Multi-connected air conditioning system and control method thereof

Abstract

The application discloses a multi-connected air conditioning system and a control method thereof, relates to the technical field of air conditioners, and aims to solve the problem of affecting the continuous operation of the multi-connected air conditioning system when the electrical box has the risk of frost formation. The multi-connected air conditioning system comprises an outdoor unit, a controller and a plurality of indoor units. The outdoor unit comprises an electrical box, the electrical box is provided with a refrigerant heat dissipation module, the refrigerant heat dissipation module comprises a refrigerant inlet and a refrigerant outlet, the outdoor heat exchanger comprises a first end and a second end, the refrigerant inlet is connected with the first end, the indoor heat exchanger comprises a third end and a fourth end, the third end is connected with the second end, and the refrigerant outlet is connected with the fourth end. The controller is configured to: acquire the temperature T sc of the refrigerant at the refrigerant inlet, the ambient temperature T a around the electrical box and the temperature T fin inside the electrical box, and control the refrigerant temperature flowing through the refrigerant heat dissipation module to rise when the value of T a -T sc is greater than or equal to a first preset value and / or the value of T a -T fin is greater than or equal to a second preset value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air conditioners, in particular to a multi-split air conditioning system and a control method thereof. BACKGROUND

[0002] The common heat dissipation mode of the electrical box of the multi-split air conditioning system is air cooling and refrigerant cooling. Although the refrigerant cooling has good effect, in special cases, the refrigerant pressure in the refrigerant cooling pipe is low, resulting in low refrigerant temperature. The low-temperature refrigerant conducted to the refrigerant cooling module on the electrical box causes condensation on the electrical box when the temperature of the refrigerant flowing through the refrigerant cooling module is lower than the dew point temperature of the air around the electrical box, affecting the normal use of the electrical components in the electrical box.

[0003] In the existing control method of the multi-split air conditioning system, when the temperature of the refrigerant flowing through the refrigerant cooling module is lower than the dew point temperature of the air around the electrical box, i.e., the electrical box has a condensation risk, the multi-split air conditioning system is controlled to stop. If the multi-split air conditioning system stops frequently due to low refrigerant temperature flowing through the refrigerant cooling module, the multi-split air conditioning system will be controlled to alarm, and the multi-split air conditioning system will not be able to start again, which needs to be repaired by a service engineer, affecting the continuous operation of the multi-split air conditioning system. SUMMARY

[0004] The present application provides a multi-split air conditioning system and a control method thereof, which are used to solve the problem that the continuous operation of the multi-split air conditioning system is affected when the electrical box has a condensation risk.

[0005] To achieve the above-mentioned purpose, the embodiments of the present application adopt the following technical solutions:

[0006] The embodiments of the present application provide a multi-split air conditioning system, which comprises: an outdoor unit, the outdoor unit comprising an outdoor heat exchanger and an electrical box, the electrical box being provided with a refrigerant cooling module, the refrigerant cooling module comprising a refrigerant inlet and a refrigerant outlet, the outdoor heat exchanger comprising a first end and a second end, the refrigerant inlet being connected to the first end; a plurality of indoor units, each indoor unit comprising an indoor heat exchanger, the indoor heat exchanger comprising a third end and a fourth end, the third end being connected to the second end, and the refrigerant outlet being connected to the fourth end; and a controller, the controller being configured to: acquire the temperature T sc of the refrigerant at the refrigerant inlet, the ambient temperature T a around the electrical box, and the temperature T fin inside the electrical box, and control the temperature of the refrigerant flowing through the refrigerant cooling module to be increased when the value of T a -T sc is greater than or equal to a first preset value, and / or the value of T a -T fin is greater than or equal to a second preset value.

[0007] The multi-split air conditioning system provided by the embodiment of the present application can ensure continuous operation of the multi-split air conditioning system, ensure user experience, and reduce the risk of complaints. a -T sc is greater than or equal to the first preset value, and the value of T a -T fin is greater than or equal to the second preset value, it indicates that the temperature T sc of the refrigerant flowing through the heat dissipation module will be lower than the dew point temperature of the air around the electrical box, and the electrical box is at risk of condensation, so the temperature of the refrigerant flowing through the refrigerant heat dissipation module is increased to increase the temperature of the electrical box, so that the temperature of the electrical box is higher than the dew point temperature of the air around the electrical box, to avoid condensation on the electrical box, thereby avoiding shutdown of the multi-split air conditioning system, avoiding frequent shutdown of the multi-split air conditioning system, and thus avoiding the multi-split air conditioning system being unable to start, thereby ensuring continuous operation of the multi-split air conditioning system, ensuring user experience, and reducing the risk of complaints.

[0008] In some embodiments, the outdoor unit further includes a compressor connected between the second end and the third end; when the multi-split air conditioning system is in the cooling mode, the controller is further configured to: obtain the discharge pressure P d of the compressor; d when P m -0.2, and the value of T a -T sc is greater than or equal to the value of A-C, the air exchange amount of the outdoor unit is reduced, so that the air exchange amount of the outdoor unit is reduced from the first air exchange amount to the second air exchange amount; wherein the value of A-C is the first preset value, P m is greater than or equal to 3 and less than or equal to 4, i.e. 3≤P m ≤4, A is greater than 0 and less than or equal to 10, i.e. 0<A≤10, C is greater than or equal to 1 and less than or equal to 5, i.e. 1≤C≤5, and A is greater than C, i.e. A>C.

[0009] In some embodiments, the controller is further configured to: after the air exchange amount of the indoor unit is reduced from the first air exchange amount to the second air exchange amount, obtain the saturation temperature T c corresponding to the outdoor heat exchanger outlet pressure and the outdoor heat exchanger outlet temperature T e , when P d is greater than or equal to P1, and the value of T c -T e is less than or equal to SC, and the value of T a -T sc is less than the value of A-C, the air exchange amount of the outdoor unit is increased, so that the air exchange amount of the outdoor unit is increased from the second air exchange amount to the third air exchange amount, and the third air exchange amount is less than or equal to the second air exchange amount; wherein SC is greater than or equal to 1 and less than or equal to 10, i.e. 1≤SC≤10.

[0010] In some embodiments, the outdoor unit further includes a compressor connected between the second and third terminals; when the multi-split air conditioning system is in heating mode, the controller is further configured to: acquire the compressor's discharge pressure P d ;P d Less than or equal to P m -0.2, and T a -T fin When the value of P is greater than or equal to the value of BC, the air exchange rate of the indoor unit is reduced; where the value of BC is the second preset value, and P... m Greater than or equal to 3 and less than or equal to 4, i.e., 3 ≤ P m ≤4, B is greater than 0 and less than or equal to 10, 0<B≤10, C is greater than or equal to 1 and less than or equal to 5, that is, 1≤C≤5, B is greater than C, that is, B>C.

[0011] In some embodiments, the controller is further configured to: acquire the saturation temperature T corresponding to the outlet pressure of the indoor heat exchanger after the air exchange rate of the indoor unit decreases from a first air exchange rate to a second air exchange rate. c and indoor heat exchanger outlet temperature T e When P d Greater than or equal to P1, and T c -T e The value of T is less than or equal to SC. a -T fin When the value is less than the value of BC, increase the air exchange volume of the indoor unit, so that the air exchange volume of the indoor unit increases from the second air exchange volume to the third air exchange volume, and the third air exchange volume is less than or equal to the second air exchange volume;

[0012] Where SC is greater than or equal to 1 and less than or equal to 10, that is, 1≤SC≤10.

[0013] In some embodiments, the outdoor unit further includes: a subcooler connected between the fourth terminal and the refrigerant outlet; when the multi-split air conditioning system is operating in cooling mode, the controller is further configured to: when T a -T sc When the value is greater than or equal to the value of AD, and / or when T a -T fin When the value of AD is greater than or equal to the value of BD, the refrigerant flow rate through the cooler is increased; where the value of AD is the first preset value, the value of BD is the second preset value, A is greater than 0 and less than or equal to 10, that is, 0 < A ≤ 10, B is greater than 0 and less than or equal to 10, that is, 0 < B ≤ 10, D is greater than 2 and less than or equal to 8, that is, 2 < D ≤ 8, A is greater than D, that is, A > D, B is greater than D, that is, B > D.

[0014] In some embodiments, when the multi-split air conditioning system is operating in heating mode, the controller is also configured to: according to T a -Tsc the value of T a -T fin the value of T

[0015] In some embodiments, when the multi-split air conditioning system operates in the heating mode, the controller is further configured to: when the value of T a -T sc ≥ A-D+2, and / or the value of T a -T fin ≥ B-D+2, control the refrigerant flow rate through the indoor heat exchanger to be a first refrigerant flow rate.

[0016] In some embodiments, the controller is further configured to: when the value of T a -T sc ≥ A-D+1, and / or the value of T a -T fin ≥ B-D+1, control the refrigerant flow rate through the indoor heat exchanger to be a second refrigerant flow rate, wherein the second refrigerant flow rate is less than the first refrigerant flow rate.

[0017] In some embodiments, the controller is further configured to: when the value of T a -T sc ≥ A-D, and / or the value of T a -T fin ≥ B-D, control the refrigerant flow rate through the indoor heat exchanger to be a third refrigerant flow rate, wherein the third refrigerant flow rate is less than the second refrigerant flow rate.

[0018] In some embodiments, when at least one of the plurality of indoor units has a fresh air function, the controller is further configured to: when the indoor unit with the fresh air function operates in the heating mode, increase the refrigerant flow rate through the indoor unit with the fresh air function according to the value of T a -T sc , and / or according to the value of T a -T fin .

[0019] In some embodiments, the controller is further configured to: when the value of T a -T sc ≥ A-D+2, and / or the value of T a -T fin ≥ B-D+2, control the refrigerant flow rate through the fresh air machine to be a first flow rate.

[0020] In some embodiments, the controller is further configured to: when the value of T a -T sc ≥ A-D+1, and / or the value of T a -T fin ≥ B-D+1, control the refrigerant flow rate through the fresh air machine to be a second flow rate, wherein the second flow rate is less than the first flow rate.

[0021] In some embodiments, the controller is further configured to control the refrigerant flow rate through the fresh air machine to a third flow rate when T a -T sc ≥ A-D, and / or T a -T fin ≥ B-D, the third flow rate being less than the second flow rate.

[0022] In some embodiments, the outdoor unit further comprises a compressor located between the second end and the third end; the controller is further configured to decrease the frequency of the compressor when T a -T sc is greater than or equal to a third preset value for a time period, and T a -T fin is greater than or equal to a fourth preset value for a time period, the third preset value being greater than the first preset value, and the fourth preset value being greater than the second preset value.

[0023] In some embodiments, the controller is further configured to control the frequency of the compressor to a first frequency when T a -T sc is greater than or equal to the third preset value for a first time period, and T a -T fin is greater than or equal to the fourth preset value for the first time period.

[0024] In some embodiments, the controller is further configured to control the frequency of the compressor to a second frequency when T a -T sc is greater than or equal to the third preset value for a second time period, and T a -T fin is greater than or equal to the fourth preset value for the second time period, the second time period being greater than the first time period, and the second frequency being less than the first frequency.

[0025] In some embodiments, the controller is further configured to control the frequency of the compressor to a third frequency when T a -T sc is greater than or equal to the third preset value for a third time period, and T a -T fin is greater than or equal to the fourth preset value for the third time period, the third time period being greater than the second time period, and the third frequency being less than the second frequency.

[0026] Another embodiment of this application provides a control method for a multi-split air conditioning system, comprising: an outdoor unit, the outdoor unit including an outdoor heat exchanger and an electrical box, the electrical box being provided with a refrigerant heat dissipation module, the refrigerant heat dissipation module including a refrigerant inlet and a refrigerant outlet, the outdoor heat exchanger including a first end and a second end, the refrigerant inlet being connected to the first end; multiple indoor units, each indoor unit including an indoor heat exchanger, the indoor heat exchanger including a third end and a fourth end, the third end being connected to the second end, the refrigerant outlet being connected to the fourth end; the control method comprising: acquiring the temperature T of the refrigerant at the refrigerant inlet. sc The ambient temperature T around the electrical box a and the temperature T inside the electrical box fin and in T a -T sc The value is greater than or equal to the first preset value, and / or T a -T fin When the value is greater than or equal to the second preset value, the temperature of the refrigerant flowing through the refrigerant heat dissipation module is controlled to rise.

[0027] This application provides a control method for a multi-split air conditioning system, when T a -T sc The value of T is greater than or equal to the first preset value, and T a -T fin When the value is greater than or equal to the second preset value, it indicates that the temperature T of the refrigerant flowing through the heat dissipation module is... sc When the temperature of the electrical box is about to drop below the dew point temperature of the air surrounding it, posing a risk of condensation, the temperature of the refrigerant flowing through the refrigerant heat dissipation module is controlled to increase the temperature of the electrical box. This raises the electrical box temperature above the dew point temperature of the surrounding air, preventing condensation from forming on the electrical box. Consequently, this prevents the multi-split air conditioning system from shutting down, avoiding frequent shutdowns that could prevent the system from starting. This ensures continuous operation of the multi-split air conditioning system, guarantees a better user experience, and reduces the risk of complaints. Attached Figure Description

[0028] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0029] Figure 1 This is a schematic diagram of a multi-split air conditioning system provided in some embodiments of this application;

[0030] Figure 2 for Figure 1 A schematic diagram of the electrical box shown;

[0031] Figure 3 for Figure 2Fig. 6 is a schematic view of the electrical box shown in Fig. 5 from another angle;

[0032] Figure 4 Fig. 1 is a control flowchart of a multi-split air conditioning system according to some embodiments of the present application;

[0033] Figure 5 Fig. 1 is a control flowchart of a multi-split air conditioning system according to some embodiments of the present application;

[0034] Figure 6 Fig. 1 is a control flowchart of a multi-split air conditioning system according to some embodiments of the present application;

[0035] Figure 7 Fig. 1 is a control flowchart of a multi-split air conditioning system according to some embodiments of the present application;

[0036] Figure 8 Fig. 1 is a control flowchart of a multi-split air conditioning system according to some embodiments of the present application;

[0037] Figure 9 Fig. 1 is a control flowchart of a multi-split air conditioning system according to some embodiments of the present application;

[0038] Figure 10 Fig. 1 is a control flowchart of a multi-split air conditioning system according to some embodiments of the present application.

[0039] Reference Signs:

[0040] 100, multi-split air conditioning system; 110, outdoor unit; 1101, liquid-side stop valve; 1102, gas-side stop valve; 111, compressor; 112, gas-liquid separator; 113, four-way valve; 114, high-low pressure bypass valve; 115, outdoor heat exchanger; 116, electrical box; 1161, refrigerant heat dissipation module; 1162, refrigerant inlet; 1163, refrigerant outlet; 117, subcooler; 118, bypass expansion valve; 120, indoor unit; 121, indoor unit expansion valve; 122, indoor heat exchanger. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0042] It should be noted that all the direction indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the direction indications will also change accordingly.

[0043] The terms "first", "second", "third", etc. are used only for descriptive purposes and do not connote or imply any relative importance or any priority of one element over another. Thus, a feature described as "first", "second", etc. can include one or more of the features. In the description of the present application, unless otherwise specified and limited, the term "connected" or "connection" should be interpreted broadly, for example, it can be fixed connection, detachable connection, or integral connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, when describing the pipeline, the "connected" or "connection" in the present application has the meaning of conducting. The specific meaning should be understood in combination with the context.

[0044] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "connected" and "connection" should be interpreted broadly, for example, it can be fixed connection, detachable connection, or integral connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, when describing the pipeline, the "connected" or "connection" in the present application has the meaning of conducting. The specific meaning should be understood in combination with the context.

[0045] In the embodiments of the present application, the words such as "exemplary" or "for example" are used to represent as an example, illustration or description. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the words such as "exemplary" or "for example" are intended to present the relevant concept in a specific manner.

[0046] The multi-connected air conditioning system is widely used in hotels, office buildings, hospitals or shopping malls and many other occasions as a device for adjusting indoor temperature.

[0047] Please refer to Figures 1 to 3 , Figure 1 The schematic diagram of the multi-connected air conditioning system 100 provided by some embodiments of the present application, Figure 2 is Figure 1 The schematic diagram of the electrical box 116 shown in Figure 3 is Figure 2 The schematic diagram of the electrical box 116 shown in another angle; the multi-connected air conditioning system 100 provided by the embodiments of the present application can include an outdoor unit 110 and a plurality of indoor units 120.

[0048] Specifically, the outdoor unit 110 can include a compressor 111, a four-way valve 113, an outdoor heat exchanger 115, a liquid-side stop valve 1101, a gas-side stop valve 1102, a gas-liquid separator 112, and an electrical box 116. The four-way valve 113 includes a first interface, a second interface, a third interface, and a fourth interface. The first interface is in communication with an air inlet of the compressor 111, the second interface is in communication with the outdoor heat exchanger 115, the third interface is in communication with an air outlet of the compressor 111, and the fourth interface is in communication with the indoor heat exchanger 122.

[0049] The electrical box 116 is provided with a refrigerant heat dissipation module 1161. The refrigerant heat dissipation module 1161 includes a refrigerant inlet 1162 and a refrigerant outlet 1163. The outdoor heat exchanger 115 includes a first end (e.g., the left end of the outdoor heat exchanger 115 shown in FIG. 1) and a second end (e.g., the right end of the outdoor heat exchanger shown in FIG. 1). The refrigerant inlet 1162 is connected to the first end. Figure 1 Figure 1 The indoor unit 120 can include an indoor heat exchanger 122 and an indoor unit expansion valve 121. The indoor heat exchanger 122 includes a third end (e.g., the upper end of the indoor heat exchanger 122 shown in FIG. 1) and a fourth end (e.g., the lower end of the indoor heat exchanger 122 shown in FIG. 1). The third end of the indoor heat exchanger 122 is connected to the second end of the outdoor heat exchanger 115, and the refrigerant outlet 1163 is connected to the fourth end of the indoor heat exchanger 122.

[0050] Specifically, the indoor unit 120 can include an indoor heat exchanger 122 and an indoor unit expansion valve 121. The indoor heat exchanger 122 includes a third end (e.g., the upper end of the indoor heat exchanger 122 shown in FIG. 1) and a fourth end (e.g., the lower end of the indoor heat exchanger 122 shown in FIG. 1). The third end of the indoor heat exchanger 122 is connected to the second end of the outdoor heat exchanger 115, and the refrigerant outlet 1163 is connected to the fourth end of the indoor heat exchanger 122. Figure 1 Figure 1 When all indoor units 120 of the multi-split air conditioning system 100 are in a cooling mode, the four-way valve 113 is in an OFF (de-energized) state. At this time, the second interface is in communication with the third interface, and the first interface is in communication with the fourth interface. The high-temperature and high-pressure gaseous refrigerant discharged by the compressor 111 flows to the outdoor heat exchanger 115. The outdoor heat exchanger 115 is a condenser. After being condensed by the outdoor heat exchanger 115, the refrigerant enters the refrigerant heat dissipation module 1161 through the refrigerant inlet 1162 and flows to the liquid-side stop valve 1101 through the refrigerant outlet 1163. The low-temperature gaseous refrigerant flows to the indoor unit 120 through the liquid-side stop valve 1101. After being throttled by the indoor unit expansion valve 121 of the indoor unit 120, the refrigerant flows to the indoor heat exchanger 122. The indoor heat exchanger 122 is an evaporator. The refrigerant exchanges heat with indoor air in the evaporator to reduce the temperature of the indoor environment. The exchanged refrigerant flows to the compressor 111 through the gas-side stop valve 1102, forming a cycle.

[0051]

[0052] ​​​When all the indoor units 120 of the multi-split air conditioning system 100 are in the heating mode, the four-way valve 113 is in the ON state, at this time, the first interface and the second interface are conductive, the third interface and the fourth interface are conductive, the high-temperature and high-pressure gaseous refrigerant discharged by the compressor 111 flows to the indoor unit 120 through the gas side stop valve 1102, the indoor heat exchanger 122 is a condenser, and the refrigerant exchanges heat with the indoor air in the condenser to raise the temperature of the indoor environment. The refrigerant after heat exchange flows to the refrigerant heat dissipation module 1161 on the electrical box 116 through the indoor unit expansion valve 121, and then flows to the outdoor heat exchanger 115 through the refrigerant heat dissipation module 1161. The refrigerant exchanges heat with the outdoor heat exchanger 115 and then flows to the compressor 111, forming a cycle.

[0053] In the prior art, in the control method of the multi-split air conditioning system, when the temperature of the refrigerant flowing through the refrigerant heat dissipation module is lower than the dew point temperature of the air around the electrical box, that is, the electrical box has the risk of condensation, the multi-split air conditioning system is controlled to stop. If the multi-split air conditioning system stops frequently due to the low temperature of the refrigerant flowing through the refrigerant heat dissipation module, the multi-split air conditioning system will be controlled to alarm, and the multi-split air conditioning system will not be able to start again, and needs to be repaired by a service engineer, affecting the continuous operation of the multi-split air conditioning system.

[0054] To solve the above problems, the present application provides a multi-split air conditioning system 100, which comprises an outdoor unit 110, a controller and a plurality of indoor units 120. The outdoor unit 110 comprises an outdoor heat exchanger 115 and an electrical box 116, the electrical box 116 is provided with a refrigerant heat dissipation module 1161, the refrigerant heat dissipation module 1161 comprises a refrigerant inlet 1162 and a refrigerant outlet 1163, the outdoor heat exchanger 122 comprises a first end and a second end, the refrigerant inlet 1162 is connected to the first end; the indoor unit 120 comprises an indoor heat exchanger 122, the indoor heat exchanger 122 comprises a third end and a fourth end, the third end is connected to the second end, and the refrigerant outlet 1163 is connected to the fourth end.

[0055] Among them, please refer to Figure 4 , Figure 4 The control flow chart of the multi-split air conditioning system provided by some embodiments of the present application; the control is configured to: acquire the temperature T sc of the refrigerant at the refrigerant inlet, the ambient temperature T a around the electrical box and the temperature T fin inside the electrical box, when the value of T a -T sc is greater than or equal to a first preset value, and / or the value of T a -T fin is greater than or equal to a second preset value, the control increases the temperature of the refrigerant flowing through the refrigerant heat dissipation module.

[0056] Wherein, the first preset value is greater than 0 and less than or equal to 9, and the second preset value is greater than 0 and less than or equal to 9.

[0057] It should be noted that the dew point temperature of the air around the electrical box cannot be directly obtained, and in the present application, T a The value of T sc is greater than or equal to the first preset value, and the value of T a is greater than or equal to the second preset value. fin The value of T sc greater than or equal to the second preset value indicates that the temperature of the refrigerant flowing through the refrigerant heat dissipation module T a is about to be lower than the dew point temperature of the air around the electrical box, and the electrical box is about to condense. When the electrical box is about to condense, the present application controls the temperature of the refrigerant flowing through the refrigerant heat dissipation module to rise, so as to avoid the temperature of the refrigerant flowing through the refrigerant heat dissipation module from further decreasing and causing the electrical box to frost. In some embodiments, a first temperature sensor can be arranged at the refrigerant inlet to detect the temperature T fin of the refrigerant at the refrigerant inlet; a second temperature sensor can be arranged in the outdoor unit to detect the ambient temperature T a around the electrical box; and a third temperature sensor can be arranged inside the electrical box to detect the temperature T sc inside the electrical box.

[0058] The multi-split air conditioning system provided by the embodiments of the present application controls the temperature of the refrigerant flowing through the refrigerant heat dissipation module to rise when T a The value of T fin is greater than or equal to the first preset value, and the value of T sc is greater than or equal to the second preset value, indicating that the temperature of the refrigerant flowing through the heat dissipation module T d is about to be lower than the dew point temperature of the air around the electrical box, and the electrical box is at risk of condensation. By controlling the temperature of the refrigerant flowing through the refrigerant heat dissipation module to rise, the temperature of the electrical box is increased, so that the temperature of the electrical box is higher than the dew point temperature of the air around the electrical box, avoiding the occurrence of condensation on the electrical box, and further avoiding the shutdown of the multi-split air conditioning system, the failure of the multi-split air conditioning system to start due to frequent shutdown of the multi-split air conditioning system, and further ensuring the continuous operation of the multi-split air conditioning system, ensuring the user experience, and reducing the risk of complaints.

[0059] In some embodiments, referring to Figure 1 , the outdoor unit 110 further comprises a compressor 111 connected between the second end and the third end; please refer to Figure 5 , Figure 5 for the control flowchart of the multi-split air conditioning system provided by some embodiments of the present application; when the multi-split air conditioning system is in a refrigeration mode, the controller is further configured to: obtain the discharge pressure P d of the compressor; when P m -0.2, and T a-T sc When the value of P is greater than or equal to the value of AC, the air exchange rate of the outdoor unit is reduced, causing the air exchange rate of the outdoor unit to decrease from the first air exchange rate to the second air exchange rate; where the value of AC is the first preset value, and P... m Greater than or equal to 3 and less than or equal to 4, i.e., 3 ≤ P m ≤4, A is greater than 0 and less than or equal to 10, i.e., 0<A≤10, C is greater than or equal to 1 and less than or equal to 5, i.e., 1≤C≤5, and A is greater than C, i.e., A>C.

[0060] It should be noted that P m -0.2 is greater than or equal to 2.8 and less than or equal to 3.8, that is, 2.8 ≤ P m -0.2≤3.8, AC is greater than 0 and less than or equal to 9, that is, 0<AC≤9.

[0061] For example, the outdoor unit also includes an outdoor fan. When the multi-split air conditioning system is in cooling mode, the initial speed of the outdoor fan is three. When P... d Less than or equal to P m -0.2, and T a -T sc When the value is greater than or equal to the value of AC, the outdoor fan speed is adjusted to level one, thereby reducing the fan speed in the outdoor unit, which in turn reduces the air exchange volume of the outdoor unit, thereby reducing the condensing capacity of the outdoor heat exchanger, increasing the temperature of the refrigerant discharged from the outdoor heat exchanger, and thus increasing the temperature T of the refrigerant flowing to the refrigerant inlet. sc This prevents condensation in the electrical box, avoids shutdowns of the multi-split air conditioning system, and prevents frequent shutdowns that could prevent the multi-split air conditioning system from starting up. This ensures continuous operation of the multi-split air conditioning system, guarantees user experience, and reduces the risk of complaints.

[0062] In some embodiments, a pressure sensor may be installed at the compressor's discharge port to detect the compressor's discharge pressure P. d .

[0063] In some embodiments, refer to Figure 5 The controller is also configured to: in cooling mode, when the indoor unit's air exchange rate decreases from the first air exchange rate to the second air exchange rate, obtain the saturation temperature T corresponding to the outdoor heat exchanger outlet pressure. c Obtain the outdoor heat exchanger outlet temperature T e When P d Greater than or equal to P1, and T c -T e The value of T is less than or equal to SC. a -T scwhen the value of T sc is less than the value of A-C, the air exchange amount of the outdoor unit is increased, so that the air exchange amount of the outdoor unit is increased from the second air exchange amount to a third air exchange amount, and the third air exchange amount is less than or equal to the second air exchange amount; wherein SC is greater than or equal to 1 and less than or equal to 10, that is, 1≤SC≤10.

[0064] It should be noted that T c is the saturation temperature T c corresponding to the outlet pressure of the outdoor heat exchanger. e is the outlet temperature T c of the outdoor heat exchanger. e is the supercooling degree of the outdoor heat exchanger outlet.

[0065] For example, when the multi-split air conditioning system is in a cooling mode, the damper of the fan in the outdoor unit is reduced from three gears to one gear, the saturation temperature T c corresponding to the outlet pressure of the outdoor heat exchanger is obtained, the outlet temperature T e of the outdoor heat exchanger is obtained, when P d is greater than or equal to P1, and the value of T c -T e is less than or equal to SC, the value of T a -T sc is less than the value of A-C, it indicates that the electrical box no longer has the risk of condensation, the gear of the fan in the outdoor unit is adjusted from one gear to two gears to ensure the condensing effect of the outdoor heat exchanger as a condenser, after the gear of the fan in the outdoor unit is adjusted to two gears, the saturation temperature T c corresponding to the outlet pressure of the outdoor heat exchanger is obtained again, the outlet temperature T e of the outdoor heat exchanger is obtained, when T d is greater than or equal to P1, and the value of T c -T e is less than or equal to SC, the value of T a -T sc is less than the value of A-C, the gear of the fan in the outdoor unit is adjusted from two gears to three gears to further ensure the condensing capacity of the outdoor heat exchanger as a condenser.

[0066] When the air exchange amount of the outdoor unit is reduced to ensure that the electrical box has no risk of frost, the air exchange amount of the outdoor unit is increased to ensure the condensing capacity of the outdoor heat exchanger, but the air exchange amount of the outdoor unit cannot be greater than the initial air exchange amount of the outdoor unit. It should be noted that the initial air exchange amount of the outdoor unit has caused the electrical box to have the risk of condensation, and when the air exchange amount of the outdoor unit is greater than the initial air exchange amount, the risk of condensation of the electrical box will be further increased, so the air exchange amount of the outdoor unit cannot be greater than the initial air exchange amount of the outdoor unit.

[0067] In some embodiments, with reference to Figure 6 , Figure 6The control flow chart of the multi-split air conditioning system is provided for some embodiments of the present application; when the multi-split air conditioning system is in the heating mode, the controller is further configured to: obtain the discharge pressure P d of the compressor d ; when P m -0.2, and the value of T a -T fin is greater than or equal to the value of B-C, reduce the air exchange amount of the indoor unit; wherein the value of B-C is a second preset value, P m is greater than or equal to 3 and less than or equal to 4, i.e. 3≤P m ≤4, B is greater than 0 and less than or equal to 10, i.e. 0<B≤10, C is greater than or equal to 1 and less than or equal to 5, i.e. 1≤C≤5, and B is greater than C, i.e. B>C.

[0068] It should be noted that P m -0.2 is greater than or equal to 2.8 and less than or equal to 3.8, i.e. 2.8≤P m -0.2≤3.8, B-C is greater than 0 and less than or equal to 9, i.e. 0<B-C≤9.

[0069] For example, the indoor unit further comprises an indoor fan, and the air exchange amount of the indoor unit can be adjusted by adjusting the rotating speed of the indoor fan; when the multi-split air conditioning system is in the heating mode, the initial wind block of the indoor fan is three blocks, when P d is less than or equal to P m -0.2, and the value of T a -T fin is greater than or equal to the value of B-C, the wind block of the indoor fan is adjusted to one block, thereby reducing the air exchange amount of the indoor unit, the indoor heat exchanger acts as a condenser, the condensing capacity of the condenser is reduced, thereby increasing the temperature of the refrigerant flowing out of the condenser, further increasing the temperature of the refrigerant flowing through the refrigerant heat dissipation module, further increasing the temperature T sc of the refrigerant inlet, avoiding condensation in the electrical box, avoiding shutdown of the multi-split air conditioning system, avoiding frequent shutdown of the multi-split air conditioning system leading to failure of the multi-split air conditioning system to start, thereby ensuring continuous operation of the multi-split air conditioning system, ensuring user experience, and reducing the risk of complaints.

[0070] In some embodiments, continuing to refer to Figure 6 , the controller is further configured to: after the air exchange amount of the indoor unit is reduced from the first air exchange amount to the second air exchange amount, obtain the saturation temperature T c corresponding to the outlet pressure of the indoor heat exchanger, obtain the outlet temperature T e of the indoor heat exchanger, when P d is greater than or equal to P1, and the value of T c -T e is less than or equal to SC, T a -Tfin When the value of SC is less than the value of BC, the air exchange volume of the indoor unit is increased; where SC is greater than or equal to 1 and less than or equal to 10, that is, 1≤SC≤10.

[0071] For example, when the indoor fan speed is reduced from level three to level one, the outlet temperature T of the indoor heat exchanger is obtained. e When P d Greater than or equal to P1, and T c -T e The value of T is less than or equal to SC. a -T fin When the value is less than the value of BC, it indicates that the electrical box no longer poses a risk of condensation. The indoor fan speed is adjusted from level one to level two to ensure the condensation effect of the indoor heat exchanger as a condenser. After the indoor fan speed is adjusted to level two, the saturation temperature T corresponding to the outlet pressure of the indoor heat exchanger is obtained again. c Obtain the outlet temperature T of the indoor heat exchanger. e When P d Greater than or equal to P1, and T c -T e The value of T is less than or equal to SC. a -T sc When the value is less than the value of AC, the indoor fan speed is adjusted from level two to level three to further ensure the condensing capacity of the indoor heat exchanger as a condenser.

[0072] When reducing the indoor unit's air exchange volume can ensure that there is no risk of condensation in the electrical box, the indoor unit's air exchange volume can be increased to ensure the condensation capacity of the indoor heat exchanger. However, the increase in the indoor unit's air exchange volume cannot exceed the initial air exchange volume of the indoor unit. It should be noted that the initial air exchange volume of the indoor unit already causes the electrical box to have an imminent risk of condensation. When the indoor unit's air exchange volume exceeds the initial air exchange volume, it will further increase the risk of condensation in the electrical box. Therefore, it is necessary to ensure that the increase in the indoor unit's air exchange volume does not exceed the initial air exchange volume of the indoor unit.

[0073] In some embodiments, refer to Figures 1 to 3 The outdoor unit 110 may also include a subcooler 117, which is connected between the fourth terminal and the refrigerant outlet 1163. (See reference...) Figure 7 , Figure 7 This application provides a control flowchart for a multi-split air conditioning system according to some embodiments; when the multi-split air conditioning system is operating in cooling mode, the controller is further configured to: when T a -T sc When the value is greater than or equal to the value of AD, and / or when T a -T finWhen the value of AD is greater than or equal to the value of BD, the refrigerant flow rate through the cooler is increased; where the value of AD is the first preset value, the value of BD is the second preset value, A is greater than 0 and less than or equal to 10, that is, 0 < A ≤ 10, B is greater than 0 and less than or equal to 10, that is, 0 < B ≤ 10, D is greater than 0 and less than or equal to 10, that is, 0 < D ≤ 10, the value of AD is greater than 0, that is, AD > 0, B is greater than D, that is, B > D, D > C.

[0074] Wherein, it can be when T a -T sc When AD is greater than or equal to 1, increase the refrigerant flow rate through the cooler; alternatively, when T... a -T fin When ≥BD, increase the refrigerant flow rate through the cooler; alternatively, when T a -T sc ≥AD, and T a -T fin When the value is greater than or equal to BD, increase the refrigerant flow rate through the cooler.

[0075] For example, refer to Figure 1 The outdoor unit 110 of the air conditioner may also include a bypass expansion valve 118, which is connected in parallel with the subcooler 117 between the fourth terminal and the refrigerant outlet 1163.

[0076] Reference Figure 7 When T a -T sc ≥AD, and T a -T fin When ≥BD, reduce the opening of the bypass expansion valve to increase the refrigerant pressure flowing through the cooler, increase the refrigerant temperature flowing through the cooler, thereby increasing the air temperature around the electrical box, and thus increasing the refrigerant inlet temperature T. sc This prevents condensation in the electrical box, avoids shutdowns of the multi-split air conditioning system, and prevents frequent shutdowns that could prevent the multi-split air conditioning system from starting up. This ensures continuous operation of the multi-split air conditioning system, guarantees user experience, and reduces the risk of complaints.

[0077] Among them, the controller periodically obtains T a T sc and T fin The value, for example, the controller is configured to retrieve T every 1 minute. a T sc and T fin The value of the bypass expansion valve, the initial opening of EVB(0) = 5%, and the first detection of T a -T sc ≥AD, and T a -T finWhen ≥B-D, the opening degree of the bypass expansion valve after the first adjustment is EVB(1) = EVB(0) - EVB(0) / E, and the opening degree of the bypass expansion valve after the nth adjustment is EVB(n) = EVB(n-1) - EVB(n-1) / E, where EVB(n-1) is the opening degree of the bypass expansion valve after the (n-1)th adjustment, and E is greater than or equal to 2 and less than or equal to 20, that is, 2≤E≤20. a -T sc ≥A-D, and T a -T fin When ≥B-D, the opening degree of the bypass expansion valve after the first adjustment is EVB(1) = EVB(0) - EVB(0) / E, and the opening degree of the bypass expansion valve after the nth adjustment is EVB(n) = EVB(n-1) - EVB(n-1) / E, where EVB(n-1) is the opening degree of the bypass expansion valve after the (n-1)th adjustment, and E is greater than or equal to 2 and less than or equal to 20, that is, 2≤E≤20.

[0078] In some embodiments, with reference to Figure 8 , Figure 8 A control flowchart of a multi-split air conditioning system provided by some embodiments of the present application; when the multi-split air conditioning system operates in a heating mode, the controller is further configured to: according to the value of T a -T sc , and / or according to the value of T a -T fin , increase the refrigerant flow rate flowing through the indoor heat exchanger.

[0079] Specifically, the refrigerant flow rate flowing through the indoor heat exchanger can be increased according to the value of T a -T sc ; the refrigerant flow rate flowing through the indoor heat exchanger can also be increased according to the value of T a -T fin ; the refrigerant flow rate flowing through the indoor heat exchanger can also be increased according to the values of T a -T sc and T a -T fin .

[0080] For example, when T a -T sc ≥A-D+2, and T a -T fin ≥B-D+2, the indoor unit expansion valve is adjusted to a first opening degree EVI(1) so that the refrigerant flow rate flowing through the indoor heat exchanger is a first refrigerant flow rate; when T a -T sc ≥A-D+1, and T a -T fin ≥B-D+1, the indoor unit expansion valve is adjusted to a second opening degree EVI(2) so that the refrigerant flow rate flowing through the indoor heat exchanger is a second refrigerant flow rate; when T a -T sc ≥A-D, and T a -T finWhen B-D, the indoor unit expansion valve is adjusted to a third opening degree EVI(3) to make the refrigerant flow rate through the indoor heat exchanger a third refrigerant flow rate, wherein the second refrigerant flow rate is greater than the third refrigerant flow rate and less than the first refrigerant flow rate.

[0081] It should be noted that the opening degree EVI of the indoor unit expansion valve when fully open is 2000 Pls, the initial opening degree EVI(0) of the indoor unit expansion valve is 100 Pls, the first opening degree EVI(1) of the indoor unit expansion valve = EVI(0) + △EVI(1), wherein △EVI(1) is the opening degree change amount of the first opening degree relative to the initial opening degree, and △EVI(1) is 250 Pls; the second opening degree EVI(2) of the indoor unit expansion valve = EVI(0) + △EVI(2), wherein △EVI(2) is the opening degree change amount of the second opening degree relative to the initial opening degree, and △EVI(2) is 180 Pls; and the third opening degree EVI(3) of the indoor unit expansion valve = EVI(0) + △EVI(3), wherein △EVI(3) is the opening degree change amount of the second opening degree relative to the initial opening degree, and △EVI(3) is 100 Pls.

[0082] In some embodiments, with reference to Figure 9 , Figure 9 A control flowchart of a multi-split air conditioning system provided by some embodiments of the present application; when at least one of the plurality of indoor units has a fresh air function, and the indoor unit with the fresh air function operates in a heating mode, the controller is further configured to: according to the value of T a -T sc , and / or according to the value of T a -T fin , increase the refrigerant flow rate through the indoor unit with the fresh air function.

[0083] Wherein the indoor unit with the fresh air function has an air inlet, and the air inlet is in communication with the external environment.

[0084] It should be noted that after increasing the refrigerant flow rate of the indoor unit with the fresh air function, the refrigerant pressure in the indoor unit with the fresh air function is increased, and then the temperature of the refrigerant is increased, when the refrigerant flowing out of the indoor unit with the fresh air function passes through the refrigerant heat dissipation module, the temperature T sc of the refrigerant flowing through the refrigerant inlet is increased, thereby avoiding the phenomenon of condensation in the electrical box, avoiding the shutdown of the multi-split air conditioning system, avoiding the frequent shutdown of the multi-split air conditioning system leading to the failure of the multi-split air conditioning system to start, thereby ensuring the continuous operation of the multi-split air conditioning system, ensuring the user's experience, and reducing the risk of complaints.

[0085] For example, when T a -T sc ≥ A-D+2, and / or T a -T finWhen T a -T sc ≥ A - D + 1, and / or T a -T fin ≥ B - D + 1, the opening degree of the indoor unit expansion valve in the indoor unit with fresh air function is controlled to EVImax / 4, so that the refrigerant flow flowing through the indoor unit with fresh air function is the second flow, which is less than the first flow; when T a -T sc ≥ A - D, and / or T a -T fin ≥ B - D, the opening degree of the indoor unit expansion valve in the indoor unit with fresh air function is controlled to EVImax / 5, so that the refrigerant flow flowing through the indoor unit with fresh air function is the third flow, which is less than the second flow, wherein EVImax is the maximum opening degree of the indoor unit expansion valve in the indoor unit with fresh air function, for example, the initial opening degree of the indoor unit expansion valve of the indoor unit with fresh air function is 5%, the maximum opening degree of the indoor unit expansion valve is 90%, EVImax / 3 is 30%, EVImax / 4 is 22.5%, and EVImax / 5 is 18%.

[0086] In some embodiments, with reference to Figure 10 , Figure 10 a control flowchart of the multi-split air conditioning system provided by some embodiments of the present application; the controller is further configured to: according to the value of T a -T sc being greater than or equal to the third preset value for a time, and the value of T a -T fin being greater than or equal to the fourth preset value for a time, reduce the frequency of the compressor, wherein the third preset value is greater than the first preset value, and the fourth preset value is greater than the second preset value.

[0087] It should be noted that reducing the frequency of the compressor can reduce the condensing capacity of the condenser, thereby increasing the temperature of the refrigerant flowing out of the condenser, the refrigerant flowing out of the condenser flows to the refrigerant inlet, thereby increasing the temperature T sc at the refrigerant inlet, avoiding the phenomenon of condensation in the electrical box, avoiding the shutdown of the multi-split air conditioning system, avoiding the frequent shutdown of the multi-split air conditioning system leading to the failure of the multi-split air conditioning system to start, thereby ensuring the continuous operation of the multi-split air conditioning system, ensuring the user experience, and reducing the risk of complaints.

[0088] For example, the initial frequency of the compressor is Hz (0), when T a -T sc ≥ A for a period of time, and Ta -T fin ≥B for a period of time, Hz(1) = Hz(0) - Hz(0) / F, wherein Hz(1) is the compressor frequency at the present moment; when T a -T sc ≥A for 1 min, and T a -T fin ≥B for 1 min, Hz(n) = Hz(n) - Hz(n-1) / F; when T a -T sc ≥A for 2 min, and T a -T fin ≥B for 2 min, Hz(n) = Hz(n) - Hz(n-1) / (F-1); when T a -T sc ≥A for 3 min, and T a -T fin ≥B for 3 min, Hz(n) = Hz(n) - Hz(n-1) / (F-2); when T a -T sc ≥A for n min, and T a -T fin ≥B for n min, Hz(n) = Hz(n) - Hz(n-1) / [F-(n-1)]; wherein Hz(n) is the compressor frequency at the present period, Hz(n-1) is the compressor frequency at the last period, F is greater than or equal to 5 and less than or equal to 20, i.e. 5≤F≤20.

[0089] In some embodiments, with reference to Figure 1 The outdoor unit can further include a high-low pressure bypass valve 114 connected in parallel with the compressor 111 between the second end and the third end. When the frequency of the compressor 111 is reduced to the minimum frequency Hzmin of the compressor 111, the electrical box 116 is still at risk of condensation, and the high-low pressure bypass valve 114 can be opened to further limit the compression capacity of the compressor 111.

[0090] In other embodiments, the present application also proposes a control method of a multi-split air conditioning system, with reference to Figures 1 to 3The multi-split air conditioning system 100 includes an outdoor unit 110, a controller, and a plurality of indoor units 120. The outdoor unit 110 includes an outdoor heat exchanger 115 and an electrical box 116, the electrical box 116 is provided with a refrigerant heat dissipation module 1161, the refrigerant heat dissipation module 1161 includes a refrigerant inlet 1162 and a refrigerant outlet 1163, the outdoor heat exchanger 115 includes a first end and a second end, the refrigerant inlet 1162 is connected to the first end; the indoor unit 120 includes an indoor heat exchanger 122, the indoor heat exchanger 122 includes a third end and a fourth end, the third end is connected to the second end, and the refrigerant outlet 1163 is connected to the fourth end.

[0091] With reference to Figure 4 , the control method includes: obtaining the temperature T sc of the refrigerant at the refrigerant inlet, the ambient temperature T a around the electrical box, and the temperature T fin inside the electrical box, and controlling the refrigerant temperature flowing through the refrigerant heat dissipation module to rise when the value of T a -T sc is greater than or equal to a first preset value, and / or the value of T a -T fin is greater than or equal to a second preset value.

[0092] The multi-split air conditioning system provided by the embodiments of the present application can control the refrigerant temperature flowing through the refrigerant heat dissipation module to rise when the value of T a -T sc is greater than or equal to the first preset value, and the value of T fin -T a is less than or equal to the second preset value, which means that the refrigerant temperature T sc flowing through the heat dissipation module will be lower than the dew point temperature of the air around the electrical box, and the electrical box is at risk of condensation. By controlling the refrigerant temperature flowing through the refrigerant heat dissipation module to rise, the temperature of the electrical box is increased, so that the temperature of the electrical box is higher than the dew point temperature of the air around the electrical box, and condensation on the electrical box is avoided, thereby avoiding the shutdown of the multi-split air conditioning system, avoiding the frequent shutdown of the multi-split air conditioning system, and thus ensuring the continuous operation of the multi-split air conditioning system, ensuring the user experience, and reducing the risk of complaints.

[0093] It should be noted that the above-mentioned embodiments can be applied to the multi-split air conditioning system shown in Figure 1 .

[0094] The above is merely specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A multi-split air conditioning system, characterized in that, include: The outdoor unit includes an outdoor heat exchanger and an electrical box. The electrical box is equipped with a refrigerant heat dissipation module, which includes a refrigerant inlet and a refrigerant outlet. The outdoor heat exchanger includes a first end and a second end, and the refrigerant inlet is connected to the first end. Multiple indoor units, each indoor unit including an indoor heat exchanger, the indoor heat exchanger including a third end and a fourth end, the third end being connected to the second end, and the refrigerant outlet being connected to the fourth end; The controller is configured to acquire the temperature T of the refrigerant at the refrigerant inlet. sc The ambient temperature T around the electrical box a and the temperature T inside the electrical box fin and in T a -T sc The value is greater than or equal to the first preset value, and / or T a -T fin When the value is greater than or equal to the second preset value, the temperature of the refrigerant flowing through the refrigerant heat dissipation module is controlled to rise. The outdoor unit also includes a compressor, which is connected between the second end and the third end; When the multi-split air conditioning system is in cooling mode, the controller is also configured to: acquire the discharge pressure P of the compressor. d ; When the P d Less than or equal to P m -0.2, and T a -T sc When the value is greater than or equal to the value of AC, the air exchange volume of the outdoor unit is reduced, so that the air exchange volume of the outdoor unit is reduced from the first air exchange volume to the second air exchange volume. When the air exchange rate of the outdoor unit decreases from the first air exchange rate to the second air exchange rate, the saturation temperature T corresponding to the outlet pressure of the outdoor heat exchanger is obtained. c and the outdoor heat exchanger outlet temperature T e ; When the P d Greater than or equal to P1, and T c -T e The value of T is less than or equal to SC. a -T sc When the value is less than the value of AC, the air exchange volume of the outdoor unit is increased, so that the air exchange volume of the outdoor unit increases from the second air exchange volume to the third air exchange volume; Wherein, the value of AC is the first preset value, and P m 3 or greater than or equal to 4 and 0 or less than or equal to 10, C or greater than or equal to 1 and less than or equal to 5, and A is greater than C, SC is greater than or equal to 1 and less than or equal to 10, and P1 is the preset value of the compressor's discharge pressure.

2. The multi-split air conditioning system according to claim 1, characterized in that, When the multi-split air conditioning system is in heating mode, the controller is also configured to: acquire the compressor's discharge pressure P. d ; When the P d Less than or equal to P m -0.2, and T a -T fin When the value is greater than or equal to the value of BC, the air exchange volume of the indoor unit is reduced, so that the air exchange volume of the indoor unit is reduced from the first air exchange volume to the second air exchange volume; Wherein, the value of BC is the second preset value, and P m A is greater than or equal to 3 and less than or equal to 4, B is greater than 0 and less than or equal to 10, C is greater than or equal to 1 and less than or equal to 5, and B is greater than C.

3. The multi-split air conditioning system according to claim 2, characterized in that, The controller is further configured to: when the air exchange rate of the indoor unit decreases from the first air exchange rate to the second air exchange rate, obtain the saturation temperature T corresponding to the outlet pressure of the indoor heat exchanger. c and the outlet temperature T of the indoor heat exchanger e ; When the P d Greater than or equal to P1, and T c -T e The value of T is less than or equal to SC. a -T fin When the value is less than the value of BC, the air exchange volume of the indoor unit is increased, so that the air exchange volume of the indoor unit increases from the second air exchange volume to the third air exchange volume; Wherein, SC is greater than or equal to 1 and less than or equal to 10, and P1 is the preset value of the compressor's discharge pressure.

4. The multi-split air conditioning system according to claim 1, characterized in that, When the multi-split air conditioning system is operating in heating mode, the controller is also configured to: according to T a -T sc The value, and / or according to T a -T fin The value of increases the refrigerant flow rate through the indoor heat exchanger.

5. The multi-split air conditioning system according to claim 1, characterized in that, When at least one of the multiple indoor units has a fresh air function, and the indoor unit with the fresh air function operates in heating mode, the controller is further configured to: according to T a -T sc The value, and / or according to T a -T fin The value of increases the refrigerant flow through the indoor unit with fresh air function.

6. The multi-split air conditioning system according to claim 1, characterized in that, The controller is also configured to: according to T a -T sc The duration of the value being greater than or equal to the third preset value and T a -T fin If the value is greater than or equal to the fourth preset value for a certain period of time, the frequency of the compressor will be reduced. Wherein, the third preset value is greater than the first preset value, and the fourth preset value is greater than the second preset value.

7. A control method for a multi-split air conditioning system, characterized in that, include: The outdoor unit includes an outdoor heat exchanger and an electrical box. The electrical box is equipped with a refrigerant heat dissipation module, which includes a refrigerant inlet and a refrigerant outlet. The outdoor heat exchanger includes a first end and a second end, and the refrigerant inlet is connected to the first end. Multiple indoor units, each indoor unit including an indoor heat exchanger, the indoor heat exchanger including a third end and a fourth end, the third end being connected to the second end, and the refrigerant outlet being connected to the fourth end; The outdoor unit also includes a compressor, which is connected between the second end and the third end; The control method includes: acquiring the temperature T of the refrigerant at the refrigerant inlet. sc The ambient temperature T around the electrical box a and the temperature T inside the electrical box fin and in T a -T sc The value is greater than or equal to the first preset value, and / or T a -T fin When the value is greater than or equal to the second preset value, the temperature of the refrigerant flowing through the refrigerant heat dissipation module is controlled to rise. When the multi-split air conditioning system is in cooling mode, the discharge pressure P of the compressor is obtained. d ; When the P d Less than or equal to P m -0.2, and T a -T sc When the value is greater than or equal to the value of AC, the air exchange volume of the outdoor unit is reduced, so that the air exchange volume of the outdoor unit is reduced from the first air exchange volume to the second air exchange volume. When the air exchange rate of the outdoor unit decreases from the first air exchange rate to the second air exchange rate, the saturation temperature T corresponding to the outlet pressure of the outdoor heat exchanger is obtained. c and the outdoor heat exchanger outlet temperature T e ; When the P d Greater than or equal to P1, and T c -T e The value of T is less than or equal to SC. a -T sc When the value is less than the value of AC, the air exchange volume of the outdoor unit is increased, so that the air exchange volume of the outdoor unit increases from the second air exchange volume to the third air exchange volume; Wherein, the value of AC is the first preset value, and P m 3 or greater than or equal to 4 and 0 or less than or equal to 10, C or greater than or equal to 1 and less than or equal to 5, and A is greater than C, SC is greater than or equal to 1 and less than or equal to 10, and P1 is the preset value of the compressor's discharge pressure.

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