger based on the suction dryness of the parallel compressor; and calculate the opening values ​​of the first electronic expansion valve and the second electronic expansion valve respectively based on the refrigerant flow rate of the first heat exchanger.

[0008] In some implementations, controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the first parameter and a preset calculation method includes: substituting the first parameter into the preset calculation method to obtain the opening degree values ​​of the first electronic expansion valve and the second electronic expansion valve; and controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the opening degree values ​​of the first electronic expansion valve and the second electronic expansion valve.

[0009] In some embodiments, controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the operating mode of the air conditioning system, the second parameter, and a preset calculation method includes: when the operating mode of the air conditioning system is cooling mode, calculating the suction dryness of the parallel compressor according to the second parameter; determining whether the suction dryness of the parallel compressor is within a set range; if the suction dryness of the parallel compressor is not within the set range, controlling the opening degree of the second electronic expansion valve according to the second parameter; then, substituting the current operating parameters of the air conditioning system into the preset calculation method to obtain the opening degree value of the first electronic expansion valve; and controlling the opening degree of the first electronic expansion valve according to the opening degree value of the first electronic expansion valve.

[0010] In some embodiments, controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the operating mode of the air conditioning system, the second parameter, and the preset calculation method further includes: when the operating mode of the air conditioning system is heating mode, calculating the suction dryness of the parallel compressor according to the second parameter; determining whether the suction dryness of the parallel compressor is within a set range; if the suction dryness of the parallel compressor is not within the set range, controlling the opening degree of the first electronic expansion valve according to the second parameter; then, substituting the current operating parameters of the air conditioning system into the preset calculation method to obtain the opening degree value of the second electronic expansion valve; and controlling the opening degree of the second electronic expansion valve according to the opening degree value of the second electronic expansion valve.

[0011] In conjunction with the above method, another aspect of the present invention provides a control device for an air conditioning system, the air conditioning system comprising: a parallel compressor, a four-way valve, a first heat exchanger, a second heat exchanger, a first electronic expansion valve, a second electronic expansion valve, and a flash evaporator; the parallel compressor includes a compressor main cylinder and a compressor auxiliary cylinder; the four-way valve is connected to the outlet of the parallel compressor, the first heat exchanger, the inlet of the compressor main cylinder, and the second heat exchanger respectively; the first heat exchanger is connected to the first electronic expansion valve; the first electronic expansion valve is connected to the flash evaporator; one end of the outlet of the flash evaporator is connected to the second electronic expansion valve, and the other end is connected to the inlet of the compressor auxiliary cylinder; the second electronic expansion valve... An expansion valve is connected to the second heat exchanger; the device includes: an acquisition unit configured to acquire operating parameters of the air conditioning system, denoted as a first parameter, when the air conditioning system is operating in cooling mode or heating mode; a control unit configured to control the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve according to the first parameter and a preset calculation method; thereafter, the acquisition unit is further configured to acquire the operating parameters of the air conditioning system again, denoted as a second parameter, after a set time; the control unit is further configured to control the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve according to the operating mode of the air conditioning system, the second parameter, and the preset calculation method, respectively.

[0012] In some embodiments, the first parameter and the second parameter include: the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, the inlet temperature of the second heat exchanger, and the outlet temperature of the first heat exchanger; the preset calculation method includes: in refrigeration mode, calculating the suction dryness fraction of the parallel compressor based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the outlet temperature of the first heat exchanger; based on the magnitude of the suction dryness fraction of the parallel compressor, Calculate the refrigerant flow rate of the second heat exchanger; based on the refrigerant flow rate of the second heat exchanger, calculate the opening values ​​of the first electronic expansion valve and the second electronic expansion valve respectively; and / or, in heating mode, calculate the suction dryness of the parallel compressor based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the inlet temperature of the second heat exchanger; calculate the refrigerant flow rate of the first heat exchanger based on the suction dryness of the parallel compressor; and calculate the opening values ​​of the first electronic expansion valve and the second electronic expansion valve respectively based on the refrigerant flow rate of the first heat exchanger.

[0013] In some embodiments, the control unit controls the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the first parameter and a preset calculation method, including: substituting the first parameter into the preset calculation method to obtain the opening degree values ​​of the first electronic expansion valve and the second electronic expansion valve; and controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the opening degree values ​​of the first electronic expansion valve and the second electronic expansion valve.

[0014] In some embodiments, the control unit controls the opening degree of the first electronic expansion valve and the second electronic expansion valve respectively according to the operating mode of the air conditioning system, the second parameter, and a preset calculation method, including: when the operating mode of the air conditioning system is cooling mode, calculating the suction dryness of the parallel compressor according to the second parameter; determining whether the suction dryness of the parallel compressor is within a set range; if the suction dryness of the parallel compressor is not within the set range, controlling the opening degree of the second electronic expansion valve according to the second parameter; then substituting the current operating parameters of the air conditioning system into the preset calculation method to obtain the opening degree value of the first electronic expansion valve; and controlling the opening degree of the first electronic expansion valve according to the opening degree value of the first electronic expansion valve.

[0015] In some embodiments, the control unit controls the opening degree of the first electronic expansion valve and the second electronic expansion valve respectively according to the operating mode of the air conditioning system, the second parameter, and the preset calculation method. The control unit further includes: when the operating mode of the air conditioning system is heating mode, calculating the suction dryness of the parallel compressor according to the second parameter; determining whether the suction dryness of the parallel compressor is within a set range; if the suction dryness of the parallel compressor is not within the set range, controlling the opening degree of the first electronic expansion valve according to the second parameter; then, substituting the current operating parameters of the air conditioning system into the preset calculation method to obtain the opening degree value of the second electronic expansion valve; and controlling the opening degree of the second electronic expansion valve according to the opening degree value of the second electronic expansion valve.

[0016] In conjunction with the above-described device, the present invention further provides an air conditioning system, comprising: the control device for the air conditioning system described above.

[0017] In conjunction with the above method, the present invention further provides a storage medium comprising a stored program, wherein, when the program is executed, the device on which the storage medium is located controls the execution of the control method of the air conditioning system described above.

[0018] The present invention controls the opening degree of the first electronic expansion valve and the second electronic expansion valve respectively according to the operating parameters at different times and the preset calculation method when the air conditioning system is operating in cooling mode or heating mode. This decouples the opening degree control of the first electronic expansion valve and the second electronic expansion valve, reduces the complexity of the air conditioning system, and improves the control response speed and operational reliability of the air conditioning system.

[0019] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating an embodiment of the control method for an air conditioning system according to the present invention;

[0022] Figure 2 This is a schematic flowchart of an embodiment of the method of the present invention for controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve;

[0023] Figure 3 This is a schematic flowchart of an embodiment of the method of the present invention, which controls the opening degree of the first electronic expansion valve and the second electronic expansion valve respectively in the cooling mode.

[0024] Figure 4 This is a schematic flowchart of an embodiment of the method of the present invention, which controls the opening degree of the first electronic expansion valve and the second electronic expansion valve respectively in the heating mode.

[0025] Figure 5 This is a schematic diagram of the structure of an embodiment of the control device for the air conditioning system of the present invention;

[0026] Figure 6 This is a schematic diagram of a system structure of an embodiment of the air conditioning system of the present invention;

[0027] Figure 7 This is a flowchart illustrating an embodiment of the control method for an air conditioning system in cooling mode according to the present invention;

[0028] Figure 8 This is a flowchart illustrating an embodiment of the control method for the air conditioning system in heating mode according to the present invention.

[0029] Figure 9 This is a flowchart illustrating an embodiment of the electronic expansion valve opening calculation method for an air conditioning system in cooling mode according to the present invention.

[0030] Figure 10This is a flowchart illustrating an embodiment of the electronic expansion valve opening calculation method for an air conditioning system in heating mode according to the present invention.

[0031] Referring to the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0032] 1-Parallel compressor auxiliary cylinder; 2-Parallel compressor main cylinder; 3-Four-way valve; 4-First heat exchanger; 5-First electronic expansion valve; 6-Flash evaporator; 7-Second electronic expansion valve; 8-Second heat exchanger; 102-Acquisition unit; 104-Control unit. Detailed Implementation

[0033] 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.

[0034] According to an embodiment of the present invention, a control method for an air conditioning system is provided. The air conditioning system includes: a parallel compressor, a four-way valve, a first heat exchanger, a second heat exchanger, a first electronic expansion valve, a second electronic expansion valve, and a flash evaporator. The parallel compressor includes a compressor main cylinder and a compressor auxiliary cylinder. The outlet of the compressor main cylinder is connected to the outlet of the compressor auxiliary cylinder and then connected to the four-way valve. The four-way valve is connected to the outlet of the parallel compressor, the first heat exchanger, the inlet of the compressor main cylinder, and the second heat exchanger. The first heat exchanger is connected to the first electronic expansion valve. The first electronic expansion valve is connected to the flash evaporator. One end of the outlet of the flash evaporator is connected to the second electronic expansion valve, and the other end is connected to the inlet of the compressor auxiliary cylinder. The second electronic expansion valve is connected to the second heat exchanger. Specifically, as shown... Figure 6The diagram shows the structural structure of the air conditioning system, which includes: a parallel compressor auxiliary cylinder 1, a parallel compressor main cylinder 2, a four-way valve 3, a first heat exchanger 4, a first electronic expansion valve 5, a flash evaporator 6, a second electronic expansion valve 7, and a second heat exchanger 8. When the air conditioning system is operating in cooling mode, the slider of the four-way valve 3 moves to the left, connecting the E and S ends and the D and C ends. The high-temperature, high-pressure refrigerant gas discharged from the compressor main cylinder 2 and the high-temperature, high-pressure refrigerant gas discharged from the compressor auxiliary cylinder 1 mix and enter the first heat exchanger 4 through the four-way valve 3. After cooling and condensing, the refrigerant passes through the first electronic expansion valve 5 to a throttled pressure state and enters the flash evaporator 6. In the flash evaporator, gas and liquid are separated into saturated or near-saturated gas and liquid. The saturated or near-saturated gas enters the compressor auxiliary cylinder 1 through the supplementary gas branch to complete the second refrigerant cycle; the saturated or near-saturated liquid enters the second heat exchanger 8 through the second electronic expansion valve 7, where it absorbs heat from the indoor air and evaporates. Then, it passes through the four-way valve 3 and enters the compressor main cylinder 2 to complete the first refrigerant cycle. When the air conditioning system is operating in heating mode, the slider of the four-way valve 3 moves to the right, opening the connection between terminals C and S, and between terminals D and E. The refrigerant gas discharged from the compressor passes through the four-way valve 3 and enters the second heat exchanger 8 for circulation. Figure 1 The diagram shows a flowchart of an embodiment of the method of the present invention. The control method of the air conditioning system may include steps S110 to S140.

[0035] In step S110, when the air conditioning system is operating in cooling mode or heating mode, the operating parameters of the air conditioning system are acquired and recorded as the first parameter.

[0036] In step S120, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled according to the first parameter and the preset calculation method.

[0037] In step S130, after a set time, the operating parameters of the air conditioning system are acquired again and recorded as the second parameter.

[0038] In some embodiments, the first parameter and the second parameter include: the operating frequency of the parallel compressor, the exhaust temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, the inlet temperature of the second heat exchanger, and the outlet temperature of the first heat exchanger; wherein, the temperature at the first heat exchanger and the temperature at the second heat exchanger refer to the temperature in the middle of the heat exchanger flow path, specifically the temperature in the middle of the heat exchanger or at the small bend of the U-tube relative to the middle.

[0039] In step S140, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled according to the operating mode of the air conditioning system, the second parameter and the preset calculation method.

[0040] In some embodiments, the preset calculation method includes: in refrigeration mode, calculating the suction dryness of the parallel compressor based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the outlet temperature of the first heat exchanger; calculating the refrigerant flow rate of the second heat exchanger based on the suction dryness of the parallel compressor; and calculating the opening values ​​of the first electronic expansion valve and the second electronic expansion valve based on the refrigerant flow rate of the second heat exchanger.

[0041] Specifically, the preset calculation method includes pre-set parameters for calculation, including: parallel compressor displacement V. rev ; First electronic expansion valve flow correction coefficient K c1 , is the conversion coefficient between refrigerant flow and air flow of the electronic expansion valve, which is an empirical value; the second electronic expansion valve flow correction coefficient K. c2 , is the conversion coefficient between refrigerant flow rate and air flow rate of the electronic expansion valve, which is an empirical value; the air flow rate coefficient C of the first electronic expansion valve. 1_1 C 1_2 C 1_3 , where is the correlation coefficient for fitting the airflow curve of the first electronic expansion valve; and C is the airflow coefficient of the second electronic expansion valve. 2_1 C 2_2 C 2_3 , where is the correlation coefficient for fitting the air flow curve of the second electronic expansion valve.

[0042] Figure 9 This is a flowchart illustrating an embodiment of the electronic expansion valve opening calculation method for an air conditioning system in cooling mode according to the present invention. The electronic expansion valve opening calculation method in cooling mode includes steps 1 to 10.

[0043] Step 1, obtain the temperature t at the second heat exchanger. e The discharge temperature t of the parallel compressor dis Temperature t at the first heat exchanger c The outlet temperature t of the first heat exchanger c_o The operating frequency f of the parallel compressor.

[0044] Step 2: Calculate the liquid pipe saturation temperature drop dt based on the operating frequency f of the parallel compressor. sat_ll With the saturation temperature drop dt of the intake line sat_suc The suction saturation temperature t is calculated based on the temperature at the second heat exchanger and the saturation temperature drop in the suction line. suc_sat .

[0045] Specifically, the liquid pipe refers to the pipe between the second electronic expansion valve and the second heat exchanger. The calculation of the liquid pipe saturation temperature drop dt is then performed. sat_llThe formula is: dt sat_ll = a1*f*f+b1*f+c1, where a1, b1, and c1 are empirical values, and f is the operating frequency of the parallel compressor.

[0046] Calculate the saturation temperature drop dt of the intake line sat_suc The formula is: dt sat_suc = a2*f*f+b2*f+c2, where a2, b2, and c2 are empirical values.

[0047] Calculate the intake saturation temperature t suc_sat The formula is: t suc_sat =t e -dt sat_suc .

[0048] Step 3, based on the outlet temperature t of the first heat exchanger c_o Intake saturation temperature t suc_sat Given the operating frequency f of the parallel compressor, calculate the target flash temperature t. ft_target According to the outlet temperature t of the first heat exchanger c_o and target flash temperature t ft_target Calculate the specific enthalpy h at the outlet of the first heat exchanger. c_o Enthalpy of flash saturated liquid h f latent heat of flash phase transition h fg Flash dryness of flash generator x ft .

[0049] Specifically, the target flash temperature t is calculated. ft_target The formula is: t ft_target =a3*t c_o +b3*t suc_sat +c3*f+d3, where a3, b3, c3, and d3 are empirical values.

[0050] The specific enthalpy h of a subcooled / saturated refrigerant is given by: h = a⁴ * t * t + b⁴ * t + c⁴, where a⁴, b⁴, and c⁴ are values ​​obtained from refrigerant property software, and t is the temperature. For example, for R32 refrigerant, h = 0.0039 * t * t + 1.7246 * t + 200.06. This formula can be used to calculate the specific enthalpy h at the outlet of the first heat exchanger. c_o Enthalpy h of flash saturated liquid f .

[0051] Calculate the latent heat of flash phase transition h fg The formula is: h=a5*t*t+b5*t+c5, where a5, b5, and c5 are values ​​obtained by fitting from refrigerant property software, and t is the temperature value. For example, for R32 refrigerant, h=-0.0181*t*t-1.1988*t+313.22.

[0052] Calculate the flash dryness of the flash generator x ft The formula is: x ft =(h c_o -h f ) / h fg .

[0053] Step 4, based on the temperature t at the first heat exchanger c The discharge temperature t of the parallel compressor dis Intake saturation temperature t suc_sat Given the operating frequency f of the parallel compressor, calculate the suction dryness fraction x of the parallel compressor. suc Parallel compressor volumetric efficiency η v Specific volume of inhaled saturated gas v sat_g Specific volume of saturated liquid during intake (v) sat_l .

[0054] Specifically, calculate the suction dryness of the parallel compressor x. suc The formula is: x suc =a6*t c +b6*t suc_sat +c6*t dis +d6*f+e6, where a6, b6, c6, d6, and e6 are empirical values.

[0055] Calculate the volumetric efficiency η of the parallel compressor v The formula is: η v =a7*t c +b7*t suc_sat +c7*f+d7, where a7, b7, c7, and d7 are empirical values.

[0056] Calculate the specific volume v of the saturated inhaled gas. sat_g The formula is: v sat_g =a8*t suc_sat *t suc_sat +b8*t suc_sat +c8, where a8, b8, and c8 are values ​​fitted from refrigerant property software, for example, for R32 refrigerant, v sat_g =1.5991*10 -5 *t suc_sat *t suc_sat -1.3561*10 -3 *t suc_sat +4.5105*10 -2 .

[0057] Calculate the specific volume v of the saturated getter liquid. sat_l The formula is: v sat_l =a9*t suc_sat *t suc_sat +b9*t suc_sat+c9, where a9, b9, and c9 are values ​​fitted from refrigerant property software, for example, R32 refrigerant, v sat_l =2.8252*10 -8 *t suc_sat *t suc_sat +3.0*10 -6 *t suc_sat +9.4781*10 -4 .

[0058] Step 5, determine the inhalation dryness x suc The size, if the absorbance dryness x suc If the value is greater than 1, then based on the temperature t at the first heat exchanger... c The discharge temperature t of the parallel compressor dis Intake saturation temperature t suc_sat Calculate the operating frequency f of the parallel compressor and the suction superheat dt of the parallel compressor. suc_sh Furthermore, the specific volume of intake gas under superheated conditions, v, was calculated. suc If the inhalation dryness is x suc If ≤1, then based on the suction dryness fraction of the parallel compressor x suc Specific volume of inhaled saturated gas v sat_g Specific volume of saturated liquid during intake (v) sat_l The specific volume of the intake gas under two-phase conditions, v, was calculated using a dryness-weighted method. suc .

[0059] Specifically, the suction superheat dt of the parallel compressor is calculated. suc_sh The formula is: dt suc_sh =a 10 *t c +b 10 *t suc_sat +c 10 *t dis +d 10 *f+e 10 , where a 10 b 10 c 10 d 10 e 10 These are empirical values.

[0060] Inhalation dryness x suc When >1, calculate the specific volume of intake gas under superheated conditions, v. suc The formula is: v suc =v sat_g *(a 11 *t suc_sat +b 11 *dt suc_sh +c 11 ), where a 11 b11 c 11 To obtain numerical values ​​from refrigerant property software, such as R32 refrigerant, v suc =v sat_g *(1.976*10 -3 *t suc_sat +7.649*10 -3 *dt suc_sh +0.9988).

[0061] Inhalation dryness x suc When ≤1, calculate the specific volume of intake gas v under two-phase conditions. suc The formula is: v suc =x suc *v sat_g +(1-x suc )*v sat_l .

[0062] Step 6, according to the preset parameters, compressor displacement V rev The operating frequency f of the parallel compressor and the volumetric efficiency η of the parallel compressor. v Inspiratory specific volume v suc The refrigerant flow rate M of the second heat exchanger was calculated. e Calculate the refrigerant flow rate M of the second heat exchanger. e The formula is: M e =V rev *f*η v / v suc The refrigerant flow rate M of the second heat exchanger e That is, the refrigerant flow rate M of the second electronic expansion valve r_2 .

[0063] Step 7, based on the saturation temperatures (t) before and after the first and second electronic expansion valves. c t ft_target ) and (t ft_target t e +dt sat_ll The pressure difference Δp across the first and second electronic expansion valves was calculated. r1 , △p r2 ; and based on the outlet temperature t of the first heat exchanger c_o and target flash temperature t ft_target The inlet densities ρ of the first and second electronic expansion valves were calculated respectively. r1 ρ r2 .

[0064] Specifically, the saturated vapor pressure of the refrigerant is p = a 12 *t*t+b 12 *t+c 12 , where a12 b 12 c 12 To obtain numerical values ​​from refrigerant property software, for example, for R32 refrigerant, p = 509.46 * t * t + 20853 * t + 839607. Based on the formula for calculating the saturated vapor pressure of the refrigerant, the pressure difference Δp across the second electronic expansion valve can be calculated. r2 =f(t) ft_target ,t e ,dt sat_ll The pressure difference Δp across the first electronic expansion valve and the first electronic expansion valve r1 =f(t) c ,t ft_target ).

[0065] Refrigerant saturated liquid density ρ=a 13 *t*t+b 13 *t+c 13 , where a 13 b 13 c 13 To obtain numerical values ​​from refrigerant property software, for example, for R32 refrigerant, ρ = -0.031*t*t - 2.7548t + 1051.3. The inlet density ρ of the first electronic expansion valve. r1 =f(t) c_o The inlet density ρ of the second electronic expansion valve r2 =f(t) ft_target ).

[0066] Step 8, based on the refrigerant flow rate M of the second electronic expansion valve r_2 Flash dryness x ft Calculate the refrigerant flow rate M of the first electronic expansion valve. r_1 The formula is: M r_1 =M r_2 / (1-(1+E)x ft ), where E is the liquid carryover rate (the ratio of liquid mass flow rate to gas mass flow rate). When the flash generator has a good gas-liquid separation effect and the gas supply path is saturated gas, E is 0.

[0067] Step 9: According to the preset parameters, the flow correction coefficient K of the two electronic expansion valves is adjusted. c1 and K c2 and the pressure difference Δp across the first electronic expansion valve r1 The pressure difference Δp across the second electronic expansion valve r2 The inlet density ρ of the first electronic expansion valve r1 The inlet density ρ of the second electronic expansion valve r2 Second electronic expansion valve refrigerant flow rate M r_2 First electronic expansion valve refrigerant flow rate M r_1The air flow rate V of the first electronic expansion valve was calculated. a_o_1 Second electronic expansion valve air flow V a_o_2 The formula is: V a_o =K c M r_ / (ρ r *△p r 0.5 ).

[0068] Step 10, based on the air flow rate V of the first electronic expansion valve a_o_1 Second electronic expansion valve air flow V a_o_2 Calculate the opening degree B1 of the first electronic expansion valve and the opening degree B2 of the second electronic expansion valve. The formula is V a_o =C1*B*B+C2*B+C3, where B is the opening value of the electronic expansion valve, and C1, C2, and C3 are fitted values. For example, the opening value of the first electronic expansion valve in the figure is B1 = (-C 1_1 +(C 1_1 2 -4*C 1_2 *(C 1_0 -V a_o_1 )) 0.5 ) / (2*C 1_2 ); The opening degree of the second electronic expansion valve B2 = (-C 2_1 +(C 2_1 2 -4*C 2_1 *(C 2_0 -V a_o_2 )) 0.5 ) / (2*C 2_2 ).

[0069] The present invention empirically fits the potential relationships between various state parameters of the air conditioning system and various physical parameters of the refrigerant. Based on the acquired temperature data, it accurately calculates the operating parameters of the air conditioning system and the opening degree of the electronic expansion valve, thereby reducing the complexity of control and improving the accuracy and response rate of the air conditioning system control.

[0070] In some embodiments, the preset calculation method further includes: in heating mode, calculating the suction dryness of the parallel compressor based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the inlet temperature of the second heat exchanger; calculating the refrigerant flow rate of the first heat exchanger based on the suction dryness of the parallel compressor; and calculating the opening values ​​of the first electronic expansion valve and the second electronic expansion valve based on the refrigerant flow rate of the first heat exchanger.

[0071] Figure 10This is a flowchart illustrating an embodiment of the electronic expansion valve opening calculation method for an air conditioning system in heating mode according to the present invention. The electronic expansion valve opening calculation method in heating mode includes steps 31 to 40.

[0072] Step 31, obtain the temperature t at the second heat exchanger. e The discharge temperature t of the parallel compressor dis Temperature t at the first heat exchanger c The inlet temperature t of the second heat exchanger e_in The operating frequency f of the parallel compressor.

[0073] Step 32: Calculate the liquid pipe saturation temperature drop dt based on the operating frequency f of the parallel compressor. sat_ll With the saturation temperature drop dt of the intake line sat_suc The suction saturation temperature t is calculated based on the temperature at the second heat exchanger and the saturation temperature drop in the suction line. suc_sat .

[0074] Specifically, the liquid pipe refers to the pipe between the second electronic expansion valve and the second heat exchanger. The calculation of the liquid pipe saturation temperature drop dt is then performed. sat_ll The formula is: dt sat_ll = a1*f*f+b1*f+c1, where a1, b1, and c1 are empirical values, and f is the operating frequency of the parallel compressor.

[0075] Calculate the saturation temperature drop dt of the intake line sat_suc The formula is: dt sat_suc = a2*f*f+b2*f+c2, where a2, b2, and c2 are empirical values.

[0076] Calculate the intake saturation temperature t suc_sat The formula is: t suc_sat =t c -dt sat_suc .

[0077] Step 33, based on the inlet temperature t of the second heat exchanger e_in Intake saturation temperature t suc_sat Given the operating frequency f of the parallel compressor, calculate the target flash temperature t. ft_target According to the inlet temperature t of the second heat exchanger e_in and target flash temperature t ft_target Calculate the specific enthalpy h at the inlet of the second heat exchanger. e_in Enthalpy of flash saturated liquid h f latent heat of flash phase transition h fg Flash dryness of flash generator x ft .

[0078] Specifically, the target flash temperature t is calculated. ft_target The formula is: tft_target =a3*t e_in +b3*t suc_sat +c3*f+d3, where a3, b3, c3, and d3 are empirical values.

[0079] The specific enthalpy h of a subcooled / saturated refrigerant is given by: h = a⁴ * t * t + b⁴ * t + c⁴, where a⁴, b⁴, and c⁴ are values ​​obtained from refrigerant property software, and t is the temperature. For example, for R32 refrigerant, h = 0.0039 * t * t + 1.7246 * t + 200.06. This formula can be used to calculate the inlet specific enthalpy h of the second heat exchanger. e_in Enthalpy h of flash saturated liquid f .

[0080] Calculate the latent heat of flash phase transition h fg The formula is: h=a5*t*t+b5*t+c5, where a5, b5, and c5 are values ​​obtained by fitting from refrigerant property software, and t is the temperature value. For example, for R32 refrigerant, h=-0.0181*t*t-1.1988*t+313.22.

[0081] Calculate the flash dryness of the flash generator x ft The formula is: x ft =(h e_in -h f ) / h fg .

[0082] Step 34, based on the temperature t at the second heat exchanger e The discharge temperature t of the parallel compressor dis Intake saturation temperature t suc_sat Given the operating frequency f of the parallel compressor, calculate the suction dryness fraction x of the parallel compressor. suc Parallel compressor volumetric efficiency η v Specific volume of inhaled saturated gas v sat_g Specific volume of saturated liquid during intake (v) sat_l .

[0083] Specifically, calculate the suction dryness of the parallel compressor x. suc The formula is: x suc =a6*t e +b6*t suc_sat +c6*t dis +d6*f+e6, where a6, b6, c6, d6, and e6 are empirical values.

[0084] Calculate the volumetric efficiency η of a parallel compressor v The formula is: η v =a7*t e +b7*t suc_sat+c7*f+d7, where a7, b7, c7, and d7 are empirical values.

[0085] Calculate the specific volume v of the saturated inhaled gas. sat_g The formula is: v sat_g =a8*t suc_sat *t suc_sat +b8*t suc_sat +c8, where a8, b8, and c8 are values ​​fitted from refrigerant property software, for example, for R32 refrigerant, v sat_g =1.5991*10 -5 *t suc_sat *t suc_sat -1.3561*10 -3 *t suc_sat +4.5105*10 -2 .

[0086] Calculate the specific volume v of the saturated getter liquid. sat_l The formula is: v sat_l =a9*t suc_sat *t suc_sat +b9*t suc_sat +c9, where a9, b9, and c9 are values ​​fitted from refrigerant property software, for example, R32 refrigerant, v sat_l =2.8252*10 -8 *t suc_sat *t suc_sat +3.0*10 -6 *t suc_sat +9.4781*10 -4 .

[0087] Step 35, determine the inhalation dryness x suc The size, if the absorbance dryness x suc If the value is greater than 1, then based on the temperature t at the second heat exchanger... e The discharge temperature t of the parallel compressor dis Intake saturation temperature t suc_sat Calculate the operating frequency f of the parallel compressor and the suction superheat dt of the parallel compressor. suc_sh Furthermore, the specific volume of intake gas under superheated conditions, v, was calculated. suc If the inhalation dryness is x suc If ≤1, then based on the suction dryness fraction of the parallel compressor x suc Specific volume of inhaled saturated gas v sat_g Specific volume of saturated liquid during intake (v) sat_l The specific volume of the intake gas under two-phase conditions, v, was calculated using a dryness-weighted method. suc .

[0088] Specifically, the suction superheat dt of the parallel compressor is calculated.suc_sh The formula is: dt suc_sh =a 10 *t e +b 10 *t suc_sat +c 10 *t dis +d 10 *f+e 10 , where a 10 b 10 c 10 d 10 e 10 These are empirical values.

[0089] Inhalation dryness x suc When >1, calculate the specific volume of intake gas under superheated conditions, v. suc The formula is: v suc =v sat_g *(a 11 *t suc_sat +b 11 *dt suc_sh +c 11 ), where a 11 b 11 c 11 To obtain numerical values ​​from refrigerant property software, such as R32 refrigerant, v suc =v sat_g *(1.976*10 -3 *t suc_sat +7.649*10 -3 *dt suc_sh +0.9988).

[0090] Inhalation dryness x suc When ≤1, calculate the specific volume of intake gas v under two-phase conditions. suc The formula is: v suc =x suc *v sat_g +(1-x suc )*v sat_l .

[0091] Step 36, according to the preset parameter, compressor displacement V rev The operating frequency f of the parallel compressor and the volumetric efficiency η of the parallel compressor. v Inspiratory specific volume v suc The refrigerant flow rate M of the first heat exchanger was calculated. c Calculate the refrigerant flow rate M of the first heat exchanger. c The formula is: M c =V rev *f*η v / v sucThe refrigerant flow rate M of the first heat exchanger c That is, the refrigerant flow rate M of the first electronic expansion valve r_1 .

[0092] Step 37, based on the saturation temperatures (t) before and after the first electronic expansion valve and the second electronic expansion valve. c t ft_target ) and (t ft_target t e +dt sat_ll The pressure difference Δp across the first and second electronic expansion valves was calculated. r1 , △p r2 ; and based on the inlet temperature t of the second heat exchanger e_in and target flash temperature t ft_target The inlet densities ρ of the first and second electronic expansion valves were calculated respectively. r1 ρ r2 .

[0093] Specifically, the saturated vapor pressure of the refrigerant is p = a 12 *t*t+b 12 *t+c 12 , where a 12 b 12 c 12 To obtain numerical values ​​from refrigerant property software, for example, for R32 refrigerant, p = 509.46 * t * t + 20853 * t + 839607. Based on the formula for calculating the saturated vapor pressure of the refrigerant, the pressure difference Δp across the first electronic expansion valve can be derived. r1 =f(t) ft_target ,t c ,dt sat_ll The pressure difference Δp across the second electronic expansion valve r2 =f(t) e ,t ft_target ).

[0094] Refrigerant saturated liquid density ρ=a 13 *t*t+b 13 *t+c 13 , where a 13 b 13 c 13 To obtain numerical values ​​from refrigerant property software, for example, for R32 refrigerant, ρ = -0.031*t*t - 2.7548t + 1051.3. The inlet density ρ of the second electronic expansion valve... r2 =f(t) e_in ), the inlet density ρ of the first electronic expansion valve r1 =f(t) ft_target ).

[0095] Step 38, based on the refrigerant flow rate M of the first electronic expansion valve r_1 Flash dryness x ft Calculate the refrigerant flow rate M of the second electronic expansion valve. r_2 The formula is: M r_2 =M r_1 / (1-(1+E)x ft ), where E is the liquid carryover rate (the ratio of liquid mass flow rate to gas mass flow rate). When the flash generator has a good gas-liquid separation effect and the gas supply path is saturated gas, E is 0.

[0096] Step 39: Based on the preset parameters, the flow correction coefficients K of the two electronic expansion valves are adjusted. c1 and K c2 and the pressure difference Δp across the first electronic expansion valve r1 The pressure difference Δp across the second electronic expansion valve r2 The inlet density ρ of the first electronic expansion valve r1 The inlet density ρ of the second electronic expansion valve r2 Second electronic expansion valve refrigerant flow rate M r_2 First electronic expansion valve refrigerant flow rate M r_1 The air flow rate V of the first electronic expansion valve was calculated. a_o_1 Second electronic expansion valve air flow V a_o_2 The formula is: V a_o =K c M r_ / (ρ r *△p r 0.5 ).

[0097] Step 40, based on the air flow rate V of the first electronic expansion valve a_o_1 Second electronic expansion valve air flow V a_o_2 Calculate the opening degree B1 of the first electronic expansion valve and the opening degree B2 of the second electronic expansion valve. The formula is V a_o =C1*B*B+C2*B+C3, where B is the opening value of the electronic expansion valve, and C1, C2, and C3 are fitted values. For example, the opening value of the first electronic expansion valve in the figure is B1 = (-C 1_1 +(C 1_1 2 -4*C 1_2 *(C 1_0 -V a_o_1 )) 0.5 ) / (2*C 1_2 ); The opening degree of the second electronic expansion valve B2 = (-C 2_1 +(C 2_1 2 -4*C 2_1 *(C 2_0 -Va_o_2 )) 0.5 ) / (2*C 2_2 ).

[0098] The present invention empirically fits the potential relationships between various state parameters of the air conditioning system and various refrigerant property parameters. Based on the acquired temperature data, it accurately calculates the operating parameters of the air conditioning system and the opening degree of the electronic expansion valve, thereby reducing the complexity of control and improving the accuracy and response rate of the air conditioning system control.

[0099] In some implementations, step S120 involves the specific process of controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the first parameter and a preset calculation method, such as... Figure 2 As shown, it includes steps S210 and S220.

[0100] Step S210: Substitute the first parameter into the preset calculation method to obtain the opening values ​​of the first electronic expansion valve and the second electronic expansion valve.

[0101] Step S220: Control the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the opening degree value of the first electronic expansion valve and the second electronic expansion valve.

[0102] In some implementations, step S140 involves the specific process of controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the operating mode of the air conditioning system, the second parameter, and the preset calculation method, such as... Figure 3 As shown, it includes steps S310 to S350.

[0103] Step S310: When the air conditioning system is in cooling mode, the suction dryness of the parallel compressor is calculated based on the second parameter.

[0104] Step S320: Determine whether the suction dryness of the parallel compressor is within the set range.

[0105] Step S330: If the suction dryness of the parallel compressor is not within the set range, the opening of the second electronic expansion valve is controlled according to the second parameter. Specifically, the opening of the second electronic expansion valve is adjusted according to the suction dryness feedback method.

[0106] Step S340: Substitute the current operating parameters of the air conditioning system into the preset calculation method to obtain the opening value of the first electronic expansion valve. The current operating parameters are of the same parameter type as the second parameter.

[0107] Step S350: Based on the opening value of the first electronic expansion valve, control the opening of the first electronic expansion valve, and then re-control the opening of the first electronic expansion valve and the second electronic expansion valve based on the operating mode of the air conditioning system, the second parameter and the preset calculation method.

[0108] The present invention addresses the issue of unstable suction dryness in parallel compressors by adjusting the openings of the first electronic expansion valve and the second electronic expansion valve separately based on different temperature data and opening adjustment methods, thereby achieving decoupled control of the two electronic expansion valves. Furthermore, based on empirical fitting formulas, the control process is made faster and more efficient, reducing control complexity and improving control response rate.

[0109] Figure 7 This is a flowchart illustrating an embodiment of the control method for an air conditioning system in cooling mode according to the present invention, as shown below. Figure 7 As shown, the control method of the present invention in cooling mode includes steps 15 to 18.

[0110] Step 15: When the air conditioning system is running in cooling mode, determine the operating frequency of the parallel compressor, the indoor fan speed, and the outdoor fan speed based on the indoor ambient temperature, outdoor ambient temperature, set temperature, and set indoor unit fan speed.

[0111] Step 16: Detect the temperature of each temperature sensor, specifically the temperature t at the second heat exchanger. e Exhaust temperature t dis Temperature t at the first heat exchanger c The outlet temperature t of the first heat exchanger c_o These parameters are then input into a preset calculation method to obtain the opening values ​​of the first electronic expansion valve and the second electronic expansion valve, and the opening of the first electronic expansion valve and the second electronic expansion valve are adjusted accordingly.

[0112] Step 17: After adjusting the opening of the first and second electronic expansion valves for a time T1 (T1 time ranges from 0 to 10 minutes, with a preferred value of 5 minutes), the temperature of each sensing bulb is detected again, and the suction dryness of the parallel compressor is calculated. suc Determine the suction dryness of the parallel compressor (x) suc Whether it is within the preset range, that is, whether a≤x suc ≤b (a<b, where a ranges from 0.98 to 1.0, and b ranges from 1.0 to 1.015). If a≤x suc If a ≤ b, the air conditioning system is determined to be in the target operating state, and after time T2 (T2 ranges from 0 minutes to 10 minutes, with a preferred value of 5 minutes), the process returns to step 16 and executes again; if a ≤ x is not satisfied... sucIf the value is less than or equal to b, then the air conditioning system is determined to be not in the target operating state, and step 18 is executed.

[0113] Step 18: Adjust the opening of the second electronic expansion valve according to the inhalation dryness feedback method. Specifically, when the inhalation dryness is less than a certain standard value, decrease the opening of the second electronic expansion valve; when the inhalation dryness is greater than a certain standard value, increase the opening of the second electronic expansion valve. Then, detect the temperature of each temperature sensor again and input these parameters into the preset calculation method to obtain the opening value of the first electronic expansion valve, and adjust the opening of the first electronic expansion valve accordingly.

[0114] This solution determines whether the air conditioning system is fluctuating based on the suction dryness of the parallel compressor. When fluctuations occur, it calculates the operating parameters of the air conditioning system and the opening of the electronic expansion valve in real time, and quickly adjusts the opening of the electronic expansion valve to near the optimal opening, thus shortening the adjustment time and improving the energy efficiency, stability and reliability of the air conditioning system.

[0115] In some implementations, step S140 involves the specific process of controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the operating mode of the air conditioning system, the second parameter, and the preset calculation method, such as... Figure 4 As shown, it includes steps S410 to S450.

[0116] Step S410: When the air conditioning system is in heating mode, the suction dryness of the parallel compressor is calculated based on the second parameter.

[0117] Step S420: Determine whether the suction dryness of the parallel compressor is within the set range.

[0118] Step S430: If the suction dryness of the parallel compressor is not within the set range, the opening of the first electronic expansion valve is controlled according to the second parameter. Specifically, the opening of the first electronic expansion valve is adjusted according to the suction dryness feedback method.

[0119] Step S440: Substitute the current operating parameters of the air conditioning system into the preset calculation method to obtain the opening value of the second electronic expansion valve; the current operating parameters are of the same parameter type as the second parameters.

[0120] Step S450: Based on the opening value of the second electronic expansion valve, control the opening of the second electronic expansion valve, and then re-control the opening of the first electronic expansion valve and the second electronic expansion valve based on the operating mode of the air conditioning system, the second parameter and the preset calculation method.

[0121] Figure 8 This is a flowchart illustrating an embodiment of the control method for an air conditioning system in heating mode according to the present invention, as shown below. Figure 8 As shown, the control method of the present invention in cooling mode includes steps 20 to 23.

[0122] Step 20: When the air conditioning system is running in heating mode, determine the operating frequency of the parallel compressor, the indoor fan speed, and the outdoor fan speed based on the indoor ambient temperature, the outdoor ambient temperature, the set temperature, and the set indoor unit fan speed.

[0123] Step 21: Detect the temperature of each temperature sensor, specifically the temperature t at the second heat exchanger. e Exhaust temperature t dis Temperature t at the first heat exchanger c The outlet temperature t of the first heat exchanger c_o These parameters are then input into a preset calculation method to obtain the opening values ​​of the first electronic expansion valve and the second electronic expansion valve, and the opening of the first electronic expansion valve and the second electronic expansion valve are adjusted accordingly.

[0124] Step 22: After adjusting the opening of the first and second electronic expansion valves for a time T1 (T1 time ranges from 0 to 10 minutes, with a preferred value of 5 minutes), the temperature of each sensing bulb is detected again, and the suction dryness of the parallel compressor is calculated. suc Determine the suction dryness of the parallel compressor (x) suc Whether it is within the preset range, that is, whether a≤x suc ≤b (a<b, where a ranges from 0.98 to 1.0, and b ranges from 1.0 to 1.015). If a≤x suc If a ≤ b, the air conditioning system is determined to be in the target operating state, and after time T2 (T2 ranges from 0 minutes to 10 minutes, with a preferred value of 5 minutes), the process returns to step 21 and executes again; if a ≤ x is not satisfied... suc If the value is less than or equal to b, then the air conditioning system is determined to be not in the target operating state, and step 23 is executed.

[0125] Step 23: Adjust the opening of the first electronic expansion valve according to the inhalation dryness feedback method. Specifically, when the inhalation dryness is less than a certain standard value, decrease the opening of the first electronic expansion valve; when the inhalation dryness is greater than a certain standard value, increase the opening of the first electronic expansion valve. Then, detect the temperature of each temperature sensor again and input these parameters into the preset calculation method to obtain the opening value of the second electronic expansion valve, and adjust the opening of the second electronic expansion valve accordingly.

[0126] This solution determines whether the air conditioning system is fluctuating based on the suction dryness of the parallel compressor. When fluctuations occur, it calculates the operating parameters of the air conditioning system and the opening of the electronic expansion valve in real time, and quickly adjusts the opening of the electronic expansion valve to near the optimal opening, thus shortening the adjustment time and improving the energy efficiency, stability and reliability of the air conditioning system.

[0127] By adopting the technical solution of this embodiment, when the air conditioning system is operating in cooling mode or heating mode, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled according to the operating parameters at different times and the preset calculation method, respectively. This achieves decoupling of the opening degree control of the first electronic expansion valve and the second electronic expansion valve, reduces the complexity of the air conditioning system, and improves the control response speed and operational reliability of the air conditioning system.

[0128] According to an embodiment of the present invention, a control device for an air conditioning system corresponding to a control method for an air conditioning system is also provided. The air conditioning system includes: a parallel compressor, a four-way valve, a first heat exchanger, a second heat exchanger, a first electronic expansion valve, a second electronic expansion valve, and a flash evaporator; the parallel compressor includes a compressor main cylinder and a compressor auxiliary cylinder, the outlet of the compressor main cylinder is connected to the outlet of the compressor auxiliary cylinder, and then connected to the four-way valve; the four-way valve is connected to the outlet of the parallel compressor, the first heat exchanger, the inlet of the compressor main cylinder, and the second heat exchanger; the first heat exchanger is connected to the first electronic expansion valve; the first electronic expansion valve is connected to the flash evaporator; one end of the outlet of the flash evaporator is connected to the second electronic expansion valve, and the other end is connected to the inlet of the compressor auxiliary cylinder; the second electronic expansion valve is connected to the second heat exchanger. Specifically, as... Figure 6 The diagram shows the structural structure of the air conditioning system, which includes: a parallel compressor auxiliary cylinder 1, a parallel compressor main cylinder 2, a four-way valve 3, a first heat exchanger 4, a first electronic expansion valve 5, a flash evaporator 6, a second electronic expansion valve 7, and a second heat exchanger 8. When the air conditioning system is operating in cooling mode, the slider of the four-way valve 3 moves to the left, connecting the E and S ends and the D and C ends. The high-temperature, high-pressure refrigerant gas discharged from the compressor main cylinder 2 and the high-temperature, high-pressure refrigerant gas discharged from the compressor auxiliary cylinder 1 mix and enter the first heat exchanger 4 through the four-way valve 3. After cooling and condensing, the refrigerant passes through the first electronic expansion valve 5 to a throttled pressure state and enters the flash evaporator 6. In the flash evaporator, gas and liquid are separated into saturated or near-saturated gas and liquid. The saturated or near-saturated gas enters the compressor auxiliary cylinder 1 through the supplementary gas branch to complete the second refrigerant cycle; the saturated or near-saturated liquid enters the second heat exchanger 8 through the second electronic expansion valve 7, where it absorbs heat from the indoor air and evaporates. Then, it passes through the four-way valve 3 and enters the compressor main cylinder 2 to complete the first refrigerant cycle. When the air conditioning system is operating in heating mode, the slider of the four-way valve 3 moves to the right, opening the connection between terminals C and S, and between terminals D and E. The refrigerant gas discharged from the compressor passes through the four-way valve 3 into the second heat exchanger 8 and circulates. (See also...) Figure 5 The diagram shows a structural schematic of an embodiment of the device of the present invention. The control device of the air conditioning system may include: an acquisition unit 102 and a control unit 104.

[0129] The acquisition unit 102 is configured to acquire the operating parameters of the air conditioning system when the air conditioning system is operating in cooling mode or heating mode, and record them as the first parameter. For the specific functions and processing of the acquisition unit 102, please refer to step S110.

[0130] Control unit 104 is configured to control the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the first parameter and a preset calculation method. The specific functions and processing of control unit 104 are described in step S120.

[0131] The acquisition unit 102 is further configured to acquire the operating parameters of the air conditioning system again after a set time, and record them as the second parameter. For the specific functions and processing of the acquisition unit 102, please refer to step S130.

[0132] In some embodiments, the first parameter and the second parameter include: the operating frequency of the parallel compressor, the exhaust temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, the inlet temperature of the second heat exchanger, and the outlet temperature of the first heat exchanger; wherein, the temperature at the first heat exchanger and the temperature at the second heat exchanger refer to the temperature in the middle of the heat exchanger flow path, specifically the temperature in the middle of the heat exchanger or at the small bend of the U-tube relative to the middle.

[0133] The control unit 104 is further configured to control the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve according to the operating mode of the air conditioning system, the second parameter, and the preset calculation method. The specific functions and processing of the control unit 104 are described in step S140.

[0134] In some embodiments, the preset calculation method includes: in refrigeration mode, calculating the suction dryness of the parallel compressor based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the outlet temperature of the first heat exchanger; calculating the refrigerant flow rate of the second heat exchanger based on the suction dryness of the parallel compressor; and calculating the opening values ​​of the first electronic expansion valve and the second electronic expansion valve based on the refrigerant flow rate of the second heat exchanger.

[0135] Specifically, the preset calculation method includes pre-set parameters for calculation, including: parallel compressor displacement V. rev ; First electronic expansion valve flow correction coefficient K c1 , is the conversion coefficient between refrigerant flow and air flow of the electronic expansion valve, which is an empirical value; the second electronic expansion valve flow correction coefficient K. c2, is the conversion coefficient between refrigerant flow rate and air flow rate of the electronic expansion valve, which is an empirical value; the air flow rate coefficient C of the first electronic expansion valve. 1_1 C 1_2 C 1_3 , where is the correlation coefficient for fitting the airflow curve of the first electronic expansion valve; and C is the airflow coefficient of the second electronic expansion valve. 2_1 C 2_2 C 2_3 , where is the correlation coefficient for fitting the air flow curve of the second electronic expansion valve.

[0136] Figure 9 This is a flowchart illustrating an embodiment of the electronic expansion valve opening calculation method for an air conditioning system in cooling mode according to the present invention. The electronic expansion valve opening calculation method in cooling mode includes steps 1 to 10.

[0137] Step 1, obtain the temperature t at the second heat exchanger. e The discharge temperature t of the parallel compressor dis Temperature t at the first heat exchanger c The outlet temperature t of the first heat exchanger c_o The operating frequency f of the parallel compressor.

[0138] Step 2: Calculate the liquid pipe saturation temperature drop dt based on the operating frequency f of the parallel compressor. sat_ll With the saturation temperature drop dt of the intake line sat_suc The suction saturation temperature t is calculated based on the temperature at the second heat exchanger and the saturation temperature drop in the suction line. suc_sat .

[0139] Specifically, the liquid pipe refers to the pipe between the second electronic expansion valve and the second heat exchanger. The calculation of the liquid pipe saturation temperature drop dt is then performed. sat_ll The formula is: dt sat_ll = a1*f*f+b1*f+c1, where a1, b1, and c1 are empirical values, and f is the operating frequency of the parallel compressor.

[0140] Calculate the saturation temperature drop dt of the intake line sat_suc The formula is: dt sat_suc = a2*f*f+b2*f+c2, where a2, b2, and c2 are empirical values.

[0141] Calculate the intake saturation temperature t suc_sat The formula is: t suc_sat =t e -dt sat_suc .

[0142] Step 3, based on the outlet temperature t of the first heat exchanger c_o Intake saturation temperature t suc_satGiven the operating frequency f of the parallel compressor, calculate the target flash temperature t. ft_target According to the outlet temperature t of the first heat exchanger c_o and target flash temperature t ft_target Calculate the specific enthalpy h at the outlet of the first heat exchanger. c_o Enthalpy of flash saturated liquid h f latent heat of flash phase transition h fg Flash dryness of flash generator x ft .

[0143] Specifically, the target flash temperature t is calculated. ft_target The formula is: t ft_target =a3*t c_o +b3*t suc_sat +c3*f+d3, where a3, b3, c3, and d3 are empirical values.

[0144] The specific enthalpy h of a subcooled / saturated refrigerant is given by: h = a⁴ * t * t + b⁴ * t + c⁴, where a⁴, b⁴, and c⁴ are values ​​obtained from refrigerant property software, and t is the temperature. For example, for R32 refrigerant, h = 0.0039 * t * t + 1.7246 * t + 200.06. This formula can be used to calculate the specific enthalpy h at the outlet of the first heat exchanger. c_o Enthalpy h of flash saturated liquid f .

[0145] Calculate the latent heat of flash phase transition h fg The formula is: h=a5*t*t+b5*t+c5, where a5, b5, and c5 are values ​​obtained by fitting from refrigerant property software, and t is the temperature value. For example, for R32 refrigerant, h=-0.0181*t*t-1.1988*t+313.22.

[0146] Calculate the flash dryness of the flash generator x ft The formula is: x ft =(h c_o -h f ) / h fg .

[0147] Step 4, based on the temperature t at the first heat exchanger c The discharge temperature t of the parallel compressor dis Intake saturation temperature t suc_sat Given the operating frequency f of the parallel compressor, calculate the suction dryness fraction x of the parallel compressor. suc Parallel compressor volumetric efficiency η v Specific volume of inhaled saturated gas v sat_g Specific volume of saturated liquid during intake (v) sat_l .

[0148] Specifically, calculate the suction dryness of the parallel compressor x.suc The formula is: x suc =a6*t c +b6*t suc_sat +c6*t dis +d6*f+e6, where a6, b6, c6, d6, and e6 are empirical values.

[0149] Calculate the volumetric efficiency η of a parallel compressor v The formula is: η v =a7*t c +b7*t suc_sat +c7*f+d7, where a7, b7, c7, and d7 are empirical values.

[0150] Calculate the specific volume v of the saturated inhaled gas. sat_g The formula is: v sat_g =a8*t suc_sat *t suc_sat +b8*t suc_sat +c8, where a8, b8, and c8 are values ​​fitted from refrigerant property software, for example, for R32 refrigerant, v sat_g =1.5991*10 -5 *t suc_sat *t suc_sat -1.3561*10 -3 *t suc_sat +4.5105*10 -2 .

[0151] Calculate the specific volume v of the saturated getter liquid. sat_l The formula is: v sat_l =a9*t suc_sat *t suc_sat +b9*t suc_sat +c9, where a9, b9, and c9 are values ​​fitted from refrigerant property software, for example, R32 refrigerant, v sat_l =2.8252*10 -8 *t suc_sat *t suc_sat +3.0*10 -6 *t suc_sat +9.4781*10 -4 .

[0152] Step 5, determine the inhalation dryness x suc The size, if the absorbance dryness x suc If the value is greater than 1, then based on the temperature t at the first heat exchanger... c The discharge temperature t of the parallel compressor dis Intake saturation temperature t suc_sat Calculate the operating frequency f of the parallel compressor and the suction superheat dt of the parallel compressor.suc_sh Furthermore, the specific volume of intake gas under superheated conditions, v, was calculated. suc If the inhalation dryness is x suc If ≤1, then based on the suction dryness fraction of the parallel compressor x suc Specific volume of inhaled saturated gas v sat_g Specific volume of saturated liquid during intake (v) sat_l The specific volume of the intake gas under two-phase conditions, v, was calculated using a dryness-weighted method. suc .

[0153] Specifically, the suction superheat dt of the parallel compressor is calculated. suc_sh The formula is: dt suc_sh =a 10 *t c +b 10 *t suc_sat +c 10 *t dis +d 10 *f+e 10 , where a 10 b 10 c 10 d 10 e 10 These are empirical values.

[0154] Inhalation dryness x suc When >1, calculate the specific volume of intake gas under superheated conditions, v. suc The formula is: v suc =v sat_g *(a 11 *t suc_sat +b 11 *dt suc_sh +c 11 ), where a 11 b 11 c 11 To obtain numerical values ​​from refrigerant property software, such as R32 refrigerant, v suc =v sat_g *(1.976*10 -3 *t suc_sat +7.649*10 -3 *dt suc_sh +0.9988).

[0155] Inhalation dryness x suc When ≤1, calculate the specific volume of intake gas v under two-phase conditions. suc The formula is: v suc =x suc *v sat_g +(1-x suc )*v sat_l .

[0156] Step 6, according to the preset parameters, compressor displacement V rev The operating frequency f of the parallel compressor and the volumetric efficiency η of the parallel compressor. v Inspiratory specific volume v suc The refrigerant flow rate M of the second heat exchanger was calculated. e Calculate the refrigerant flow rate M of the second heat exchanger. e The formula is: M e =V rev *f*η v / v suc The refrigerant flow rate M of the second heat exchanger e That is, the refrigerant flow rate M of the second electronic expansion valve r_2 .

[0157] Step 7, based on the saturation temperatures (t) before and after the first and second electronic expansion valves. c t ft_target ) and (t ft_target t e +dt sat_ll The pressure difference Δp across the first and second electronic expansion valves was calculated. r1 , △p r2 ; and based on the outlet temperature t of the first heat exchanger c_o and target flash temperature t ft_target The inlet densities ρ of the first and second electronic expansion valves were calculated respectively. r1 ρ r2 .

[0158] Specifically, the saturated vapor pressure of the refrigerant is p = a 12 *t*t+b 12 *t+c 12 , where a 12 b 12 c 12 To obtain numerical values ​​from refrigerant property software, for example, for R32 refrigerant, p = 509.46 * t * t + 20853 * t + 839607. Based on the formula for calculating the saturated vapor pressure of the refrigerant, the pressure difference Δp across the second electronic expansion valve can be calculated. r2 =f(t) ft_target ,t e ,dt sat_ll The pressure difference Δp across the first electronic expansion valve and the first electronic expansion valve r1 =f(t) c ,t ft_target ).

[0159] Refrigerant saturated liquid density ρ=a 13 *t*t+b 13 *t+c 13 , where a13 b 13 c 13 To obtain numerical values ​​from refrigerant property software, for example, for R32 refrigerant, ρ = -0.031*t*t - 2.7548t + 1051.3. The inlet density ρ of the first electronic expansion valve. r1 =f(t) c_o The inlet density ρ of the second electronic expansion valve r2 =f(t) ft_target ).

[0160] Step 8, based on the refrigerant flow rate M of the second electronic expansion valve r_2 Flash dryness x ft Calculate the refrigerant flow rate M of the first electronic expansion valve. r_1 The formula is: M r_1 =M r_2 / (1-(1+E)x ft ), where E is the liquid carryover rate (the ratio of liquid mass flow rate to gas mass flow rate). When the flash generator has a good gas-liquid separation effect and the gas supply path is saturated gas, E is 0.

[0161] Step 9: According to the preset parameters, the flow correction coefficient K of the two electronic expansion valves is adjusted. c1 and K c2 And the pressure difference Δp across the first electronic expansion valve r1 The pressure difference Δp across the second electronic expansion valve r2 The inlet density ρ of the first electronic expansion valve r1 The inlet density ρ of the second electronic expansion valve r2 Second electronic expansion valve refrigerant flow rate M r_2 First electronic expansion valve refrigerant flow rate M r_1 The air flow rate V of the first electronic expansion valve was calculated. a_o_1 Second electronic expansion valve air flow V a_o_2 The formula is: V a_o =K c M r_ / (ρ r *△p r 0.5 ).

[0162] Step 10, based on the air flow rate V of the first electronic expansion valve a_o_1 Second electronic expansion valve air flow V a_o_2 Calculate the opening degree B1 of the first electronic expansion valve and the opening degree B2 of the second electronic expansion valve. The formula is V a_o =C1*B*B+C2*B+C3, where B is the opening value of the electronic expansion valve, and C1, C2, and C3 are fitted values. For example, the opening value of the first electronic expansion valve in the figure is B1 = (-C 1_1+(C 1_1 2 -4*C 1_2 *(C 1_0 -V a_o_1 )) 0.5 ) / (2*C 1_2 ); The opening degree of the second electronic expansion valve B2 = (-C 2_1 +(C 2_1 2 -4*C 2_1 *(C 2_0 -V a_o_2 )) 0.5 ) / (2*C 2_2 ).

[0163] The present invention empirically fits the potential relationships between various state parameters of the air conditioning system and various physical parameters of the refrigerant. Based on the acquired temperature data, it accurately calculates the operating parameters of the air conditioning system and the opening degree of the electronic expansion valve, thereby reducing the complexity of control and improving the accuracy and response rate of the air conditioning system control.

[0164] In some embodiments, the preset calculation method further includes: in heating mode, calculating the suction dryness of the parallel compressor based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the inlet temperature of the second heat exchanger; calculating the refrigerant flow rate of the first heat exchanger based on the suction dryness of the parallel compressor; and calculating the opening values ​​of the first electronic expansion valve and the second electronic expansion valve based on the refrigerant flow rate of the first heat exchanger.

[0165] Figure 10 This is a flowchart illustrating an embodiment of the electronic expansion valve opening calculation method for an air conditioning system in heating mode according to the present invention. The electronic expansion valve opening calculation method in heating mode includes steps 31 to 40.

[0166] Step 31, obtain the temperature t at the second heat exchanger. e The discharge temperature t of the parallel compressor dis Temperature t at the first heat exchanger c The inlet temperature t of the second heat exchanger e_in The operating frequency f of the parallel compressor.

[0167] Step 32: Calculate the liquid pipe saturation temperature drop dt based on the operating frequency f of the parallel compressor. sat_ll With the saturation temperature drop dt of the intake line sat_suc The suction saturation temperature t is calculated based on the temperature at the second heat exchanger and the saturation temperature drop in the suction line. suc_sat .

[0168] Specifically, the liquid pipe refers to the pipe between the second electronic expansion valve and the second heat exchanger. The calculation of the liquid pipe saturation temperature drop dt is then performed. sat_ll The formula is: dt sat_ll = a1*f*f+b1*f+c1, where a1, b1, and c1 are empirical values, and f is the operating frequency of the parallel compressor.

[0169] Calculate the saturation temperature drop dt of the intake line sat_suc The formula is: dt sat_suc = a2*f*f+b2*f+c2, where a2, b2, and c2 are empirical values.

[0170] Calculate the intake saturation temperature t suc_sat The formula is: t suc_sat =t c -dt sat_suc .

[0171] Step 33, based on the inlet temperature t of the second heat exchanger e_in Intake saturation temperature t suc_sat Given the operating frequency f of the parallel compressor, calculate the target flash temperature t. ft_target According to the inlet temperature t of the second heat exchanger e_in and target flash temperature t ft_target Calculate the specific enthalpy h at the inlet of the second heat exchanger. e_in Enthalpy of flash saturated liquid h f latent heat of flash phase transition h fg Flash dryness of flash generator x ft .

[0172] Specifically, the target flash temperature t is calculated. ft_target The formula is: t ft_target =a3*t e_in +b3*t suc_sat +c3*f+d3, where a3, b3, c3, and d3 are empirical values.

[0173] The specific enthalpy h of a subcooled / saturated refrigerant is given by: h = a⁴ * t * t + b⁴ * t + c⁴, where a⁴, b⁴, and c⁴ are values ​​obtained from refrigerant property software, and t is the temperature. For example, for R32 refrigerant, h = 0.0039 * t * t + 1.7246 * t + 200.06. This formula can be used to calculate the inlet specific enthalpy h of the second heat exchanger. e_in Enthalpy h of flash saturated liquid f .

[0174] Calculate the latent heat of flash phase transition h fgThe formula is: h=a5*t*t+b5*t+c5, where a5, b5, and c5 are values ​​obtained by fitting from refrigerant property software, and t is the temperature value. For example, for R32 refrigerant, h=-0.0181*t*t-1.1988*t+313.22.

[0175] Calculate the flash dryness of the flash generator x ft The formula is: x ft =(h e_in -h f ) / h fg .

[0176] Step 34, based on the temperature t at the second heat exchanger e The discharge temperature t of the parallel compressor dis Intake saturation temperature t suc_sat Given the operating frequency f of the parallel compressor, calculate the suction dryness fraction x of the parallel compressor. suc Parallel compressor volumetric efficiency η v Specific volume of inhaled saturated gas v sat_g Specific volume of saturated liquid during intake (v) sat_l .

[0177] Specifically, calculate the suction dryness of the parallel compressor x. suc The formula is: x suc =a6*t e +b6*t suc_sat +c6*t dis +d6*f+e6, where a6, b6, c6, d6, and e6 are empirical values.

[0178] Calculate the volumetric efficiency η of the parallel compressor v The formula is: η v =a7*t e +b7*t suc_sat +c7*f+d7, where a7, b7, c7, and d7 are empirical values.

[0179] Calculate the specific volume v of the saturated inhaled gas. sat_g The formula is: v sat_g =a8*t suc_sat *t suc_sat +b8*t suc_sat +c8, where a8, b8, and c8 are values ​​fitted from refrigerant property software, for example, for R32 refrigerant, v sat_g =1.5991*10 -5 *t suc_sat *t suc_sat -1.3561*10 -3 *t suc_sat +4.5105*10 -2 .

[0180] Calculate the specific volume v of the saturated getter liquid. sat_l The formula is: v sat_l =a9*t suc_sat *t suc_sat +b9*t suc_sat +c9, where a9, b9, and c9 are values ​​fitted from refrigerant property software, for example, R32 refrigerant, v sat_l =2.8252*10 -8 *t suc_sat *t suc_sat +3.0*10 -6 *t suc_sat +9.4781*10 -4 .

[0181] Step 35, determine the inhalation dryness x suc The size, if the absorbance dryness x suc If the value is greater than 1, then based on the temperature t at the second heat exchanger... e The discharge temperature t of the parallel compressor dis Intake saturation temperature t suc_sat Calculate the operating frequency f of the parallel compressor and the suction superheat dt of the parallel compressor. suc_sh Furthermore, the specific volume of intake gas under superheated conditions, v, was calculated. suc If the inhalation dryness is x suc If ≤1, then based on the suction dryness fraction of the parallel compressor x suc Specific volume of inhaled saturated gas v sat_g Specific volume of saturated liquid during intake (v) sat_l The specific volume of the intake gas under two-phase conditions, v, was calculated using a dryness-weighted method. suc .

[0182] Specifically, the suction superheat dt of the parallel compressor is calculated. suc_sh The formula is: dt suc_sh =a 10 *t e +b 10 *t suc_sat +c 10 *t dis +d 10 *f+e 10 , where a 10 b 10 c 10 d 10 e 10 These are empirical values.

[0183] Inhalation dryness x suc When >1, calculate the specific volume of intake gas under superheated conditions, v. suc The formula is: v suc=v sat_g *(a 11 *t suc_sat +b 11 *dt suc_sh +c 11 ), where a 11 b 11 c 11 To obtain numerical values ​​from refrigerant property software, such as R32 refrigerant, v suc =v sat_g *(1.976*10 -3 *t suc_sat +7.649*10 -3 *dt suc_sh +0.9988).

[0184] Inhalation dryness x suc When ≤1, calculate the specific volume of intake gas v under two-phase conditions. suc The formula is: v suc =x suc *v sat_g +(1-x suc )*v sat_l .

[0185] Step 36, according to the preset parameter, compressor displacement V rev The operating frequency f of the parallel compressor and the volumetric efficiency η of the parallel compressor. v Inspiratory specific volume v suc The refrigerant flow rate M of the first heat exchanger was calculated. c Calculate the refrigerant flow rate M of the first heat exchanger. c The formula is: M c =V rev *f*η v / v suc The refrigerant flow rate M of the first heat exchanger c That is, the refrigerant flow rate M of the first electronic expansion valve r_1 .

[0186] Step 37, based on the saturation temperatures (t) before and after the first electronic expansion valve and the second electronic expansion valve. c t ft_target ) and (t ft_target t e +dt sat_ll The pressure difference Δp across the first and second electronic expansion valves was calculated. r1 , △p r2 ; and based on the inlet temperature t of the second heat exchanger e_in and target flash temperature t ft_target The inlet densities ρ of the first and second electronic expansion valves were calculated respectively. r1ρ r2 .

[0187] Specifically, the saturated vapor pressure of the refrigerant is p = a 12 *t*t+b 12 *t+c 12 , where a 12 b 12 c 12 To obtain numerical values ​​from refrigerant property software, for example, for R32 refrigerant, p = 509.46 * t * t + 20853 * t + 839607. Based on the formula for calculating the saturated vapor pressure of the refrigerant, the pressure difference Δp across the first electronic expansion valve can be derived. r1 =f(t) ft_target ,t c ,dt sat_ll The pressure difference Δp across the second electronic expansion valve r2 =f(t) e ,t ft_target ).

[0188] Refrigerant saturated liquid density ρ=a 13 *t*t+b 13 *t+c 13 , where a 13 b 13 c 13 To obtain numerical values ​​from refrigerant property software, for example, for R32 refrigerant, ρ = -0.031*t*t - 2.7548t + 1051.3. The inlet density ρ of the second electronic expansion valve... r2 =f(t) e_in ), the inlet density ρ of the first electronic expansion valve r1 =f(t) ft_target ).

[0189] Step 38, based on the refrigerant flow rate M of the first electronic expansion valve r_1 Flash dryness x ft Calculate the refrigerant flow rate M of the second electronic expansion valve. r_2 The formula is: M r_2 =M r_1 / (1-(1+E)x ft ), where E is the liquid carryover rate (the ratio of liquid mass flow rate to gas mass flow rate). When the flash generator has a good gas-liquid separation effect and the gas supply path is saturated gas, E is 0.

[0190] Step 39: Based on the preset parameters, the flow correction coefficients K of the two electronic expansion valves are adjusted. c1 and K c2 and the pressure difference Δp across the first electronic expansion valve r1 The pressure difference Δp across the second electronic expansion valve r2The inlet density ρ of the first electronic expansion valve r1 The inlet density ρ of the second electronic expansion valve r2 Second electronic expansion valve refrigerant flow rate M r_2 First electronic expansion valve refrigerant flow rate M r_1 The air flow rate V of the first electronic expansion valve was calculated. a_o_1 Second electronic expansion valve air flow V a_o_2 The formula is: V a_o =K c M r_ / (ρ r *△p r 0.5 ).

[0191] Step 40, based on the air flow rate V of the first electronic expansion valve a_o_1 Second electronic expansion valve air flow V a_o_2 Calculate the opening degree B1 of the first electronic expansion valve and the opening degree B2 of the second electronic expansion valve. The formula is V a_o =C1*B*B+C2*B+C3, where B is the opening value of the electronic expansion valve, and C1, C2, and C3 are fitted values. For example, the opening value of the first electronic expansion valve in the figure is B1 = (-C 1_1 +(C 1_1 2 -4*C 1_2 *(C 1_0 -V a_o_1 )) 0.5 ) / (2*C 1_2 ); The opening degree of the second electronic expansion valve B2 = (-C 2_1 +(C 2_1 2 -4*C 2_1 *(C 2_0 -V a_o_2 )) 0.5 ) / (2*C 2_2 ).

[0192] The present invention empirically fits the potential relationships between various state parameters of the air conditioning system and various refrigerant property parameters. Based on the acquired temperature data, it accurately calculates the operating parameters of the air conditioning system and the opening degree of the electronic expansion valve, thereby reducing the complexity of control and improving the accuracy and response rate of the air conditioning system control.

[0193] In some embodiments, the control unit 104 controls the opening degree of the first electronic expansion valve and the second electronic expansion valve according to the first parameter and a preset calculation method, including:

[0194] The control unit 104 is further configured to input the first parameter into the preset calculation method to obtain the opening values ​​of the first electronic expansion valve and the second electronic expansion valve. The specific functions and processing of the control unit 104 are described in step S210.

[0195] The control unit 104 is further configured to control the opening degree of the first electronic expansion valve and the second electronic expansion valve based on their opening values. The specific functions and processing of this control unit 104 are described in step S220.

[0196] In some embodiments, the control unit controls the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve respectively, based on the operating mode of the air conditioning system, the second parameter, and a preset calculation method, including:

[0197] The control unit 104 is further configured to calculate the suction dryness of the parallel compressor based on the second parameter when the air conditioning system is operating in cooling mode. The specific functions and processing of the control unit 104 are described in step S310.

[0198] The control unit 104 is further configured to determine whether the suction dryness of the parallel compressor is within a set range. The specific functions and processing of the control unit 104 are described in step S320.

[0199] The control unit 104 is further configured to control the opening of the second electronic expansion valve according to the second parameter if the suction dryness of the parallel compressor is not within the set range. Specifically, the opening of the second electronic expansion valve is adjusted according to the suction dryness feedback. The specific functions and processing of this control unit 104 are described in step S330.

[0200] The control unit 104 is further configured to input the current operating parameters of the air conditioning system into the preset calculation method to obtain the opening value of the first electronic expansion valve; the current operating parameters are of the same parameter type as the second parameter. For the specific functions and processing of the control unit 104, please refer to step S340.

[0201] The control unit 104 is further configured to control the opening degree of the first electronic expansion valve based on the opening degree value of the first electronic expansion valve, and then re-control the opening degree of the first electronic expansion valve and the second electronic expansion valve based on the operating mode of the air conditioning system, the second parameter, and the preset calculation method. The specific functions and processing of this control unit 104 are described in step S350.

[0202] The present invention addresses the issue of unstable suction dryness in parallel compressors by adjusting the openings of the first electronic expansion valve and the second electronic expansion valve separately based on different temperature data and opening adjustment methods, thereby achieving decoupled control of the two electronic expansion valves. Furthermore, based on empirical fitting formulas, the control process is made faster and more efficient, reducing control complexity and improving response speed.

[0203] Figure 7 This is a flowchart illustrating an embodiment of the control method for an air conditioning system in cooling mode according to the present invention, as shown below. Figure 7 As shown, the control method of the present invention in cooling mode includes steps 15 to 18.

[0204] Step 15: When the air conditioning system is running in cooling mode, determine the operating frequency of the parallel compressor, the indoor fan speed, and the outdoor fan speed based on the indoor ambient temperature, outdoor ambient temperature, set temperature, and set indoor unit fan speed.

[0205] Step 16: Detect the temperature of each temperature sensor, specifically the temperature t at the second heat exchanger. e Exhaust temperature t dis Temperature t at the first heat exchanger c The outlet temperature t of the first heat exchanger c_o These parameters are then input into a preset calculation method to obtain the opening values ​​of the first electronic expansion valve and the second electronic expansion valve, and the opening of the first electronic expansion valve and the second electronic expansion valve are adjusted accordingly.

[0206] Step 17: After adjusting the opening of the first and second electronic expansion valves for a time T1 (T1 time ranges from 0 to 10 minutes, with a preferred value of 5 minutes), the temperature of each sensing bulb is detected again, and the suction dryness of the parallel compressor is calculated. suc Determine the suction dryness of the parallel compressor (x) suc Whether it is within the preset range, that is, whether a≤x suc ≤b (a<b, where a ranges from 0.98 to 1.0, and b ranges from 1.0 to 1.015). If a≤x suc If a ≤ b, the air conditioning system is determined to be in the target operating state, and after time T2 (T2 ranges from 0 minutes to 10 minutes, with a preferred value of 5 minutes), the process returns to step 16 and executes again; if a ≤ x is not satisfied... suc If the value is less than or equal to b, then the air conditioning system is determined to be not in the target operating state, and step 18 is executed.

[0207] Step 18: Adjust the opening of the second electronic expansion valve according to the inhalation dryness feedback method. Specifically, when the inhalation dryness is less than a certain standard value, decrease the opening of the second electronic expansion valve; when the inhalation dryness is greater than a certain standard value, increase the opening of the second electronic expansion valve. Then, detect the temperature of each temperature sensor again and input these parameters into the preset calculation method to obtain the opening value of the first electronic expansion valve, and adjust the opening of the first electronic expansion valve accordingly.

[0208] This solution determines whether the air conditioning system is fluctuating based on the suction dryness of the parallel compressor. When fluctuations occur, it calculates the operating parameters of the air conditioning system and the opening of the electronic expansion valve in real time, and quickly adjusts the opening of the electronic expansion valve to near the optimal opening, thus shortening the adjustment time and improving the energy efficiency, stability and reliability of the air conditioning system.

[0209] In some embodiments, the control unit 104, based on the operating mode of the air conditioning system, the second parameter, and a preset calculation method, controls the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve, respectively, and further includes:

[0210] The control unit 104 is further configured to calculate the suction dryness of the parallel compressor based on the second parameter when the air conditioning system is in heating mode. The specific functions and processing of the control unit 104 are described in step S410.

[0211] The control unit 104 is further configured to determine whether the suction dryness of the parallel compressor is within a set range. The specific functions and processing of the control unit 104 are described in step S420.

[0212] The control unit 104 is further configured to control the opening of the first electronic expansion valve according to the second parameter if the suction dryness of the parallel compressor is not within the set range. Specifically, the opening of the first electronic expansion valve is adjusted according to the suction dryness feedback. The specific functions and processing of this control unit 104 are described in step S430.

[0213] The control unit 104 is further configured to input the current operating parameters of the air conditioning system into the preset calculation method to obtain the opening value of the second electronic expansion valve; the current operating parameters and the second parameter have the same parameter type. For the specific functions and processing of the control unit 104, please refer to step S440.

[0214] The control unit 104 is further configured to control the opening degree of the second electronic expansion valve based on the opening value of the second electronic expansion valve, and then re-control the opening degree of the first electronic expansion valve and the second electronic expansion valve based on the operating mode of the air conditioning system, the second parameter, and the preset calculation method. The specific functions and processing of this control unit 104 are described in step S450.

[0215] Figure 8 This is a flowchart illustrating an embodiment of the control method for an air conditioning system in heating mode according to the present invention, as shown below. Figure 8 As shown, the control method of the present invention in cooling mode includes steps 20 to 23.

[0216] Step 20: When the air conditioning system is running in heating mode, determine the operating frequency of the parallel compressor, the indoor fan speed, and the outdoor fan speed based on the indoor ambient temperature, the outdoor ambient temperature, the set temperature, and the set indoor unit fan speed.

[0217] Step 21: Detect the temperature of each temperature sensor, specifically the temperature t at the second heat exchanger. e Exhaust temperature t dis Temperature t at the first heat exchanger c The outlet temperature t of the first heat exchanger c_o These parameters are then input into a preset calculation method to obtain the opening values ​​of the first electronic expansion valve and the second electronic expansion valve, and the opening of the first electronic expansion valve and the second electronic expansion valve are adjusted accordingly.

[0218] Step 22: After adjusting the opening of the first and second electronic expansion valves for a time T1 (T1 time ranges from 0 to 10 minutes, with a preferred value of 5 minutes), the temperature of each sensing bulb is detected again, and the suction dryness of the parallel compressor is calculated. suc Determine the suction dryness of the parallel compressor (x) suc Whether it is within the preset range, that is, whether a≤x suc ≤b (a<b, where a ranges from 0.98 to 1.0, and b ranges from 1.0 to 1.015). If a≤x suc If a ≤ b, the air conditioning system is determined to be in the target operating state, and after time T2 (T2 ranges from 0 minutes to 10 minutes, with a preferred value of 5 minutes), the process returns to step 21 and executes again; if a ≤ x is not satisfied... suc If the value is less than or equal to b, then the air conditioning system is determined to be not in the target operating state, and step 23 is executed.

[0219] Step 23: Adjust the opening of the first electronic expansion valve according to the inhalation dryness feedback method. Specifically, when the inhalation dryness is less than a certain standard value, decrease the opening of the first electronic expansion valve; when the inhalation dryness is greater than a certain standard value, increase the opening of the first electronic expansion valve. Then, detect the temperature of each temperature sensor again and input these parameters into the preset calculation method to obtain the opening value of the second electronic expansion valve, and adjust the opening of the second electronic expansion valve accordingly.

[0220] This solution determines whether the air conditioning system is fluctuating based on the suction dryness of the parallel compressor. When fluctuations occur, it calculates the operating parameters of the air conditioning system and the opening of the electronic expansion valve in real time, and quickly adjusts the opening of the electronic expansion valve to near the optimal opening, thus shortening the adjustment time and improving the energy efficiency, stability and reliability of the air conditioning system.

[0221] Since the processing and functions implemented by the device in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in the description of this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0222] By adopting the technical solution of the present invention, when the air conditioning system is operating in cooling mode or heating mode, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled according to the operating parameters at different times and the preset calculation method, respectively. This achieves decoupling of the opening degree control of the first electronic expansion valve and the second electronic expansion valve, reduces the complexity of the air conditioning system, and improves the control response speed and operational reliability of the air conditioning system.

[0223] According to an embodiment of the present invention, an air conditioning system corresponding to a control device for an air conditioning system is also provided. This air conditioning system may include the control device for the air conditioning system described above.

[0224] Since the processing and functions implemented by the air conditioning system in this embodiment are basically the same as those of the aforementioned device embodiments, principles and examples, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0225] By adopting the technical solution of the present invention, when the air conditioning system is operating in cooling mode or heating mode, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled according to the operating parameters at different times and the preset calculation method, respectively. This achieves decoupling of the opening degree control of the first electronic expansion valve and the second electronic expansion valve, reduces the complexity of the air conditioning system, and improves the control response speed and operational reliability of the air conditioning system.

[0226] According to an embodiment of the present invention, a storage medium corresponding to a control method for an air conditioning system is also provided. The storage medium includes a stored program, wherein the program controls the device where the storage medium is located to execute the control method for the air conditioning system described above when it is executed.

[0227] Since the processing and functions implemented by the storage medium in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0228] By adopting the technical solution of the present invention, when the air conditioning system is operating in cooling mode or heating mode, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled according to the operating parameters at different times and the preset calculation method, respectively. This achieves decoupling of the opening degree control of the first electronic expansion valve and the second electronic expansion valve, reduces the complexity of the air conditioning system, and improves the control response speed and operational reliability of the air conditioning system.

[0229] In summary, it is readily understood by those skilled in the art that, without conflict, the aforementioned advantageous methods can be freely combined and superimposed.

[0230] 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 for an air conditioning system, characterized in that, The air conditioning system includes: a parallel compressor, a four-way valve, a first heat exchanger, a second heat exchanger, a first electronic expansion valve, a second electronic expansion valve, and a flash evaporator; the parallel compressor includes a compressor main cylinder and a compressor auxiliary cylinder; the four-way valve is connected to the outlet of the parallel compressor, the first heat exchanger, the inlet of the compressor main cylinder, and the second heat exchanger respectively; the first heat exchanger is connected to the first electronic expansion valve; the first electronic expansion valve is connected to the flash evaporator; one end of the outlet of the flash evaporator is connected to the second electronic expansion valve, and the other end is connected to the inlet of the compressor auxiliary cylinder; the second electronic expansion valve is connected to the second heat exchanger; the method includes: When the air conditioning system is operating in cooling mode or heating mode, the operating parameters of the air conditioning system are acquired and recorded as the first parameter; Based on the first parameter and the preset calculation method, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled; then, After a set time, the operating parameters of the air conditioning system are obtained again and recorded as the second parameter; According to the operating mode of the air conditioning system, the second parameter, and the preset calculation method, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled respectively. The first parameter and the second parameter include: the operating frequency of the parallel compressor, the exhaust temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, the inlet temperature of the second heat exchanger, and the outlet temperature of the first heat exchanger. The preset calculation method includes: In refrigeration mode, the suction dryness of the parallel compressor is calculated based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the outlet temperature of the first heat exchanger. The refrigerant flow rate of the second heat exchanger is calculated based on the suction dryness of the parallel compressor. The pressure difference across the first and second electronic expansion valves is calculated based on the saturation temperatures before and after the first and second electronic expansion valves. The inlet densities of the first electronic expansion valve and the second electronic expansion valve are calculated based on the outlet temperature of the first heat exchanger and the target flash temperature, respectively. The refrigerant flow rate of the second heat exchanger is used as the refrigerant flow rate of the second electronic expansion valve, and the refrigerant flow rate of the first electronic expansion valve is calculated based on the refrigerant flow rate of the second electronic expansion valve and the flash dryness. Based on preset parameters, the pressure difference between the first and second electronic expansion valves, the inlet density, and the refrigerant flow rate, the air flow rate of the first and second electronic expansion valves is calculated. Based on the air flow rates of the first and second electronic expansion valves, calculate the opening values ​​of the first and second electronic expansion valves. And / or, In heating mode, the suction dryness of the parallel compressor is calculated based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the inlet temperature of the second heat exchanger. The refrigerant flow rate of the first heat exchanger is calculated based on the suction dryness of the parallel compressor. The pressure difference across the first and second electronic expansion valves is calculated based on the saturation temperatures before and after the first and second electronic expansion valves. The inlet densities of the first and second electronic expansion valves are calculated based on the inlet temperature of the second heat exchanger and the target flash temperature, respectively. The refrigerant flow rate of the first heat exchanger is used as the refrigerant flow rate of the first electronic expansion valve, and the refrigerant flow rate of the second electronic expansion valve is calculated based on the refrigerant flow rate of the first electronic expansion valve and the flash dryness. Based on preset parameters, the pressure difference between the first and second electronic expansion valves, the inlet density, and the refrigerant flow rate, the air flow rate of the first and second electronic expansion valves is calculated. The opening values ​​of the first and second electronic expansion valves are calculated based on the air flow rates of the first and second electronic expansion valves.

2. The control method for the air conditioning system according to claim 1, characterized in that, Based on the first parameter and a preset calculation method, controlling the opening degree of the first electronic expansion valve and the second electronic expansion valve includes: Substitute the first parameter into the preset calculation method to obtain the opening values ​​of the first electronic expansion valve and the second electronic expansion valve; The opening degree of the first electronic expansion valve and the second electronic expansion valve is controlled according to their opening values.

3. The control method for the air conditioning system according to claim 1, characterized in that, Based on the operating mode of the air conditioning system, the second parameter, and the preset calculation method, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled respectively, including: When the air conditioning system is in cooling mode, the suction dryness of the parallel compressor is calculated based on the second parameter. Determine whether the suction dryness of the parallel compressor is within the set range; If the suction dryness of the parallel compressor is not within the set range, the opening degree of the second electronic expansion valve is controlled according to the second parameter; then, The current operating parameters of the air conditioning system are input into the preset calculation method to obtain the opening value of the first electronic expansion valve; The opening degree of the first electronic expansion valve is controlled according to the opening degree value of the first electronic expansion valve.

4. The control method for an air conditioning system according to claim 1, characterized in that, Based on the operating mode of the air conditioning system, the second parameter, and the preset calculation method, the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve are controlled respectively, and the method further includes: When the air conditioning system is in heating mode, the suction dryness of the parallel compressor is calculated based on the second parameter. Determine whether the suction dryness of the parallel compressor is within the set range; If the suction dryness of the parallel compressor is not within the set range, the opening degree of the first electronic expansion valve is controlled according to the second parameter; then, The current operating parameters of the air conditioning system are input into the preset calculation method to obtain the opening value of the second electronic expansion valve; The opening degree of the second electronic expansion valve is controlled according to the opening degree value of the second electronic expansion valve.

5. A control device for an air conditioning system, characterized in that, The air conditioning system includes: a parallel compressor, a four-way valve, a first heat exchanger, a second heat exchanger, a first electronic expansion valve, a second electronic expansion valve, and a flash evaporator; the parallel compressor includes a compressor main cylinder and a compressor auxiliary cylinder; the four-way valve is connected to the outlet of the parallel compressor, the first heat exchanger, the inlet of the compressor main cylinder, and the second heat exchanger respectively; the first heat exchanger is connected to the first electronic expansion valve; the first electronic expansion valve is connected to the flash evaporator; one end of the outlet of the flash evaporator is connected to the second electronic expansion valve, and the other end is connected to the inlet of the compressor auxiliary cylinder; the second electronic expansion valve is connected to the second heat exchanger; the device includes: The acquisition unit is configured to acquire the operating parameters of the air conditioning system when the air conditioning system is operating in cooling mode or heating mode, and record them as the first parameter; The control unit is configured to control the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve according to the first parameter and a preset calculation method; thereafter, The acquisition unit is further configured to acquire the operating parameters of the air conditioning system again after a set time, and record them as the second parameter; The control unit is further configured to control the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve respectively according to the operating mode of the air conditioning system, the second parameter and the preset calculation method. The first parameter and the second parameter include: the operating frequency of the parallel compressor, the exhaust temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, the inlet temperature of the second heat exchanger, and the outlet temperature of the first heat exchanger. The preset calculation method includes: In cooling mode, the suction dryness of the parallel compressor is calculated based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the outlet temperature of the first heat exchanger. The refrigerant flow rate of the second heat exchanger is calculated based on the suction dryness of the parallel compressor. The pressure difference across the first and second electronic expansion valves is calculated based on the saturation temperatures before and after the first and second electronic expansion valves. The inlet densities of the first electronic expansion valve and the second electronic expansion valve are calculated based on the outlet temperature of the first heat exchanger and the target flash temperature, respectively. The refrigerant flow rate of the second heat exchanger is used as the refrigerant flow rate of the second electronic expansion valve, and the refrigerant flow rate of the first electronic expansion valve is calculated based on the refrigerant flow rate of the second electronic expansion valve and the flash dryness. Based on preset parameters, the pressure difference between the first and second electronic expansion valves, the inlet density, and the refrigerant flow rate, the air flow rate of the first and second electronic expansion valves is calculated. Based on the air flow rates of the first and second electronic expansion valves, calculate the opening values ​​of the first and second electronic expansion valves. And / or, In heating mode, the suction dryness of the parallel compressor is calculated based on the operating frequency of the parallel compressor, the discharge temperature of the parallel compressor, the temperature at the first heat exchanger, the temperature at the second heat exchanger, and the inlet temperature of the second heat exchanger. The refrigerant flow rate of the first heat exchanger is calculated based on the suction dryness of the parallel compressor. The pressure difference across the first and second electronic expansion valves is calculated based on the saturation temperatures before and after the first and second electronic expansion valves. The inlet densities of the first and second electronic expansion valves are calculated based on the inlet temperature of the second heat exchanger and the target flash temperature, respectively. The refrigerant flow rate of the first heat exchanger is used as the refrigerant flow rate of the first electronic expansion valve, and the refrigerant flow rate of the second electronic expansion valve is calculated based on the refrigerant flow rate of the first electronic expansion valve and the flash dryness. Based on preset parameters, the pressure difference between the first and second electronic expansion valves, the inlet density, and the refrigerant flow rate, the air flow rate of the first and second electronic expansion valves is calculated. The opening values ​​of the first and second electronic expansion valves are calculated based on the air flow rates of the first and second electronic expansion valves.

6. The control device for the air conditioning system according to claim 5, characterized in that, The control unit, based on the first parameter and a preset calculation method, controls the opening degree of the first electronic expansion valve and the second electronic expansion valve, including: Substitute the first parameter into the preset calculation method to obtain the opening values ​​of the first electronic expansion valve and the second electronic expansion valve; The opening degree of the first electronic expansion valve and the second electronic expansion valve is controlled according to their opening values.

7. An air conditioning system, characterized in that, include: The control device for the air conditioning system as described in claim 5 or 6.

8. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, the device containing the storage medium is controlled to perform the control method of the air conditioning system according to any one of claims 1 to 4.

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