Air conditioning system and control method thereof

Abstract

The invention relates to an air conditioning system. An outdoor heat exchanger is connected with an indoor heat exchanger through a liquid pipeline; the nominal diameter of the first electronic expansion valve is larger than that of the second electronic expansion valve, and the first electronic expansion valve and the second electronic expansion valve are connected to a liquid pipeline in parallel. The controller is configured to control the first electronic expansion valve to keep a minimum opening state after detecting that the opening of the first electronic expansion valve is smaller than or equal to a first preset opening, and control the opening of the second electronic expansion valve according to the actual exhaust superheat degree and the target exhaust superheat degree; after it is detected that the opening degree of the second electronic expansion valve is larger than or equal to the second preset opening degree, the second electronic expansion valve is controlled to keep the minimum opening degree state, and the opening degree of the first electronic expansion valve is controlled according to the actual exhaust superheat degree and the target exhaust superheat degree; the flow of the second electronic expansion valve under the second preset opening degree is larger than that of the first electronic expansion valve under the first preset opening degree; and the performance of the air-conditioning system is improved.

Description

Technical Field

[0001] This application relates to the field of air conditioning technology, and in particular to an air conditioning system and its control method. Background Technology

[0002] With the continuous improvement of people's living standards, air conditioners have become an indispensable household appliance in modern life. The main function of an air conditioning system is to provide users with a comfortable indoor environment by regulating the indoor temperature. However, the performance and user experience of air conditioning systems in related technologies are still unsatisfactory. Summary of the Invention

[0003] Therefore, it is necessary to provide an air conditioning system and its control method to address the above-mentioned technical problems, which can improve the performance of the air conditioning system and the user experience.

[0004] In a first aspect, this application provides an air conditioning system, which includes a refrigerant circulation loop, a first electronic expansion valve, a second electronic expansion valve, and a controller;

[0005] The refrigerant circulation loop includes a compressor, an outdoor heat exchanger, and an indoor heat exchanger connected in sequence. The outdoor heat exchanger and the indoor heat exchanger are connected by a liquid pipe. The compressor is used to drive the refrigerant to circulate in the refrigerant circulation loop.

[0006] The nominal diameter of the first electronic expansion valve is larger than the nominal diameter of the second electronic expansion valve. The first electronic expansion valve and the second electronic expansion valve are connected in parallel to the liquid pipeline. The first electronic expansion valve and the second electronic expansion valve are respectively connected to the controller.

[0007] The controller is configured to:

[0008] After detecting that the opening degree of the first electronic expansion valve is less than or equal to the first preset opening degree, the first electronic expansion valve is controlled to maintain the minimum opening degree, and the opening degree of the second electronic expansion valve is controlled according to the actual exhaust superheat and the target exhaust superheat.

[0009] After detecting that the opening degree of the second electronic expansion valve is greater than or equal to the second preset opening degree, the second electronic expansion valve is controlled to maintain the minimum opening degree, and the opening degree of the first electronic expansion valve is controlled according to the actual exhaust superheat and the target exhaust superheat.

[0010] Wherein, the flow rate of the second electronic expansion valve at the second preset opening degree is greater than the flow rate of the first electronic expansion valve at the first preset opening degree.

[0011] Secondly, embodiments of this application provide an air conditioning system control method, wherein the air conditioning system includes a refrigerant circulation loop, a first electronic expansion valve, and a second electronic expansion valve;

[0012] The refrigerant circulation loop includes a compressor, an outdoor heat exchanger, and an indoor heat exchanger connected in sequence. The outdoor heat exchanger and the indoor heat exchanger are connected by a liquid pipe. The compressor is used to drive the refrigerant to circulate in the refrigerant circulation loop.

[0013] The nominal diameter of the first electronic expansion valve is larger than the nominal diameter of the second electronic expansion valve, and the first electronic expansion valve and the second electronic expansion valve are connected in parallel to the liquid pipeline;

[0014] The method includes:

[0015] After detecting that the opening degree of the first electronic expansion valve is less than or equal to the first preset opening degree, the first electronic expansion valve is controlled to maintain the minimum opening degree, and the opening degree of the second electronic expansion valve is controlled according to the actual exhaust superheat and the target exhaust superheat.

[0016] After detecting that the opening degree of the second electronic expansion valve is greater than or equal to the second preset opening degree, the second electronic expansion valve is controlled to maintain the minimum opening degree, and the opening degree of the first electronic expansion valve is controlled according to the actual exhaust superheat and the target exhaust superheat.

[0017] Wherein, the flow rate of the second electronic expansion valve at the second preset opening degree is greater than the flow rate of the first electronic expansion valve at the first preset opening degree.

[0018] In the aforementioned air conditioning system and its control method, the refrigerant circulation loop includes a compressor, an outdoor heat exchanger, and an indoor heat exchanger connected in sequence. The outdoor heat exchanger and the indoor heat exchanger are connected via a liquid pipe. A first electronic expansion valve and a second electronic expansion valve are connected in parallel on the liquid pipe, wherein the nominal diameter of the first electronic expansion valve is larger than the nominal diameter of the second electronic expansion valve. Therefore, the controller can be configured to: upon detecting that the opening degree of the first electronic expansion valve is less than or equal to a first preset opening degree, implement exhaust superheat control based on the second electronic expansion valve, and control the first electronic expansion valve to maintain a minimum opening degree; upon detecting that the opening degree of the second electronic expansion valve is greater than or equal to a second preset opening degree, implement exhaust superheat control based on the first electronic expansion valve, and control the second electronic expansion valve to maintain a minimum opening degree; wherein the flow rate of the second electronic expansion valve at the second preset opening degree is greater than the flow rate of the first electronic expansion valve at the first preset opening degree.

[0019] Thus, when a larger refrigerant flow requirement is needed (e.g., under high-frequency operation of the air conditioning system), requiring an electronic expansion valve with a larger nominal diameter, the controller can control the exhaust superheat based on the first electronic expansion valve and keep the second electronic expansion valve at its minimum opening, thereby ensuring stable operation of the air conditioning system and improving its performance. When a smaller refrigerant flow requirement is needed (e.g., under low-frequency operation of the air conditioning system), requiring an electronic expansion valve with a smaller nominal diameter, the controller can switch to controlling the exhaust superheat based on the second electronic expansion valve and keep the first electronic expansion valve at its minimum opening, thereby ensuring that the air conditioning system meets indoor load requirements and improving the user experience. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the air conditioning system in one embodiment;

[0022] Figure 2 This is one of the schematic diagrams of the control method of the controller in one embodiment;

[0023] Figure 3 This is a second schematic diagram of the control method flow of the controller in one embodiment;

[0024] Figure 4 This is the third schematic diagram of the control method flow of the controller in one embodiment;

[0025] Figure 5 This is the fourth schematic diagram of the control method flow of the controller in one embodiment;

[0026] Figure 6 This is the fifth schematic diagram of the control method flow of the controller in one embodiment;

[0027] Figure 7 This is a schematic diagram of the control method of the controller in one embodiment;

[0028] Figure 8 This is the seventh schematic diagram of the control method flow of the controller in one embodiment;

[0029] Figure 9 This is the eighth schematic diagram of the control method flow of the controller in one embodiment.

[0030] Explanation of reference numerals in the attached diagram: 1-Compressor, 2-Exhaust temperature sensor, 3-High pressure switch, 4-Four-way valve, 5-Outdoor heat exchanger, 6-Outdoor temperature sensor, 7-Internal temperature sensor of outdoor heat exchanger, 8-First electronic expansion valve, 9-Second electronic expansion valve, 10-Liquid line shut-off valve, 11-Gas line shut-off valve, 12-Low pressure switch, 13-Indoor heat exchanger, 14-Indoor temperature sensor, 15-Internal temperature sensor of indoor heat exchanger. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0033] As mentioned in the background section, the performance and user experience of air conditioning systems in related technologies are still unsatisfactory. The inventors of this application have discovered that the reasons are as follows:

[0034] In related technologies, air conditioning systems are equipped with only a single electronic expansion valve, and the nominal diameter (bore) of this single electronic expansion valve is selected to match the high-frequency operating conditions of the compressor (i.e., the nominal diameter is adapted to the high refrigerant flow requirements under high-frequency conditions). When the compressor gradually switches from high-frequency operation to low-frequency operation (usually when the indoor ambient temperature is close to the user's set temperature and the system load decreases), since the refrigerant flow required by the system under low-frequency conditions is much smaller than that required by the system under high-frequency conditions, the nominal diameter expansion valve adapted to high-frequency conditions will have an excessively high minimum controllable flow threshold, making it difficult to accurately adjust the small flow rate. Specifically, even a slight adjustment of the valve core opening can lead to excessive fluctuations in refrigerant flow, which in turn causes the air conditioning system to operate unstably (such as fluctuations in indoor temperature, evaporator frosting / abnormal superheat, etc.). The air conditioning system needs to frequently start and stop or adjust the compressor frequency to compensate for the flow deviation, ultimately resulting in a significant decrease in operating energy efficiency, an increase in the power consumption of the air conditioning system, and thus a reduction in the performance of the air conditioning system.

[0035] Conversely, if the nominal diameter of the single electronic expansion valve is selected to match the compressor's low-frequency operating conditions (i.e., the nominal diameter is adapted to the low refrigerant flow requirements under low frequency): when the compressor switches to high-frequency operation (such as when the indoor and outdoor temperature difference is large or the system load increases sharply), the nominal diameter expansion valve adapted to low frequency will result in insufficient refrigerant flow capacity due to the nominal diameter limitation. At this time, the system refrigerant cannot be delivered to the evaporator (cooling condition) or condenser (heating condition) quickly and in sufficient quantity, which can easily cause the compressor suction superheat to rise abnormally (during cooling) or the discharge temperature to exceed the limit. At the same time, the condenser side may trigger high-pressure protection due to refrigerant accumulation. The above abnormalities will trigger the safety protection mechanism of the air conditioning system, causing the compressor to stop high-frequency operation and trip, ultimately resulting in a sharp drop in the air conditioning's cooling or heating capacity, which cannot meet the indoor load demand, thereby affecting the user experience.

[0036] In view of this, this application provides an air conditioning system that can improve the performance of the air conditioning system and the user experience.

[0037] In some exemplary embodiments, reference is made to Figure 1 An air conditioning system is provided, comprising a refrigerant circulation loop, a first electronic expansion valve 8, a second electronic expansion valve 9, and a controller. Figure 1 (The controller is not shown in the image).

[0038] The refrigerant circulation loop includes a compressor 1, an outdoor heat exchanger 5, and an indoor heat exchanger 13 connected in sequence. The outdoor heat exchanger 5 and the indoor heat exchanger 13 are connected via liquid lines. The refrigerant circulation loop is configured to circulate the refrigerant. (Reference) Figure 1 The air conditioning system may also include: an exhaust temperature sensor 2, a high-pressure switch 3, a four-way valve 4, an outdoor temperature sensor 6, a mid-temperature sensor in the outdoor heat exchanger 7, a liquid line shut-off valve 10, a gas line shut-off valve 11, a low-pressure switch 12, an indoor temperature sensor 14, and a mid-temperature sensor in the indoor heat exchanger 15. Figure 1 The solid arrows in the diagram indicate the direction of refrigerant flow in the refrigeration cycle. Figure 1 The dashed arrows in the diagram indicate the direction of refrigerant flow in the heating cycle.

[0039] The nominal diameter of the first electronic expansion valve 8 is larger than that of the second electronic expansion valve 9. The first electronic expansion valve 8 and the second electronic expansion valve 9 are connected in parallel to the liquid pipeline. The first electronic expansion valve 8 and the second electronic expansion valve 9 are each connected to a controller. It is understandable that, because the nominal diameters of the first electronic expansion valve 8 and the second electronic expansion valve 9 are different, for the same flow rate, the opening degree of the first electronic expansion valve 8 will be different from that of the second electronic expansion valve 9.

[0040] refer to Figure 2 The controller is configured to perform the following steps S201~S202.

[0041] S201, after detecting that the opening degree of the first electronic expansion valve 8 is less than or equal to the first preset opening degree, exhaust superheat control is realized based on the second electronic expansion valve 9 and the first electronic expansion valve 8 is controlled to maintain the minimum opening degree.

[0042] In this embodiment of the application, the exhaust superheat control is achieved based on the second electronic expansion valve 9 and the first electronic expansion valve 8 is kept at its minimum opening state. This can be understood as: the first electronic expansion valve 8 is kept at its minimum opening state, and the opening of the second electronic expansion valve 9 is controlled according to the actual exhaust superheat and the target exhaust superheat.

[0043] In this embodiment, in cooling mode: exhaust superheat = exhaust temperature - outdoor heat exchanger coil temperature; in heating mode: exhaust superheat = exhaust temperature - indoor heat exchanger coil temperature. The target exhaust superheat is a preset value and can be set as needed according to actual application.

[0044] Understandably, when the opening of the first electronic expansion valve 8 is detected to be less than or equal to the first preset opening, it indicates that the refrigerant flow demand is low, and the air conditioning system may be entering a low-frequency operating condition. In this case, a smaller nominal diameter electronic expansion valve is required. Therefore, the controller can switch to using the second electronic expansion valve 9 to control exhaust superheat while maintaining the first electronic expansion valve 8 at its minimum opening. This ensures that the air conditioning system meets the indoor load demand and improves the user experience. At its minimum opening, the flow rate of the first electronic expansion valve 8 is zero or very small, close to zero.

[0045] S202, after detecting that the opening degree of the second electronic expansion valve 9 is greater than or equal to the second preset opening degree, exhaust superheat control is implemented based on the first electronic expansion valve 8 and the second electronic expansion valve 9 is controlled to maintain the minimum opening degree; wherein, the flow rate of the second electronic expansion valve 9 at the second preset opening degree is greater than the flow rate of the first electronic expansion valve 8 at the first preset opening degree.

[0046] In this embodiment, controlling exhaust superheat based on the first electronic expansion valve 8 and maintaining the second electronic expansion valve 9 at its minimum opening can be understood as: controlling the second electronic expansion valve 9 to maintain its minimum opening, and controlling the opening of the first electronic expansion valve 8 according to the actual exhaust superheat and the target exhaust superheat. In this embodiment, the flow rates of both the first electronic expansion valve 8 and the second electronic expansion valve 9 at a specific opening can refer to air flow.

[0047] Understandably, when the opening of the second electronic expansion valve 9 is detected to be greater than or equal to the second preset opening, it indicates a high refrigerant flow demand, and the air conditioning system may be entering a high-frequency operating condition. In this case, a larger nominal diameter electronic expansion valve is required. Therefore, the controller can switch to control based on the solid line exhaust superheat of the first electronic expansion valve 8 and maintain the second electronic expansion valve 9 at its minimum opening, thereby ensuring stable operation of the air conditioning system and improving its performance. At its minimum opening, the flow rate of the second electronic expansion valve 9 is zero or very small, close to zero.

[0048] Optionally, the flow rate of the second electronic expansion valve 9 at the second preset opening can be equal to the flow rate of the first electronic expansion valve 8 at the third preset opening. The third preset opening of the first electronic expansion valve 8 is equal to the sum of the first preset opening and the preset compensation opening of the first electronic expansion valve 8. The preset compensation opening can, for example, be between 10 and 100.

[0049] In some exemplary embodiments, reference is made to Figure 3 The controller is also configured to perform the following step S301.

[0050] S301, when exhaust superheat control is achieved based on the first electronic expansion valve 8 and the second electronic expansion valve 9 is kept at its minimum opening: after detecting that the opening of the first electronic expansion valve 8 is less than or equal to the first preset opening d and continues for a first preset duration e, exhaust superheat control is achieved based on the second electronic expansion valve 9 and the first electronic expansion valve 8 is kept at its minimum opening.

[0051] It is understandable that configuring a first preset duration e ensures that after detecting that the opening of the first electronic expansion valve 8 is less than or equal to the first preset opening d and continues for the first preset duration e, the system switches to control the exhaust superheat based on the second electronic expansion valve 9. This avoids frequent or erroneous switching between the first electronic expansion valve 8 and the second electronic expansion valve 9 due to normal fluctuations in refrigerant flow, thereby ensuring the stability of the system.

[0052] Optional, see reference Figure 4 The controller is also configured to perform the following step S401.

[0053] S401, after controlling the first electronic expansion valve 8 to close to the minimum opening at the end of the first preset time e, and controlling the second electronic expansion valve 9 to open to the first target opening at the end of the first preset time e, exhaust superheat control is achieved based on the second electronic expansion valve 9 and the first electronic expansion valve 8 is controlled to maintain the minimum opening state; wherein, the flow rate of the second electronic expansion valve 9 at the first target opening is the same as the flow rate of the first electronic expansion valve 8 at the end of the first preset time e.

[0054] It is understandable that the second electronic expansion valve 9 is opened to the first target opening degree at the end of the first preset time e, so as to ensure that the refrigerant flow does not fluctuate drastically when switching between the first electronic expansion valve 8 and the second electronic expansion valve 9, and the refrigerant flow is connected naturally during the switching process, thereby ensuring the stability of the system state.

[0055] Optional, see reference Figure 5 The controller is also configured to perform the following step S501.

[0056] S501, at the end of the first preset time e, the second electronic expansion valve 9 is controlled to open to the first target opening degree and continue for a second preset time f; after the second preset time f, exhaust superheat control is realized based on the second electronic expansion valve 9.

[0057] It is understandable that configuring a second preset duration f allows the second electronic expansion valve 9 to open to the first target opening degree and remain open for the second preset duration f before switching to exhaust superheat control based on the second electronic expansion valve 9. This ensures that the refrigerant flow does not fluctuate drastically when switching between the first electronic expansion valve 8 and the second electronic expansion valve 9, thereby ensuring the stability of the system.

[0058] Similarly, in some exemplary embodiments, reference is made to... Figure 6 The controller is also configured to perform the following step S601.

[0059] S601, when exhaust superheat control is achieved based on the second electronic expansion valve 9 and the first electronic expansion valve 8 is kept at its minimum opening: after detecting that the opening of the second electronic expansion valve 9 is greater than or equal to the second preset opening g and continues for a first preset duration e, exhaust superheat control is achieved based on the first electronic expansion valve and the second electronic expansion valve 9 is kept at its minimum opening.

[0060] Optional, see reference Figure 7 The controller is also configured to perform the following step S701.

[0061] S701, after controlling the second electronic expansion valve 9 to close to the minimum opening at the end of the first preset time e, and controlling the first electronic expansion valve 8 to open to the second target opening at the end of the first preset time e, exhaust superheat control is realized based on the first electronic expansion and the second electronic expansion valve 9 is controlled to maintain the minimum opening state; wherein, the flow rate of the first electronic expansion valve 8 at the second target opening is the same as the flow rate of the second electronic expansion valve 9 at the end of the first preset time e.

[0062] Optional, see reference Figure 8 The controller is also configured to perform the following step S801.

[0063] S801, at the end of the first preset time e, the first electronic expansion valve 8 is controlled to open to the second target opening degree and continue for the second preset time f; after the second preset time f, exhaust superheat control is realized based on the first electronic expansion.

[0064] In some exemplary embodiments, the controller is configured with a first database and a second database; the first database includes the correspondence between the opening degree of the first electronic expansion valve 8 and the flow rate, and the second database includes the correspondence between the opening degree of the second electronic expansion valve 9 and the flow rate.

[0065] The controller is also configured as follows:

[0066] Based on the first database and the opening degree of the first electronic expansion valve 8 at the end of the first preset time e, the flow rate of the first electronic expansion valve 8 at the end of the first preset time e is determined; based on the second database and the flow rate of the first electronic expansion valve 8 at the end of the first preset time e, the first target opening degree of the second electronic expansion valve 9 is determined.

[0067] It is understandable that the flow rate (denoted as flow rate 1) corresponding to the opening degree of the first electronic expansion valve 8 at the end of the first preset time e can be queried in the first database; then, the opening degree of the second electronic expansion valve 9 corresponding to flow rate 1 can be queried in the second database, which serves as the first target opening degree of the second electronic expansion valve 9.

[0068] Based on the second database and the opening degree of the second electronic expansion valve 9 at the end of the first preset time e, the flow rate of the second electronic expansion valve 9 at the end of the first preset time e is determined; based on the first database and the flow rate of the second electronic expansion valve 9 at the end of the first preset time e, the second target opening degree of the first electronic expansion valve 8 is determined.

[0069] It is understandable that the flow rate (denoted as flow rate 2) corresponding to the opening degree of the second electronic expansion valve 9 at the end of the first preset time e can be queried in the second database; then, the opening degree of the first electronic expansion valve 8 corresponding to flow rate 2 can be queried in the first database as the second target opening degree of the first electronic expansion valve 8.

[0070] In some exemplary embodiments, the target electronic expansion valve is a first electronic expansion valve 8 or a second electronic expansion valve 9, and the controller implements exhaust superheat control based on the target electronic expansion valve, including:

[0071] The opening of the target electronic expansion valve is controlled once at preset intervals. Specifically, when the actual exhaust superheat is greater than the first target exhaust superheat, the opening of the target electronic expansion valve is increased; when the actual exhaust superheat is less than the second target exhaust superheat, the opening of the target electronic expansion valve is decreased; when the actual exhaust superheat is greater than or equal to the second target exhaust superheat and less than or equal to the first target exhaust superheat, the opening of the target electronic expansion valve remains unchanged. The first target exhaust superheat is greater than the second target exhaust superheat.

[0072] As an example, the first target exhaust superheat = initial target exhaust superheat + b1, and the second target exhaust superheat = initial target exhaust superheat - b1; b1 and b2 are correction parameters and are non-negative numbers, which can be configured according to actual application needs, and there are no specific limitations on them.

[0073] The following detailed embodiment, in conjunction with the above embodiments, provides a supplementary explanation of the technical solution of this application:

[0074] refer to Figure 9 The controller is configured to perform the following steps S901~S913.

[0075] S901 received the power-on command.

[0076] S902 determines the target frequency of the compressor and obtains the actual frequency of the compressor based on the outdoor ambient temperature or the temperature difference between the indoor ambient temperature and the set temperature.

[0077] S903, determine whether the target frequency is greater than or equal to the preset frequency X. If yes, proceed to steps S904~S906. If no, proceed to steps S909~S911.

[0078] S904, when the target frequency is greater than or equal to the preset frequency X, control the second electronic expansion valve 9 to maintain the minimum opening state, and control the opening of the first electronic expansion valve 8 according to the outdoor ambient temperature and the actual frequency, for a third preset duration c.

[0079] It is understandable that this mode is used to facilitate the transition period during the first few minutes after startup, as the entire system is in a period of rapid change, including exhaust temperature and indoor and outdoor heat exchanger coil temperatures. For example, c could be 4 to 8 minutes.

[0080] S905, based on the first electronic expansion valve 8, realizes exhaust superheat control and controls the second electronic expansion valve 9 to maintain the minimum opening state.

[0081] S906, determine whether the opening degree of the first electronic expansion valve 8 is less than or equal to the first preset opening degree d and continues for a first preset duration e. If yes, proceed to steps S907~S908; if no, return to step S905.

[0082] S907, at the end of the first preset duration e, the first electronic expansion valve 8 is controlled to close to the minimum opening, and at the end of the first preset duration e, the second electronic expansion valve 9 is controlled to open to the first target opening and continue for the second preset duration f; wherein, the flow rate of the second electronic expansion valve 9 at the first target opening is the same as the flow rate of the first electronic expansion valve 8 at the end of the first preset duration e.

[0083] S908, based on the second electronic expansion, realizes exhaust superheat control while the first electronic expansion valve 8 is kept at the minimum opening.

[0084] S909, when the target frequency is less than the preset frequency X, controls the first electronic expansion valve 8 to maintain the minimum opening state, and controls the opening of the second electronic expansion valve 9 according to the outdoor ambient temperature and the actual frequency, for a third preset duration c.

[0085] It is understandable that this mode is used to facilitate the transition period during the first few minutes after startup, as the entire system is in a period of rapid change, including exhaust temperature and indoor and outdoor heat exchanger coil temperatures. For example, c could be 4 to 8 minutes.

[0086] S910, based on the second electronic expansion valve 9, realizes exhaust superheat control and controls the first electronic expansion valve 8 to maintain the minimum opening state.

[0087] S911, determine whether the opening degree of the second electronic expansion valve 9 is greater than or equal to the second preset opening degree g and continues for a first preset duration e. If yes, proceed to steps S912~S913; if no, return to step S910.

[0088] S912, at the end of the first preset duration e, the second electronic expansion valve 9 is controlled to close to the minimum opening, and at the end of the first preset duration, the first electronic expansion valve 8 is controlled to open to the second target opening and continue for the second preset duration f; wherein, the flow rate of the first electronic expansion valve 8 at the second target opening is the same as the flow rate of the second electronic expansion valve 9 at the end of the first preset duration e.

[0089] S913, exhaust superheat control is achieved based on the first electronic expansion and the second electronic expansion valve 9 is kept at the minimum opening.

[0090] In this embodiment, the specific values ​​of the preset frequency X, the first preset opening degree d, the second preset opening degree g, the first preset duration e, the second preset duration f, and the third preset duration c can be configured according to actual application needs, and no specific limitation is made thereto; wherein, g can be obtained by converting the flow rate of the first electronic expansion valve 8 opening degree d + h, and h can be configured according to actual application needs. Introducing h can better maintain the stability of the air conditioning system and avoid frequent switching of the electronic expansion valve.

[0091] The following scenario embodiment, in conjunction with the above embodiments, provides a supplementary explanation of the technical solution of this application:

[0092] Set X=45, c=4, d=110, e=5, f=2, g=280;

[0093] Upon receiving the start-up command, the air conditioning system calculates a target frequency of 70Hz > 45Hz based on the outdoor ambient temperature or the temperature difference between the indoor ambient temperature and the set temperature. The second electronic expansion valve 9 closes to its minimum opening. The first electronic expansion valve 8 performs calculations and real-time adjustments based on the outdoor ambient temperature and the actual frequency. This adjustment is maintained for 4 minutes. After 4 minutes, the second electronic expansion valve 9 remains closed to its minimum opening. The air conditioning system then controls the exhaust superheat of the first electronic expansion valve 8 to bring the actual exhaust superheat close to the target exhaust superheat. After the air conditioning system has been cooling for a period of time, the indoor ambient temperature approaches the user's set temperature. The compressor frequency then decreases from 70Hz to 30Hz, reducing the cooling capacity output. The required refrigerant flow decreases after the compressor frequency decreases, meaning the opening of the second electronic expansion valve 9 decreases. After operating at the reduced frequency for a period of time, the opening of the first electronic expansion valve 8 begins to fall below 110°C. The opening of the first electronic expansion valve 8 was 96 at the 5th minute. The program recorded that the flow rate at the 96-degree opening corresponded to the opening of the second electronic expansion valve 9 at 200. At the 5th minute, the opening of the first electronic expansion valve 8 was closed to its minimum, and the opening of the second electronic expansion valve 9 was adjusted to 200 and maintained for 2 minutes. Subsequently, the exhaust superheat of the second electronic expansion valve 9 was controlled. When the air conditioner needed to increase its frequency to increase its cooling capacity, after running at higher frequencies for a period of time, the opening of the second electronic expansion valve 9 was higher than 280 and lasted for 5 minutes. At the 5th minute, the opening of the second electronic expansion valve 9 was 298. The program recorded that the flow rate at the 298-degree opening corresponded to the opening of the first electronic expansion valve 8 at 130. At the 5th minute, the opening of the second electronic expansion valve 9 was closed to its minimum, and the opening of the first electronic expansion valve 8 was adjusted to 130 and maintained for 2 minutes. Subsequently, the exhaust superheat of the first electronic expansion valve 8 was controlled.

[0094] In some exemplary embodiments, an air conditioning system control method is also provided, the air conditioning system including a refrigerant circulation loop, a first electronic expansion valve, and a second electronic expansion valve;

[0095] The refrigerant circulation loop includes a compressor, an outdoor heat exchanger, and an indoor heat exchanger connected in sequence. The outdoor heat exchanger and the indoor heat exchanger are connected by a liquid pipe. The compressor is used to drive the refrigerant to circulate in the refrigerant circulation loop.

[0096] The nominal diameter of the first electronic expansion valve is larger than the nominal diameter of the second electronic expansion valve. The first electronic expansion valve and the second electronic expansion valve are connected in parallel on the liquid pipeline.

[0097] The methods include:

[0098] After detecting that the opening degree of the first electronic expansion valve is less than or equal to the first preset opening degree, the first electronic expansion valve is controlled to maintain the minimum opening degree, and the opening degree of the second electronic expansion valve is controlled according to the actual exhaust superheat and the target exhaust superheat.

[0099] After detecting that the opening degree of the second electronic expansion valve is greater than or equal to the second preset opening degree, the second electronic expansion valve is controlled to maintain the minimum opening degree, and the opening degree of the first electronic expansion valve is controlled according to the actual exhaust superheat and the target exhaust superheat.

[0100] The flow rate of the second electronic expansion valve at the second preset opening degree is greater than the flow rate of the first electronic expansion valve at the first preset opening degree.

[0101] In this application embodiment, the air conditioning system control method and the air conditioning system belong to the same inventive concept, can solve the same technical problem, and thus achieve the same technical effect. Repeated content will not be repeated here.

[0102] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0103] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this application. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An air conditioning system, characterized by, The air conditioning system comprises a refrigerant circulation loop, a first electronic expansion valve, a second electronic expansion valve, and a controller; The refrigerant circulation loop comprises a compressor, an outdoor heat exchanger, and an indoor heat exchanger connected in sequence, wherein the outdoor heat exchanger and the indoor heat exchanger are connected by a liquid pipe, and the compressor is used to drive the refrigerant to circulate in the refrigerant circulation loop; The nominal diameter of the first electronic expansion valve is greater than that of the second electronic expansion valve, and the first electronic expansion valve and the second electronic expansion valve are connected in parallel on the liquid pipe, and the first electronic expansion valve and the second electronic expansion valve are connected with the controller respectively; The controller is configured to: After detecting that the opening degree of the first electronic expansion valve is less than or equal to a first preset opening degree, control the first electronic expansion valve to keep a minimum opening degree state, and control the opening degree of the second electronic expansion valve according to an actual exhaust gas superheat degree and a target exhaust gas superheat degree; After detecting that the opening degree of the second electronic expansion valve is greater than or equal to a second preset opening degree, control the second electronic expansion valve to keep a minimum opening degree state, and control the opening degree of the first electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree; Wherein, the flow rate of the second electronic expansion valve at the second preset opening degree is greater than the flow rate of the first electronic expansion valve at the first preset opening degree.

2. The air conditioning system of claim 1, wherein, The controller is further configured to: In the case of controlling the second electronic expansion valve to keep a minimum opening degree state and controlling the opening degree of the first electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree: After detecting that the opening degree of the first electronic expansion valve is less than or equal to the first preset opening degree and lasts for a first preset time length, control the first electronic expansion valve to keep a minimum opening degree state, and control the opening degree of the second electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree.

3. The air conditioning system of claim 2, wherein, The controller is further configured to: At the end of the first preset time length, control the first electronic expansion valve to close to a minimum opening degree, and after controlling the second electronic expansion valve to open to a first target opening degree at the end of the first preset time length, control the first electronic expansion valve to keep a minimum opening degree state, and control the opening degree of the second electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree; Wherein, the flow rate of the second electronic expansion valve at the first target opening degree is the same as the flow rate of the first electronic expansion valve at the end of the first preset time length.

4. The air conditioning system of claim 3, wherein, The controller is further configured to: At the end of the first preset time length, control the second electronic expansion valve to open to the first target opening degree and last for a second preset time length; After the second preset time length, control the opening degree of the second electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree.

5. The air conditioning system of claim 1, wherein, The controller is further configured to: In the case of controlling the first electronic expansion valve to keep a minimum opening degree state and controlling the opening degree of the second electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree: After detecting that the opening degree of the second electronic expansion valve is greater than or equal to a second preset opening degree and lasts for the first preset time length, the second electronic expansion valve is controlled to keep a minimum opening degree state, and the opening degree of the first electronic expansion valve is controlled according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree.

6. The air conditioning system of claim 5, wherein, The controller is further configured to: control the second electronic expansion valve to close to a minimum opening degree at the end time of the first preset time length, and after controlling the first electronic expansion valve to open to a second target opening degree at the end time of the first preset time length, control the second electronic expansion valve to keep a minimum opening degree state, and control the opening degree of the first electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree; wherein the flow rate of the first electronic expansion valve at the second target opening degree is the same as the flow rate of the second electronic expansion valve at the end time of the first preset time length.

7. The air conditioning system of claim 6, wherein, The controller is further configured to: control the first electronic expansion valve to open to the second target opening degree and last for a second preset time length at the end time of the first preset time length; after the second preset time length, control the opening degree of the first electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree.

8. The air conditioning system of claim 1, wherein, The air conditioning system further comprises: an outdoor temperature sensor arranged on the outdoor heat exchanger and configured to collect an outdoor environment temperature corresponding to an outdoor environment where the air conditioning system is located; an indoor temperature sensor arranged on the indoor heat exchanger and configured to collect an indoor environment temperature corresponding to an indoor environment where the air conditioning system is located; The controller is further configured to: after receiving a start-up instruction, determine a target frequency of the compressor according to the outdoor environment temperature or according to a temperature difference between the indoor environment temperature and a set temperature; obtain an actual frequency of the compressor; in a case where the target frequency is greater than or equal to a preset frequency, control the second electronic expansion valve to keep a minimum opening degree state, and after controlling the opening degree of the first electronic expansion valve according to the outdoor environment temperature and the actual frequency for a third preset time length, control the second electronic expansion valve to keep a minimum opening degree state, and control the opening degree of the first electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree; in a case where the target frequency is less than the preset frequency, control the first electronic expansion valve to keep a minimum opening degree state, and after controlling the opening degree of the second electronic expansion valve according to the outdoor environment temperature and the actual frequency for the third preset time length, control the first electronic expansion valve to keep a minimum opening degree state, and control the opening degree of the second electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree.

9. The air conditioning system of claim 3 or 6, wherein The controller is configured with a first database and a second database; the first database comprises a corresponding relationship between the opening degree and the flow rate of the first electronic expansion valve, and the second database comprises a corresponding relationship between the opening degree and the flow rate of the second electronic expansion valve; The controller is further configured to: determine the flow rate of the first electronic expansion valve at the end time of the first preset time length according to the first database and the opening degree of the first electronic expansion valve at the end time of the first preset time length; determine the first target opening degree of the second electronic expansion valve according to the second database and the flow rate of the first electronic expansion valve at the end time of the first preset time length; determine the flow rate of the second electronic expansion valve at the end time of the first preset time length according to the second database and the opening degree of the second electronic expansion valve at the end time of the first preset time length; determine the second target opening degree of the first electronic expansion valve according to the first database and the flow rate of the second electronic expansion valve at the end time of the first preset time length.

10. An air conditioning system control method characterized by comprising: The air conditioning system comprises a refrigerant circulation loop, a first electronic expansion valve, and a second electronic expansion valve. The refrigerant circulation loop comprises a compressor, an outdoor heat exchanger, and an indoor heat exchanger connected in sequence, wherein the outdoor heat exchanger and the indoor heat exchanger are connected by a liquid pipe circuit, and the compressor is used to drive the circulation of refrigerant in the refrigerant circulation loop. The nominal diameter of the first electronic expansion valve is greater than that of the second electronic expansion valve, and the first electronic expansion valve and the second electronic expansion valve are connected in parallel on the liquid pipe circuit. The method comprises: after detecting that the opening degree of the first electronic expansion valve is less than or equal to a first preset opening degree, controlling the first electronic expansion valve to remain in a minimum opening state, and controlling the opening degree of the second electronic expansion valve according to an actual exhaust gas superheat degree and a target exhaust gas superheat degree; after detecting that the opening degree of the second electronic expansion valve is greater than or equal to a second preset opening degree, controlling the second electronic expansion valve to remain in a minimum opening state, and controlling the opening degree of the first electronic expansion valve according to the actual exhaust gas superheat degree and the target exhaust gas superheat degree; wherein the flow rate of the second electronic expansion valve at the second preset opening degree is greater than the flow rate of the first electronic expansion valve at the first preset opening degree.

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