Magnetic suspension centrifugal compressor air conditioning system with partition defrosting function and control method

Abstract

The invention discloses a magnetic suspension centrifugal compressor air conditioning system with a partition defrosting function and a control method. An outlet of a first-stage compressor is connected with an inlet of a second-stage compressor; the first three-way valve, the second three-way valve and the third three-way valve are all connected with the exhaust end of the second-stage compressor; an inlet of the first outdoor heat exchanger is connected with the first three-way valve; an inlet of the second outdoor heat exchanger is connected with the second three-way valve; an inlet of the indoor heat exchanger is connected with the third three-way valve; the heat exchanger is provided with a first heat exchange side and a second heat exchange side. The inner valve is connected with at least one indoor heat exchanger outlet, and the other end of the inner valve is connected with the first heat exchange side of the heat exchanger; the second heat exchange side utilizes the outlet side of the inner valve to supplement air; and the refrigerant subjected to heat exchange by the heat exchanger is introduced between the first-stage compressor and the second-stage compressor. The operation stability and the system reliability of the magnetic suspension centrifugal compressor can be effectively improved.

Description

Technical Field

[0001] This invention relates to air conditioning compressor technology, and in particular to an air conditioning system and control method for a magnetic levitation centrifugal compressor with zoned defrosting. Background Technology

[0002] During winter heating operation, heat pump air conditioners typically absorb heat from the ambient air and release it into the indoor environment through an outdoor heat exchanger. Due to the low outdoor ambient temperature, the outdoor heat exchanger operates at a low temperature. When its surface temperature is below the air dew point and below zero degrees Celsius, moisture in the air easily condenses and frosts on the surface of the outdoor heat exchanger. As operating time increases, the frost layer thickens, gradually covering the heat exchanger surface and airflow channels, leading to a significant decrease in heat exchange efficiency. In severe cases, this can prevent the outdoor heat exchanger from effectively absorbing heat from the air, affecting the normal heating operation of the air conditioning system.

[0003] To remove frost from the outdoor heat exchanger, existing heat pump air conditioners typically enter forced defrost mode after detecting frost formation. The most common defrosting method currently is reverse cycle defrosting, which involves switching the refrigerant flow via a four-way valve, switching the air conditioning system from heating to cooling mode. The high-temperature refrigerant then heats the outdoor heat exchanger to melt the frost. During reverse cycle defrosting, the indoor heat exchanger changes from a heat-releasing state to a heat-absorbing state, while the outdoor heat exchanger changes from a heat-absorbing state to a heat-releasing state, thus removing the frost.

[0004] However, the aforementioned reverse-cycle defrosting method has significant limitations in magnetic levitation centrifugal compressor air conditioning units. Magnetic levitation centrifugal compressors are highly sensitive to changes in system operating conditions, and their stable operation depends on the continuous and stable flow, pressure, and direction of the refrigerant. When the system performs reverse-cycle defrosting or switches back to heating mode, components such as compressor speed, four-way valve reversing, and fan start / stop require frequent operation, which can easily cause drastic changes in refrigerant flow direction, pressure, and mass flow rate. During this process, a certain amount of liquid refrigerant often returns to the compressor along with the gaseous refrigerant, which can easily lead to operational risks such as surge, rotor instability, and even liquid slugging in the magnetic levitation centrifugal compressor, seriously affecting the system's reliability and service life.

[0005] Furthermore, existing reverse-cycle defrosting systems typically require interrupting continuous heating during defrosting, leading to indoor temperature fluctuations and reduced user comfort. For heat pump air conditioning systems using magnetic levitation centrifugal compressors, achieving uninterrupted heating and continuous operation during defrosting while ensuring stable compressor operation has become a pressing technical challenge. Summary of the Invention

[0006] The purpose of this invention is to provide a magnetic levitation centrifugal compressor air conditioning system and control method with zoned defrosting, in order to solve the problems of the prior art.

[0007] This invention discloses a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting, comprising: a primary compressor (11) and a secondary compressor (12), wherein the outlet of the primary compressor (11) is connected to the inlet of the secondary compressor (12) for two-stage compression of refrigerant; a first three-way valve (21), a second three-way valve (22), and a third three-way valve (23), all connected to the exhaust end of the secondary compressor (12) for selective distribution of the refrigerant discharged from the secondary compressor (12); a first outdoor heat exchanger (31), the inlet of which is connected to the first three-way valve (21); a second outdoor heat exchanger (32), the inlet of which is connected to the second three-way valve (22); and at least one indoor heat exchanger, the inlet of which is connected to the third three-way valve (23) for... Heat exchange with indoor air; heat exchanger (51) has a first heat exchange side and a second heat exchange side; at least an inner valve, correspondingly connected to the outlet of the at least one indoor heat exchanger, the other end of the inner valve being connected to the first heat exchange side of the heat exchanger (51); the second heat exchange side is replenished with gas using the outlet side of the inner valve and is connected between the first-stage compressor (11) and the second-stage compressor (12); wherein, the refrigerant after heat exchange by the heat exchanger (51) is introduced between the first-stage compressor (11) and the second-stage compressor (12) to form intermediate replenishment gas; by switching control of the first three-way valve (21) and the second three-way valve (22), the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) can alternately enter the defrost state without performing a system-wide reverse cycle switching.

[0008] According to one embodiment of the air conditioning system of the present invention, the heat exchanger (51) is a plate heat exchanger (51).

[0009] According to an embodiment of the air conditioning system of the present invention, the first three-way valve (21), the second three-way valve (22) and the third three-way valve (23) all have a return gas connection function, which is used to return the refrigerant after evaporation in the corresponding heat exchanger to the inlet of the first-stage compressor (11).

[0010] According to an embodiment of the air conditioning system of the present invention, the gas supply valve (52) is connected to the second heat exchange side of the heat exchanger (51) to control a portion of the refrigerant to enter the second heat exchange side of the heat exchanger (51) after throttling, so that the refrigerants under different pressure states can exchange heat and be introduced between the first-stage compressor (11) and the second-stage compressor (12).

[0011] According to an embodiment of the air conditioning system of the present invention, a first three-way valve (21) is disposed between the secondary compressor (12) and the first outdoor heat exchanger (31) for selectively allowing refrigerant from the secondary compressor (12) to enter the first outdoor heat exchanger (31), and the first outdoor heat exchanger (31) is connected to the inlet of the primary compressor (11) through the first three-way valve (21); a second three-way valve (22) is disposed between the secondary compressor (12) and the second outdoor heat exchanger (32) for selectively allowing refrigerant from the secondary compressor (12) to enter the second outdoor heat exchanger (32), and the second outdoor heat exchanger (32) is connected to the inlet of the primary compressor (11) through the second three-way valve (22); a third three-way valve (23) is disposed between the secondary compressor (12) and the indoor heat exchanger for selectively allowing refrigerant from the secondary compressor (12) to enter the indoor heat exchanger, and the refrigerant output from the indoor heat exchanger is connected to the inlet of the primary compressor (11).

[0012] According to an embodiment of the air conditioning system of the present invention, in the partition defrosting operation state, by controlling the valve positions of the first three-way valve (21) and the second three-way valve (22), one of the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) is connected to the second-stage compressor (12) to receive refrigerant from the second-stage compressor (12), thereby performing heat release defrosting on the outdoor heat exchanger; the other outdoor heat exchanger is connected to the first-stage compressor (11); the third three-way valve (23) remains connected to the indoor heat exchanger, so that the refrigerant from the second-stage compressor (12) enters the indoor heat exchanger and releases heat to the indoor environment, wherein, after defrosting the outdoor heat exchanger is completed, by switching the valve positions of the first three-way valve (21) and the second three-way valve (22), the other outdoor heat exchanger is put into the heat release defrosting state.

[0013] According to an embodiment of the air conditioning system of the present invention, in the cooling operation state, by controlling the valve positions of the first three-way valve (21) and the second three-way valve (22), the refrigerant from the secondary compressor (12) simultaneously enters the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32), and the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) release heat to the outdoor environment; by controlling the valve position of the third three-way valve (23), the refrigerant from the secondary compressor (12) enters the indoor heat exchanger after releasing heat through the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32), so that the indoor heat exchanger absorbs heat from the indoor environment and achieves cooling; wherein, the refrigerant evaporated in the indoor heat exchanger enters the plate heat exchanger (51) for heat exchange under the control of the inner valve, and returns to the primary compressor (11) after completing the heat exchange, so as to form a closed loop in the cooling operation state.

[0014] According to an embodiment of the air conditioning system of the present invention, in the heating operation state, the valve position of the third three-way valve (23) is controlled to allow the refrigerant from the secondary compressor (12) to enter the indoor heat exchanger and allow the indoor heat exchanger to release heat to the indoor environment; the valve positions of the first three-way valve (21) and the second three-way valve (22) are controlled to connect the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) with the first compressor (11) to absorb heat from the outdoor environment; wherein, the refrigerant evaporated in the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) returns to the first compressor (11) under the control of the three-way valve, and after being compressed by the first compressor (11) and the second compressor (12), it re-enters the indoor heat exchanger, thereby forming a closed loop in the heating operation state; the plate heat exchanger (51) is used to allow part of the refrigerant to participate in heat exchange before entering the second compressor (12) to improve the operating stability of the system in the heating condition.

[0015] According to an embodiment of the air conditioning system of the present invention, the system further includes: a first valve (41) connected to the outlet of the first outdoor heat exchanger (31); and a second valve (42) connected to the outlet of the second outdoor heat exchanger (32).

[0016] A control method for the above-mentioned air conditioning system includes: selectively distributing the refrigerant discharged from the secondary compressor (12) by controlling the valve positions of the first three-way valve (21), the second three-way valve (22), and the third three-way valve (23), thereby switching the system between a cooling operation state, a heating operation state, and a zone defrosting operation state; wherein, in the cooling operation state, the first three-way valve (21) and the second three-way valve (22) are controlled to allow the refrigerant to enter the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) and release heat to the outdoor environment, and the third three-way valve (23) is controlled to allow the refrigerant to enter the indoor heat exchanger and absorb heat from the indoor environment, thereby achieving cooling operation; in the heating operation state, the third three-way valve (23) is controlled to allow the refrigerant to enter the indoor heat exchanger and release heat to the indoor environment, and the first three-way valve (21) and the second three-way valve (23) are ... The two-way valve (22) allows refrigerant to enter the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) and absorb heat from the outdoor environment, thereby achieving heating operation. In the zone defrosting operation state, by switching the valve positions of the first three-way valve (21) and the second three-way valve (22), the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) alternately receive refrigerant from the second-stage compressor (12) for heat release defrosting, keeping the third three-way valve (23) connected to the indoor heat exchanger, and continuously supplying heat to the indoor environment during the defrosting process. In the cooling operation state, heating operation state and zone defrosting operation state, the heat exchanger (51) is used to exchange heat with refrigerant under different pressure states, and the heat-exchanged refrigerant is introduced between the first-stage compressor (11) and the second-stage compressor (12) to form intermediate gas replenishment, thereby improving the stability of system operation.

[0017] This invention discloses a magnetic levitation centrifugal compressor air conditioning system and control method with zoned defrosting, which enables the outdoor heat exchanger to alternate between condensation and heat release and evaporation and heat absorption states within the same system. This allows for zoned defrosting without overall reverse circulation switching or system shutdown, thereby achieving continuous indoor heating, stable compressor operation, and improved system reliability during the defrosting process. Attached Figure Description

[0018] Figure 1 The diagram shown is a schematic diagram of a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting function according to the present invention.

[0019] Figure 2 The diagram shows the refrigerant circulation flow in the cooling mode of a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting function.

[0020] Figure 3 The diagram shows the refrigerant circulation flow in heating mode of a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting function.

[0021] Figure 4The diagram shows the refrigerant circulation flow in the defrosting mode of a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting function.

[0022] Figure 5 The diagram shows the refrigerant circulation flow of a magnetic levitation centrifugal compressor air conditioning system with zone defrosting function after defrosting and resuming heating mode. Detailed Implementation

[0023] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0024] Figure 1 The diagram shown is a schematic diagram of a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting function according to the present invention. Figure 1 As shown, this invention discloses a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting function, comprising: a primary compressor 11 and a secondary compressor 12 connected in sequence. Three-way valves 21, 22, and 23 are connected to the discharge end of the secondary compressor 12. Three-way valve 21 is connected to an outdoor heat exchanger 31, and three-way valve 22 is connected to an outdoor heat exchanger 32. Valve 41 is connected to the outlet of outdoor heat exchanger 31, and valve 42 is connected to the outlet of outdoor heat exchanger 32. Three-way valve 3 is connected to an indoor heat exchanger, wherein there can be n indoor heat exchangers, designated as indoor heat exchangers 1-n, and each of the n indoor heat exchanger outlets is connected to one of the n indoor valves a1-a1. n Plate heat exchanger 51 is connected to n internal valves a1-a n At the other end, a make-up gas branch is connected between the outlet of the first-stage compressor 11 and the inlet of the second-stage compressor 12 and the plate heat exchanger 51, and valve 52 is connected to the make-up gas branch of the plate heat exchanger 51. All components are interconnected via the main refrigerant pipeline to form a closed-loop system. The main pipeline, as described below, is a general term for the main refrigerant circulation pipeline, which performs the functions of exhaust, return gas, or liquid refrigerant delivery at different locations.

[0025] like Figure 1As shown, the primary compressor 11 and the secondary compressor 12 are connected sequentially along the refrigerant flow direction. The outlet of the primary compressor 11 is connected to the inlet of the secondary compressor 12. The outlet of the secondary compressor 12 is led out through the exhaust main pipeline to form the main pipeline. The main pipeline is connected to three-way valves 21, 22, and 23 respectively, allowing the high-temperature and high-pressure refrigerant discharged from the secondary compressor 12 to selectively flow to the corresponding heat exchange branches of the outdoor heat exchanger 31, outdoor heat exchanger 32, or indoor heat exchangers 1-n under different valve positions. This also allows each heat exchange branch, when operating on the evaporator side, to connect to the inlet of the primary compressor 11 through the return gas passage of the corresponding three-way valve. The return gas ends of three-way valves 21, 22, and 23 are all connected to the inlet-side main pipeline of the primary compressor 11, so that the return gas from the corresponding heat exchange branch when operating on the evaporator side can return to the primary compressor 11.

[0026] like Figure 1 As shown, a three-way valve 21 is located between the main pipeline and the inlet branch of the outdoor heat exchanger 31. It selectively introduces the refrigerant from the main pipeline into the outdoor heat exchanger 31, and when the outdoor heat exchanger 31 operates as an evaporator, its outlet return gas connects to the inlet of the first-stage compressor 11 via the three-way valve 21. A three-way valve 22 is located between the main pipeline and the inlet branch of the outdoor heat exchanger 32. It selectively introduces the refrigerant from the main pipeline into the outdoor heat exchanger 32, and when the outdoor heat exchanger 32 operates as an evaporator, its outlet return gas connects to the inlet of the first-stage compressor 11 via the three-way valve 22. A three-way valve 23 is located between the main pipeline and the branch containing the indoor heat exchangers 1-n. It selectively introduces the refrigerant from the main pipeline into the indoor heat exchange branch 1-n, and when the indoor heat exchangers 1-n operate as an evaporator, its outlet return gas connects to the inlet of the first-stage compressor 11 via the three-way valve 23.

[0027] like Figure 1As shown, outdoor heat exchangers 31 and 32 are two independently configured sets of outdoor heat exchangers, each located in a separate heat exchange branch. The inlet of outdoor heat exchanger 31 is connected to one output port of three-way valve 21, and the outlet of outdoor heat exchanger 31 is connected to valve 41. The outlet of valve 41 is connected to the main pipeline, allowing refrigerant to flow from outdoor heat exchanger 31 through valve 41 into the subsequent main pipeline. Similarly, the inlet of outdoor heat exchanger 32 is connected to one output port of three-way valve 22, and the outlet of outdoor heat exchanger 32 is connected to valve 42. The outlet of valve 42 is connected to the main pipeline, allowing refrigerant to flow from outdoor heat exchanger 32 through valve 42 into the subsequent main pipeline. By setting up independent branches for outdoor heat exchangers 31 and 32 and independently connecting three-way valves 21 and 22, outdoor heat exchangers 31 and 32 are structurally equipped with the basis for zone switching, that is, they can achieve the structural condition of one set of outdoor heat exchangers being in the condensation and heat release state and the other set of outdoor heat exchangers being in the evaporation and heat absorption state within the same system.

[0028] like Figure 1 As shown, the indoor unit includes indoor heat exchangers 1-n, and multiple indoor heat exchangers 1-n are connected in parallel on the main pipeline. The inlet end of each indoor heat exchanger 1-n is connected to one output port of a three-way valve 23, and its outlet end is connected to the corresponding internal valve a1-a. n Connection; the inner valve a1-a n The outlet is connected to the main pipeline. The connection control of the indoor heat exchange branch is achieved through the three-way valve 23, which allows the high-temperature and high-pressure refrigerant discharged from the secondary compressor 12 to selectively enter the indoor heat exchanger 1-n for heat exchange, thereby forming the indoor heat exchange branch.

[0029] like Figure 1 As shown, the plate heat exchanger 51 is located between the main pipeline and the make-up gas branch. The plate heat exchanger 51 has two flow channels that exchange heat with each other, one of which is connected to the main pipeline and the other is connected to the make-up gas branch.

[0030] like Figure 1 As shown, valve 52 is installed on the gas supply branch. The inlet of valve 52 is connected to the main pipeline, and the outlet of valve 52 is connected to the gas supply side inlet of plate heat exchanger 51. This allows the refrigerant in the gas supply branch to be throttled and depressurized by valve 52 before entering plate heat exchanger 51 to exchange heat with the refrigerant on the main pipeline side. After heat exchange in plate heat exchanger 51, the refrigerant forms an intermediate pressure refrigerant and is introduced by the gas supply branch to the connection between the outlet of the first-stage compressor 11 and the inlet of the second-stage compressor 12, thus forming a two-stage compression and intermediate gas supply structural unit. The refrigerant in the main pipeline obtains a subcooling effect after heat exchange with the gas supply side refrigerant in plate heat exchanger 51, thereby reducing the pressure of the refrigerant entering valves 41, 42, and inner valves a1-a. n The refrigerant tends to be in a more stable liquid state.

[0031] like Figure 1 As shown, in the magnetic levitation centrifugal compressor air conditioning system with zoned defrosting function of the present invention, when each heat exchange branch operates as the evaporator side under different operating conditions, its outlet refrigerant is connected to the inlet of the first-stage compressor 11 via three-way valve 21, three-way valve 22, or three-way valve 23 and returns to the first-stage compressor 11, thereby forming a closed-loop system. Through the switching connection relationship of three-way valves 21, 22, and 23, the outdoor heat exchanger 31, outdoor heat exchanger 32, and indoor heat exchangers 1-n can be selectively connected structurally, thereby forming refrigerant flow combinations corresponding to cooling mode, heating mode, and zoned defrosting mode under the same hardware structure.

[0032] This invention discloses a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting function. Through a two-stage compression structure of a primary compressor 11 and a secondary compressor 12, combined with the selective switching of refrigerant flow direction by three-way valves 21, 22, and 23, stable operation in cooling, heating, and zoned defrosting modes is achieved. Using the high-temperature, high-pressure refrigerant discharged from the secondary compressor 12 as an energy source, the refrigerant is controlled by three-way valves 21, 22, and 23 to enter the outdoor heat exchanger 31, outdoor heat exchanger 32, or indoor heat exchangers 1-n, thereby changing the operating state of each heat exchanger under different operating modes. A plate heat exchanger 51 is installed between the main pipeline and the make-up gas branch, and a valve 52 is installed on the make-up gas branch. This allows some refrigerant to enter the plate heat exchanger 51 after throttling and depressurization, exchanging heat with the refrigerant in the main pipeline. This provides subcooling to the refrigerant in the main pipeline and creates intermediate-pressure refrigerant, which is then introduced between the first-stage compressor 11 and the second-stage compressor 12, thus achieving a combined two-stage compression and intermediate make-up gas operation. With this structural arrangement, without changing the compressor rotation direction or performing overall reverse cycle switching, the outdoor heat exchangers 31 and 32 can be alternately placed in condensation and heat release or evaporation and heat absorption states simply by switching between three-way valves 21 and 22. This achieves zoned defrosting of the outdoor heat exchangers and maintains continuous system operation during defrosting.

[0033] Figure 2 The diagram shown illustrates the refrigerant circulation flow in the cooling mode of a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting capability. Figure 2As shown, in cooling mode, the magnetic levitation centrifugal compressor air conditioning system with zoned defrosting function provides cooling capacity to the indoor environment. During system operation, the main pipeline delivers low-temperature, low-pressure refrigerant gas evaporated from indoor heat exchangers 1-n via three-way valve 23 to the inlet of the first-stage compressor 11. After compression by the first-stage compressor 11, the refrigerant enters the second-stage compressor 12 for further compression, and is discharged by the second-stage compressor 12 to form a high-temperature, high-pressure refrigerant. The high-temperature, high-pressure refrigerant then enters three-way valves 21 and 22 via the main pipeline. In cooling mode, three-way valves 21 and 22 are in the open position to outdoor heat exchangers 31 and 32, respectively, allowing the refrigerant to enter these two heat exchangers. The refrigerant releases heat to the outdoor environment and condenses in the outdoor heat exchangers 31 and 32, forming a medium-temperature, high-pressure liquid refrigerant, which then enters the main pipeline via valves 41 and 42. The refrigerant in the main pipeline flows through plate heat exchanger 51, where it exchanges heat with the refrigerant in the make-up gas branch, thus subcooling the refrigerant in the main pipeline. The subcooled refrigerant then passes through each internal valve a1-a n The refrigerant is throttled and enters the corresponding indoor heat exchangers 1-n. In the indoor heat exchangers 1-n, the refrigerant absorbs heat from the indoor air and evaporates, thus cooling the indoor environment. The evaporated low-temperature, low-pressure refrigerant gas returns to the inlet of the first-stage compressor 11 via the corresponding three-way valve 23, completing the cycle in cooling mode. Simultaneously, a portion of the refrigerant in the main pipeline enters the make-up gas branch via valve 52. After being throttled and depressurized at valve 52, it enters the plate heat exchanger 51, where it exchanges heat with the refrigerant in the main pipeline to form an intermediate-pressure refrigerant. This intermediate-pressure refrigerant is then introduced between the first-stage compressor 11 and the second-stage compressor 12, achieving a continuous intermediate make-up gas process.

[0034] Figure 3 The diagram shown illustrates the refrigerant circulation flow in heating mode of a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting capability. Figure 3 As shown, in heating mode, the system provides heat to the indoor environment. During system operation, the main pipeline delivers low-temperature, low-pressure refrigerant gas evaporated from outdoor heat exchangers 31 and 32 to the first-stage compressor 11 via three-way valves 21 and 22, respectively. The refrigerant is then compressed sequentially by the first-stage compressor 11 and the second-stage compressor 12, before being discharged as high-temperature, high-pressure refrigerant by the second-stage compressor 12. The high-temperature, high-pressure refrigerant then enters the three-way valve 23 via the main pipeline. In heating mode, the three-way valve 23 is in the position that opens to the indoor heat exchange branch, allowing the high-temperature, high-pressure refrigerant to enter the indoor heat exchangers 1-n. The refrigerant releases heat to the indoor air and condenses in the indoor heat exchangers 1-n, thus providing heat to the indoor environment. The condensed refrigerant then passes through internal valves a1-a... nThe refrigerant enters the main pipeline. In the main pipeline, the refrigerant flows through plate heat exchanger 51, where it exchanges heat with the refrigerant in the make-up gas branch to form subcooled liquid refrigerant. The subcooled refrigerant is then throttled and depressurized by valves 41 and 42 before entering outdoor heat exchangers 31 and 32. In outdoor heat exchangers 31 and 32, the refrigerant absorbs heat from the outdoor air and evaporates. The evaporated refrigerant returns to the inlet of the first-stage compressor 11 via the return gas passage of three-way valve 21 and / or three-way valve 22, completing the cycle in heating mode. During operation in heating mode, valve 52 is opened and closed as needed to activate the make-up gas branch, ensuring a stable intermediate make-up gas process and improving the system's operational stability under low-temperature heating conditions.

[0035] Figure 4 The diagram shown illustrates the refrigerant circulation flow in the defrost mode of a magnetic levitation centrifugal compressor air conditioning system with zoned defrost functionality. Figure 4 As shown, when the outdoor heat exchanger frosts and requires defrosting, the system enters a zone defrosting mode. In zone defrosting mode, the system does not switch between overall cooling and heating modes. Instead, it uses three-way valves 21 and 22 to alternately defrost outdoor heat exchangers 31 and 32. During the first stage of defrosting, three-way valve 21 switches to the position that opens to outdoor heat exchanger 31, allowing the high-temperature, high-pressure refrigerant discharged from the secondary compressor 12 to enter outdoor heat exchanger 31. Simultaneously, three-way valve 22 switches to the position that connects outdoor heat exchanger 32 to the main pipeline, allowing outdoor heat exchanger 32 to continue operating as an evaporator. At this time, outdoor heat exchanger 31 is in a condensation and heat release state, where the refrigerant releases heat internally and melts the frost layer on its surface; outdoor heat exchanger 32 is in an evaporation and heat absorption state, providing a stable source of return gas for the system. During this stage, the three-way valve 23 remains open to the indoor heat exchange branch, allowing a portion of the high-temperature, high-pressure refrigerant to continuously enter the indoor heat exchangers 1-n. The indoor heat exchangers 1-n continuously supply heat to the indoor environment, thus ensuring uninterrupted indoor heating during defrosting. Once the outdoor heat exchanger 31 has completed defrosting, the three-way valves 21 and 22 switch positions, introducing the high-temperature, high-pressure refrigerant into the outdoor heat exchanger 32. This causes the outdoor heat exchanger 32 to enter a condensation and heat release state for defrosting, while the outdoor heat exchanger 31 returns to an evaporation and heat absorption state. By controlling the defrosting sequence of the outdoor heat exchanger 31 first, followed by the outdoor heat exchanger 32, secondary icing is avoided as defrost water flows towards the still-evaporating heat exchanger under gravity, thus ensuring stable outdoor heat exchange performance. Of course, the above defrosting sequence and selection can be flexibly adjusted as needed, and this invention is not limited to this.

[0036] Figure 5 The diagram shows the refrigerant circulation flow of a magnetic levitation centrifugal compressor air conditioning system with zone defrosting function after defrosting and resuming heating mode. Figure 5As shown, after both outdoor heat exchangers 31 and 32 have completed defrosting, three-way valves 21 and 22 return to their respective positions corresponding to the heating mode, and the system re-enters normal heating operation. Throughout the entire zone defrosting process, the primary compressor 11 and secondary compressor 12 operate continuously, and the plate heat exchanger 51 and the gas injection branch continue to work, keeping the refrigerant mass flow rate of the system relatively stable, thereby effectively avoiding compressor surge or operational instability caused by reverse cycle switching.

[0037] This invention addresses the problems of existing magnetic levitation centrifugal compressor heat pump air conditioning systems, which suffer from easy frosting of outdoor heat exchangers under low-temperature heating conditions and commonly employ reverse cycle defrosting. This leads to drastic fluctuations in refrigerant flow direction, pressure, and flow rate, potentially causing compressor surge, operational instability, and even liquid slugging, and interrupting continuous indoor heating during defrosting. This invention provides a magnetic levitation centrifugal compressor air conditioning system with zoned defrosting functionality. By setting up multiple independent outdoor heat exchangers and using a three-way valve to selectively control the refrigerant flow direction, the outdoor heat exchangers can alternate between condensation (heat release) and evaporation (heat absorption) states within the same system. This achieves zoned defrosting without overall reverse cycle switching or system shutdown. Simultaneously, through a two-stage compression and intermediate gas injection structure, the system maintains relative stability in refrigerant mass flow rate and operating conditions during defrosting and mode switching, effectively preventing surge or instability caused by sudden changes in operating conditions in the magnetic levitation centrifugal compressor. This ensures continuous indoor heating during defrosting, stable compressor operation, and improved system reliability.

[0038] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A magnetic levitation centrifugal compressor air conditioning system with zoned defrosting, characterized in that, include: A primary compressor (11) and a secondary compressor (12), wherein the outlet of the primary compressor (11) is connected to the inlet of the secondary compressor (12) for two-stage compression of the refrigerant; The first three-way valve (21), the second three-way valve (22), and the third three-way valve (23) are all connected to the discharge end of the second-stage compressor (12) and are used to selectively distribute the refrigerant discharged by the second-stage compressor (12). The first outdoor heat exchanger (31) has its inlet connected to the first three-way valve (21); The second outdoor heat exchanger (32) has its inlet connected to the second three-way valve (22); At least one indoor heat exchanger, the inlet of which is connected to a third three-way valve (23) for exchanging heat with indoor air; The heat exchanger (51) has a first heat exchange side and a second heat exchange side; At least one inner valve is connected to the outlet of the at least one indoor heat exchanger, and the other end of the inner valve is connected to the first heat exchange side of the heat exchanger (51). The second heat exchange side is supplied with gas through the outlet side of the internal valve and is connected between the first-stage compressor (11) and the second-stage compressor (12); The refrigerant after heat exchange in the heat exchanger (51) is introduced between the first-stage compressor (11) and the second-stage compressor (12) to form intermediate replenishment gas. By switching control of the first three-way valve (21) and the second three-way valve (22), the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) can alternately enter the defrost state without the overall system reverse circulation switching.

2. The air conditioning system as described in claim 1, characterized in that, The heat exchanger (51) is a plate heat exchanger (51).

3. The air conditioning system as described in claim 1, characterized in that, The first three-way valve (21), the second three-way valve (22), and the third three-way valve (23) all have a return gas connection function, which is used to return the refrigerant after evaporation in the corresponding heat exchanger to the inlet of the first-stage compressor (11).

4. The air conditioning system as described in claim 1, characterized in that, The gas supply valve (52) is connected to the second heat exchange side of the heat exchanger (51) to control a portion of the refrigerant to enter the second heat exchange side of the heat exchanger (51) after throttling, so that refrigerants under different pressure states can exchange heat and be introduced between the first-stage compressor (11) and the second-stage compressor (12).

5. The air conditioning system as described in claim 1, characterized in that, The first three-way valve (21) is located between the second-stage compressor (12) and the first outdoor heat exchanger (31) to selectively allow refrigerant from the second-stage compressor (12) to enter the first outdoor heat exchanger (31). The first outdoor heat exchanger (31) is connected to the inlet of the first-stage compressor (11) through the first three-way valve (21). The second three-way valve (22) is located between the second-stage compressor (12) and the second outdoor heat exchanger (32) to selectively allow refrigerant from the second-stage compressor (12) to enter the second outdoor heat exchanger (32). The second outdoor heat exchanger (32) is connected to the inlet of the first-stage compressor (11) through the second three-way valve (22). The third three-way valve (23) is located between the secondary compressor (12) and the indoor heat exchanger to selectively allow the refrigerant from the secondary compressor (12) to enter the indoor heat exchanger. The refrigerant output from the indoor heat exchanger is connected to the inlet of the primary compressor (11).

6. The air conditioning system as described in claim 1, characterized in that, In the partition defrosting operation state, by controlling the valve positions of the first three-way valve (21) and the second three-way valve (22), one of the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) is connected to the second-stage compressor (12) to receive refrigerant from the second-stage compressor (12), thereby defrosting the outdoor heat exchanger by releasing heat; and the other outdoor heat exchanger is connected to the first-stage compressor (11). The third three-way valve (23) remains connected to the indoor heat exchanger, allowing refrigerant from the second-stage compressor (12) to enter the indoor heat exchanger and release heat to the indoor environment. After defrosting one outdoor heat exchanger, the other outdoor heat exchanger is put into a defrosting state by switching the valve positions of the first three-way valve (21) and the second three-way valve (22).

7. The air conditioning system as described in claim 2, characterized in that, In the refrigeration operation state, by controlling the valve positions of the first three-way valve (21) and the second three-way valve (22), the refrigerant from the second-stage compressor (12) enters the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) at the same time, and the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) release heat to the outdoor environment. By controlling the valve position of the third three-way valve (23), the refrigerant from the second-stage compressor (12) is allowed to enter the indoor heat exchanger after releasing heat through the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32), so that the indoor heat exchanger absorbs the heat of the indoor environment and achieves cooling. The refrigerant evaporated in the indoor heat exchanger enters the plate heat exchanger (51) under the control of the inner valve for heat exchange, and returns to the first-stage compressor (11) after heat exchange is completed, so as to form a closed loop in the refrigeration operation state.

8. The air conditioning system as described in claim 2, characterized in that, In heating operation mode, control the valve position of the third three-way valve (23) to allow refrigerant from the second-stage compressor (12) to enter the indoor heat exchanger and cause the indoor heat exchanger to release heat to the indoor environment; Control the valve positions of the first three-way valve (21) and the second three-way valve (22) to connect the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) to the first stage compressor (11) to absorb heat from the outdoor environment; The refrigerant evaporated in the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) returns to the first-stage compressor (11) under the control of the three-way valve, and is compressed by the first-stage compressor (11) and the second-stage compressor (12) before entering the indoor heat exchanger again, thus forming a closed loop in the heating operation state. The plate heat exchanger (51) is used to allow some of the refrigerant to participate in heat exchange before entering the secondary compressor (12) in order to improve the system's operational stability under heating conditions.

9. The air conditioning system as described in claim 1, characterized in that, Also includes: The first valve (41) is connected to the outlet of the first outdoor heat exchanger (31); the second valve (42) is connected to the outlet of the second outdoor heat exchanger (32).

10. A control method for an air conditioning system according to any one of claims 1-9, characterized in that, include: By controlling the valve positions of the first three-way valve (21), the second three-way valve (22) and the third three-way valve (23), the refrigerant discharged by the second-stage compressor (12) is selectively distributed, so that the system can switch between cooling operation mode, heating operation mode and zone defrosting operation mode. In the refrigeration operation state, the first three-way valve (21) and the second three-way valve (22) are controlled to allow the refrigerant to enter the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) and release heat to the outdoor environment. The third three-way valve (23) is controlled to allow the refrigerant to enter the indoor heat exchanger and absorb heat from the indoor environment, thereby realizing the refrigeration operation. In the heating operation state, control the third three-way valve (23) to allow the refrigerant to enter the indoor heat exchanger and release heat to the indoor environment, control the first three-way valve (21) and the second three-way valve (22) to allow the refrigerant to enter the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) and absorb heat from the outdoor environment, thereby realizing the heating operation; In the partition defrosting operation state, by switching the valve positions of the first three-way valve (21) and the second three-way valve (22), the first outdoor heat exchanger (31) and the second outdoor heat exchanger (32) alternately receive refrigerant from the second stage compressor (12) for heat release defrosting, while keeping the third three-way valve (23) connected to the indoor heat exchanger, and continuously supplying heat to the indoor environment during the defrosting process; In the cooling operation, heating operation and zone defrosting operation, the heat exchanger (51) is used to exchange heat between refrigerants under different pressure states, and the heat-exchanged refrigerant is introduced between the first-stage compressor (11) and the second-stage compressor (12) to form intermediate gas replenishment, thereby improving the stability of system operation.

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