CN117053352A - Defrosting method and device for multi-split air conditioning system and multi-split air conditioning system - Google Patents

Abstract

The application relates to the technical field of air conditioners, and discloses a defrosting method for a multi-split air conditioning system, which comprises the following steps: acquiring an operation mode of each outdoor unit and a frosting state of each outdoor unit; according to the running mode and frosting state of each outdoor unit, the conduction state of the refrigerant circulation pipeline of each outdoor unit is controlled, the conduction state of the liquid pipeline of each outdoor unit and/or the gas pipeline of each outdoor unit is controlled, and the conduction state of the bypass pipeline is controlled. The application can intelligently defrost the frosted outdoor heat exchanger, ensures the heat supply continuity and is beneficial to ensuring the comfort level of users. The application also discloses a device for the multi-split air conditioning system and the multi-split air conditioning system.

Description

Defrosting method and device for multi-split air conditioning system and multi-split air conditioning system

Technical Field

The application relates to the technical field of air conditioners, in particular to a defrosting method and device for a multi-split air conditioning system and the multi-split air conditioning system.

Background

At present, with the rapid development of science and technology, air conditioners are widely applied in different technical fields. The multi-split air conditioning system comprises a plurality of outdoor units connected in parallel, and is favored by commercial places such as large office buildings, super business and the like. The multi-split air conditioning system not only can meet the refrigeration requirement of a large space, but also can meet the heating and heat supply requirements of the large space. Because the large space has higher heating requirements in winter and in early spring, however, when the existing multi-split air conditioning system operates in winter, the outdoor heat exchanger arranged on the outdoor unit is extremely easy to frost due to lower outdoor environment temperature.

In order to solve the technical problems, under the condition that the outdoor heat exchanger frosts, the related technology adopts a four-way valve reversing scheme configured for the multi-split air conditioning system so as to realize the defrosting treatment of the outdoor heat exchanger by absorbing the heat of the indoor unit through the outdoor unit.

In the process of implementing the embodiments of the present disclosure, it is found that at least the following problems exist in the related art:

the related art adopts the mode that the indoor unit is switched from the heating mode to the refrigerating mode to realize the defrosting treatment of the outdoor heat exchanger, so that the refrigeration of a large space is interrupted, the indoor temperature value of the large space is greatly fluctuated, and the comfort level of a user is influenced.

It should be noted that the information disclosed in the above background section is only for enhancing understanding of the background of the application and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art.

Disclosure of Invention

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview, and is intended to neither identify key/critical elements nor delineate the scope of such embodiments, but is intended as a prelude to the more detailed description that follows.

The embodiment of the disclosure provides a defrosting method and device for a multi-split air conditioning system and the multi-split air conditioning system, which are used for intelligently defrosting an outdoor frosted heat exchanger, guaranteeing heat supply continuity, avoiding large-amplitude temperature fluctuation in an indoor space and guaranteeing comfort level of a user.

In some embodiments, the multi-split air conditioning system includes a first outdoor unit and a second outdoor unit, a liquid pipe line of the first outdoor unit and a liquid pipe line of the second outdoor unit are connected in parallel and connected to a first end of the indoor unit, a gas pipe line of the first outdoor unit and a gas pipe line of the second outdoor unit are connected in parallel and connected to a second end of the indoor unit, and a gas outlet of the first compressor is connected to a gas outlet of the second compressor through a bypass line, the method includes: acquiring an operation mode of each outdoor unit and a frosting state of each outdoor unit; according to the running mode and frosting state of each outdoor unit, the conduction state of the refrigerant circulation pipeline of each outdoor unit is controlled, the conduction state of the liquid pipeline of each outdoor unit and/or the gas pipeline of each outdoor unit is controlled, and the conduction state of the bypass pipeline is controlled.

In some embodiments, the apparatus comprises: the defrosting method for the multi-split air conditioning system comprises a processor and a memory storing program instructions, wherein the processor is configured to execute the defrosting method for the multi-split air conditioning system when the program instructions are executed.

In some embodiments, the multi-split air conditioning system includes: the indoor unit comprises a plurality of indoor units connected in parallel, and the indoor unit comprises a first end and a second end; the first outdoor unit comprises a first refrigerant circulating pipeline which is sequentially connected, the first refrigerant circulating pipeline comprises a first compressor, a first four-way valve and a first heat exchanger, the first heat exchanger is connected with a first end through a first liquid pipe pipeline, and the first four-way valve is connected with a second end through a first air pipe pipeline; the second outdoor unit comprises a second refrigerant circulation pipeline which is sequentially connected, the second refrigerant circulation pipeline comprises a second compressor, a second four-way valve and a second heat exchanger, the second heat exchanger is connected with the first end through a second liquid pipe pipeline, and the second four-way valve is connected with the second end through a first air pipe pipeline; one end of the bypass pipeline is communicated with the exhaust port of the first compressor, the other end of the bypass pipeline is communicated with the exhaust port of the second compressor, and a bypass electromagnetic valve is arranged; and the defrosting device for the multi-split air conditioning system is arranged on the first outdoor unit, the second outdoor unit and the bypass pipeline.

The defrosting method and device for the multi-split air conditioning system and the multi-split air conditioning system provided by the embodiment of the disclosure can realize the following technical effects:

After the operation mode of each outdoor unit and the frosting state of each outdoor unit are obtained, the embodiment of the disclosure controls the conduction state of the refrigerant circulation pipeline of each outdoor unit, controls the conduction state of the liquid pipe pipeline of each outdoor unit and/or the air pipe pipeline of each outdoor unit, and controls the conduction state of the bypass pipeline according to the operation mode and frosting state of each outdoor unit. Therefore, defrosting treatment of the frosted outdoor unit by using the outdoor unit without frosting can be realized by switching on and off the refrigerant training loop and the liquid pipe pipeline and/or the gas pipe pipeline and the bypass pipeline, so that defrosting operation of the outdoor unit by switching the indoor unit from a heating mode to a refrigerating mode is avoided, heat supply continuity is ensured, great temperature fluctuation in an indoor space is avoided, and comfort level of a user is ensured.

The foregoing general description and the following description are exemplary and explanatory only and are not restrictive of the application.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which like reference numerals refer to similar elements, and in which:

Fig. 1 is a schematic structural diagram of a multi-split air conditioning system according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a defrost method for a multi-split air conditioning system provided in an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of another defrost method for a multi-split air conditioning system provided in an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of another defrost method for a multi-split air conditioning system provided in an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of another defrost method for a multi-split air conditioning system provided in an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of another defrost method for a multi-split air conditioning system provided in an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of another defrost method for a multi-split air conditioning system provided in an embodiment of the present disclosure;

FIG. 8 is a schematic illustration of an application of an embodiment of the present disclosure;

fig. 9 is a schematic diagram of a defrosting device for a multi-split air conditioning system according to an embodiment of the present disclosure.

Reference numerals:

100: a processor; 101: a memory; 102: a communication interface; 103: a bus;

200: an indoor unit;

300: defrosting device for multi-split air conditioning system;

200a: a first end; 200b: a second end;

400: a first outdoor unit; 401: a first refrigerant circulation line;

402: a first liquid pipe line; 403: a first gas line;

4011: a first compressor; 4012: a first four-way valve;

4013: a first heat exchanger; 4014: a first gas-liquid separator;

4021: a first electronic expansion valve; 4022: a first liquid pipe stop valve;

4031: a first air pipe electromagnetic valve;

500: a second outdoor unit; 501: a second refrigerant circulation line;

502: a second liquid pipe line; 503: a second tracheal tube;

5011: a second compressor; 5012: a second four-way valve;

5013: a second heat exchanger; 5014: a second gas-liquid separator;

5021: a second electronic expansion valve; 5022: a second liquid pipe stop valve;

5031: a second air pipe electromagnetic valve;

600: a bypass line; 600a: and (5) bypassing the electromagnetic valve.

Detailed Description

So that the manner in which the features and techniques of the disclosed embodiments can be understood in more detail, a more particular description of the embodiments of the disclosure, briefly summarized below, may be had by reference to the appended drawings, which are not intended to be limiting of the embodiments of the disclosure. In the following description of the technology, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may still be practiced without these details. In other instances, well-known structures and devices may be shown simplified in order to simplify the drawing.

The terms first, second and the like in the description and in the claims of the embodiments of the disclosure and in the above-described figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe embodiments of the present disclosure. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.

The term "plurality" means two or more, unless otherwise indicated.

In the embodiment of the present disclosure, the character "/" indicates that the front and rear objects are an or relationship. For example, A/B represents: a or B.

The term "and/or" is an associative relationship that describes an object, meaning that there may be three relationships. For example, a and/or B, represent: a or B, or, A and B.

The term "corresponding" may refer to an association or binding relationship, and the correspondence between a and B refers to an association or binding relationship between a and B.

The embodiment of the disclosure provides a multi-split air conditioning system, which comprises a first outdoor unit and a second outdoor unit. The liquid pipe pipeline of the first outdoor unit and the liquid pipe pipeline of the second outdoor unit are connected in parallel and connected to the first end of the indoor unit. The air pipe of the first outdoor unit is connected in parallel with the air pipe of the second outdoor unit and is connected to the second end of the indoor unit. The exhaust port of the first compressor is connected with the exhaust port of the second compressor through a bypass pipeline.

In a specific example, referring to fig. 1, a multi-split air conditioning system includes an indoor unit 200, a first outdoor unit 400, a second outdoor unit 500, and a bypass line 600.

The indoor unit 200 includes a plurality of indoor units connected in parallel. The indoor unit 200 includes a first end 200a and a second end 200b.

The first outdoor unit 400 includes a first refrigerant circulation line 401. The first refrigerant circulation line 401 includes a first compressor 4011, a first four-way valve 4012, and a first heat exchanger 4013 that are sequentially connected, the first heat exchanger 4013 is connected to the first end 200a through a first liquid pipe line 402, and the first four-way valve 4012 is connected to the second end 200b through a first gas pipe line 403.

The second outdoor unit 500 includes a second refrigerant circulation line 501. The second refrigerant circulation circuit 501 includes a second compressor 5011, a second four-way valve 5012, and a second heat exchanger 5013 connected in sequence, the second heat exchanger 5013 is connected to the first end 200a through a second liquid pipe line 502, and the second four-way valve 5012 is connected to the second end 200b through a second gas pipe line 503.

The bypass line 600 has one end communicating with the exhaust port of the first compressor 4011 and the other end communicating with the exhaust port of the second compressor 5011, and is provided with a bypass solenoid valve 600a. The method comprises the steps of,

Alternatively, the first liquid pipe line 402 is provided with a first electronic expansion valve 4021 and a first liquid pipe shut-off valve 4022 connected in series. The second liquid pipe line 502 is provided with a second electronic expansion valve 5021 and a second liquid pipe shut-off valve 5022 connected in series.

Optionally, the first gas line 403 is configured with a first gas line solenoid valve 4031. The second air pipe line 503 is provided with a second air pipe solenoid valve 5031.

Optionally, as shown in connection with fig. 1, the first refrigerant circulation line 401 further includes a first gas-liquid separator 4014. One end of the first gas-liquid separator 4014 is connected with the first compressor 4011, and the other end is connected with an S port of the first four-way valve 4012. The second refrigerant circulation line 501 further includes a second gas-liquid separator 5014. Two ends of the second gas-liquid separator 5014 are connected with the second compressor 5011, and the other two ends are connected with the S port of the second four-way valve 5012.

Based on the multi-split air conditioning system, referring to fig. 2, an embodiment of the disclosure provides a defrosting method for the multi-split air conditioning system, including:

s01, the processor acquires the operation mode of each outdoor unit and the frosting state of each outdoor unit.

S02, the processor controls the conduction state of the refrigerant circulation pipeline of each outdoor unit, controls the conduction state of the liquid pipeline of each outdoor unit and/or the gas pipeline of each outdoor unit and controls the conduction state of the bypass pipeline according to the running mode and the frosting state of each outdoor unit.

By adopting the defrosting method for the multi-split air conditioning system provided by the embodiment of the disclosure, after the operation mode of each outdoor unit and the frosting state of each outdoor unit are obtained, the conduction state of the refrigerant circulation pipeline of each outdoor unit is controlled, the conduction state of the liquid pipe pipeline of each outdoor unit and/or the gas pipe pipeline of each outdoor unit is controlled, and the conduction state of the bypass pipeline is controlled according to the operation mode and the frosting state of each outdoor unit. Therefore, defrosting treatment of the frosted outdoor unit by using the outdoor unit without frosting can be realized by switching on and off the refrigerant training loop and the liquid pipe pipeline and/or the gas pipe pipeline and the bypass pipeline, so that defrosting operation of the outdoor unit by switching the indoor unit from a heating mode to a refrigerating mode is avoided, heat supply continuity is ensured, great temperature fluctuation in an indoor space is avoided, and comfort level of a user is ensured.

Optionally, referring to fig. 3, the processor controls a conduction state of a refrigerant circulation pipeline of each outdoor unit and a liquid pipe pipeline of each outdoor unit and/or a gas pipe pipeline of each outdoor unit according to an operation mode and a frosting state of each outdoor unit, and controls a conduction state of a bypass pipeline, including:

S11, the processor acquires the frosting state of the first heat exchanger under the condition that the second outdoor unit is in standby and the first outdoor unit is in a heating mode.

And S12, under the condition that the frosting state indicates that the first heat exchanger is severely frosted, the processor controls the first refrigerant circulation pipeline to be cut off, controls the first air pipe pipeline to be cut off, and controls the first four-way valve to be switched to be on for refrigeration. Wherein, refrigeration conduction represents the four-way valve conduction state when the first outdoor refrigeration is operated.

S13, the processor controls the second refrigerant circulation pipeline to be conducted, and controls the second air pipe pipeline to be conducted.

S14, the processor controls the bypass pipeline to be conducted, and defrosting operation is carried out on the first heat exchanger through bypassing the high-temperature refrigerant of the second compressor to the first refrigerant circulation pipeline.

In this way, in the embodiment of the disclosure, when the second outdoor unit is in standby and the first outdoor unit is in the heating mode, the frosting state of the first outdoor unit in the cooling mode is obtained. When the severe frosting of the first heat exchanger is determined, in order to maintain the reliability and the high efficiency of the heating of the multi-split air conditioning system, the first outdoor unit is controlled to stop the heating operation, and the second outdoor unit in standby is utilized to defrost the first outdoor unit. Specifically, the first outdoor unit is stopped from heating by controlling the first refrigerant circulation line to be turned off and controlling the first air pipe line to be turned off. And the first four-way valve is controlled to be switched on for refrigeration, the second refrigerant is controlled to be switched on in a circulating reflux way, and the second air pipe is controlled to be switched on, so that the second outdoor unit is used for supplying heat to the indoor unit instead of the first outdoor unit, and the continuity of heat supply is ensured. And meanwhile, the bypass pipeline is controlled to be conducted, so that high-temperature refrigerant of the second compressor enters the first refrigerant circulation pipeline, and defrosting control is performed on the first heat exchanger. Therefore, frosting can be performed on the frosted outdoor heat exchanger, the continuity of heat supply of the indoor unit can be guaranteed, and the comfort level of a user is effectively guaranteed.

Optionally, the processor controls the first refrigerant circulation pipeline to be cut off and controls the first gas pipe pipeline to be cut off, including:

the processor controls the first compressor and the first outdoor fan to stop running.

The processor controls the first electronic expansion valve to be opened to a preset opening degree.

The processor controls the first air pipe electromagnetic valve to be closed.

In this way, the embodiment of the disclosure can avoid the aggravation trend of the frosting degree of the first outdoor unit by controlling the first refrigerant circulation pipeline to be switched to be cut off and controlling the first air pipe electromagnetic valve to disconnect the first air pipe pipeline. Meanwhile, the first electronic expansion valve is controlled to a preset opening degree, so that when the bypass pipeline is conducted, high-temperature refrigerant can flow into the first refrigerant circulation pipeline through the bypass pipeline, and defrosting control of the first heat exchanger is facilitated.

Optionally, the processor controls the first electronic expansion valve to be opened to a preset opening degree, including: the processor controls the first electronic expansion valve to be opened to a preset opening K0, and the K0 is set according to the specific application environment of the multi-split system.

Optionally, the processor controls the second refrigerant circulation pipeline to be turned on, and controls the second air pipe pipeline to be turned on, including:

the processor controls the second compressor and the second outdoor fan to start running.

The processor controls the second four-way valve to be switched to be heated and conducted. The heating conduction state represents a four-way valve conduction state when the second outdoor machine is in heating operation.

The processor controls the second electronic expansion valve to be opened, and controls the second air pipe electromagnetic valve to be opened.

Therefore, the second outdoor unit can rapidly replace the first outdoor unit to supply heat to the indoor unit, and the heat supply persistence is ensured.

Optionally, after the processor controls the second electronic expansion valve to open, the method further includes: and the processor adjusts the opening value according to the second target superheat degree related to the second electronic expansion valve.

Optionally, as shown in fig. 1 and fig. 4, the processor controls the conduction state of the refrigerant circulation pipeline of each outdoor unit and the conduction state of the liquid pipe pipeline of each outdoor unit and/or the air pipe pipeline of each outdoor unit according to the operation mode and the frosting state of each outdoor unit, and controls the conduction state of the bypass pipeline, including:

s21, the processor acquires the frosting state of the first heat exchanger under the condition that the second outdoor unit is in standby and the first outdoor unit is in a heating mode.

S22, when the frosting state indicates that the first heat exchanger is severely frosted, the processor controls the first refrigerant circulation pipeline to be cut off, controls the first air pipe pipeline to be cut off, and controls the first four-way valve to be switched to be on.

S23, the processor controls the second refrigerant circulation pipeline to be conducted, and controls the second air pipe pipeline to be conducted.

And S24, the processor controls the bypass pipeline to be conducted, and defrosting operation is carried out on the first heat exchanger by bypassing the high-temperature refrigerant of the second compressor to the first refrigerant circulation pipeline.

S25, the processor acquires the frosting state of the first heat exchanger again.

And S26, controlling the bypass pipeline to be cut off and controlling the first four-way valve to be switched to be heated and conducted under the condition that the new frosting state indicates that defrosting of the first heat exchanger is finished by the processor.

And S27, the processor controls the first electronic expansion valve to be closed.

In this way, when the severe frosting of the first heat exchanger is determined, the embodiment of the disclosure controls the first outdoor unit to stop the heating operation, and uses the standby second outdoor unit to defrost the first outdoor unit, so that the second outdoor unit takes over the first outdoor unit to supply heat to the indoor unit, and simultaneously controls the bypass pipeline to be conducted, so that the high-temperature refrigerant of the second compressor enters the first refrigerant circulation pipeline to defrost the first heat exchanger. And then, acquiring the frosting state of the first heat exchanger in real time, and when the new frosting state indicates that the frosting of the first heat exchanger is finished, indicating that the surface of the first heat exchanger is thoroughly frosted, and finishing the defrosting treatment of the first outdoor unit by the second outdoor unit. At this time, the bypass line is not required to be continuously used to convey the high-temperature refrigerant to the first refrigerant circulation line. Therefore, the embodiment of the disclosure controls the bypass pipeline to be cut off and controls the first four-way valve to be switched to be heated and conducted so as to restore the valve state of the first four-way valve before defrosting of the first heat exchanger. Meanwhile, if the first electronic expansion valve is continuously opened, the refrigerant in the second refrigerant circulation pipeline is split into the first refrigerant circulation pipeline, so that the operation of the two outdoor units is mutually interfered. In order to avoid operation interference caused by refrigerant diversion, the first electronic expansion valve is controlled to be closed, and the reliability of the subsequent operation of the first outdoor unit is ensured.

It should be noted that, after the processor controls the bypass pipeline to be cut off and controls the first four-way valve to be switched to heat conduction, the processor controls the first outdoor unit to be switched to standby or to re-heat operation according to the load requirement of the indoor unit. It will be appreciated that the load requirements of the indoor units are different, and the subsequent operation of the first outdoor unit is different.

Optionally, in a case where the second outdoor unit is in standby and the first outdoor unit is in heating mode, the processor acquires a frosting state of each outdoor unit as follows:

the processor obtains a heat exchanger temperature value of a heat exchanger operating in a heating mode. Wherein the heat exchanger temperature value represents a heat exchanger surface temperature value.

And under the condition that the temperature value of the heat exchanger is continuously smaller than the first preset temperature value within the first preset time period, the processor determines that the heat exchanger is frosted again. Or,

and under the condition that the temperature value of the heat exchanger is continuously larger than the second preset temperature value within the second preset time period, the processor determines that defrosting of the heat exchanger is finished.

The first preset temperature value represents a critical temperature value of the heat exchanger entering defrosting, and the second preset temperature value represents a critical temperature value of the heat exchanger exiting defrosting.

Therefore, the frosting condition of each outdoor unit can be accurately judged, and the accurate triggering of the subsequent defrosting operation can be realized.

In one specific example, in the event Ta > T1 and for T1, the processor determines that the first heat exchanger defrosting is complete, i.e., determines that the first heat exchanger surface frost layer is completely defrosted.

In the case of Ta < T0 and for T0, the processor determines that the first heat exchanger is severely frosted.

Wherein Ta represents a first heat exchanger temperature value, T0 represents a first preset temperature value, and T1 represents a second preset temperature value. t0 represents a first preset time period, and t1 represents a second preset time period.

Alternatively, T0 is less than or equal to minus 20 ℃ and less than or equal to minus 5 ℃, and T1 is less than or equal to 5 ℃ and less than or equal to 10 ℃. T0 is less than or equal to 1min and less than or equal to 5min, t1 is less than or equal to 1min and less than or equal to 5min. min represents minutes.

Optionally, as shown in fig. 5 and 8, the processor controls the conduction state of the refrigerant circulation pipeline of each outdoor unit and the conduction state of the liquid pipe pipeline of each outdoor unit and/or the air pipe pipeline of each outdoor unit, and controls the conduction state of the bypass pipeline according to the operation mode and the frosting state of each outdoor unit, including:

s31, the processor acquires respective frosting states of the first heat exchanger and the second heat exchanger under the condition that the second outdoor unit and the first outdoor unit are both in a heating mode.

And S32, under the condition that the first heat exchanger is frosted again and the second heat exchanger is not frosted, the processor controls the first refrigerant circulation pipeline to be cut off, controls the first air pipe pipeline to be cut off, and controls the first four-way valve to be switched to be on for refrigeration. Wherein, the non-frosting indicates that the surface of the heat exchanger has no frosting layer or indicates that the frosting degree of the surface of the heat exchanger is acceptable.

In this step, when both the second outdoor unit and the first outdoor unit are in the heating mode, the processor frosts the first heat exchanger again and the second heat exchanger does not frost according to the following manner:

and determining that the first heat exchanger is severely frosted and the second heat exchanger is not frosted under the condition that the heat exchanger temperature value of the first heat exchanger is continuously smaller than the first preset temperature value in the first preset time period and the heat exchanger temperature value of the second heat exchanger is continuously larger than the third preset temperature value in the first preset time period.

The third preset temperature value is equal to the sum of the first preset temperature value and the preset temperature deviation value. For example, t2=t0+Δt, where T2 represents a third preset temperature value, T0 represents a first preset temperature value, and Δt represents a preset temperature bias value. Alternatively, the temperature is 3 ℃ or more and the delta T or less than 10 ℃.

In one specific example, with Ta < T0 and for T0, and Tb > (t0+Δt) and for T0, the processor determines that the first heat exchanger is severely frosted and the second heat exchanger is not frosted. Wherein Ta represents the first heat exchanger temperature value and Tb represents the first heat exchanger temperature value. T0 represents a first preset temperature value, and T0 represents a first preset time period.

S33, the processor controls the second compressor to increase the operating frequency.

And S34, the processor controls the bypass pipeline to be conducted, and defrosting operation is carried out on the first heat exchanger by bypassing the high-temperature refrigerant of the second compressor to the first refrigerant circulation pipeline.

Thus, after the respective frosting states of the two heat exchangers are obtained, if the first heat exchanger is frosted again and the second heat exchanger is not frosted, the embodiment of the disclosure shows that the first heat exchanger needs to be frosted temporarily and the second heat exchanger does not need to be frosted temporarily. At this time, the first refrigerant circulation pipeline is controlled to be cut off, the first air pipe pipeline is controlled to be cut off, and the first four-way valve is controlled to be switched on for refrigeration, so that the first outdoor unit is controlled to stop heating operation. Meanwhile, the second compressor is controlled to raise the operating frequency, so that only the second outdoor unit which can still perform refrigeration operation is utilized to continuously supply heat to the indoor unit in a frequency raising mode, and the continuity of heat supply is ensured. In addition, the bypass pipeline is conducted, so that the high-temperature refrigerant of the second compressor enters the first refrigerant circulation pipeline to defrost the first heat exchanger. In summary, according to the embodiment of the disclosure, when two outdoor units are both in heating operation and one of the outdoor units has a defrosting requirement, the other outdoor unit without the defrosting requirement is used for defrosting the outdoor heat exchanger of the outdoor unit, and meanwhile, continuous heat supply is ensured through the frequency-raising operation of the compressor of the other outdoor unit, so that the comfort level of a user is effectively ensured.

It should be noted that, the processor controls the bypass pipeline to be turned on, and after the defrosting operation is performed on the first heat exchanger by bypassing the high-temperature refrigerant of the second compressor to the first refrigerant circulation pipeline, the frosting state of the first heat exchanger can be obtained again, and when the new frosting state indicates that the defrosting of the first heat exchanger is finished, the process can be performed with reference to the foregoing steps S26 to S27. The embodiments of the present disclosure will not be described in detail.

Optionally, the processor controls the second compressor to increase the operating frequency, comprising:

the processor controls the second compressor to up-convert to n0×f0. Wherein f0 represents the current frequency of the second compressor, and n0 represents a third preset frequency coefficient of the second compressor. Alternatively, 1.05.ltoreq.n1.ltoreq.2. It will be appreciated that the specific value of the third preset frequency coefficient of the second compressor may be determined according to the specific application environment.

Optionally, as shown in fig. 6 and 8, the processor controls the conduction state of the refrigerant circulation pipeline of each outdoor unit and the conduction state of the liquid pipe pipeline of each outdoor unit and/or the air pipe pipeline of each outdoor unit, and controls the conduction state of the bypass pipeline according to the operation mode and the frosting state of each outdoor unit, including:

S41, the processor obtains respective frosting states of the first heat exchanger and the second heat exchanger under the condition that the second outdoor unit and the first outdoor unit are both in a heating mode. S42 or S45 is performed.

S42, when the first heat exchanger is frosted again and the second heat exchanger is not frosted, the processor controls the first refrigerant circulation pipeline to be cut off, controls the first air pipe pipeline to be cut off, and controls the first four-way valve to be switched to be on for refrigeration.

S43, the processor controls the second compressor to increase the operating frequency.

And S44, the processor controls the bypass pipeline to be conducted, and defrosting operation is carried out on the first heat exchanger by bypassing the high-temperature refrigerant of the second compressor to the first refrigerant circulation pipeline.

And S45, controlling the first compressor to reduce the operating frequency by the processor under the condition that the first heat exchanger is frosted again and the second heat exchanger is frosted moderately.

S46, the processor controls the second compressor to increase the operating frequency.

Thus, after obtaining the frosting states of the two heat exchangers, the embodiment of the disclosure indicates that the two heat exchangers have defrosting requirements if the first heat exchanger is frosted again and the second heat exchanger is frosted moderately. At this time, on the basis of defrosting, in order to ensure the sustainability of heat supply of the indoor unit, the embodiment of the disclosure controls the second compressor to execute the frequency-raising operation on the basis of the second outdoor machine heating operation, and controls the first compressor to execute the frequency-raising operation on the basis of the first outdoor machine heating operation. Meanwhile, the frequency-reducing amplitude value of the first compressor is smaller than that of the second compressor. In this way, further exacerbation of the frosting degree of the first heat exchanger is avoided.

Optionally, in the case that both the second outdoor unit and the first outdoor unit are in the heating mode, the processor determines that the first heat exchanger is severely frosted and the second heat exchanger is moderately frosted according to the following manner:

and under the condition that the temperature value of the heat exchanger of the first heat exchanger is continuously smaller than a first preset temperature value in a first preset time period and the temperature value of the heat exchanger of the second heat exchanger is continuously larger than the first preset temperature value and continuously smaller than a third preset temperature value in the first preset time period, the processor determines that the first heat exchanger is severely frosted and the second heat exchanger is moderately frosted.

The third preset temperature value is equal to the sum of the first preset temperature value and the preset temperature deviation value. For example, t2=t0+Δt, where T2 represents a third preset temperature value, T0 represents a first preset temperature value, and Δt represents a preset temperature bias value. Alternatively, the temperature is 3 ℃ or more and the delta T or less than 10 ℃.

In one specific example, where Ta < T0 and last T0, and T0< Tb < (t0+Δt) and last T0, the processor determines that the first heat exchanger is heavily frosted and the second heat exchanger is moderately frosted. Wherein Ta represents the first heat exchanger temperature value and Tb represents the first heat exchanger temperature value. T0 represents a first preset temperature value, and T0 represents a first preset time period.

Optionally, the processor controls the first compressor to reduce the operating frequency and controls the second compressor to increase the operating frequency in the case that the first heat exchanger is frosted again and the second heat exchanger is frosted moderately, including:

and the processor controls the first compressor to be down-converted to n1 xf 1 and controls the second compressor to be up-converted to n2 xf 1 under the condition that the first heat exchanger is frosted again and the second heat exchanger is frosted again.

Wherein f1 represents the current frequency of the compressor, and the current frequencies of the first compressor and the second compressor are equal, n1 represents a first preset frequency coefficient of the first compressor, and n2 represents a second preset frequency coefficient of the second compressor.

Alternatively, 0.7.ltoreq.n1.ltoreq.0.99 and 1.01.ltoreq.n2.ltoreq.1.5. It will be appreciated that the specific values of the first preset frequency coefficient of the first compressor and the second preset frequency coefficient of the second compressor may be determined according to the specific application environment.

Optionally, as shown in fig. 7 and 8, the processor controls the on state of the refrigerant circulation pipeline of each outdoor unit and the on state of the liquid pipe pipeline of each outdoor unit and/or the air pipe pipeline of each outdoor unit, and controls the on state of the bypass pipeline according to the operation mode and the frosting state of each outdoor unit, including:

S51, the processor obtains respective frosting states of the first heat exchanger and the second heat exchanger under the condition that the second outdoor unit and the first outdoor unit are both in a heating mode. S52 or S55 is performed.

And S52, under the condition that the first heat exchanger is frosted again and the second heat exchanger is not frosted, the processor controls the first refrigerant circulation pipeline to be cut off, controls the first air pipe pipeline to be cut off, and controls the first four-way valve to be switched to be on for refrigeration.

And S53, the processor controls the second compressor to increase the operating frequency.

And S54, the processor controls the bypass pipeline to be conducted, and defrosting operation is carried out on the first heat exchanger by bypassing the high-temperature refrigerant of the second compressor to the first refrigerant circulation pipeline.

And S55, the processor controls the bypass pipeline to be closed under the condition that the first heat exchanger and the second heat exchanger are frosted at equal weights.

And S56, the processor controls all the outdoor fans and all the indoor fans of the indoor unit to stop running, and controls the first four-way valve and the second four-way valve to be switched to refrigeration conduction.

And S57, the processor controls the first electronic expansion valve and the second electronic expansion valve to be opened, and controls the first air pipe line and the second air pipe line to be communicated.

S58, the processor controls the first compressor to operate at a first preset defrosting frequency, and controls the second compressor to operate at a second preset defrosting frequency. In this step, the first preset defrosting frequency may be the same as or different from the second preset defrosting frequency.

In this way, after the respective frosting states of the two heat exchangers are obtained, if the first heat exchanger and the second heat exchanger are frosted at equal weights, the two heat exchangers are indicated to have defrosting requirements. At this time, the bypass pipeline is controlled to be closed, all outdoor fans and all indoor fans of the indoor unit are controlled to stop running, and the first four-way valve and the second four-way valve are controlled to be switched to be in refrigeration conduction. Simultaneously, the first electronic expansion valve and the second electronic expansion valve are controlled to be opened, and the first air pipe pipeline and the second air pipe pipeline are controlled to be conducted. On the basis, the first compressor is controlled to operate at a first preset defrosting frequency, and the second compressor is controlled to operate at a second preset defrosting frequency. Therefore, through the arrangement, the defrosting operation is carried out on the first refrigerant circulating pipeline and the second refrigerant circulating pipeline, and the defrosting efficiency of the first heat exchanger and the second heat exchanger is improved.

Optionally, when the second outdoor unit and the first outdoor unit are both in the heating mode, the processor determines that the first heat exchanger and the second heat exchanger are frosted at the same weight according to the following manner:

and under the condition that the temperature value of the heat exchanger of the first heat exchanger is continuously smaller than the first preset temperature value in the first preset time period and the temperature value of the heat exchanger of the second heat exchanger is continuously smaller than the first preset temperature value in the first preset time period, the processor determines that the average weights of the first heat exchanger and the second heat exchanger are frosted.

It should be noted that, after the processor controls the first compressor to operate at the first preset defrosting frequency and controls the second compressor to operate at the second preset defrosting frequency, the method further includes:

the processor reacquires the frosting state of each of the first heat exchanger and the second heat exchanger.

And under the condition that the frosting state indicates that the defrosting of the first heat exchanger and the defrosting of the second heat exchanger are finished, the processor controls the first outdoor unit to switch to standby or reheating operation and/or controls the second outdoor unit to switch to standby or reheating operation according to the load requirement of the indoor unit.

As shown in connection with fig. 9, an embodiment of the present disclosure provides a defroster 300 for a multi-split air conditioning system, including a processor (processor) 100 and a memory (memory) 101. Optionally, the apparatus may further comprise a communication interface (Communication Interface) 102 and a bus 103. The processor 100, the communication interface 102, and the memory 101 may communicate with each other via the bus 103. The communication interface 102 may be used for information transfer. Processor 100 may invoke logic instructions in memory 101 to perform the defrost method for the multi-split air conditioning system of the above-described embodiments.

Further, the logic instructions in the memory 101 described above may be implemented in the form of software functional units and may be stored in a computer readable storage medium when sold or used as a stand alone product.

The memory 101 is a computer readable storage medium that can be used to store a software program, a computer executable program, such as program instructions/modules corresponding to the methods in the embodiments of the present disclosure. The processor 100 executes the program instructions/modules stored in the memory 101 to perform the function application and the data processing, i.e., to implement the defrosting method for the multi-split air conditioning system in the above embodiment.

The memory 101 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, at least one application program required for a function; the storage data area may store data created according to the use of the terminal device, etc. Further, the memory 101 may include a high-speed random access memory, and may also include a nonvolatile memory.

Referring to fig. 1, an embodiment of the present disclosure provides a multi-split air conditioning system, which includes an indoor unit 200, a first outdoor unit 400, a second outdoor unit 500, a bypass line 600, and the defrosting device for the multi-split air conditioning system.

The indoor unit 200 includes a plurality of indoor units connected in parallel. The indoor unit 200 includes a first end 200a and a second end 200b. The first outdoor unit 400 includes a first refrigerant circulation line 401. The first refrigerant circulation line 401 includes a first compressor 4011, a first four-way valve 4012, and a first heat exchanger 4013 that are sequentially connected, the first heat exchanger 4013 is connected to the first end 200a through a first liquid pipe line 402, and the first four-way valve 4012 is connected to the second end 200b through a first gas pipe line 403. The second outdoor unit 500 includes a second refrigerant circulation line 501. The second refrigerant circulation circuit 501 includes a second compressor 5011, a second four-way valve 5012, and a second heat exchanger 5013 connected in sequence, the second heat exchanger 5013 is connected to the first end 200a through a second liquid pipe line 502, and the second four-way valve 5012 is connected to the second end 200b through a second gas pipe line 503. The bypass line 600 has one end communicating with the exhaust port of the first compressor 4011 and the other end communicating with the exhaust port of the second compressor 5011, and is provided with a bypass solenoid valve 600a.

The defrosting apparatus 300 for the multi-split air conditioning system is installed at the first and second outdoor units 400 and 500, and the bypass line 600.

The mounting relationships described herein are not limited to placement within a product, but include mounting connections to other components of a product, including but not limited to physical, electrical, or signal transmission connections, etc. Those skilled in the art will appreciate that the defroster for a multi-split air conditioning system may be adapted to the available product body to achieve other possible embodiments.

Embodiments of the present disclosure provide a computer-readable storage medium storing computer-executable instructions configured to perform the above defrosting method for a multi-split air conditioning system.

The computer readable storage medium may be a transitory computer readable storage medium or a non-transitory computer readable storage medium.

Embodiments of the present disclosure may be embodied in a software product stored on a storage medium, including one or more instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of a method according to embodiments of the present disclosure. And the aforementioned storage medium may be a non-transitory storage medium including: a plurality of media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or a transitory storage medium.

The above description and the drawings illustrate embodiments of the disclosure sufficiently to enable those skilled in the art to practice them. Other embodiments may involve structural, logical, electrical, process, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in, or substituted for, those of others. Moreover, the terminology used in the present application is for the purpose of describing embodiments only and is not intended to limit the claims. As used in the description of the embodiments and the claims, the singular forms "a," "an," and "the" (the) are intended to include the plural forms as well, unless the context clearly indicates otherwise. Similarly, the term "and/or" as used in this disclosure is meant to encompass any and all possible combinations of one or more of the associated listed. Furthermore, when used in the present disclosure, the terms "comprises," "comprising," and/or variations thereof, mean that the recited features, integers, steps, operations, elements, and/or components are present, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Without further limitation, an element defined by the phrase "comprising one …" does not exclude the presence of other like elements in a process, method or apparatus comprising such elements. In this context, each embodiment may be described with emphasis on the differences from the other embodiments, and the same similar parts between the various embodiments may be referred to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method sections disclosed in the embodiments, the description of the method sections may be referred to for relevance.

Those of skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. The skilled artisan may use different methods for each particular application to achieve the described functionality, but such implementation should not be considered to be beyond the scope of the embodiments of the present disclosure. It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.

In the embodiments disclosed herein, the disclosed methods, articles of manufacture (including but not limited to devices, apparatuses, etc.) may be practiced in other ways. For example, the apparatus embodiments described above are merely illustrative, and for example, the division of the units may be merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form. The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to implement the present embodiment. In addition, each functional unit in the embodiments of the present disclosure may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.

The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. In the description corresponding to the flowcharts and block diagrams in the figures, operations or steps corresponding to different blocks may also occur in different orders than that disclosed in the description, and sometimes no specific order exists between different operations or steps. For example, two consecutive operations or steps may actually be performed substantially in parallel, they may sometimes be performed in reverse order, which may be dependent on the functions involved. Each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

Claims (11)

1. The utility model provides a defrosting method for many online air conditioning system, its characterized in that, many online air conditioning system includes first off-premises station and second off-premises station, and the liquid pipe pipeline of first off-premises station and the liquid pipe pipeline of second off-premises station connect in parallel and insert the first end of indoor unit, and the air pipe pipeline of first off-premises station and the air pipe pipeline of second off-premises station connect in parallel and insert the second end of indoor unit, and the gas vent of first compressor is connected with the gas vent of second compressor through the bypass line, the method includes:

acquiring an operation mode of each outdoor unit and a frosting state of each outdoor unit;

according to the running mode and frosting state of each outdoor unit, the conduction state of the refrigerant circulation pipeline of each outdoor unit is controlled, the conduction state of the liquid pipeline of each outdoor unit and/or the gas pipeline of each outdoor unit is controlled, and the conduction state of the bypass pipeline is controlled.

2. The method of claim 1, wherein the first outdoor unit comprises a first refrigerant circulation line, the first refrigerant circulation line comprises a first compressor, a first four-way valve and a first heat exchanger which are sequentially connected, the first heat exchanger is connected with the first end through a first liquid pipe line, and the first four-way valve is connected with the second end through a first gas pipe line; the second outdoor unit comprises a second refrigerant circulation pipeline, the second refrigerant circulation pipeline comprises a second compressor, a second four-way valve and a second heat exchanger which are sequentially connected, the second heat exchanger is connected with the first end through a second liquid pipe pipeline, and the second four-way valve is connected with the second end through a second air pipe pipeline; according to the operation mode and the frosting state of each outdoor unit, the control of the conduction state of the refrigerant circulation pipeline of each outdoor unit, the control of the conduction state of the liquid pipe pipeline of each outdoor unit and/or the air pipe pipeline of each outdoor unit, and the control of the conduction state of the bypass pipeline include:

Acquiring a frosting state of the first heat exchanger under the condition that the second outdoor unit is in standby and the first outdoor unit is in a heating mode;

under the condition that the frosting state indicates that the first heat exchanger is severely frosted, the first refrigerant circulation pipeline is controlled to be cut off, the first air pipe pipeline is controlled to be cut off, and the first four-way valve is controlled to be switched to be on for refrigeration;

controlling the second refrigerant circulation pipeline to be conducted, and controlling the second air pipe pipeline to be conducted;

and controlling the bypass pipeline to be conducted, and defrosting the first heat exchanger by bypassing the high-temperature refrigerant of the second compressor to the first refrigerant circulation pipeline.

3. The method of claim 2, wherein the first gas line is configured with a first gas line solenoid valve, the controlling the first refrigerant circulation line to shut off and the first gas line to shut off, comprising:

controlling the first compressor and the first outdoor fan to stop running;

controlling the first electronic expansion valve to be opened to a preset opening degree;

and controlling the first air pipe electromagnetic valve to be closed.

4. The method of claim 2, wherein the second gas line is configured with a second gas line solenoid valve, said controlling the second refrigerant circulation line to conduct, and controlling the second gas line to conduct, comprising:

Controlling the second compressor and the second outdoor fan to start running;

controlling the second four-way valve to be switched to heating conduction;

and controlling the second electronic expansion valve to be opened, and controlling the second air pipe electromagnetic valve to be opened.

5. The method of claim 2, further comprising, after said controlling bypass line to be conductive:

re-acquiring the frosting state of the first heat exchanger;

under the condition that the new frosting state indicates that defrosting of the first heat exchanger is finished, controlling the bypass pipeline to be cut off, and controlling the first four-way valve to be switched to be heated and conducted;

and controlling the first electronic expansion valve to be closed.

6. The method of any one of claims 2 to 5, wherein in the case where the second outdoor unit is in standby and the first outdoor unit is in heating mode, the frosting state of each outdoor unit is obtained as follows:

acquiring a heat exchanger temperature value of a heat exchanger operating in a heating mode;

determining that the heat exchanger is frosted again under the condition that the temperature value of the heat exchanger is continuously smaller than the first preset temperature value within the first preset time period; or,

determining that defrosting of the heat exchanger is finished under the condition that the temperature value of the heat exchanger is continuously larger than a second preset temperature value within a second preset time period;

The first preset temperature value represents a critical temperature value of the heat exchanger entering defrosting, and the second preset temperature value represents a critical temperature value of the heat exchanger exiting defrosting.

7. The method of claim 1, wherein the first outdoor unit comprises a first refrigerant circulation line, the first refrigerant circulation line comprises a first compressor, a first four-way valve and a first heat exchanger which are sequentially connected, the first heat exchanger is connected with the first end through a first liquid pipe line, and the first four-way valve is connected with the second end through a first gas pipe line; the second outdoor unit comprises a second refrigerant circulation pipeline, the second refrigerant circulation pipeline comprises a second compressor, a second four-way valve and a second heat exchanger which are sequentially connected, the second heat exchanger is connected with the first end through a second liquid pipe pipeline, and the second four-way valve is connected with the second end through a second air pipe pipeline; according to the operation mode and the frosting state of each outdoor unit, the control of the conduction state of the refrigerant circulation pipeline of each outdoor unit, the control of the conduction state of the liquid pipe pipeline of each outdoor unit and/or the air pipe pipeline of each outdoor unit, and the control of the conduction state of the bypass pipeline include:

acquiring respective frosting states of the first heat exchanger and the second heat exchanger under the condition that the second outdoor unit and the first outdoor unit are both in a heating mode;

Under the condition that the first heat exchanger is frosted again and the second heat exchanger is not frosted, the first refrigerant circulation pipeline is controlled to be cut off, the first air pipe pipeline is controlled to be cut off, and the first four-way valve is controlled to be switched to be in refrigeration conduction;

controlling the second compressor to raise the operating frequency;

and controlling the bypass pipeline to be conducted, and defrosting the first heat exchanger by bypassing the high-temperature refrigerant of the second compressor to the first refrigerant circulation pipeline.

8. The method of claim 7, further comprising, in the case where both the second outdoor unit and the first outdoor unit are in the heating mode;

controlling the first compressor to reduce the operating frequency under the condition that the first heat exchanger is frosted again and the second heat exchanger is frosted moderately;

the second compressor is controlled to raise the operating frequency.

9. The method of claim 7, wherein the first outdoor unit comprises a first refrigerant circulation line, the first refrigerant circulation line comprising a first compressor and a first four-way valve, a first heat exchanger connected in sequence, the first heat exchanger connected to the first end through a first liquid line, the first four-way valve connected to the second end through a first gas line; the second outdoor unit comprises a second refrigerant circulation pipeline, the second refrigerant circulation pipeline comprises a second compressor, a second four-way valve and a second heat exchanger which are sequentially connected, the second heat exchanger is connected with the first end through a second liquid pipe pipeline, and the second four-way valve is connected with the second end through a second air pipe pipeline; the method further comprises the step of under the condition that the second outdoor unit and the first outdoor unit are both in a heating mode;

Under the condition that the first heat exchanger and the second heat exchanger are frosted at equal weights, the bypass pipeline is controlled to be closed;

controlling all outdoor fans and all indoor fans of the indoor unit to stop running, and controlling the first four-way valve and the second four-way valve to be switched to refrigeration conduction;

the first electronic expansion valve and the second electronic expansion valve are controlled to be opened, and the first air pipe line and the second air pipe line are controlled to be communicated;

the first compressor is controlled to operate at a first preset defrost frequency and the second compressor is controlled to operate at a second preset defrost frequency.

10. A defrosting apparatus for a multi-split air conditioning system comprising a processor and a memory storing program instructions, wherein the processor is configured to perform the defrosting method for a multi-split air conditioning system according to any one of claims 1 to 9 when the program instructions are executed.

11. A multi-split air conditioning system, comprising:

the indoor unit comprises a plurality of indoor units connected in parallel, and the indoor unit comprises a first end and a second end;

the first outdoor unit comprises a first refrigerant circulating pipeline which is sequentially connected, the first refrigerant circulating pipeline comprises a first compressor, a first four-way valve and a first heat exchanger, the first heat exchanger is connected with a first end through a first liquid pipe pipeline, and the first four-way valve is connected with a second end through a first air pipe pipeline;

The second outdoor unit comprises a second refrigerant circulation pipeline which is sequentially connected, the second refrigerant circulation pipeline comprises a second compressor, a second four-way valve and a second heat exchanger, the second heat exchanger is connected with the first end through a second liquid pipe pipeline, and the second four-way valve is connected with the second end through a first air pipe pipeline;

one end of the bypass pipeline is communicated with the exhaust port of the first compressor, the other end of the bypass pipeline is communicated with the exhaust port of the second compressor, and a bypass electromagnetic valve is arranged; the method comprises the steps of,

the defrosting apparatus for a multi-split air conditioning system of claim 10, installed to the first and second outdoor units, bypass line.