Parallel multi-split air conditioning system and defrosting control method

Abstract

The invention relates to a parallel multi-split air conditioning system and a defrosting control method.The parallel multi-split air conditioning system comprises at least two outdoor units connected in parallel, each outdoor unit comprises a four-way valve, a compressor, an outdoor heat exchanger, a plate heat exchanger, a first pipeline and a second pipeline, and the four-way valve is provided with a first end and a third end which are oppositely arranged; the air inlet end of the compressor is connected with the first end through an air inlet pipe, the exhaust end of the compressor is connected with the third end through an exhaust pipe, the second end is connected with one end of the first pipeline, and the fourth end is connected with one end of the outdoor heat exchanger. The other end of the outdoor heat exchanger is connected with one end of the plate heat exchanger through a first branch pipe, a first electromagnetic valve is arranged on the first branch pipe, and the other end of the plate heat exchanger is connected with one end of the second pipeline. The energy utilization rate can be effectively increased, the defrosting effect is improved, the defrosting time is shortened, and indoor temperature fluctuation is reduced.

Description

TECHNICAL FIELD

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

[0002] At present, in the air conditioning system, the common defrosting mode is reverse cycle defrosting, that is, when the air conditioner is heating, the defrosting effect of the outdoor unit is realized by switching the flow direction of the refrigerant. However, during the defrosting process, the indoor unit needs to be switched to the refrigeration mode, which causes the cold air to be directly blown into the indoor environment, resulting in a decrease in indoor temperature, thereby causing the indoor temperature to fluctuate; in addition, the net heat loss of single defrosting process is large, and the redundant defrosting ratio is relatively high, which is easy to cause resource waste. SUMMARY

[0003] Therefore, the purpose of the present application is to overcome the shortcomings of the prior art, provide a parallel multi-split air conditioning system and a defrosting control method, which can effectively improve the energy utilization rate, thereby improving the defrosting effect and shortening the defrosting time, and reducing the indoor temperature fluctuation.

[0004] In order to achieve the above purpose, the present application provides a parallel multi-split air conditioning system, comprising at least two outdoor units connected in parallel, at least one of the outdoor units forming a first defrosting unit, and the remaining outdoor units forming a second defrosting unit; the outdoor unit comprises a four-way valve, a compressor, an outdoor heat exchanger, a plate heat exchanger, a first pipeline and a second pipeline, the four-way valve has a first end and a third end arranged opposite to each other, and a second end and a fourth end arranged opposite to each other, the intake end of the compressor is connected with the first end through an intake pipe, the exhaust end of the compressor is connected with the third end through an exhaust pipe, the second end is connected with one end of the first pipeline, the fourth end is connected with one end of the outdoor heat exchanger, the other end of the outdoor heat exchanger is connected with one end of the plate heat exchanger through a first branch pipe, a first electromagnetic valve is arranged on the first branch pipe, the other end of the plate heat exchanger is connected with one end of the second pipeline; the plate heat exchanger is connected with a plate inlet pipe and a plate outlet pipe, the plate inlet pipe is connected with the part of the first branch pipe between the first electromagnetic valve and the plate heat exchanger, and a second electromagnetic valve is arranged on the plate inlet pipe, the plate outlet pipe is connected with the intake pipe;

[0005] The other end of the first pipeline of each outdoor unit is connected to each other, and the other end of the second pipeline of each outdoor unit is connected to each other; the four-way valve has a first mode and a second mode, and the four-way valve can be switched between the first mode and the second mode, when the four-way valve is in the first mode, the first end and the fourth end are in conduction, the second end and the third end are in conduction, when the four-way valve is in the second mode, the first end and the second end are in conduction, the third end and the fourth end are in conduction.

[0006] As an embodiment, further comprising an indoor unit, the other end of the first pipeline of each outdoor unit is connected to one end of the indoor unit, and the other end of the second pipeline of each outdoor unit is connected to the other end of the indoor unit.

[0007] As an embodiment, the other end of the first pipeline of each outdoor unit is connected to each other through a first connecting pipe, and the other end of the second pipeline of each outdoor unit is connected to each other through a second connecting pipe.

[0008] As an embodiment, when one or all outdoor units of the first defrosting unit defrost, the four-way valve of the defrosting outdoor unit is switched to the second mode, the first electromagnetic valve and the second electromagnetic valve of the defrosting outdoor unit are opened, so that the defrosting outdoor unit is switched to the refrigeration mode; the four-way valve of the outdoor unit of the second defrosting unit is kept in the first mode, the first electromagnetic valve of the outdoor unit of the second defrosting unit is opened, and the second electromagnetic valve is closed, so that the outdoor unit of the second defrosting unit is kept in the heating mode.

[0009] As an embodiment, when one or all outdoor units of the second defrosting unit defrost, the four-way valve of the defrosting outdoor unit is switched to the second mode, the first electromagnetic valve and the second electromagnetic valve of the defrosting outdoor unit are opened, so that the defrosting outdoor unit is switched to the refrigeration mode; the four-way valve of the outdoor unit of the first defrosting unit is switched to the first mode, the first electromagnetic valve of the outdoor unit of the first defrosting unit is opened, and the second electromagnetic valve is closed, so that the outdoor unit of the first defrosting unit is switched to the heating mode.

[0010] As an embodiment, the first defrosting unit comprises two outdoor units, and the second defrosting unit comprises one outdoor unit, when the two outdoor units of the first defrosting unit defrost, the four-way valve of the two defrosting outdoor units is switched to the second mode, the first electromagnetic valve and the second electromagnetic valve of the two defrosting outdoor units are opened, so that the two defrosting outdoor units are switched to the refrigeration mode.

[0011] As an implementation form, the four-way valve of one of the outdoor units of the first defrosting unit is switched to the first mode, and the first electromagnetic valve and the second electromagnetic valve of the outdoor unit are closed, so that the outdoor unit is in the stop mode.

[0012] As an implementation form, the number of the outdoor units is three or more.

[0013] Therefore, according to the parallel multi-split air conditioning system of the present application, when the parallel multi-split air conditioning system defrosts, the refrigerant can form a loop between the outdoor units without flowing through the indoor units, thereby significantly reducing the influence on the indoor environment temperature of the indoor units and effectively reducing the indoor temperature fluctuation; when one of the defrosting units defrosts, the suction refrigerant thereof is compressed twice, thereby significantly increasing the temperature of the refrigerant and greatly improving the defrosting effect of the air conditioning system; and the pipe temperature of the outdoor unit can reach the target temperature faster during defrosting, thereby effectively shortening the defrosting time and reducing the energy consumption loss.

[0014] In addition, the present application provides a defrosting control method of a parallel multi-split air conditioning system, comprising the following steps: S1: before the air conditioning system defrosts, switching the four-way valves of all the outdoor units to the first mode, opening the first electromagnetic valves of all the outdoor units, and closing the second electromagnetic valves of all the outdoor units, so that all the outdoor units are switched to the heating mode and normally run; S2: when the air conditioning system defrosts, maintaining the second defrosting unit in the heating mode, stopping all the outdoor units of the first defrosting unit for a period of time T1, switching the four-way valves of all the outdoor units of the first defrosting unit to the second mode, opening the first electromagnetic valves and the second electromagnetic valves of all the outdoor units of the first defrosting unit, so that all the outdoor units of the first defrosting unit are switched to the refrigeration mode, and when the time T1 is up, opening all the outdoor units of the first defrosting unit, and the first defrosting unit defrosts; S3: after the first defrosting unit defrosts for a period of time T2, stopping all the outdoor units for a period of time T3, switching the four-way valves of all the outdoor units of the first defrosting unit to the first mode, opening the first electromagnetic valves of all the outdoor units of the first defrosting unit, and closing the second electromagnetic valves of all the outdoor units of the first defrosting unit, so that all the outdoor units of the first defrosting unit are switched to the heating mode, switching the four-way valves of all the outdoor units of the second defrosting unit to the second mode, opening the first electromagnetic valves and the second electromagnetic valves of all the outdoor units of the second defrosting unit, so that all the outdoor units of the second defrosting unit are switched to the refrigeration mode; and when the time T3 is up, opening all the outdoor units, and the second defrosting unit defrosts; S4: When the second defrosting unit defrosts for a period of time T4, all outdoor units are stopped for a period of time T5, the four-way valve of all outdoor units of the second defrosting unit is switched to the first mode, the first electromagnetic valve of all outdoor units of the second defrosting unit is opened, and the second electromagnetic valve of all outdoor units of the second defrosting unit is closed, so that all outdoor units are switched to the heating mode, and when the time T5 is up, all outdoor units are turned on and all outdoor units are re-heated.

[0015] Thus, according to the defrosting control method of the parallel multi-split air conditioning system, when defrosting, the refrigerant can form a loop between the outdoor units without flowing through the indoor units, thereby significantly reducing the influence on the indoor environment temperature of the indoor units and effectively reducing the indoor temperature fluctuation; when one of the defrosting units defrosts, the suction refrigerant thereof is subjected to secondary compression, which can significantly increase the temperature of the refrigerant, thereby greatly improving the defrosting effect of the air conditioning system; and the pipe temperature of the outdoor unit can reach the target temperature faster during defrosting, thereby effectively shortening the defrosting time and reducing the energy consumption loss.

[0016] In order to better understand and implement, the present application is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The structure schematic diagram of the parallel multi-split air conditioning system of the embodiment of the present application; Figure 2 The structure schematic diagram of the four-way valve of the embodiment of the present application; Figure 3 The schematic diagram of the normal operation of the parallel multi-split air conditioning system of the embodiment of the present application; Figure 4 The schematic diagram of the first defrosting unit stopping and the second defrosting unit heating of the embodiment of the present application; Figure 5 The schematic diagram of the first defrosting unit defrosting and the second defrosting unit heating of the embodiment of the present application; Figure 6 The schematic diagram of the first defrosting unit defrosting and the second defrosting unit heating of the embodiment of the present application; Figure 7 The schematic diagram of the stopping of the parallel multi-split air conditioning system of the embodiment of the present application; Figure 8 The schematic diagram of the first defrosting unit heating and the second defrosting unit defrosting of the embodiment of the present application; Figure 9 The flow schematic diagram of the defrosting control method of the parallel multi-split air conditioning system of the embodiment of the present application.

[0018] Explanation of reference signs: 10, four-way valve; 20, compressor; 30, outdoor heat exchanger; 40, plate heat exchanger; 50, first electromagnetic valve; 60, second electromagnetic valve; 100, outdoor unit; 101, first pipeline; 102, second pipeline; 103, gas inlet pipe; 104, gas outlet pipe; 105, first branch pipe; 106, plate inlet pipe; 107, plate outlet pipe; 108, first connecting pipe; 109, second connecting pipe; 200, indoor unit. DETAILED DESCRIPTION

[0019] To make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. It should be noted that the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. 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.

[0020] The terms used in the present application are merely for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein means and includes any or all possible combinations of one or more associated listed items.

[0021] The following description refers to the accompanying drawings. In the following description, same numbers in different drawings represent the same or similar elements unless otherwise represented. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of apparatuses and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are used only to distinguish similar objects, and do not necessarily have to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0022] In the related art, at present, in the air conditioning system, the common defrosting method is reverse cycle defrosting, that is, when the air conditioner is heating, the defrosting effect of the outdoor unit is realized by switching the flow direction of the refrigerant. However, during the defrosting process, the indoor unit needs to be switched to the cooling mode, which causes the cold air to be directly blown into the indoor environment, resulting in a drop in indoor temperature, thereby causing fluctuations in indoor temperature. In addition, the net heat loss of a single defrosting process is large, and the redundancy defrosting ratio is relatively high, which is easy to cause resource waste.

[0023] In view of this, the application provides a parallel multi-connected air conditioning system and a defrosting control method.

[0024] Please refer to Figures 1 to 8 The application provides a parallel multi-connected air conditioning system, comprising at least two outdoor units 100 connected in parallel, at least one outdoor unit 100 forming a first defrosting unit, and the rest of the outdoor units 100 forming a second defrosting unit; the outdoor unit 100 comprises a four-way valve 10, a compressor 20, an outdoor heat exchanger 30, a plate heat exchanger 40, a first pipeline 101, and a second pipeline 102; the four-way valve 10 has a first end and a third end arranged oppositely, and a second end and a fourth end arranged oppositely; the air inlet end of the compressor 20 is connected to the first end through an air inlet pipe 103, and the air outlet end of the compressor 20 is connected to the third end through an air outlet pipe 104; the second end is connected to one end of the first pipeline 101, and the fourth end is connected to one end of the outdoor heat exchanger 30; the other end of the outdoor heat exchanger 30 is connected to one end of the plate heat exchanger 40 through a first branch pipe 105, and the first branch pipe 105 is provided with a first electromagnetic valve 50; the other end of the plate heat exchanger 40 is connected to one end of the second pipeline 102; the plate heat exchanger 40 is connected to a plate inlet pipe 106 and a plate outlet pipe 107; the plate inlet pipe 106 is connected to the part of the first branch pipe 105 between the first electromagnetic valve 50 and the plate heat exchanger 40, and the plate inlet pipe 106 is provided with a second electromagnetic valve 60; and the plate outlet pipe 107 is connected to the air inlet pipe 103. The other end of the first pipeline 101 of each outdoor unit 100 is connected to each other, and the other end of the second pipeline 102 of each outdoor unit 100 is connected to each other; the four-way valve 10 has a first mode and a second mode, and can be switched between the first mode and the second mode; when the four-way valve 10 is in the first mode, the first end and the fourth end are in conduction, and the second end and the third end are in conduction; when the four-way valve 10 is in the second mode, the first end and the second end are in conduction, and the third end and the fourth end are in conduction. In addition, the parallel multi-connected air conditioning system of the application further comprises an indoor unit 200; the other end of the first pipeline 101 of each outdoor unit 100 is connected to one end of the indoor unit 200, and the other end of the second pipeline 102 of each outdoor unit 100 is connected to the other end of the indoor unit 200.

[0025] Among them, the other end of the first pipeline 101 of each outdoor unit 100 is connected to each other through a first connecting pipe 108, and the other end of the second pipeline 102 of each outdoor unit 100 is connected to each other through a second connecting pipe 109.

[0026] When one or all of the outdoor units 100 of the first defrosting group defrost, the four-way valve 10 of the defrosting outdoor unit 100 is switched to the second mode, the first solenoid valve 50 and the second solenoid valve 60 of the defrosting outdoor unit 100 are opened, so that the defrosting outdoor unit 100 is switched to the refrigeration mode; the four-way valve 10 of the outdoor unit 100 of the second defrosting group is kept in the first mode, the first solenoid valve 50 of the outdoor unit 100 of the second defrosting group is opened, and the second solenoid valve 60 is closed, so that the outdoor unit 100 of the second defrosting group keeps the heating mode. For example, the first defrosting group includes two outdoor units 100, and the second defrosting group includes one outdoor unit 100, when the two outdoor units 100 of the first defrosting group defrost, the four-way valves 10 of the two outdoor units 100 are switched to the second mode, the first solenoid valves 50 and the second solenoid valves 60 of the two outdoor units 100 are opened, so that the two outdoor units 100 are switched to the refrigeration mode and defrost. Further, the four-way valve 10 of one of the outdoor units 100 of the first defrosting group is switched to the first mode, and the first solenoid valve 50 and the second solenoid valve 60 of the outdoor unit 100 are closed, so that the outdoor unit 100 is in the stop mode, and the other outdoor unit 100 of the first defrosting group continues to defrost.

[0027] When one or all of the outdoor units 100 of the second defrosting group defrost, the four-way valve 10 of the defrosting outdoor unit 100 is switched to the second mode, the first solenoid valve 50 and the second solenoid valve 60 of the defrosting outdoor unit 100 are opened, so that the defrosting outdoor unit 100 is switched to the refrigeration mode; the four-way valve 10 of the outdoor unit 100 of the first defrosting group is switched to the first mode, the first solenoid valve 50 of the outdoor unit 100 of the first defrosting group is opened, and the second solenoid valve 60 is closed, so that the outdoor unit 100 of the first defrosting group is switched to the heating mode.

[0028] Therefore, according to the parallel multi-split air conditioning system of the present application, when the parallel multi-split air conditioning system defrosts, the refrigerant can form a loop between the outdoor units 100 without flowing through the indoor unit 200, thereby significantly reducing the influence on the indoor environment temperature of the indoor unit 200 and effectively reducing the indoor temperature fluctuation; when one of the defrosting groups defrosts, the suction refrigerant of the defrosting group is compressed twice, which can significantly increase the temperature of the refrigerant, thereby greatly improving the defrosting effect of the air conditioning system; and the pipe temperature of the outdoor unit 100 can reach the target temperature faster during defrosting, thereby effectively shortening the defrosting time and reducing the energy consumption loss.

[0029] The parallel multi-split air conditioning system of the present application will be described in detail below with reference to a specific embodiment, and it should be understood that the following is only an exemplary description and should not be construed as a limitation of the present application. Figures 1 to 8 The parallel multi-split air conditioning system of the present application will be described in detail below with reference to a specific embodiment, and it should be understood that the following is only an exemplary description and should not be construed as a limitation of the present application.

[0030] This embodiment provides a parallel multi-split air conditioning system, including three outdoor units 100 connected in parallel. Two outdoor units 100 form a first defrosting unit, and the other outdoor unit 100 forms a second defrosting unit. Each outdoor unit 100 includes a four-way valve 10, a compressor 20, an outdoor heat exchanger 30, a plate heat exchanger 40, a first pipe 101, and a second pipe 102. The four-way valve 10 has a first end and a third end, and a second end and a fourth end, arranged opposite to each other. The compressor 20's inlet end is connected to the first end via an inlet pipe 103, and its outlet end is connected to the third end via an outlet pipe 104. The second end is connected to one end of the first pipe 101, and the fourth end is connected to one end of the outdoor heat exchanger 30. The other end of the outdoor heat exchanger 30 is connected to one end of the plate heat exchanger 40 via a first branch pipe 105. A first electrical... The other end of the solenoid valve 50 and the plate heat exchanger 40 are connected to one end of the second pipe 102. The plate heat exchanger 40 is connected to a plate inlet pipe 106 and a plate outlet pipe 107. The plate inlet pipe 106 is connected to the part of the first branch pipe 105 located between the first solenoid valve 50 and the plate heat exchanger 40. A second solenoid valve 60 is provided on the plate inlet pipe 106. The plate outlet pipe 107 is connected to the air inlet pipe 103. The other ends of the first pipes 101 of each outdoor unit 100 are connected to each other. The other ends of the second pipes 102 of each outdoor unit 100 are connected to each other. The four-way valve 10 has a first mode and a second mode. The four-way valve 10 can switch between the first mode and the second mode. When the four-way valve 10 is in the first mode, the first end is connected to the fourth end and the second end is connected to the third end. When the four-way valve 10 is in the second mode, the first end is connected to the second end and the third end is connected to the fourth end. In addition, this embodiment also includes an indoor unit 200. The other end of the first pipe 101 of each outdoor unit 100 is connected to one end of the indoor unit 200, and the other end of the second pipe 102 of each outdoor unit 100 is connected to the other end of the indoor unit 200. The other ends of the first pipe 101 of each outdoor unit 100 are interconnected via a first connecting pipe 108, and the other ends of the second pipe 102 of each outdoor unit 100 are interconnected via a second connecting pipe 109.

[0031] In this embodiment, before defrosting, the four-way valves 10 of all three outdoor units 100 in the parallel multi-split air conditioning system are switched to heating mode, and the first solenoid valve 50 of the three outdoor units 100 is opened and the second solenoid valve 60 is closed, so that the three outdoor units 100 are switched to heating mode and operate normally. When the first defrosting unit is defrosting, the four-way valves 10 of the two outdoor units 100 of the first defrosting unit are switched to the second mode, and the first solenoid valves 50 and the second solenoid valve 60 of the two outdoor units 100 of the first defrosting unit are opened, so that the two outdoor units 100 of the first defrosting unit are switched to cooling mode and defrost; in addition, the outdoor unit 100 of the second defrosting unit is kept in heating mode. After the two outdoor units 100 of the first defrosting unit have been defrosting for a period of time, the four-way valve 10 of one of the outdoor units 100 is switched to the first mode, and the first solenoid valve 50 and the second solenoid valve 60 of that outdoor unit 100 are closed, so that the outdoor unit 100 is in the shutdown mode, while the other outdoor unit 100 of the first defrosting unit continues to defrost. When the outdoor unit 100 of the second defrosting unit is defrosting, the four-way valve 10 of the two outdoor units 100 of the first defrosting unit is switched to the first mode, the first solenoid valve 50 of the outdoor unit 100 of the first defrosting unit is opened, and the second solenoid valve 60 of the outdoor unit 100 of the first defrosting unit is closed, so that the outdoor unit 100 of the first defrosting unit switches to the heating mode and starts heating. Then, the four-way valve 10 of the outdoor unit 100 of the second defrosting unit is switched to the second mode, and the first solenoid valve 50 and the second solenoid valve 60 of the outdoor unit 100 of the second defrosting unit are opened, so that the outdoor unit 100 of the second defrosting unit switches to the cooling mode and starts defrosting. After the second defrosting unit completes defrosting, the outdoor unit 100 of the second defrosting unit is switched back to heating mode, thereby restoring the parallel multi-split air conditioning system to normal operation.

[0032] In addition, such as Figure 9 As shown, the present invention provides a defrosting control method for a parallel multi-split air conditioning system, comprising the following steps: S1: Before the air conditioning system defrosts, switch the four-way valve 10 of all outdoor units 100 to the first mode, open the first solenoid valve 50 of all outdoor units 100, and close the second solenoid valve 60 of all outdoor units 100 so that all outdoor units 100 switch to heating mode and operate normally. S2: When the air conditioning system is defrosting, the second defrosting unit is kept in heating mode, all outdoor units 100 of the first defrosting unit are shut down for a period of time T1, and the four-way valves 10 of all outdoor units 100 of the first defrosting unit are switched to the second mode. The first solenoid valves 50 and the second solenoid valves 60 of all outdoor units 100 of the first defrosting unit are opened so that all outdoor units 100 of the first defrosting unit are switched to cooling mode. When time T1 is up, all outdoor units 100 of the first defrosting unit are turned on and the first defrosting unit begins defrosting. S3: After the first defrosting unit has been defrosting for a period of time T2, all outdoor units 100 are shut down for a period of time T3. The four-way valves 10 of all outdoor units 100 of the first defrosting unit are switched to the first mode, the first solenoid valves 50 of all outdoor units 100 of the first defrosting unit are opened, and the second solenoid valves 60 of all outdoor units 100 of the first defrosting unit are closed, so that all outdoor units 100 of the first defrosting unit are switched to heating mode. The four-way valves 10 of all outdoor units 100 of the second defrosting unit are switched to the second mode, and the first solenoid valves 50 and the second solenoid valves 60 of all outdoor units 100 of the second defrosting unit are opened, so that all outdoor units 100 of the second defrosting unit are switched to cooling mode. When time T3 is up, all outdoor units 100 are turned on, and the second defrosting unit begins defrosting. S4: After the second defrosting unit defrosts for a period of time (T4), all outdoor units 100 are shut down for a period of time (T5). The four-way valves 10 of all outdoor units 100 of the second defrosting unit are switched to the first mode. The first solenoid valves 50 of all outdoor units 100 of the second defrosting unit are opened, and the second solenoid valves 60 of all outdoor units 100 of the second defrosting unit are closed, so that all outdoor units 100 are switched to heating mode. When time T5 is completed, all outdoor units 100 are turned on and all outdoor units 100 are restarted for heating.

[0033] Therefore, according to the defrosting control method of the parallel multi-split air conditioning system, during defrosting, the refrigerant can form a loop between each outdoor unit 100 without flowing through the indoor unit 200, thereby significantly reducing the impact on the indoor ambient temperature of the indoor unit 200 and effectively reducing indoor temperature fluctuations. When one of the defrosting units is defrosting, the refrigerant it draws in undergoes secondary compression, which can significantly increase the temperature of the refrigerant, thereby greatly improving the defrosting effect of the air conditioning system. Furthermore, during defrosting, the pipe temperature of the outdoor unit 100 can reach the target temperature more quickly, thereby effectively shortening the defrosting time and reducing energy consumption loss.

[0034] The above embodiments are merely illustrative of several implementation methods of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the parallel multi-split air conditioning system and defrosting control method of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A parallel multi-split air conditioning system, characterized in that: The system includes at least two outdoor units connected in parallel, with at least one outdoor unit forming a first defrosting unit and the remaining outdoor units forming a second defrosting unit. Each outdoor unit includes a four-way valve, a compressor, an outdoor heat exchanger, a plate heat exchanger, a first pipeline, and a second pipeline. The four-way valve has a first end and a third end, as well as a second end and a fourth end, arranged opposite to each other. The compressor's inlet end is connected to the first end via an inlet pipe, and the compressor's outlet end is connected to the third end via an outlet pipe. The second end is connected to one end of the first pipeline. The fourth end is connected to one end of the outdoor heat exchanger, and the other end of the outdoor heat exchanger is connected to one end of the plate heat exchanger through a first branch pipe. A first solenoid valve is installed on the first branch pipe. The other end of the plate heat exchanger is connected to one end of the second pipeline. The plate heat exchanger is connected to a plate inlet pipe and a plate outlet pipe. The plate inlet pipe is connected to the portion of the first branch pipe located between the first solenoid valve and the plate heat exchanger. A second solenoid valve is installed on the plate inlet pipe. The plate outlet pipe is connected to the air inlet pipe. The other ends of the first pipes of each outdoor unit are connected to each other, and the other ends of the second pipes of each outdoor unit are connected to each other; the four-way valve has a first mode and a second mode, and the four-way valve can switch between the first mode and the second mode. When the four-way valve is in the first mode, the first end is connected to the fourth end, and the second end is connected to the third end. When the four-way valve is in the second mode, the first end is connected to the second end, and the third end is connected to the fourth end.

2. The parallel multi-split air conditioning system according to claim 1, characterized in that: It also includes an indoor unit, with the other end of the first pipe of each outdoor unit connected to one end of the indoor unit, and the other end of the second pipe of each outdoor unit connected to the other end of the indoor unit.

3. The parallel multi-split air conditioning system according to claim 1, characterized in that: The other ends of the first pipes of each outdoor unit are connected to each other through the first connecting pipe, and the other ends of the second pipes of each outdoor unit are connected to each other through the second connecting pipe.

4. The parallel multi-split air conditioning system according to claim 1, characterized in that: When one or all outdoor units of the first defrosting unit are defrosting, the four-way valve of the defrosting outdoor unit is switched to the second mode, and the first and second solenoid valves of the defrosting outdoor unit are opened so that the defrosting outdoor unit switches to cooling mode; the four-way valve of the outdoor unit of the second defrosting unit is kept in the first mode, and the first solenoid valve of the outdoor unit of the second defrosting unit is opened and the second solenoid valve is closed so that the outdoor unit of the second defrosting unit remains in heating mode.

5. The parallel multi-split air conditioning system according to claim 4, characterized in that: When one or all outdoor units of the second defrosting unit are defrosting, the four-way valve of the defrosting outdoor unit is switched to the second mode, and the first and second solenoid valves of the defrosting outdoor unit are opened, so that the defrosting outdoor unit switches to cooling mode; the four-way valve of the outdoor unit of the first defrosting unit is switched to the first mode, and the first solenoid valve of the outdoor unit of the first defrosting unit is opened and the second solenoid valve is closed, so that the outdoor unit of the first defrosting unit switches to heating mode.

6. The parallel multi-split air conditioning system according to claim 4, characterized in that: The first defrosting unit includes two outdoor units, and the second defrosting unit includes one outdoor unit. When the two outdoor units of the first defrosting unit are defrosting, the four-way valve of the two outdoor units being defrosted is switched to the second mode, and the first solenoid valve and the second solenoid valve of the two outdoor units being defrosted are opened so that the two outdoor units being defrosted are switched to cooling mode.

7. The parallel multi-split air conditioning system according to claim 6, characterized in that: Switch the four-way valve of one of the outdoor units of the first defrosting unit to the first mode, and close the first and second solenoid valves of the outdoor unit to put the outdoor unit into the shutdown mode.

8. The parallel multi-split air conditioning system according to claim 1, characterized in that: The number of outdoor units is three or more.

9. A defrosting control method for a parallel multi-split air conditioning system, characterized in that, Includes the following steps: S1: Before the air conditioning system defrosts, switch the four-way valves of all outdoor units to the first mode, open the first solenoid valves of all outdoor units, and close the second solenoid valves of all outdoor units so that all outdoor units switch to heating mode and operate normally. S2: When the air conditioning system is defrosting, the second defrosting unit is kept in heating mode, all outdoor units of the first defrosting unit are shut down for a period of time T1, the four-way valves of all outdoor units of the first defrosting unit are switched to the second mode, and the first and second solenoid valves of all outdoor units of the first defrosting unit are opened so that all outdoor units of the first defrosting unit are switched to cooling mode. When time T1 is up, all outdoor units of the first defrosting unit are turned on and the first defrosting unit begins defrosting. S3: After the first defrosting unit defrosts for a period of time T2, all outdoor units are shut down for a period of time T3. The four-way valves of all outdoor units of the first defrosting unit are switched to the first mode, the first solenoid valves of all outdoor units of the first defrosting unit are opened, and the second solenoid valves of all outdoor units of the first defrosting unit are closed, so that all outdoor units of the first defrosting unit switch to heating mode. The four-way valves of all outdoor units of the second defrosting unit are switched to the second mode, and the first and second solenoid valves of all outdoor units of the second defrosting unit are opened, so that all outdoor units of the second defrosting unit switch to cooling mode. When time T3 is up, all outdoor units are turned on, and the second defrosting unit begins defrosting. S4: After the second defrosting unit defrosts for a period of time (T4), all outdoor units are shut down for a period of time (T5). The four-way valves of all outdoor units of the second defrosting unit are switched to the first mode. The first solenoid valves of all outdoor units of the second defrosting unit are opened, and the second solenoid valves of all outdoor units of the second defrosting unit are closed, so that all outdoor units are switched to heating mode. When time T5 is up, all outdoor units are turned on and all outdoor units are restarted to heat.

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