Compressor switching method and multi-split air conditioner

Abstract

The embodiment of the application provides a compressor switching method and a multi-connected air conditioner, and belongs to the technical field of air conditioners.For the multi-connected air conditioner, during a period from starting to reduce the frequency of a compressor to starting the compressor for a first preset time length, according to the exhaust temperature of the compressor, the opening degree of an indoor expansion valve is controlled according to a preset first type rule, and meanwhile, the opening degree of an outdoor supercooling expansion valve is controlled according to a preset second type rule, so that the opening degree of the indoor expansion valve is not less than the opening degree of the indoor expansion valve at a previous moment when switching from single-compressor operation to double-compressor operation, the refrigerant circulation can be carried out at a high speed during the frequency reduction starting period, the exhaust temperature and pressure are avoided from being too high to a certain extent, the shutdown probability is reduced, the reliability of the unit is improved, and the comfortable experience of a user is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air conditioning, in particular to a compressor switching method and a multi-split air conditioner. BACKGROUND

[0002] In a multi-split air conditioning system including two compressors, when the cooling or heating capacity demand of the indoor unit is small, only one compressor needs to be started to meet the system demand. When the cooling or heating capacity of the indoor unit increases and one compressor cannot meet the system capacity demand, the system switches from one compressor to two compressors.

[0003] Currently, in the control method of the switching process from a single compressor to a double compressor, in order to avoid the failure of the compressor to start due to high pressure difference leading to shutdown, the running compressor is usually reduced in frequency to a set frequency, and then the shutdown compressor is started, that is, the running compressor is first reduced in frequency, and then the shutdown compressor is started, and then the two compressors are increased in frequency together. However, when the running compressor is first reduced in frequency and then the shutdown compressor is started, the air conditioning system is prone to shutdown due to excessively high exhaust temperature, affecting the comfort experience of the user. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a compressor switching method and a multi-split air conditioner, which can improve the problem that the air conditioning system is prone to shutdown due to excessively high exhaust temperature when switching from a single compressor to a double compressor, and improve the comfort experience of the user.

[0005] In order to achieve the above-mentioned purpose, the technical solutions adopted by the embodiments of the present application are as follows:

[0006] In a first aspect, the present application provides a compressor switching method applied to a multi-split air conditioner, and the method comprises:

[0007] During the frequency reduction and start-up period of switching from single compressor operation to double compressor operation, the opening degree of the indoor expansion valve is controlled according to the exhaust temperature of the compressor according to a preset first type of rule, so that the opening degree of the indoor expansion valve is not less than a first reference opening degree;

[0008] The frequency reduction and start-up period is a period of time from the start of frequency reduction of the running compressor to the start of the shutdown compressor for a first preset time length; and the first reference opening degree is the opening degree of the indoor expansion valve at a time point before switching from single compressor operation to double compressor operation.

[0009] During the frequency reduction and start-up period of switching from single compressor operation to double compressor operation, the opening degree of the outdoor supercooling expansion valve is controlled according to the exhaust temperature of the compressor according to a preset second type of rule, so that the opening degree of the outdoor supercooling expansion valve is not less than a second reference opening degree;

[0010] Wherein, the second reference opening degree is the opening degree of the outdoor unit's subcooling expansion valve at the moment before switching from single compressor operation to dual compressor operation.

[0011] Furthermore, the step of controlling the opening degree of the indoor unit expansion valve according to a preset rule based on the compressor's exhaust temperature includes:

[0012] Obtain the discharge temperature of the two compressors at the current moment, as well as the outlet and inlet temperatures of the evaporator, and use the difference between the outlet and inlet temperatures as the actual superheat.

[0013] Based on the exhaust temperature and the actual superheat, a type of opening change and a type of adjustment cycle are calculated according to a preset type of rule.

[0014] Within the aforementioned adjustment cycle, the opening degree of the indoor unit expansion valve is controlled by the aforementioned opening degree change amount;

[0015] When the first type of adjustment cycle ends, but the frequency reduction start-up period is still in progress, return to the step of obtaining the exhaust temperature of the two compressors at the current moment, as well as the outlet and inlet temperatures of the evaporator.

[0016] Furthermore, the aforementioned set of rules includes a set of temperature thresholds and a set of calculation rules. The step of calculating a set of opening changes and a set of adjustment cycles based on the exhaust temperature and actual superheat, according to the preset set of rules, includes:

[0017] From the exhaust temperatures of the two compressors, the higher exhaust temperature is selected as the target temperature, and the temperature level of the target temperature is determined based on the first type of temperature threshold.

[0018] Based on the aforementioned calculation rules, a type of adjustment cycle matching the temperature level is determined, and a type of opening change matching the temperature level is calculated in conjunction with the actual superheat.

[0019] Furthermore, the aforementioned type of calculation rule includes:

[0020]

[0021] as well as,

[0022]

[0023] Where ΔP1 represents a type of opening change, T represents the target temperature, and S h S0 represents the target superheat, K1, A, B, C, and D are all constants, T1 represents a type of adjustment period, and T represents the actual superheat. 11 and T 12t3 represents a type of temperature threshold, and t3 represents a type of reference period.

[0024] Furthermore, the step of controlling the opening of the external unit's subcooling expansion valve according to the compressor's discharge temperature and a preset second-class rule includes:

[0025] Obtain the discharge temperature of the two compressors at the current moment, as well as the outlet and inlet temperatures of the evaporator, and use the difference between the outlet and inlet temperatures as the actual superheat.

[0026] Based on the exhaust temperature and actual superheat, and according to the preset Class II rules, the Class II opening change and Class II adjustment cycle are calculated.

[0027] Within the second type of adjustment cycle, the opening degree of the outdoor unit's subcooling expansion valve is controlled by the second type of opening degree change.

[0028] When the second type of adjustment cycle ends, but the frequency reduction start-up period is still in progress, return to the step of obtaining the exhaust temperature of the two compressors at the current moment, as well as the outlet and inlet temperatures of the evaporator.

[0029] Furthermore, the second type of rules includes a second type of temperature threshold and a second type of calculation rules. The step of calculating the second type of opening change and the second type of adjustment cycle by combining the exhaust temperature and the actual superheat according to the preset second type of rules includes:

[0030] From the exhaust temperatures of the two compressors, the higher exhaust temperature is selected as the target temperature, and the temperature level of the target temperature is determined based on the two types of temperature thresholds.

[0031] Based on the aforementioned two types of calculation rules, a two-type adjustment cycle matching the temperature level is determined, and the change in the two-type opening degree matching the temperature level is calculated in conjunction with the actual superheat.

[0032] Furthermore, the two types of calculation rules include:

[0033]

[0034] as well as,

[0035]

[0036] Where ΔP2 represents the type II opening change, T represents the target temperature, and S h S0 represents the target superheat, K2, E, F, G, and H are all constants, T2 represents the type II regulation period, and T represents the actual superheat. 21 and T 22 t4 represents a type of temperature threshold, and t4 represents a type of reference period.

[0037] Furthermore, the step of switching from single-compressor operation to dual-compressor operation includes:

[0038] Upon receiving the switching command, the operating compressor is frequency-reduced. After the operating compressor is frequency-reduced to the first frequency, the stopped compressor is started and its frequency is increased to the first frequency.

[0039] After controlling the stopped compressor to maintain a second preset duration at a first frequency, the frequencies of the running compressor and the stopped compressor are synchronously increased to the target frequency.

[0040] Furthermore, the method also includes:

[0041] After the frequency reduction start-up period, the difference between the outlet pipe temperature and the inlet pipe temperature of the evaporator is taken as the actual superheat. Based on the actual superheat, the opening degree of the indoor unit expansion valve and the opening degree of the outdoor unit subcooling expansion valve are controlled.

[0042] Secondly, embodiments of the present invention also provide a multi-split air conditioner, including a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor, and the air conditioner implements the compressor switching method as described in the first aspect.

[0043] The compressor switching method and multi-split air conditioner provided by this invention, for multi-split air conditioners, during the frequency reduction start-up period when switching from single-compressor operation to dual-compressor operation (i.e., from the start of frequency reduction of the running compressor to the start-up of the shut-off compressor for a first preset time period), controls the opening of the indoor unit expansion valve according to a preset first-class rule based on the compressor's exhaust temperature. Simultaneously, it controls the opening of the outdoor unit subcooling expansion valve according to a preset second-class rule. This ensures that the opening of the indoor unit expansion valve is not less than its own opening at the moment before switching from single-compressor operation to dual-compressor operation, and that the openings of both the indoor unit expansion valve and the outdoor unit subcooling expansion valve are not less than their own openings at the moment before switching from single-compressor operation to dual-compressor operation. This allows for higher-speed refrigerant circulation during the frequency reduction start-up period, thereby preventing excessively high exhaust temperature and pressure, reducing the probability of shutdown, improving unit reliability, and enhancing user comfort.

[0044] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 A schematic diagram of the structure of a multi-split air conditioner provided in an embodiment of the present invention is shown.

[0047] Figure 2 This is a schematic flowchart of one of the compressor switching methods provided by an embodiment of the present invention.

[0048] Figure 3 The second schematic flowchart of the compressor switching method provided by the embodiment of the present invention is shown.

[0049] Figure 4 It shows Figure 2 or Figure 3 One of the flowcharts for some sub-steps in step S15.

[0050] Figure 5 It shows Figure 4 A flowchart illustrating some sub-steps of step S153.

[0051] Figure 6 It shows Figure 2 or Figure 3 The second flowchart of some sub-steps in step S15.

[0052] Figure 7 It shows Figure 6 A flowchart illustrating some sub-steps of step S152.

[0053] Figure 8 A block diagram of a compressor switching device provided in an embodiment of the present invention is shown.

[0054] Figure 9 A block diagram of an electronic device provided by an embodiment of the present invention is shown.

[0055] Reference numerals: 100-Multi-split air conditioner; 10-Indoor unit; 101-Indoor heat exchanger; 102-Indoor unit expansion valve; 20-Outdoor unit; 201-Compressor; 202-Four-way valve; 203-Outdoor heat exchanger; 204-Outdoor unit thermal expansion valve; 205-Outdoor unit subcooling expansion valve; 30-Controller; 40-Compressor switching device; 401-First start-up module; 402-Second start-up module; 403-Post-start control module; 50-Electronic equipment. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Generally, the components of the embodiments of the present invention described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0057] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0058] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0059] Currently, in the control methods for switching from a single compressor to a dual compressor, in order to avoid the shutdown compressor failing to start due to high pressure difference, the operating compressor is usually reduced to a set frequency before the shutdown compressor is started. That is, the operating compressor is reduced in frequency first and then the shutdown compressor is started, and then both compressors are increased in frequency together.

[0060] However, when the compressor operates at a reduced frequency, the refrigerant circulation volume of the air conditioning system decreases, and the opening of the electronic expansion valve (also known as the indoor unit expansion valve) and the subcooling electronic expansion valve of the outdoor unit decreases accordingly. When both compressors increase their frequency at the same time, due to the rapid increase in frequency, the opening of the indoor unit expansion valve and the subcooling expansion valve of the outdoor unit is prone to adjustment lag, resulting in excessively high exhaust temperature and shutdown, which affects the user's comfort experience.

[0061] Based on the above considerations, the present invention provides a compressor switching method that can improve the problems of excessively high exhaust temperature and shutdown when switching from a single compressor to a dual compressor, thereby enhancing the user's comfort experience.

[0062] The compressor switching method provided in this invention can be applied to... Figure 1 The multi-split air conditioner 100 shown may include an outdoor unit 20 and multiple parallel indoor units 10. The multiple outdoor units 20 are connected to the indoor units 10 through pipes to transfer refrigerant. Each indoor unit 10 includes an indoor heat exchanger 101 and an indoor expansion valve 102. Each outdoor unit 20 includes a compressor 201, a four-way valve 202, an outdoor heat exchanger 203, an outdoor thermal expansion valve 204, and an outdoor subcooling expansion valve 205. There may be two compressors 201 connected in parallel. The sequentially connected compressor 201, outdoor heat exchanger 203, outdoor thermal expansion valve 204, outdoor subcooling expansion valve 205, and indoor heat exchanger 101 form a refrigerant circuit. The refrigerant circulates in the refrigerant circuit, exchanging heat with the air through the outdoor heat exchanger 203 and indoor heat exchanger 101 respectively, to achieve either cooling or heating mode of the air conditioner.

[0063] Compressor 201 is used to compress refrigerant to form high-pressure refrigerant from low-pressure refrigerant. Depending on the cooling or heating capacity requirements, only one compressor 201 may operate, or both compressors 201 may operate simultaneously. In this embodiment, the compressor 201 in operation is referred to as the running compressor 201, and the compressor 201 in shutdown is referred to as the shutdown compressor 201.

[0064] The outdoor heat exchanger 203 is used to exchange heat between outdoor air and the refrigerant transported within it. For example, in the cooling mode of the multi-split air conditioner 100, the outdoor heat exchanger 203 operates as a condenser, causing the refrigerant compressed by the compressor 201 to dissipate heat to the outdoor air and condense. In the heating mode of the multi-split air conditioner 100, the outdoor heat exchanger 203 operates as an evaporator, causing the depressurized refrigerant to absorb heat from the outdoor air and evaporate.

[0065] The outdoor unit thermal expansion valve 204, the outdoor unit subcooling expansion valve 205, and the indoor unit expansion valve 102 are connected between the outdoor heat exchanger 203 and the indoor heat exchanger 101. The opening degree of the outdoor unit thermal expansion valve 204, the outdoor unit subcooling expansion valve 205, and the indoor unit expansion valve 102 regulates the refrigerant pressure flowing through the outdoor heat exchanger 203 and the indoor heat exchanger 101, thereby regulating the refrigerant flow rate between the outdoor heat exchanger 203 and the indoor heat exchanger 101. The flow rate and pressure of the refrigerant flowing between the outdoor heat exchanger 203 and the indoor heat exchanger 101 will affect the heat exchange performance of the outdoor heat exchanger 203 and the indoor heat exchanger 101. The outdoor unit thermal expansion valve 204, the outdoor unit subcooling expansion valve 205, and the indoor unit expansion valve 102 can be electronic valves, and their opening degree is adjustable to control the flow rate and pressure of the refrigerant flowing through the outdoor unit thermal expansion valve 204, the outdoor unit subcooling expansion valve 205, and the indoor unit expansion valve 102.

[0066] The four-way valve 202 is connected to the refrigerant circuit. The four-way valve 202 is used to switch the flow direction of the refrigerant in the refrigerant circuit so that the multi-split air conditioner 100 can perform cooling mode or heating mode.

[0067] The indoor heat exchanger 101 is used to exchange heat between indoor air and the refrigerant transported within it. For example, in the cooling mode of the multi-split air conditioner 100, the indoor heat exchanger 101 operates as an evaporator, causing the refrigerant, after dissipating heat via the outdoor heat exchanger 203, to absorb heat from the indoor air and evaporate. In the heating mode of the multi-split air conditioner 100, the indoor heat exchanger 101 operates as a condenser, causing the refrigerant, after absorbing heat via the outdoor heat exchanger 203, to dissipate heat to the indoor air and condense.

[0068] The multi-split air conditioner 100 also includes a controller 30. The controller 30 controls the operation of the compressor 201, and also controls the opening degree of the outdoor unit thermal expansion valve 204, the outdoor unit subcooling expansion valve 205, and the outdoor unit expansion valve. The controller 30 is connected to the compressor 201, the outdoor unit thermal expansion valve 204, the outdoor unit subcooling expansion valve 205, and the outdoor unit expansion valve via a data cable to transmit communication information.

[0069] It should be understood that the multi-split air conditioner 100 may also include components such as a fan, which will not be described in detail in this embodiment.

[0070] In one possible implementation, the present invention provides a compressor switching method, referring to... Figure 2 This may include the following steps. In this embodiment, the compressor switching method is applied to... Figure 1 Let's take controller 30 as an example.

[0071] S13, determine whether it is in the frequency reduction start-up period of switching from single compressor operation to dual compressor operation. If so, proceed to step S15.

[0072] In this embodiment, the frequency reduction start-up period is the time period from when the running compressor starts to reduce its frequency until the shutdown compressor starts for a first preset duration.

[0073] S15, based on the compressor's discharge temperature, controls the opening of the indoor unit's expansion valve according to a preset first-class rule, and controls the opening of the outdoor unit's subcooling expansion valve according to a preset second-class rule, so that the opening of the indoor unit's expansion valve is not less than the first reference opening, and the opening of the outdoor unit's subcooling expansion valve is not less than the second reference opening.

[0074] In this embodiment, the first reference opening degree refers to the opening degree of the indoor unit's expansion valve at the moment before switching from single-compressor operation to dual-compressor operation. The second reference opening degree refers to the opening degree of the outdoor unit's subcooling expansion valve at the moment before switching from single-compressor operation to dual-compressor operation.

[0075] The specific value of the first preset duration can be adjusted according to actual needs, and is not specifically limited in this embodiment. In one possible embodiment, the value of the first preset duration can be 3-5 minutes.

[0076] When a multi-split air conditioner 100 operating with a single compressor 201 determines that the single compressor 201 cannot meet the indoor cooling or heating demand, the controller 30 generates a switching command to switch to dual compressor 201 operation. Upon detecting this command, the controller 30 controls the operating compressor 201 to reduce its frequency. After reducing to a set frequency, the controller 30 controls the stopped compressor 201 to start, thus switching from single compressor 201 operation to dual compressor 201 operation.

[0077] During the switching process, when the controller 30 determines that it is in the period from when the running compressor 201 starts to reduce its frequency to when the shut-off compressor 201 starts for the first preset duration, that is, when it is in the frequency reduction start-up period, it controls the opening of the indoor unit expansion valve 102 according to the discharge temperature of the compressor 201 and controls the opening of the outdoor unit subcooling expansion valve 205 according to the preset second-class rule, so that the opening of the indoor unit expansion valve 102 is not less than its own opening before the switching, and the opening of the outdoor unit subcooling expansion valve 205 is not less than its own opening before the switching.

[0078] Compared with the traditional control method of switching from single compressor operation to dual compressor operation, the above compressor switching method ensures that during the period from when the running compressor starts to reduce its frequency to when the shut-off compressor starts for the first preset time, the opening degree of the indoor unit expansion valve and the outdoor unit subcooling expansion valve is not less than their original opening degree before the switch. This allows the refrigerant to circulate at a higher speed during the frequency reduction start-up period, thereby avoiding excessively high exhaust temperature and pressure to a certain extent, reducing the probability of shutdown, improving the reliability of the air conditioning unit, and enhancing the user's comfort experience.

[0079] Furthermore, refer to Figure 3 The compressor switching method provided in this embodiment of the invention may further include the following steps, through which the switching from single compressor operation to dual compressor operation is achieved.

[0080] S11, after receiving the switching command, controls the frequency reduction of the running compressor. After the running compressor is reduced to the first frequency, it controls the shutdown compressor to start and raises the frequency of the shutdown compressor to the first frequency.

[0081] S12, after controlling the stopped compressor to maintain the second preset time at the first frequency, the frequencies of the running compressor and the stopped compressor are synchronously increased to the target frequency.

[0082] It should be understood that the switching command refers to the command to switch from single compressor operation to dual compressor operation.

[0083] After the controller 30 determines that a single compressor 201 cannot meet the indoor unit's cooling or heating capacity requirements, it generates a switching command. Upon detecting this command, the controller 30 controls the operating compressor 201 to reduce its frequency to a first frequency. After the operating compressor 201 reduces its frequency to the first frequency, the controller starts the shutdown compressor 201 and controls it to increase its frequency to the first frequency. After the shutdown compressor 201 increases its frequency to the first frequency, it maintains this frequency for a second preset duration. After the second preset duration ends, the frequencies of both the operating compressor 201 and the shutdown compressor 201 are synchronously increased to the target frequency.

[0084] The specific values ​​of the first frequency and the second preset duration can be adjusted according to actual needs, and are not specifically limited in this embodiment. The target frequency is determined by the set cooling or heating value. In one possible embodiment, the value of the first frequency can be in the range of 10Hz-50Hz, and the value of the second preset duration can be in the range of 10s-60s.

[0085] During steps S11 and S12, the controller 30 also performs control steps S13 to S15.

[0086] For step S15, refer to Figure 4 The control of the opening degree of the indoor unit's expansion valve can be further implemented through the following steps.

[0087] S151: Obtain the discharge temperature of the two compressors at the current moment, as well as the outlet and inlet temperatures of the evaporator, and use the difference between the outlet and inlet temperatures as the actual superheat.

[0088] S153, combining exhaust temperature and actual superheat, calculates a type of opening change and a type of adjustment cycle according to a preset type of rule.

[0089] S155 controls the opening of the indoor unit's expansion valve with a certain amount of opening change within a certain adjustment cycle.

[0090] S157: After the first type of adjustment cycle ends, determine whether the frequency reduction start-up period is still in effect. If so, return to step S151.

[0091] Furthermore, refer to Figure 5 Step S153 can be further implemented as follows.

[0092] S1531 selects the higher exhaust temperature from the two compressors as the target temperature and determines the temperature level of the target temperature based on a type of temperature threshold.

[0093] S1532, based on a type of calculation rule, determines a type of adjustment cycle that matches the temperature level, and calculates a type of opening change that matches the temperature level in combination with the actual superheat.

[0094] One type of calculation rule includes formulas for calculating the change in opening degree and formulas for calculating the period.

[0095] In this embodiment, the formula for calculating the change in opening degree of a certain type of calculation rule can be:

[0096]

[0097] ΔP1 represents a type of opening change, T represents the target temperature, and S h The actual superheat is represented by S0, the target superheat is represented by K1, A, and C, which are all constants, and T is the actual superheat. 11 and T 12 This represents a type of temperature threshold.

[0098] The period calculation formula for a certain type of calculation rule can be:

[0099]

[0100] T1 represents a type of adjustment period, t3 represents a type of reference period, and B and D are both constants.

[0101] It should be noted that T 12 >T 11A≤C, B≥D. In one possible implementation, T 11 The value range of T can be [95℃, 105℃]. 12 The range of values ​​for t3 can be [100℃, 110℃], the range of values ​​for t3 can be [20s, 60s], the range of values ​​for A can be [1, 2], the range of values ​​for B can be [0.6, 1], the range of values ​​for C can be [2, 4], and the range of values ​​for D can be [0.4, 0.8].

[0102] The value of K1 is determined by the reliability and adjustment speed of the air conditioning system. Different air conditioning systems have different reliability and adjustment speed, so the value of K1 will also be different. In one possible implementation, K1 can be any value between [2, 8].

[0103] Through steps S151 to S157 above, during the frequency reduction start-up period, if the exhaust temperature is high, the opening range and adjustment speed of the indoor unit expansion valve are accelerated, meaning the indoor unit expansion valve opens rapidly to increase the refrigerant circulation volume in the system and lower the exhaust temperature. If the exhaust temperature is very high, the opening range and adjustment speed of the indoor unit expansion valve are further increased to achieve a rapid reduction in exhaust temperature. Therefore, during the frequency reduction start-up period, the opening of the indoor unit expansion valve is controlled to be no lower than the opening before the compressor's frequency reduction operation, to avoid excessively high exhaust temperature and pressure.

[0104] Similarly, for step S15, refer to Figure 6 Controlling the opening degree of the subcooling expansion valve of the external unit can be further implemented through the following steps.

[0105] S152, combining exhaust temperature and actual superheat, calculates the second-class opening change and the second-class adjustment cycle according to the preset second-class rules.

[0106] S154 controls the opening of the outdoor unit's subcooling expansion valve by adjusting the second-class opening change during the second-class regulation cycle.

[0107] S156, after the second type of adjustment cycle ends, determine whether it is still in the frequency reduction start-up period. If so, return to step S151.

[0108] Furthermore, refer to Figure 7 The above step S152 can be further implemented as the following steps.

[0109] S1521 selects the higher exhaust temperature from the two compressors as the target temperature and determines the temperature level of the target temperature based on the second-class temperature threshold.

[0110] S1522, based on the Class II calculation rules, determines the Class II regulation cycle that matches the temperature level, and calculates the Class II opening change that matches the temperature level in combination with the actual superheat.

[0111] Among them, the second type of calculation rules includes the calculation formula for the change in opening degree and the calculation formula for the period.

[0112] In one possible implementation, the formula for calculating the change in opening degree under the two types of calculation rules can be:

[0113]

[0114] ΔP2 represents the type II aperture change, T represents the target temperature, and S h The actual superheat is represented by S0, the target superheat is represented by K2, E and G are constants, and T is the actual superheat. 21 and T 22 This indicates a Class II temperature threshold.

[0115] The period calculation formula for the second type of calculation rule can be:

[0116]

[0117] T2 represents the second type of adjustment period, t4 represents the second type of reference period, and F and H are both constants.

[0118] It should be noted that T 22 >T 21 E≤G, F≥H. In one possible implementation, T 21 The value range of T can be [95℃, 105℃]. 22 The range of values ​​for t is [100℃, 110℃], the range of values ​​for t4 is [20s, 60s], the range of values ​​for K2 is [0.5, 3], the range of values ​​for E is [1, 1.5], the range of values ​​for F is [0.5, 1], the range of values ​​for G is [1.5, 3], and the range of values ​​for H is [0.2, 0.6].

[0119] Through steps S151 to S156 above, during the frequency reduction start-up period, if the exhaust temperature is high, the opening range and adjustment speed of the outdoor unit's subcooling expansion valve are accelerated, meaning the outdoor unit's subcooling expansion valve opens rapidly, increasing the system's refrigerant circulation volume and lowering the exhaust temperature. If the exhaust temperature is very high, the opening range and adjustment speed of the outdoor unit's subcooling expansion valve are further increased to achieve a rapid reduction in exhaust temperature. Therefore, during the frequency reduction start-up period, the opening of the outdoor unit's subcooling expansion valve is controlled to be no lower than the opening before the compressor's frequency reduction, to avoid excessively high exhaust temperature and pressure.

[0120] Furthermore, to achieve the target control (i.e., cooling or heating) while operating two compressors during the frequency reduction start-up period, and to avoid excessively high exhaust temperature and pressure, the opening degree control of the outdoor unit's subcooling expansion valve and the indoor unit's expansion valve is introduced. (Refer to...)Figure 8 The compressor switching method provided in this embodiment of the invention can also reduce the start-up control step, which includes: after the frequency reduction start-up period, taking the difference between the outlet pipe temperature and the inlet pipe temperature of the evaporator as the actual superheat, and controlling the opening degree of the indoor unit expansion valve and the opening degree of the outdoor unit subcooling expansion valve according to the actual superheat.

[0121] For the indoor unit expansion valve, after the frequency reduction start-up period, a reference cycle t3 is used as the adjustment cycle. Within each adjustment cycle, the actual superheat is calculated. Combined with the actual superheat, the calculation is performed according to the reference formula ΔP=K1×(S) h -S0), calculate the opening change, and use this opening change to control the opening of the indoor unit expansion valve.

[0122] For the outdoor unit's subcooling expansion valve, after the frequency reduction start-up period, it can be controlled according to the target exhaust temperature, that is, using the Class II reference period t4 as the adjustment period. Within each adjustment period, the actual superheat is calculated, and combined with the actual superheat, the reference calculation formula ΔP=K2×(S) is used. h -S0), calculate the opening change, and use this opening change to control the opening of the outdoor unit's subcooling expansion valve.

[0123] In one possible implementation, frequency follow-up control can also be performed on the outdoor unit's subcooling expansion valve after the frequency reduction start-up period. That is, based on the frequency change, the opening change is calculated according to the frequency follow-up formula ΔP=P1×(f2-f1) / f1, and the opening of the outdoor unit's subcooling expansion valve is controlled by the opening change.

[0124] The compressor switching method described in this invention, for dual-compressor or multi-compressor outdoor unit systems, ensures that during the frequency reduction start-up period when switching from single-compressor operation to dual-compressor operation, the opening degrees of both the indoor unit expansion valve and the outdoor unit subcooling expansion valve are not lower than their pre-frequency reduction opening degrees. This allows for conventional control adjustments when the exhaust temperature is low, with smaller expansion valve adjustment amplitudes and speeds, ensuring system stability. When the exhaust temperature is high, the adjustment amplitude and speed of the electronic expansion valve are appropriately increased for a faster response. When the exhaust temperature is very high, the adjustment amplitude and speed of the electronic expansion valve are further increased to rapidly increase the system circulation volume. This, to a certain extent, avoids excessively high exhaust temperatures and pressures, ensuring stable unit operation and improving user comfort.

[0125] Based on the same inventive concept as the compressor switching method described above, this invention also provides a compressor switching device 40, applied to... Figure 1 Controller 30 in the middle, refer to Figure 8 The compressor switching device 40 may include a first start-stop module 401 and a second start-stop module 402.

[0126] The first start-up module 401 is used to control the opening degree of the indoor unit expansion valve according to a preset rule based on the compressor's exhaust temperature during the frequency reduction start-up period when switching from single compressor operation to dual compressor operation, so that the opening degree of the indoor unit expansion valve is not less than the first reference opening degree.

[0127] The first start-up module 401 is also used to control the opening of the outdoor unit's subcooling expansion valve according to the compressor's exhaust temperature and a preset second-class rule during the frequency reduction start-up period when switching from single compressor operation to dual compressor operation, so that the opening of the outdoor unit's subcooling expansion valve is not less than the second reference opening.

[0128] The second start-stop module 402 is used to control the frequency reduction of the running compressor after receiving the switching command. After the running compressor is reduced to the first frequency, it controls the shutdown compressor to start and raises the frequency of the shutdown compressor to the first frequency. It also controls the shutdown compressor to maintain the first frequency for a second preset time and then synchronously raises the frequencies of the running compressor and the shutdown compressor to the target frequency.

[0129] In this embodiment, the frequency reduction start-up period is the time period from when the running compressor begins to reduce its frequency to when the shut-off compressor starts for a first preset duration. The first reference opening degree is the opening degree of the indoor unit's expansion valve at the moment before switching from single-compressor operation to dual-compressor operation. The second reference opening degree is the opening degree of the outdoor unit's subcooling expansion valve at the moment before switching from single-compressor operation to dual-compressor operation.

[0130] Furthermore, the compressor switching device 40 may also include a start-up control module 403.

[0131] The start-up control module 403 is used to take the difference between the outlet pipe temperature and the inlet pipe temperature of the evaporator as the actual superheat after the frequency reduction start-up period, and control the opening degree of the indoor unit expansion valve and the outdoor unit subcooling expansion valve according to the actual superheat.

[0132] In the compressor switching device 40 described above, through the coordinated action of the first start-up module 401 and the second start-up module 402, during the period from when the running compressor starts to reduce its frequency to when the shut-off compressor starts for a first preset time, the opening degree of the indoor unit expansion valve and the outdoor unit subcooling expansion valve is controlled to be no less than their own opening degree before the switch. This allows the refrigerant to circulate at a higher speed during the frequency reduction start-up period, thereby avoiding excessively high exhaust temperature and pressure to a certain extent, reducing the probability of shutdown, improving the reliability of the air conditioning unit, and enhancing the user's comfort experience.

[0133] Specific limitations regarding the compressor switching device 40 can be found in the limitations of the compressor switching method described above, and will not be repeated here. Each module in the compressor switching device 40 can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in the electronic device, or stored in the memory of the electronic device in software form, so that the processor can call and execute the operations corresponding to each module.

[0134] In one embodiment, an electronic device 50 is provided, which may be a multi-split air conditioner 100, and its internal structure diagram may be as shown below. Figure 9 As shown, the electronic device 50 includes a processor, memory, communication interface, and input device connected via a system bus. The processor of the electronic device 50 provides computing and control capabilities. The memory of the electronic device 50 includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The communication interface of the electronic device 50 is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, near-field communication (NFC), or other technologies. When the computer program is executed by the processor, it implements the compressor switching method provided in the above embodiment.

[0135] Figure 9 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the electronic device 50 to which the present invention is applied. The specific electronic device 50 may include, but is not limited to, the following: Figure 8 The diagram shows more or fewer components, or combinations of certain components, or different component arrangements.

[0136] In one embodiment, the compressor switching device 40 provided by the present invention can be implemented as a computer program, which can be implemented in, for example... Figure 9 The electronic device 50 shown operates on this device. The memory of the electronic device 50 can store various program modules that make up the compressor switching device 40, for example, Figure 8 The first start-up module 401 and the second start-up module 402 are shown. The computer program composed of these program modules causes the processor to execute the steps in the compressor 201 switching method described in this specification.

[0137] For example, Figure 9 The electronic device 50 shown can be accessed via, for example... Figure 8 The first start-stop module 401 in the compressor switching device 40 shown executes steps S13 and S15. The electronic device 50 can execute steps S11 and S12 through the second start-stop module 402.

[0138] In one embodiment, a multi-split air conditioner 100 is provided, including a memory and a processor. The memory stores machine-executable instructions, and the processor executes the machine-executable instructions to perform the following steps: during the frequency reduction start-up period when switching from single-compressor operation to dual-compressor operation, the opening degree of the indoor unit expansion valve is controlled according to a preset first-class rule based on the compressor's exhaust temperature, so that the opening degree of the indoor unit expansion valve is not less than a first reference opening degree; during the frequency reduction start-up period when switching from single-compressor operation to dual-compressor operation, the opening degree of the outdoor unit subcooling expansion valve is controlled according to a preset second-class rule based on the compressor's exhaust temperature, so that the opening degree of the outdoor unit subcooling expansion valve is not less than a second reference opening degree.

[0139] In one embodiment, a storage medium is provided storing a computer program that, when executed by a processor, performs the following steps: during the frequency reduction start-up period when switching from single-compressor operation to dual-compressor operation, the opening degree of the indoor unit expansion valve is controlled according to a preset first-class rule based on the compressor's exhaust temperature, so that the opening degree of the indoor unit expansion valve is not less than a first reference opening degree; during the frequency reduction start-up period when switching from single-compressor operation to dual-compressor operation, the opening degree of the outdoor unit subcooling expansion valve is controlled according to a preset second-class rule based on the compressor's exhaust temperature, so that the opening degree of the outdoor unit subcooling expansion valve is not less than a second reference opening degree.

[0140] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functions, and operations of possible implementations of apparatus, methods, and computer program products according to various embodiments of the invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0141] In addition, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0142] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part 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 to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0143] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A compressor switching method, characterized in that, Applied to multi-split air conditioners, the method includes: During the frequency reduction start-up period when switching from single compressor operation to dual compressor operation, the opening degree of the indoor unit expansion valve is controlled according to a preset rule based on the compressor's exhaust temperature, so that the opening degree of the indoor unit expansion valve is not less than the first reference opening degree. The frequency reduction start-up period is the time period from when the running compressor starts to reduce its frequency to when the stopped compressor starts for a first preset duration; the first reference opening degree is the opening degree of the indoor unit expansion valve at the moment before switching from single compressor operation to dual compressor operation; During the frequency reduction start-up period when switching from single compressor operation to dual compressor operation, the opening of the outdoor unit subcooling expansion valve is controlled according to the compressor's exhaust temperature and a preset second-class rule, so that the opening of the outdoor unit subcooling expansion valve is not less than the second reference opening. Wherein, the second reference opening degree is the opening degree of the outdoor unit's subcooling expansion valve at the moment before switching from single compressor operation to dual compressor operation; the step of controlling the opening degree of the indoor unit's expansion valve according to a preset rule based on the compressor's exhaust temperature includes: Obtain the discharge temperature of the two compressors at the current moment, as well as the outlet and inlet temperatures of the evaporator, and use the difference between the outlet and inlet temperatures as the actual superheat. Based on the exhaust temperature and the actual superheat, a type of opening change and a type of adjustment cycle are calculated according to a preset type of rule. Within the aforementioned adjustment cycle, the opening degree of the indoor unit expansion valve is controlled by the aforementioned opening degree change amount; When the first type of adjustment cycle ends, but the frequency reduction start-up period is still in progress, the process returns to the step of obtaining the current exhaust temperature of the two compressors, as well as the outlet and inlet temperatures of the evaporator. The first type of rule includes a type of temperature threshold and a type of calculation rule. The step of calculating a type of opening change and a type of adjustment cycle based on the exhaust temperature and actual superheat, according to the preset first type of rule, includes: From the exhaust temperatures of the two compressors, the higher exhaust temperature is selected as the target temperature, and the temperature level of the target temperature is determined based on the first type of temperature threshold. Based on the aforementioned calculation rules, a type of adjustment cycle matching the temperature level is determined, and a type of opening change matching the temperature level is calculated in conjunction with the actual superheat. The step of controlling the opening of the external unit's subcooling expansion valve according to the compressor's discharge temperature and a preset Class II rule includes: Obtain the discharge temperature of the two compressors at the current moment, as well as the outlet and inlet temperatures of the evaporator, and use the difference between the outlet and inlet temperatures as the actual superheat. Based on the exhaust temperature and actual superheat, and according to the preset Class II rules, the Class II opening change and Class II adjustment cycle are calculated. Within the second type of adjustment cycle, the opening degree of the outdoor unit's subcooling expansion valve is controlled by the second type of opening degree change. When the second type of adjustment cycle ends, but the frequency reduction start-up period is still in progress, the process returns to the step of obtaining the current exhaust temperature of the two compressors, as well as the outlet and inlet temperatures of the evaporator. The second type of rules includes a second type of temperature threshold and a second type of calculation rules. The step of calculating the second type of opening change and the second type of adjustment cycle by combining the exhaust temperature and the actual superheat according to the preset second type of rules includes: From the exhaust temperatures of the two compressors, the higher exhaust temperature is selected as the target temperature, and the temperature level of the target temperature is determined based on the two types of temperature thresholds. Based on the aforementioned two types of calculation rules, a two-type adjustment cycle matching the temperature level is determined, and the change in the two-type opening degree matching the temperature level is calculated in conjunction with the actual superheat.

2. The compressor switching method according to claim 1, characterized in that, The calculation rules include: as well as, in, This represents a type of change in aperture. Indicates the target temperature. Indicates the actual superheat. Indicates the target's overheating level. , , , and All are constants. This indicates a type of adjustment cycle. and This represents a class of temperature thresholds. This represents a type of benchmark period.

3. The compressor switching method according to claim 1, characterized in that, The two types of calculation rules include: as well as, in, This represents the change in the second type of aperture. Indicates the target temperature. Indicates the actual superheat. Indicates the target's overheating level. , , , and All are constants. This indicates a type II adjustment cycle. and Indicates the second type of temperature threshold. This indicates a second-class benchmark period.

4. The compressor switching method according to any one of claims 1 to 3, characterized in that, The step of switching from single-compressor operation to dual-compressor operation includes: Upon receiving the switching command, the operating compressor is frequency-reduced. After the operating compressor is frequency-reduced to the first frequency, the stopped compressor is started and its frequency is increased to the first frequency. After controlling the stopped compressor to maintain a second preset duration at a first frequency, the frequencies of the running compressor and the stopped compressor are synchronously increased to the target frequency.

5. The compressor switching method according to any one of claims 1 to 3, characterized in that, The method further includes: After the frequency reduction start-up period, the difference between the outlet pipe temperature and the inlet pipe temperature of the evaporator is taken as the actual superheat. Based on the actual superheat, the opening degree of the indoor unit expansion valve and the opening degree of the outdoor unit subcooling expansion valve are controlled.

6. A multi-split air conditioner, characterized in that, The system includes a memory and a processor, the memory storing a computer program, which, when executed by the processor, enables the multi-split air conditioner to implement the compressor switching method as described in any one of claims 1 to 5.

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