Air conditioner and control method thereof

Abstract

The embodiment of the invention belongs to the electric appliance technology, and provides an air conditioner and a control method thereof.The control method comprises the steps that in the starting stage, according to the suction pressure of a compressor and a first early warning reference value, the first target opening degree of a throttling valve is determined, and the opening degree of the throttling valve is set to be the first target opening degree; after a preset duration, determining a target stage of the centrifugal unit according to the suction pressure and the exhaust superheat degree of the compressor; and according to the target stage, the second target opening degree of the throttling valve is determined, and the opening degree of the throttling valve is adjusted to be the second target opening degree. According to the technical scheme, under different working conditions, control and adjustment modes of different throttle valve opening degrees are adopted, so that the problems that a single control and adjustment mode cannot cover the whole working conditions and air suction carries liquid due to poor operation and adjustment capacity under part of working conditions are solved, and guarantee is provided for efficient and stable operation of the system.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of electrical appliances, and more specifically, to an air conditioner and a control method thereof. Background Art

[0002] In an air conditioner, the main circuit of a centrifugal chiller typically connects a compressor, a condenser, a throttle valve, and an evaporator. The throttle valve controls the flow of refrigerant from the condenser to the evaporator by varying its opening. In related art, the throttle valve opening is typically adjusted based on the difference between the compressor's discharge pressure corresponding to the saturation temperature and the discharge temperature, as well as a set temperature deviation threshold. However, this adjustment method is difficult to meet the regulatory requirements under different operating conditions and can easily lead to reduced cooling performance and liquid hammer in the centrifugal chiller. Summary of the Invention

[0003] The embodiments of the present application provide an air conditioner and a control method thereof, so as to improve the refrigeration performance of a centrifugal unit and avoid liquid hammer.

[0004] In a first aspect, an embodiment of the present application provides an air conditioner, including a centrifugal unit, wherein the centrifugal unit includes:

[0005] a compressor configured to compress a refrigerant;

[0006] a condenser connected to the compressor and configured to condense and exchange heat on the compressed refrigerant;

[0007] a throttle valve connected to the condenser and configured to control a flow rate of the refrigerant flowing out of the condenser;

[0008] an evaporator connected to the control valve and configured to vaporize and exchange heat with the refrigerant;

[0009] A controller configured to:

[0010] During the startup phase, a first target opening of the throttle valve is determined according to the suction pressure of the compressor and a first warning reference value, and the opening of the throttle valve is set to the first target opening;

[0011] After a preset time, determining the target stage of the centrifugal unit based on the suction pressure and the exhaust superheat of the compressor;

[0012] A second target opening of the throttle valve is determined according to the target phase, and the opening of the throttle valve is adjusted to the second target opening.

[0013] Through the above technical solution, multi-stage, adaptive control and adjustment of the throttle valve opening is realized. Different control and adjustment methods are adopted under different working conditions, thus solving the problem that a single control and adjustment method cannot cover all working conditions, or the control method is not optimal under working conditions at different time periods, avoiding the problem of liquid suction caused by poor operating adjustment ability under some working conditions, and providing a guarantee for the efficient and stable operation of the system.

[0014] In some embodiments, the controller is configured to:

[0015] If the suction pressure is less than or equal to a second warning reference value, it is determined that the centrifuge unit is in the first stage; and the second warning reference value is greater than the first warning reference value;

[0016] If the suction pressure is greater than the second warning reference value, and the exhaust superheat is less than or equal to the preset superheat lower limit, determining that the centrifugal unit is in the second stage;

[0017] If the suction pressure is greater than the second warning reference value, and the exhaust superheat is greater than the preset superheat lower limit, it is determined that the centrifugal unit is in the third stage.

[0018] In some embodiments, the controller is configured to:

[0019] In the first stage, the second target opening is determined according to the current opening of the throttle valve and a preset opening change value.

[0020] In some embodiments, the controller is configured to:

[0021] In the second stage, the second target opening is determined according to the current opening of the throttle valve and a preset opening range.

[0022] In some embodiments, the controller is configured to:

[0023] If the current opening of the throttle valve is less than the lower limit of the opening range, the difference between the current opening of the throttle valve and the first limit value is used as the second target opening;

[0024] If the current opening of the throttle valve is within the opening range, the difference between the current opening of the throttle valve and the second limit value is used as the second target opening;

[0025] If the current opening of the throttle valve is greater than the upper limit of the opening range, the difference between the current opening of the throttle valve and the third limit value is used as the second target opening;

[0026] The second limit value is greater than the first limit value and less than the third limit value.

[0027] In some embodiments, the controller is configured to:

[0028] In the third stage, determining the difference between the outlet water temperature of the evaporator and the evaporation temperature of the refrigerant in the evaporator;

[0029] The second target opening is determined according to the difference, a preset temperature range, and the exhaust gas superheat of the compressor.

[0030] In some embodiments, the controller is configured to:

[0031] determining an adjustment coefficient for adjusting the throttle valve opening according to a magnitude relationship between the difference and a preset temperature range;

[0032] The second target opening is determined according to the adjustment coefficient and the exhaust gas superheat of the compressor.

[0033] In some embodiments, the adjustment coefficient includes a proportional coefficient, an integral coefficient, and a differential coefficient, and the controller is configured to:

[0034] determining a first difference between the exhaust superheat and a target exhaust superheat, and a second difference between the exhaust superheat and the exhaust superheat at a previous moment;

[0035] determining a first product of the proportional coefficient and the first difference, a second product of the integral coefficient and the first difference, and a third product of the differential coefficient and the second difference;

[0036] The second degree of superheat is determined based on the first product, the second product, and the third product.

[0037] In some embodiments, the controller is configured to:

[0038] When the centrifuge unit is in any stage, determining whether the centrifuge unit meets the conditions for entering other stages;

[0039] If the condition is satisfied, the current opening of the throttle valve is adjusted according to the second opening corresponding to the other stage.

[0040] In a second aspect, an embodiment of the present application provides a method for controlling an air conditioner, wherein the air conditioner includes a centrifugal unit, wherein the centrifugal unit includes:

[0041] a compressor configured to compress a refrigerant;

[0042] a condenser connected to the compressor and configured to condense and exchange heat on the compressed refrigerant;

[0043] a throttle valve connected to the condenser and configured to control a flow rate of the refrigerant flowing out of the condenser;

[0044] an evaporator connected to the control valve and configured to vaporize and exchange heat with the refrigerant;

[0045] The method comprises:

[0046] During the startup phase, a first target opening of the throttle valve is determined according to the suction pressure of the compressor and a first warning reference value, and the opening of the throttle valve is set to the first target opening;

[0047] After a preset time, determining the target stage of the centrifugal unit based on the suction pressure and the exhaust superheat of the compressor;

[0048] A second target opening of the throttle valve is determined according to the target phase, and the opening of the throttle valve is adjusted to the second target opening.

[0049] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the first aspect above and / or various possible implementation methods of the first aspect.

[0050] In a fourth aspect, an embodiment of the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above first aspect and / or various possible implementation methods of the first aspect.

[0051] The air conditioner and control method thereof provided in the embodiment of the present application, the air conditioner includes a centrifugal unit, the centrifugal unit including: a compressor, configured to compress refrigerant; a condenser, connected to the compressor, configured to condense and heat exchange the compressed refrigerant; a throttle valve, connected to the condenser, configured to control the flow rate of the refrigerant flowing out of the condenser; an evaporator, connected to the control valve, configured to vaporize and heat exchange the refrigerant; a controller, the controller being configured to: in the startup phase, determine a first target opening of the throttle valve according to the suction pressure of the compressor and a first warning reference value, and set the opening of the throttle valve to the first target opening; after a preset time, determine the target stage of the centrifugal unit according to the suction pressure and the exhaust superheat of the compressor; determine a second target opening of the throttle valve according to the target stage, and adjust the opening of the throttle valve to the second target opening. Through the above technical solution, multi-stage, adaptive control and adjustment of the throttle valve opening is realized. Different control and adjustment methods are adopted under different working conditions, thus solving the problem that a single control and adjustment method cannot cover all working conditions, or the control method is not optimal under working conditions at different time periods, avoiding the problem of liquid suction caused by poor operating adjustment ability under some working conditions, and providing a guarantee for the efficient and stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the implementation methods in the embodiments of the present application or related technologies, the following is a brief introduction to the drawings required for use in the embodiments or related technology descriptions. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0053] Figure 1 A schematic structural diagram of a centrifuge unit provided in this application;

[0054] Figure 2 A flow chart of a control method for an air conditioner provided in this application Figure 1 ;

[0055] Figure 3 A flow chart of a control method for an air conditioner provided in this application Figure 2 ;

[0056] Figure 4 A schematic diagram of a specific air conditioner control method provided in this application;

[0057] Figure 5 This is a structural schematic diagram of a control device for an air conditioner provided in this application.

[0058] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0059] In order to make the purpose, implementation mode and advantages of the present application clearer, the exemplary implementation mode of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0060] It should be noted that the brief descriptions of terms in this application are only for the purpose of facilitating the understanding of the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their ordinary and usual meanings.

[0061] In addition, the terms "comprises" and "comprising" and any variations thereof are intended to cover but not exclude inclusion, for example, a product or device comprising a list of components is not necessarily limited to those components expressly listed but may include other components not expressly listed or inherent to such product or device.

[0062] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0063] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0064] Figure 1 A schematic structural diagram of a centrifugal unit in an air conditioner provided in an embodiment of the present application is shown in FIG. Figure 1As shown, the centrifugal unit includes a compressor 10, a condenser 20, an orifice plate 30, a throttle valve 40, and an evaporator 50. The centrifugal unit uses the compressor 10, condenser 20, orifice plate 30, throttle valve 40, and evaporator 50 to perform a refrigeration cycle or a heating cycle. The refrigeration cycle and heating cycle include compression, condensation, expansion, and evaporation processes, and temperature regulation is achieved through the refrigerant's heat absorption and heat release processes.

[0065] The compressor 10 compresses the refrigerant gas into a high-temperature and high-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser 20.

[0066] The condenser 20 is provided with a cooling water inlet 21 and a cooling water outlet 22 that enter the condenser 20. The cooling water enters the condenser 2 through the cooling water inlet 21. The condenser 2 condenses the compressed high-temperature and high-pressure gaseous refrigerant into liquid refrigerant, and the heat is released into the cooling water through the condensation process. After absorbing the heat, the cooling water flows out of the condenser 20 through the cooling water outlet 22.

[0067] The liquid refrigerant flowing out of condenser 20 is dried and filtered by the filter drier, absorbing moisture from the refrigerant to ensure smooth flow of the refrigeration lines and proper refrigerant operation. The dried and filtered refrigerant then enters orifice plate 30 and throttle valve 40. These two valves reduce the pressure of the high-temperature, high-pressure liquid refrigerant, condensing it in condenser 20 to a low-pressure liquid refrigerant. The low-pressure liquid refrigerant flowing out of throttle valve 40 enters evaporator 50.

[0068] The evaporator 50 is provided with a cold water inlet 51 and a cold water outlet 52. Cold water enters the evaporator 20 through the cold water inlet 51. As the liquid refrigerant flows through the evaporator 50, it absorbs heat from the cold water and evaporates into a low-temperature, low-pressure refrigerant gas. The temperature of the cold water is lowered and it flows out of the cold water outlet 52. The low-temperature, low-pressure refrigerant gas returns to the compressor 10. The evaporator 50 achieves a cooling effect by utilizing the heat absorbed by the evaporation of the refrigerant to transfer heat.

[0069] When the high-temperature, high-pressure liquid refrigerant is depressurized through throttle valve 40, this can be achieved by adjusting the opening of throttle valve 40. Currently, the opening of throttle valve 40 is typically adjusted based on the difference between the saturation temperature corresponding to the compressor's discharge pressure and the discharge temperature, and a set temperature deviation threshold. However, the operating conditions of the centrifugal unit change in real time at different times, making this control method difficult to meet the requirements of operational regulation under different operating conditions. This can easily cause the centrifugal unit to enter an abnormal control phase, resulting in reduced refrigeration performance and the occurrence of problems such as "liquid hammer."

[0070] In view of this, an embodiment of the present application provides an air conditioner and a control method thereof. According to the operating parameters of the compressor, the operating process of the centrifugal unit is divided into multiple stages, and different opening determination methods are adopted in different stages to match the opening of the throttle valve with the operating process of the centrifugal unit, thereby meeting the needs of operation adjustment under different working conditions, and reducing the probability of reduced refrigeration performance due to excessive superheat of the centrifuge and the occurrence of "liquid hammer" problems in the compressor due to excessive superheat under different operating conditions.

[0071] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0072] Figure 2 This is a flow chart of a control method for an air conditioner provided by the present application. The execution subject of the embodiment of the present application may be a controller or a control module of the air conditioner, such as Figure 2 As shown, the control method includes:

[0073] S201. During a startup phase, determine a first target opening of the throttle valve according to a suction pressure of the compressor and a first warning reference value, and set the opening of the throttle valve to the first target opening.

[0074] In some embodiments, after the air conditioner is started, the centrifugal unit also starts to run synchronously, and the controller can determine whether the centrifugal unit is in the startup phase according to the running time. The startup phase can also be called the initial operation phase.

[0075] For example, when the running time is less than a preset time, it can be determined that the centrifuge unit is in the startup phase.

[0076] In some embodiments, when the centrifugal unit is in the startup phase, in order to prevent the compressor from being under low pressure protection in a short period of time due to slow change in superheat during startup, the throttle valve must be ensured to have a certain initial opening during the startup phase.

[0077] In some embodiments, the controller may determine a first target opening of the throttle valve based on a magnitude relationship between the suction pressure of the compressor and a first warning reference value, and set the opening of the throttle valve to the first target opening. The suction pressure of the compressor may be obtained by a suction pressure sensor disposed at the suction port of the compressor.

[0078] For example, the first target opening can be determined according to the following formula:

[0079]

[0080] Among them, Mn0 is the first target opening degree in the startup phase, Ps is the suction pressure of the compressor, and PsL is the first warning reference value (also called the low-pressure warning reference value).

[0081] Specifically, when the compressor suction pressure is less than or equal to a first warning reference value, the first target throttle valve opening is KA. When the compressor suction pressure is greater than the first warning reference value, the first target throttle valve opening is KB. The first warning reference value may be a value set based on actual experience.

[0082] During startup, low suction pressure may indicate insufficient evaporation pressure, necessitating an increased throttle valve opening to increase refrigerant flow, such as to 30%-50% (KA). High suction pressure is usually due to excessive refrigerant entering the evaporator, causing increased evaporation pressure and, in turn, affecting suction pressure. Therefore, the throttle valve opening should be decreased to reduce refrigerant flow, thereby lowering both evaporation and suction pressures, such as to 20%-30% (KB).

[0083] In some embodiments, during the startup phase, the controller may switch the first target throttle valve opening between KA and KB based on the relationship between the compressor's suction pressure and a first warning reference value. For example, at the first moment of the startup phase, if the compressor's suction pressure is less than the first warning reference value, the first target opening is KA. At the second moment, if the compressor's suction pressure is greater than the first warning reference value, the first target opening is adjusted from KA to KB.

[0084] S202: After a preset time period, determine the target stage of the centrifugal unit according to the suction pressure and the exhaust superheat of the compressor.

[0085] After the running time of the centrifugal unit reaches a preset time (e.g., 40-60 seconds), the centrifugal unit can transition from the startup phase to the normal operation phase. At this time, the controller can determine the specific operating phase of the current centrifugal unit based on the suction pressure and the exhaust superheat of the compressor.

[0086] For example, if the suction pressure is less than or equal to a second warning reference value, the centrifuge unit is determined to be in the first stage. The second warning reference value can be a value set based on actual experience, and the second warning reference value is greater than the first warning reference value. The first stage can also be referred to as the load mutation warning period, during which the load of the centrifuge unit has significantly changed compared to the previous stage.

[0087] If the suction pressure is greater than the second warning reference value and the exhaust superheat is less than or equal to the preset superheat lower limit, the centrifugal unit is determined to be in the second stage. The second stage may also be referred to as the minimum superheat limit stage. In this stage, the exhaust superheat is low, and the throttle valve opening needs to be adjusted to avoid liquid hammer caused by low exhaust superheat.

[0088] If the suction pressure is greater than the second warning reference value and the exhaust superheat is greater than the preset superheat lower limit, it is determined that the centrifugal unit is in the third stage, which can be called a stable operation stage.

[0089] S203: Determine a second target opening of the throttle valve according to the target stage, and adjust the opening of the throttle valve to the second target opening.

[0090] In some embodiments, the operating stage of the centrifugal unit is determined, and the controller can determine the opening of the throttle valve that matches the current stage according to the current stage.

[0091] In a possible implementation, the controller may determine the second target opening from a preset opening set according to the current stage, wherein the opening set includes openings corresponding to various stages.

[0092] In a possible implementation, at different stages, the controller may further use a preset algorithm to determine the second target opening corresponding to each stage according to operating parameters of the compressor and / or the evaporator.

[0093] The control method of the air conditioner provided in the embodiment of the present application is as follows: during the startup phase, the first target opening of the throttle valve is determined based on the suction pressure of the compressor and the first warning reference value, and the opening of the throttle valve is set to the first target opening; after a preset time, the target stage of the centrifugal unit is determined based on the suction pressure and the exhaust superheat of the compressor; according to the target stage, the second target opening of the throttle valve is determined, and the opening of the throttle valve is adjusted to the second target opening. By dividing the operation process of the centrifugal unit into multiple different stages, the throttle valve opening is adjusted to the opening that matches the current stage in different stages, thereby achieving multi-stage, adaptive control and adjustment of the throttle valve opening. Different control and adjustment methods are adopted under different working conditions, thereby solving the problem that a single control and adjustment method cannot cover all working conditions, or the control method is not optimal under different working conditions, avoiding the problem of suction liquid caused by poor operation and adjustment ability under some working conditions, and providing a guarantee for the efficient and stable operation of the system.

[0094] Based on the above embodiments, Figure 3 and Figure 4 , a detailed description is given of the process in which the controller in the embodiment of the present application determines the second target opening corresponding to each stage using a preset algorithm based on the operating parameters of the compressor and / or evaporator.

[0095] Figure 3 Schematic diagram of the process of the air conditioner control method provided in the embodiment of the present application Figure 2 ,like Figure 3 Shown, including:

[0096] S301: Determine the target stage of the centrifuge unit.

[0097] The specific implementation of S301 in the embodiment of this application is Figure 2 The specific implementation method shown in S202 in the illustrated embodiment is similar and will not be repeated here.

[0098] S302: In the first stage, determine the second target opening according to the current opening of the throttle valve and a preset opening change value.

[0099] When the suction pressure is less than or equal to the second warning reference value, it is determined that the centrifugal unit enters the first stage from the previous stage.

[0100] For example, the second warning reference value may be determined by adding a warning deviation value to the first warning reference value, for example, the second warning reference value=Ps1+Psc1 (warning deviation value).

[0101] In the first stage, the second target opening can be determined according to the following formula:

[0102] Mn1= Mn+c1

[0103] Wherein, Mn1 is the second target throttle valve opening in the first stage, Mn is the current throttle valve opening, and c1 is the preset opening change value. c1 can be set based on actual experience, such as 5%-10%.

[0104] For example, in the initial stage, the throttle valve opening is set to 25%. After a preset time, if it is detected that the centrifugal unit is in the first stage, the throttle valve opening Mn1 is adjusted to 25% (Mn) + 8% (c1).

[0105] S303: In the second stage, the second target opening is determined according to the current opening of the throttle valve and a preset opening range.

[0106] When the suction pressure is greater than the second warning reference value and the exhaust superheat is less than or equal to the preset superheat lower limit value, it is determined that the centrifugal unit enters the second stage from the previous stage.

[0107] In the second stage, the controller may determine a second target opening of the throttle valve in the second stage according to whether the current opening of the throttle valve is within a preset opening range.

[0108] Illustratively, if the current opening of the throttle valve is less than the lower limit of the opening range, the difference between the current opening of the throttle valve and the first limit value is used as the second target opening.

[0109] If the current opening of the throttle valve is within the opening range, the difference between the current opening of the throttle valve and the second limit value is used as the second target opening.

[0110] If the current opening of the throttle valve is greater than the upper limit of the opening range, the difference between the current opening of the throttle valve and the third limit value is used as the second target opening.

[0111] Exemplarily, in the second stage, the second target opening can be determined according to the following formula:

[0112]

[0113] Where Mn2 is the second target throttle valve opening in the second stage, Mn is the current throttle valve opening, Mnc1 is the lower limit of the preset opening range (e.g., 40%), Mnc2 is the upper limit of the preset opening range (e.g., 60%), and c2, c3, and c4 are preset opening limits. c2, c3, and c4 can be set based on practical experience. Optionally, the values ​​of c2, c3, and c4 increase in sequence. For example, c2, c3, and c4 can be 5%, 10%, and 15%, respectively.

[0114] For example, in the previous stage, the throttle valve opening is 55%. The controller detects that the centrifugal unit enters the second stage. Since the throttle valve opening of 55% is within the preset opening range, the throttle valve opening in the current stage is 55% (Mn) -10% (c3).

[0115] S304. In the third stage, the difference between the outlet water temperature of the evaporator and the evaporation temperature of the refrigerant in the evaporator is determined, and the second target opening is determined based on the difference, a preset temperature range, and the exhaust superheat of the compressor.

[0116] In the third stage, when the centrifugal chiller is in a stable operating state or has no load or no changes in external conditions, the throttle valve opening should be determined by the compressor's discharge superheat. Considering that control parameters need to be optimized to achieve optimal control under different operating conditions, the difference between the evaporator's water outlet temperature (Tcount) and the refrigerant's evaporation temperature (Te) in the evaporator (ΔT, also known as the evaporator approach temperature difference, ΔT = Tcount - Te) can be used to determine the different operating states of the centrifugal chiller in the second stage. Different adjustment coefficients are used according to the operating state, and the throttle valve opening is determined based on the adjustment coefficient and the discharge superheat.

[0117] In some embodiments, the controller can determine an adjustment coefficient for adjusting the throttle valve opening based on the relationship between the difference between the outlet water temperature of the evaporator and the evaporation temperature of the refrigerant in the evaporator and a preset temperature range; and determine the second target opening based on the adjustment coefficient and the exhaust superheat of the compressor.

[0118] Among them, the adjustment coefficient includes a proportional coefficient, an integral coefficient and a differential coefficient; when the difference is less than the lower limit of the preset temperature range, it corresponds to a set of adjustment coefficients; when the difference is greater than the upper limit of the preset temperature range, it corresponds to a set of adjustment coefficients; when the difference is within the preset temperature range, it corresponds to a set of adjustment coefficients.

[0119] In some embodiments, the controller may determine a first difference between the exhaust superheat and a target exhaust superheat, and a second difference between the exhaust superheat and the exhaust superheat at a previous moment. Upon obtaining the first and second differences, the controller may determine a first product of the proportional coefficient and the first difference, a second product of the integral coefficient and the first difference, and a third product of the differential coefficient and the second difference; and determine the second superheat based on the first, second, and third products.

[0120] Exemplarily, in the third stage, the second target opening can be determined according to the following formula:

[0121]

[0122] Where Mn3 is the second target throttle valve opening for the third stage, Kpi is the proportional coefficient, Kii is the integral coefficient, Kdi is the differential coefficient, Tdset is the target exhaust superheat, Tdsh is the exhaust superheat, and Tdsh(t-1) is the exhaust superheat at the previous moment. Ta is the lower limit of the preset temperature range, and Tb is the upper limit of the preset temperature range. Kpi, Kii, Kdi, Tdset, Ta, and Tb can be set based on actual experience.

[0123] In some embodiments, when ΔT < Ta, the evaporator's approach temperature difference is small, indicating strong evaporator heat transfer and more efficient heat exchange between the refrigerant and the brine. KP1, Ki1, and Kd1 are adjusted to optimize PID control. When ΔT ≥ Tb, the approach temperature difference is large, indicating weak evaporator heat transfer and insufficient heat exchange between the refrigerant and the brine. In this case, KP1, Ki1, and Kd1 need to be adjusted to optimize superheat control under these operating conditions. The evaporator's approach temperature difference and superheat control are dynamically coupled through the evaporating temperature: superheat control directly affects the evaporating temperature and is an active control measure; the approach temperature difference reflects heat exchange efficiency and is a passive monitoring indicator. The two are synergistically optimized to maximize evaporator heat exchange performance (minimize the approach temperature difference) while ensuring compressor safety (a reasonable superheat level).

[0124] Variations in outlet temperature Tcout due to evaporator load variations typically manifest as periodic fluctuations. Fixed parameter control cannot guarantee stable operation under all operating conditions. This application establishes an acceptable range for Tcout fluctuations and uses the evaporator approach temperature difference ΔT to determine whether optimization of control parameters is necessary to achieve optimal control.

[0125] In some embodiments, when adjusting the opening of the throttle valve based on the above method, if it is determined that the opening of the corresponding throttle valve is greater than the upper limit value of the throttle valve, the opening of the throttle valve is adjusted to the upper limit value; if it is determined that the opening of the corresponding throttle valve is less than the lower limit value of the throttle valve, the opening of the throttle valve is adjusted to the lower limit value.

[0126] In some embodiments, when the centrifuge unit is in any of the above-mentioned stages, as the centrifuge unit operates, the centrifuge unit switches among the above-mentioned stages. Therefore, the controller can determine whether the centrifuge unit meets the conditions for entering other stages based on the judgment conditions corresponding to each stage; if so, the second opening corresponding to the other stage is determined according to the implementation method described above, and the current opening of the throttle valve is adjusted based on the determined opening.

[0127] In summary, if Figure 4 As shown, the method for determining the opening of the throttle valve in the centrifugal unit provided in the embodiment of the present application satisfies the following formula:

[0128] Mn(t)=t0*Mn0+t3(1-t1)(1-t2)*Mn3 + t1*Mn1 + t2*(1-t1)Mn2, MnL≤Mn≤MnH

[0129] Among them, t1, t2, t3, and t4 are Boolean variables. When the unit is in the ti stage, ti=1, otherwise, ti=0, MnL is the lower limit of the throttle valve opening, and MnH is the upper limit of the throttle valve opening.

[0130] For example, if the unit is in the t0 stage, t0=1, t1, t2 and t3 are all 0, then Mn(t)=Mn0; if the unit is in the t1 stage, t1=1, t0, t2 and t3 are all 0, then Mn(t)=Mn1.

[0131] In some embodiments, the first stage, the second stage and the third stage are all stages in the operation process of the centrifuge unit. During the operation of the centrifuge unit, the judgment conditions of multiple stages may be met at the same time. In order to ensure the accuracy of the throttle valve opening setting, priorities are set for different stages.

[0132] For example, the priority order of each stage is as follows:

[0133] The first stage t1>the second stage t2>the third stage t3.

[0134] In some embodiments, by setting the coefficients in the above formula, when the judgment conditions of multiple stages are met at the same time, it can be determined which stage's opening adjustment should be performed.

[0135] For example, during stage t3, coefficient t3 = 1, t0 = 0, t1 = 0, and t2 = 0, in which case Mn = Mn3. If, during stage t3, the conditions for stages t1 and t2 are simultaneously met, a sudden load change and minimum superheat restriction occur, i.e., t3 = 1, t1 = 1, t2 = 1, and t0 = 0, then substituting into the above formula, i.e., Mn = Mn1, the opening adjustment corresponding to the first stage will take priority.

[0136] To sum up, the control method of the air conditioner provided in the embodiment of the present application can realize multi-time period, adaptive control and adjustment of the throttle valve opening, and adopt different control and adjustment methods for different working conditions, thereby solving the problem that a single control and adjustment method cannot cover all working conditions, or the control method is not optimal under different time period working conditions, avoiding the problem of liquid inhalation caused by poor operating adjustment ability under some working conditions, and providing a guarantee for efficient and stable operation of the system.

[0137] Based on the above embodiments, the present application also provides a control device for an air conditioner, which can be applied to the controller in any of the above embodiments.

[0138] Figure 5 A schematic diagram of the structure of the control device of the air conditioner provided in the embodiment of the present application is shown in FIG. Figure 5 Shown, including:

[0139] The determination module 501 is configured to determine a first target opening of the throttle valve according to the suction pressure of the compressor and a first warning reference value during a startup phase, and set the opening of the throttle valve to the first target opening.

[0140] The processing module 502 is configured to determine the target stage of the centrifugal unit according to the suction pressure and the exhaust superheat of the compressor after a preset time period.

[0141] The control module 503 is configured to determine a second target opening of the throttle valve according to the target stage, and adjust the opening of the throttle valve to the second target opening.

[0142] In some embodiments, the processing module 502 is used to determine that the centrifugal unit is in the first stage if the suction pressure is less than or equal to a second warning reference value; the second warning reference value is greater than the first warning reference value; if the suction pressure is greater than the second warning reference value, and the exhaust superheat is less than or equal to a preset superheat lower limit value, then determine that the centrifugal unit is in the second stage; if the suction pressure is greater than the second warning reference value, and the exhaust superheat is greater than the preset superheat lower limit value, then determine that the centrifugal unit is in the third stage.

[0143] In some embodiments, the control module 503 is configured to determine the second target opening according to the current opening of the throttle valve and a preset opening change value in the first stage.

[0144] In some embodiments, the control module 503 is configured to determine the second target opening according to the current opening of the throttle valve and a preset opening range in the second stage.

[0145] In some embodiments, the control module 503 is used to use the difference between the current opening of the throttle valve and the first limit value as the second target opening if the current opening of the throttle valve is less than the lower limit of the opening range; if the current opening of the throttle valve is within the opening range, use the difference between the current opening of the throttle valve and the second limit value as the second target opening; if the current opening of the throttle valve is greater than the upper limit of the opening range, use the difference between the current opening of the throttle valve and the third limit value as the second target opening; wherein, the second limit value is greater than the first limit value and less than the third limit value.

[0146] In some embodiments, the control module 503 is used to determine the difference between the outlet water temperature of the evaporator and the evaporation temperature of the refrigerant in the evaporator in the third stage; and determine the second target opening based on the difference, a preset temperature range, and the exhaust superheat of the compressor.

[0147] In some embodiments, the control module 503 is used to determine an adjustment coefficient for adjusting the throttle valve opening based on the size relationship between the difference and a preset temperature range; and determine the second target opening based on the adjustment coefficient and the exhaust superheat of the compressor.

[0148] In some embodiments, the control module 503 is used to determine a first difference between the exhaust superheat and the target exhaust superheat, and a second difference between the exhaust superheat and the exhaust superheat at the previous moment; determine a first product of the proportional coefficient and the first difference, a second product of the integral coefficient and the first difference, and a third product of the differential coefficient and the second difference; and determine the second superheat based on the first product, the second product and the third product.

[0149] In some embodiments, the control module 503 is used to determine whether the centrifuge unit meets the conditions for entering other stages when the centrifuge unit is in any stage; if so, adjust the current opening of the throttle valve according to the second opening corresponding to the other stage.

[0150] The control device of the air conditioner provided in the embodiment of the present application can execute the control method of the air conditioner in any of the above embodiments. The principles and technical effects thereof are similar and will not be repeated here.

[0151] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0152] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0153] The readable storage medium may be implemented by any type of volatile or non-volatile memory device, or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium may be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0154] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be an integral part of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0155] The division of units is merely a logical functional division; actual implementations may employ alternative divisions, such as combining or integrating multiple units or components into another system, or omitting or disabling certain features. Furthermore, any direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units, either through an interface, electrical, mechanical, or other means.

[0156] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0157] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0158] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the method of the present invention. The aforementioned storage medium includes various media that can store program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0159] Those skilled in the art will appreciate that all or part of the steps in the above-described method embodiments can be implemented using hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0160] Finally, it should be noted that those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

Claims

1. An air conditioner, characterized in that: include: A centrifugal unit, comprising: a compressor configured to compress a refrigerant; a condenser connected to the compressor and configured to condense and exchange heat on the compressed refrigerant; a throttle valve connected to the condenser and configured to control a flow rate of the refrigerant flowing out of the condenser; an evaporator connected to the control valve and configured to vaporize and exchange heat with the refrigerant; A controller configured to: During the startup phase, a first target opening of the throttle valve is determined according to the suction pressure of the compressor and a first warning reference value, and the opening of the throttle valve is set to the first target opening; After a preset time, determining the target stage of the centrifugal unit based on the suction pressure and the exhaust superheat of the compressor; A second target opening of the throttle valve is determined according to the target phase, and the opening of the throttle valve is adjusted to the second target opening.

2. The air conditioner according to claim 1, characterized in that The controller is configured to: If the suction pressure is less than or equal to a second warning reference value, it is determined that the centrifuge unit is in the first stage; and the second warning reference value is greater than the first warning reference value; If the suction pressure is greater than the second warning reference value, and the exhaust superheat is less than or equal to the preset superheat lower limit, determining that the centrifugal unit is in the second stage; If the suction pressure is greater than the second warning reference value, and the exhaust superheat is greater than the preset superheat lower limit, it is determined that the centrifugal unit is in the third stage.

3. The air conditioner according to claim 2, characterized in that The controller is configured to: In the first stage, the second target opening is determined according to the current opening of the throttle valve and a preset opening change value.

4. The air conditioner according to claim 2, characterized in that The controller is configured to: In the second stage, the second target opening is determined according to the current opening of the throttle valve and a preset opening range.

5. The air conditioner according to claim 4, characterized in that The controller is configured to: If the current opening of the throttle valve is less than the lower limit of the opening range, the difference between the current opening of the throttle valve and the first limit value is used as the second target opening; If the current opening of the throttle valve is within the opening range, the difference between the current opening of the throttle valve and the second limit value is used as the second target opening; If the current opening of the throttle valve is greater than the upper limit of the opening range, the difference between the current opening of the throttle valve and the third limit value is used as the second target opening; The second limit value is greater than the first limit value and less than the third limit value.

6. The air conditioner according to claim 2, characterized in that The controller is configured to: In the third stage, determining the difference between the outlet water temperature of the evaporator and the evaporation temperature of the refrigerant in the evaporator; The second target opening is determined according to the difference, a preset temperature range, and the exhaust gas superheat of the compressor.

7. The air conditioner according to claim 6, characterized in that The controller is configured to: determining an adjustment coefficient for adjusting the throttle valve opening according to a magnitude relationship between the difference and a preset temperature range; The second target opening is determined according to the adjustment coefficient and the exhaust gas superheat of the compressor.

8. The air conditioner according to claim 7, characterized in that The adjustment coefficient includes a proportional coefficient, an integral coefficient and a differential coefficient, and the controller is configured as follows: determining a first difference between the exhaust superheat and a target exhaust superheat, and a second difference between the exhaust superheat and the exhaust superheat at a previous moment; determining a first product of the proportional coefficient and the first difference, a second product of the integral coefficient and the first difference, and a third product of the differential coefficient and the second difference; The second degree of superheat is determined based on the first product, the second product, and the third product.

9. The air conditioner according to any one of claims 2 to 8, characterized in that: The controller is configured to: When the centrifuge unit is in any stage, determining whether the centrifuge unit meets the conditions for entering other stages; If the condition is satisfied, the current opening of the throttle valve is adjusted according to the second opening corresponding to the other stage.

10. A method for controlling an air conditioner, characterized in that: The air conditioner includes a centrifugal unit, wherein the centrifugal unit includes: a compressor configured to compress a refrigerant; a condenser connected to the compressor and configured to condense and exchange heat on the compressed refrigerant; a throttle valve connected to the condenser and configured to control a flow rate of the refrigerant flowing out of the condenser; an evaporator connected to the control valve and configured to vaporize and exchange heat with the refrigerant; The method comprises: During the startup phase, a first target opening of the throttle valve is determined according to the suction pressure of the compressor and a first warning reference value, and the opening of the throttle valve is set to the first target opening; After a preset time, determining the target stage of the centrifugal unit based on the suction pressure and the exhaust superheat of the compressor; A second target opening of the throttle valve is determined according to the target phase, and the opening of the throttle valve is adjusted to the second target opening.

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