Control method of multi-connected system, multi-connected system and readable storage medium

Abstract

The application discloses a control method of a multi-connected system, the multi-connected system and a readable storage medium. The multi-connected system comprises a spray compression machine, a four-way valve, an outdoor heat exchanger, a first-stage economizer, a second-stage economizer and a plurality of indoor units. The first-stage economizer comprises a first-stage main path and a first-stage auxiliary path. The second-stage economizer comprises a second-stage main path and a second-stage auxiliary path. The control method comprises the following steps: determining the energy demand level of the multi-connected system according to the sum of the energy demands of all the indoor units; increasing the operating frequency of the spray compression machine to the frequency range corresponding to the energy demand level according to the first adjusting speed corresponding to the energy demand level; and controlling the opening state of the first-stage auxiliary path and the second-stage auxiliary path according to the energy demand level when the operating frequency of the spray compression machine is maintained in the frequency range. The multi-connected system can meet the user demand quickly according to different capacity demands, and has good refrigeration and heating effects and energy-saving effects.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and in particular to a control method for a multi-split system, a multi-split system, and a readable storage medium. Background Technology

[0002] Currently, the capacity matching methods used in existing multi-split air conditioning systems mainly include the following: one outdoor unit supporting multiple indoor units, over-sizing to meet energy demand, allowing the total horsepower of all indoor units to be approximately 130% of the outdoor unit's horsepower; using injection enthalpy compressors to meet capacity requirements; using large-displacement compressors to meet capacity requirements; and using interference-fit heat exchangers to meet capacity requirements, etc. However, these methods generally also have corresponding drawbacks. For example, when energy demand is over-sized, poor cooling and heating performance is likely to occur, seriously affecting user comfort; first-stage injection enthalpy compressors cannot fully meet capacity requirements in harsh environments such as ultra-low and ultra-high temperatures; when energy demand is low, the compressor becomes oversized, resulting in high power consumption; large-displacement compressors are prone to abnormal noise and vibration during low-frequency operation, affecting compressor lifespan; and the heat exchanger's size / volume is too large, limited by the unit's space / user installation space, and is costly. Therefore, it is evident that existing multi-split air conditioning systems cannot simultaneously address issues related to cooling and heating performance, energy efficiency, and applicability. Summary of the Invention

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a control method for a multi-split air conditioning system, a multi-split air conditioning system and a readable storage medium, which can quickly meet user needs according to different capacity requirements, while having good cooling and heating effects and energy-saving effects.

[0004] In a first aspect, embodiments of the present invention provide a control method for a multi-split air conditioning system. The multi-split air conditioning system includes an enthalpy-injected compressor, a four-way valve, an outdoor heat exchanger, a primary economizer, a secondary economizer, and multiple indoor units. The enthalpy-injected compressor includes an exhaust port, an intake port, and an enthalpy-injection port. The primary economizer includes a primary main circuit and a primary auxiliary circuit. The secondary economizer includes a secondary main circuit and a secondary auxiliary circuit. The four-way valve is connected to the exhaust port, the outdoor heat exchanger, the intake port, and the multiple indoor units respectively. The outdoor heat exchanger, the primary main circuit, and the secondary main circuit are connected sequentially. The secondary main circuit is connected to the multiple indoor units. The primary auxiliary circuit is connected to the enthalpy-injection port, and the secondary auxiliary circuit is connected to the intake port. The method includes:

[0005] The energy requirement level of the multi-split air conditioning system is determined based on the sum of the energy requirements of all the indoor units.

[0006] The operating frequency of the injection compressor is increased to the frequency range corresponding to the energy demand level according to a first adjustment rate corresponding to the energy demand level;

[0007] While maintaining the operating frequency of the injection enthalpy compressor within the specified frequency range, the opening status of the primary auxiliary circuit and the secondary auxiliary circuit is controlled according to the energy demand level.

[0008] The control method for a multi-split air conditioning system provided by the embodiments of the present invention has at least the following beneficial effects: When the multi-split air conditioning system is in cooling operation, the refrigerant flows from the discharge port of the enthalpy-injected compressor to the four-way valve, from the four-way valve to the outdoor heat exchanger, then from the outdoor heat exchanger to the primary main circuit of the primary economizer and the secondary main circuit of the secondary economizer, then from the secondary main circuit to multiple indoor units, and finally from the multiple indoor units back to the four-way valve, and finally back to the suction port of the enthalpy-injected compressor; in addition, when the primary auxiliary circuit is opened, part of the refrigerant enters the primary auxiliary circuit of the primary economizer, and is throttled by the primary economizer. The heat absorption process increases the enthalpy difference, thereby increasing the cooling capacity and achieving first-stage enthalpy enhancement. This results in excellent cooling and energy-saving performance for the multi-split system. The refrigerant then flows from the outlet of the first-stage auxiliary circuit to the enthalpy injection port of the enthalpy-injected compressor, and returns to the compressor through the port. When the second-stage auxiliary circuit is opened, some refrigerant enters the second-stage auxiliary circuit of the second-stage economizer. Through the throttling and heat absorption effect of the second-stage economizer, the enthalpy difference is further increased, thus increasing the cooling capacity and achieving second-stage enthalpy enhancement. This further enhances the cooling and energy-saving performance. The refrigerant then flows from the outlet of the second-stage auxiliary circuit to the suction port, returning to the enthalpy-injected compressor. The control method for the multi-split air conditioning system in this embodiment of the invention determines the energy demand level of the multi-split air conditioning system based on the sum of the energy demands of all indoor units, controls the frequency increase of the injection enthalpy compressor according to the corresponding adjustment rate, and controls the opening status of the primary auxiliary circuit and the secondary auxiliary circuit according to the energy demand level. This enables the use of different enthalpy increase levels in different application scenarios, and can quickly meet user needs according to different capacity requirements while having good cooling and heating effects and energy-saving effects.

[0009] In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, the inlet of the primary auxiliary circuit is connected to the outlet of the primary main circuit through a first expansion valve, and the inlet of the secondary auxiliary circuit is connected to the outlet of the secondary main circuit through a second expansion valve; the energy demand level includes primary energy demand.

[0010] The step of controlling the opening status of the primary auxiliary road and the secondary auxiliary road according to the energy demand level includes:

[0011] When the multi-split air conditioning system is in the first-level energy demand state, control the first-level auxiliary circuit and the second-level auxiliary circuit to open;

[0012] Control the first expansion valve to open to a first preset opening degree;

[0013] The second expansion valve is controlled to open to the minimum opening degree, and the opening degree of the second expansion valve is adjusted according to the superheat of the secondary economizer so that the superheat of the secondary economizer reaches the superheat set value.

[0014] The superheat of the secondary economizer is obtained by subtracting the inlet temperature of the secondary economizer from the outlet temperature of the secondary economizer.

[0015] In the control method of the multi-unit system provided in some embodiments of the present invention, the energy demand level further includes a secondary energy demand, which is different from the primary energy demand;

[0016] The method of controlling the opening status of the primary auxiliary road and the secondary auxiliary road according to the energy demand level further includes:

[0017] When the multi-split air conditioning system is in the secondary energy demand state, the primary auxiliary circuit is opened and the secondary auxiliary circuit is closed.

[0018] The first expansion valve is controlled to open to the minimum opening degree, and the opening degree of the first expansion valve is adjusted according to the superheat of the first-stage economizer so that the superheat of the first-stage economizer reaches the superheat set value.

[0019] The superheat of the primary economizer is obtained by subtracting the inlet temperature of the primary auxiliary circuit from the outlet temperature of the primary auxiliary circuit.

[0020] In the control method of the multi-unit system provided in some embodiments of the present invention, the energy demand level further includes a third level of energy demand, which is different from the first level of energy demand;

[0021] The method of controlling the opening status of the primary auxiliary road and the secondary auxiliary road according to the energy demand level further includes:

[0022] When the multi-unit system is in the third energy demand state, the first-level auxiliary circuit and the second-level auxiliary circuit are shut down.

[0023] In some embodiments of the present invention, the control method for a multi-unit air conditioning system further includes:

[0024] Every first preset time interval, check whether all indoor units have reached the required temperature;

[0025] When the number of indoor units reaching the set temperature exceeds a preset value, the operating frequency of the injection enthalpy compressor is adjusted according to a second adjustment rate, where the second adjustment rate is less than the first adjustment rate.

[0026] Specifically, when the difference between the indoor ambient temperature of the indoor unit and the corresponding temperature setting value is less than the preset temperature value, the indoor unit reaches the set temperature.

[0027] In the control method for a multi-split air conditioning system provided in some embodiments of the present invention, when the multi-split air conditioning system is in the second-level energy demand condition:

[0028] When the number of indoor units reaching the set temperature is less than or equal to the preset value for a second preset duration, the opening of the first expansion valve is controlled to remain constant.

[0029] The secondary auxiliary circuit is controlled to open, the second expansion valve is controlled to open to the minimum opening degree, and the opening degree of the second expansion valve is adjusted according to the superheat of the secondary economizer so that the superheat of the secondary economizer reaches the superheat set value.

[0030] In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, when the time for all indoor units to reach the desired temperature reaches a third preset duration:

[0031] Control the secondary auxiliary road to close;

[0032] The timing begins and after the timing duration reaches the fourth preset duration, the operating frequency of the injection enthalpy compressor is adjusted according to the indoor ambient temperature of the indoor unit.

[0033] In the control method for a multi-split air conditioning system provided in some embodiments of the present invention, when the multi-split air conditioning system is in the third energy demand state:

[0034] When the difference between the indoor ambient temperature of the indoor unit with energy demand and the corresponding temperature setting value is greater than the preset temperature value for a period of time that reaches the fifth preset duration, the first-level auxiliary circuit is controlled to open.

[0035] The first expansion valve is controlled to open to its minimum opening degree, and the opening degree of the first expansion valve is adjusted according to the indoor ambient temperature so that the indoor ambient temperature reaches the corresponding temperature set value.

[0036] In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, when the time for all indoor units to reach the desired temperature reaches a sixth preset duration:

[0037] Control the primary auxiliary road to close;

[0038] The timing begins and after the timing reaches the seventh preset duration, the operating frequency of the enthalpy compressor is adjusted according to the indoor ambient temperature of the indoor unit where energy is needed.

[0039] In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, adjusting the opening of the first expansion valve according to the superheat of the first-stage economizer includes:

[0040] The opening adjustment rate is determined based on the difference between the superheat value of the first-stage economizer and the superheat setpoint.

[0041] Increase the opening of the first expansion valve according to the opening adjustment rate.

[0042] In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, the step of adjusting the opening of the second expansion valve according to the superheat of the secondary economizer includes:

[0043] The opening adjustment rate is determined based on the difference between the superheat value of the secondary economizer and the superheat setpoint.

[0044] Increase the opening of the second expansion valve according to the opening adjustment rate.

[0045] In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, adjusting the opening degree of the first expansion valve according to the indoor ambient temperature includes:

[0046] The opening adjustment rate is determined based on the difference between the indoor ambient temperature and the corresponding temperature set value.

[0047] Increase the opening of the first expansion valve according to the opening adjustment rate.

[0048] In a second aspect, embodiments of the present invention provide an operation control device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the control method described in the first aspect embodiment above.

[0049] Thirdly, embodiments of the present invention provide a multi-unit system, including the operation control device described in the second aspect of the embodiments above.

[0050] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer-executable instructions for causing a computer to perform the control method described in the first aspect of the embodiments above.

[0051] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0052] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0054] Figure 1 This is a schematic diagram of the multi-unit air conditioning system provided in an embodiment of the present invention;

[0055] Figure 2 This is a flowchart of the control method for a multi-unit air conditioning system provided in an embodiment of the present invention;

[0056] Figure 3 This is a schematic diagram of the energy demand levels of the multi-split air conditioning system provided in this embodiment of the invention;

[0057] Figure 4 yes Figure 2 A flowchart of the subdivisions of step S230 in the process;

[0058] Figure 5 yes Figure 2 A flowchart of another subdivision step in step S230;

[0059] Figure 6 This is a partial flowchart of a control method for a multi-unit air conditioning system provided in another embodiment of the present invention;

[0060] Figure 7 This is a partial flowchart of a control method for a multi-unit air conditioning system provided in another embodiment of the present invention;

[0061] Figure 8 This is a partial flowchart of a control method for a multi-unit air conditioning system provided in another embodiment of the present invention;

[0062] Figure 9 This is a schematic diagram of the operation control device provided in an embodiment of the present invention. Detailed Implementation

[0063] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0064] In the description of the embodiments of the present invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the number itself, while "above," "below," "within," etc. are understood to include the number itself. "At least one" refers to one or more, and "at least one of the following" and similar expressions refer to any combination of these items, including any combination of single or multiple items. If "first," "second," etc., are used in the description, they are only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of the indicated technical features.

[0065] It should be noted that the terms "setting," "installing," and "connecting" in the embodiments of this invention should be interpreted broadly. Those skilled in the art can reasonably determine the specific meaning of the above terms in the embodiments of this invention in conjunction with the specific content of the technical solution. For example, the term "connection" can be a mechanical connection, an electrical connection, or a connection that allows for mutual communication; it can be a direct connection or an indirect connection through an intermediate medium.

[0066] It should be noted that the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0067] Currently, the capacity matching methods used in existing multi-split air conditioning systems mainly include the following: one outdoor unit supporting multiple indoor units, over-sizing to meet energy demand, allowing the total horsepower of all indoor units to be approximately 130% of the outdoor unit's horsepower; using injection enthalpy compressors to meet capacity requirements; using large-displacement compressors to meet capacity requirements; and using interference-fit heat exchangers to meet capacity requirements, etc. However, these methods generally also have corresponding drawbacks. For example, when energy demand is over-sized, poor cooling and heating performance is likely to occur, seriously affecting user comfort; first-stage injection enthalpy compressors cannot fully meet capacity requirements in harsh environments such as ultra-low and ultra-high temperatures; when energy demand is low, the compressor becomes oversized, resulting in high power consumption; large-displacement compressors are prone to abnormal noise and vibration during low-frequency operation, affecting compressor lifespan; and the heat exchanger's size / volume is too large, limited by the unit's space / user installation space, and is costly. Therefore, it is evident that existing multi-split air conditioning systems cannot simultaneously address issues related to cooling and heating performance, energy efficiency, and applicability.

[0068] Based on this, embodiments of the present invention provide a control method for a multi-split air conditioning system, a multi-split air conditioning system, and a readable storage medium, which can quickly meet user needs according to different capacity requirements while having good cooling and heating effects and energy-saving effects.

[0069] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0070] Reference Figure 1 The multi-split air conditioning system provided in this embodiment of the invention includes an enthalpy-injected compressor 100, a four-way valve 200, a first-stage economizer 300, a second-stage economizer 400, an outdoor heat exchanger 500, and multiple indoor units, wherein:

[0071] The enthalpy injection compressor 100 includes an exhaust port a, an intake port b, and an enthalpy injection port c;

[0072] The four-way valve 200 includes a first end e connected to the exhaust port a, a second end f for connecting to the indoor unit via a steam side pipe, a third end g connected to the intake port b, and a fourth end h for connecting to the outdoor heat exchanger 500.

[0073] The primary economizer 300 includes a primary main circuit and a primary auxiliary circuit. The inlet of the primary main circuit is connected to the outdoor heat exchanger 500, the inlet of the primary auxiliary circuit is connected to the inlet of the primary main circuit through the first solenoid valve 310, and the outlet of the primary auxiliary circuit is connected to the enthalpy injection port c.

[0074] The secondary economizer 400 includes a secondary main circuit and a secondary auxiliary circuit. The inlet of the secondary main circuit is connected to the outlet of the primary main circuit. The outlet of the secondary main circuit is connected to the indoor unit through a liquid-side pipe. The inlet of the secondary auxiliary circuit is connected to the inlet of the secondary main circuit through a second solenoid valve 410. The outlet of the secondary auxiliary circuit is connected to the air intake port b.

[0075] It should be noted that when the multi-split system is in cooling operation, the first end e and the fourth end h of the four-way valve 200 are open, and the second end f and the third end g of the four-way valve 200 are open. The refrigerant flow direction in the multi-split system is as follows: discharge port a of the enthalpy-injected compressor 100 - first end e of the four-way valve 200 - fourth end h of the four-way valve 200 - outdoor heat exchanger 500 - primary main circuit of primary economizer 300 - secondary main circuit of secondary economizer 400 - indoor unit - second end f of the four-way valve 200 - third end g of the four-way valve 200 - suction port b of the enthalpy-injected compressor 100. The high-temperature, high-pressure gaseous refrigerant, compressed by the enthalpy-injection compressor 100, travels through the four-way valve 200 to the outdoor heat exchanger 500, where it liquefies and releases heat. It then passes through the first-stage economizer 300 and the second-stage economizer 400 to reach the indoor unit, where it vaporizes and absorbs heat, finally returning to the suction port b of the enthalpy-injection compressor 100. When the first solenoid valve 310 opens, the first-stage auxiliary circuit of the first-stage economizer 300 can directly deliver the gaseous refrigerant to the enthalpy-injection port c of the enthalpy-injection compressor 100, thus enabling the multi-split system to operate in a first-stage vapor injection and enthalpy-increasing state. When the second solenoid valve 410 also opens, the second-stage auxiliary circuit of the second-stage economizer 400 can directly deliver a portion of the refrigerant to the suction port b of the enthalpy-injection compressor 100, thereby sharing the heat exchange load of the outdoor heat exchanger 500 and increasing the evaporation temperature, thus enabling the multi-split system to operate in a second-stage vapor injection and enthalpy-increasing state.

[0076] Reference Figure 1 In the multi-split air conditioning system provided in this embodiment of the invention, a first expansion valve 320 is provided between the inlet of the primary auxiliary circuit and the first solenoid valve 310, and a second expansion valve 420 is provided between the inlet of the secondary auxiliary circuit and the second solenoid valve 410.

[0077] It should be noted that by setting a first expansion valve 320 between the inlet of the primary auxiliary circuit and the first solenoid valve 310, the liquid refrigerant flowing out of the primary main circuit is throttled and depressurized, thereby lowering the condensation point under the corresponding pressure state. This allows some of the liquid refrigerant to vaporize in the primary auxiliary circuit and also regulates the inlet flow rate of the primary auxiliary circuit, thereby regulating the amount of refrigerant delivered to the injection port c of the injection compressor 100. Similarly, by setting a second expansion valve 420 between the inlet of the secondary auxiliary circuit and the second solenoid valve 410, the inlet flow rate of the secondary auxiliary circuit can be regulated, thereby regulating the amount of refrigerant delivered to the suction port b of the injection compressor 100.

[0078] Reference Figure 1 In the multi-split system provided in this embodiment of the invention, a main electronic expansion valve 510 is also provided between the outdoor heat exchanger 500 and the inlet of the primary main circuit.

[0079] Reference Figure 1 In the multi-split air conditioning system provided in this embodiment of the invention, a refrigerant cooling ring 700 for cooling the circuit board is also provided between the main electronic expansion valve 510 and the inlet of the primary main circuit.

[0080] It should be noted that by setting up the refrigerant heat dissipation ring 700, the circuit board can be cooled using a refrigerant that is at a lower temperature than the circuit board.

[0081] Reference Figure 1 In the multi-unit system provided in this embodiment of the invention, a gas-liquid separator 800 is also included. The outlets of the third end g and the secondary auxiliary circuit are both connected to the inlet of the gas-liquid separator 800, and the outlet of the gas-liquid separator 800 is connected to the air intake port b.

[0082] It should be noted that in the evaporator of an air conditioning system, due to the evaporation of liquid refrigerant and the process of it changing from liquid to gas, some refrigerant may not completely evaporate and may directly enter the compressor, considering load changes. Because of the incompressibility of liquid refrigerant, the liquid and gas must be separated before entering the compressor to prevent the low-pressure, low-temperature vapor returning to the compressor from carrying excessive liquid refrigerant into the compressor cylinder. This ensures that only gaseous refrigerant enters the compressor, guaranteeing its normal operation.

[0083] Reference Figure 1 In the multi-unit system provided in this embodiment of the invention, a liquid storage tank 900 is also provided between the outlet and the suction port b of the gas-liquid separator 800.

[0084] Understandably, by setting up the liquid storage tank 900, excess refrigerant can be stored to balance the pressure of the multi-split system and ensure reliable operation of the multi-split system in heating mode.

[0085] Reference Figure 1 In the multi-unit system provided in the embodiments of the present invention, an oil separator 1000 is also provided between the exhaust port a and the first end e.

[0086] Since the cooling and heating functions of a multi-split air conditioning system are achieved through a compressor, the compressor needs to use lubricating oil to improve its performance. However, the lubricating oil is easily discharged from the compressor along with the refrigerant. In order to maintain a stable amount of lubricating oil in the compressor, an oil separator 1000 needs to be installed, and the lubricating oil separated in the oil separator 1000 is returned to the compressor.

[0087] Reference Figure 1 In the multi-unit system provided in this embodiment of the invention, the oil separator 1000 is also connected to the liquid storage tank 900 through the return oil capillary tube 1100.

[0088] Understandably, the lubricating oil separated by the oil separator 1000 first enters the oil return capillary tube 1100, and the lubricating oil in the oil return capillary tube 1100 then enters the suction pipe at the front end of the suction port b. While the compressor is drawing in air, it draws the lubricating oil in the suction pipe back into the compressor body.

[0089] Reference Figure 1 In the multi-unit system provided in this embodiment of the invention, filters 600 are provided at the inlet of the primary auxiliary road, the inlet of the secondary auxiliary road, and the outlet of the secondary main road.

[0090] It should be noted that installing a filter 600 at the inlet of the primary auxiliary road can prevent impurities generated during operation from accumulating and clogging the primary auxiliary road over a long period of time; similarly, installing a filter 600 at the inlet of the secondary auxiliary road can prevent impurities generated during operation from accumulating and clogging the secondary auxiliary road over a long period of time; similarly, installing a filter 600 at the outlet of the secondary main road can prevent impurities generated during operation from accumulating and clogging the liquid side pipe over a long period of time.

[0091] In the multi-unit system provided in this embodiment of the invention, temperature sensors are installed at the inlet of the primary auxiliary road, the outlet of the primary auxiliary road, the inlet of the secondary auxiliary road, and the outlet of the secondary auxiliary road.

[0092] By setting temperature sensors, the refrigerant temperatures at the inlet and outlet of the auxiliary circuit of the first-stage economizer 300 and the second-stage economizer 400 can be measured, so as to calculate the superheat of the first-stage economizer and the second-stage economizer. Based on the superheat of the first-stage economizer and the second-stage economizer, the opening of the first expansion valve 320 and the second expansion valve 420 can be adjusted.

[0093] It is understood that the multi-split air conditioning system provided in this embodiment of the invention can use a small-displacement injection enthalpy compressor, combined with a two-stage economizer injection enthalpy enhancement, and can have the following main functions: the small-displacement compressor meets the low-frequency output of low-energy-demand small indoor units in single / double operation of multi-split air conditioning systems, which is energy-saving and efficient; the two-stage economizer injection enthalpy enhancement meets the high-frequency output of high-energy-demand conditions such as over-sizing and harsh environments.

[0094] Reference Figure 2 The first aspect of the present invention provides a control method for a multi-split air conditioning system, applied to the multi-split air conditioning system of the first aspect embodiment above. The control method includes, but is not limited to, steps S210, S220 and S230:

[0095] Step S210: Determine the energy requirement level of the multi-split system based on the sum of the energy requirements of all indoor units.

[0096] Understandably, in some multi-split air conditioning systems, the total horsepower of all indoor units is allowed to be 130% of the horsepower of the outdoor units, meaning the sum of the energy requirements of all indoor units may exceed 100%. In some implementation methods, the energy requirement level of the multi-split air conditioning system can be differentiated based on the sum of the energy requirements of all indoor units, for example, referring to... Figure 3 As shown, when the sum of the energy demands of all indoor units falls within the range of 90% to 130%, it is considered a high energy demand stage; when it falls within the range of 50% to 90%, it is considered a medium energy demand stage; when it falls within the range of 20% to 50%, it is considered a low energy demand stage; and when it falls below 20%, it is considered a minimum energy demand stage. This embodiment can assume there are n indoor units, designated as Indoor Unit 1, Indoor Unit 2, Indoor Unit 3, Indoor Unit 4, Indoor Unit 5, Indoor Unit 6…Indoor Unit n. The matching ratio is then determined based on the ratio of the number of indoor units with cooling and heating demands to a preset number, or alternatively, based on the ratio of the horsepower of the indoor units with cooling and heating demands to the horsepower of the outdoor units, etc. It should also be noted that different brands of air conditioners have their own methods for determining energy demand; this embodiment does not limit this method, as long as it allows for the classification of energy demand levels.

[0097] Step S220: Increase the operating frequency of the injection enthalpy compressor 100 to the frequency range corresponding to the energy demand level according to the first adjustment rate corresponding to the energy demand level.

[0098] like Figure 3As shown, the compressor output frequency is also differentiated into different frequency ranges for each energy demand level. For example, the frequency range corresponding to the high energy demand stage is the high frequency range, the frequency range corresponding to the medium energy demand stage is the medium frequency range, the frequency range corresponding to the low energy demand stage is the low frequency range, and the frequency range corresponding to the minimum energy demand stage is the minimum frequency range. It can be understood that the frequency range of the compressor operating frequency for each energy demand level under various environmental conditions can be set through different experimental objectives. Methods include, but are not limited to, the following: meeting the capacity required for each scenario and meeting the heating requirements of the electronic control components when providing that heating capacity; meeting the indoor air outlet temperature requirement and meeting the heating requirements of the electronic control components when providing that air outlet temperature; meeting the indoor environment temperature rise and fall time requirements and meeting the heating requirements of the electronic control components when the temperature rise time is met, etc.

[0099] Furthermore, the first frequency adjustment rate of the compressor varies depending on the energy demand level. For example, the first frequency adjustment rate is 4Hz / 3s for the high energy demand stage, 3Hz / 3s for the medium energy demand stage, 2Hz / 3s for the low energy demand stage, and 1Hz / 3s for the minimum energy demand stage. It should be noted that the faster compressor frequency adjustment allows for quicker output of cooling and heating capacity.

[0100] Therefore, it is understandable that when the multi-split system is determined to be in a high energy demand stage based on the matching of its multiple indoor units, the compressor will increase its frequency at a rate of 4Hz / 3s until it reaches a high frequency range. The scenarios for other energy demand levels can be found in the references and will not be elaborated upon here.

[0101] Step S230: While maintaining the operating frequency of the injection enthalpy compressor 100 within the frequency range corresponding to the energy demand level, control the opening status of the primary auxiliary circuit and the secondary auxiliary circuit according to the energy demand level.

[0102] Understandably, ensuring that the operating frequency of the enthalpy injection compressor 100 is maintained within the frequency range corresponding to the energy demand level before deciding on the opening status of the primary and secondary auxiliary circuits can prevent the injection gas to increase enthalpy when the operating frequency of the enthalpy injection compressor 100 is low, thereby affecting the energy consumption of the multi-split system.

[0103] According to the multi-split air conditioning system provided in the embodiment of the present invention, during the cooling operation of the multi-split air conditioning system, the refrigerant flows from the discharge port a of the injection enthalpy compressor 100 to the four-way valve 200, from the four-way valve 200 to the outdoor heat exchanger 500, then from the outdoor heat exchanger 500 to the primary main circuit of the primary economizer 300 and the secondary main circuit of the secondary economizer 400, then from the secondary main circuit to multiple indoor units, and finally from the multiple indoor units back to the four-way valve 200, and finally back to the suction port b of the injection enthalpy compressor 100; in addition, when the primary auxiliary circuit is opened, part of the refrigerant enters the primary auxiliary circuit of the primary economizer 300, and through the throttling of the primary economizer 300... The refrigerant absorbs heat during the flow, increasing the enthalpy difference and thus the cooling capacity, achieving first-stage enthalpy enhancement. This results in a multi-split system with excellent cooling and energy-saving performance. The refrigerant then flows from the outlet of the first-stage auxiliary circuit to the enthalpy injection port c of the enthalpy injection compressor 100, and returns to the enthalpy injection compressor 100 through port c. When the second-stage auxiliary circuit is opened, some refrigerant enters the second-stage auxiliary circuit of the second-stage economizer 400. Through the throttling and heat absorption effect of the second-stage economizer 400, the enthalpy difference is further increased, thereby increasing the cooling capacity and achieving second-stage enthalpy enhancement. This further enhances the cooling and energy-saving performance. The refrigerant then flows from the outlet of the second-stage auxiliary circuit to the suction port b, returning to the enthalpy injection compressor 100. The control method for the multi-split air conditioning system in this embodiment of the invention determines the energy demand level of the multi-split air conditioning system based on the sum of the energy demands of all indoor units, controls the enthalpy compressor to increase its frequency by 100 according to the corresponding adjustment rate, and controls the opening status of the primary auxiliary circuit and the secondary auxiliary circuit according to the energy demand level. This enables the use of different enthalpy increase levels in different application scenarios, and can quickly meet user needs according to different capacity requirements while having good cooling and heating effects and energy-saving effects.

[0104] Reference Figure 4 In the control method of the multi-unit system provided in some embodiments of the present invention, the energy demand level includes the first level of energy demand;

[0105] Step S230, which controls the opening status of the primary and secondary auxiliary roads according to the energy demand level, includes, but is not limited to, steps S410 to S430:

[0106] Step S410: When the multi-split system is in the first-level energy demand state, control the first-level auxiliary circuit and the second-level auxiliary circuit to open;

[0107] Step S420: Control the first expansion valve 320 to open to the first preset opening degree;

[0108] Step S430: Control the second expansion valve 420 to open to the minimum opening degree, and adjust the opening degree of the second expansion valve 420 according to the superheat of the secondary economizer so that the superheat of the secondary economizer reaches the superheat set value.

[0109] The superheat of the secondary economizer is obtained by subtracting the inlet temperature of the secondary economizer 400 from the outlet temperature of the secondary economizer 400.

[0110] Specifically, the first-level energy demand corresponds to the high-energy-demand stage described above, where the sum of the energy demands of all indoor units falls within the range of 90% to 130%. At this point, the sum of the energy demands of all indoor units is relatively high, therefore the multi-split system needs to simultaneously activate the dual-stage vapor injection enthalpy enhancement. Step S410 involves controlling the opening of the first-level auxiliary circuit and the second-level auxiliary circuit, which means controlling the opening of the first solenoid valve 310 and the second solenoid valve 410. The first expansion valve 320 opens and operates at a first preset opening degree, allowing the first-level economizer 300 to output at a preset optimal superheat, thereby improving the cooling capacity of the multi-split system. The optimal superheat of the first-stage economizer 300 can be determined by the maximum heat exchange of the first-stage economizer 300, i.e., by using the temperature values ​​fed back by temperature sensor A at the auxiliary inlet of the first-stage economizer 300 and temperature sensor A' at the auxiliary outlet of the first-stage economizer 300, and thus the optimal opening degree of the first expansion valve 320. Alternatively, multiple experiments can be conducted to detect the opening degree of the first expansion valve 320 when the multi-split system is at its optimal cooling capacity, and the corresponding value can be set as the optimal superheat of the first economizer 300. While controlling the first expansion valve 320 to operate at the first preset opening, the second expansion valve 420 is controlled to operate at the minimum opening. Then, the superheat of the second economizer is used to limit the opening adjustment of the second expansion valve 420, ensuring that the multi-split system outputs the optimal cooling capacity stably. This avoids the second expansion valve 420 opening being too large, which would result in excessive refrigerant flow, causing the evaporator heat exchange capacity to be ineffective and the compressor output capacity to deteriorate, thereby reducing the cooling capacity. It also avoids the multi-split system from over-outputting cooling capacity and prevents energy waste.

[0111] Reference Figure 5 In the control method of the multi-unit system provided in some embodiments of the present invention, the energy demand level also includes a secondary energy demand, which is different from the primary energy demand;

[0112] Step S230, which controls the opening status of the primary and secondary auxiliary roads according to the energy demand level, also includes steps S510 to S520:

[0113] Step S510: When the multi-split system is in the secondary energy demand stage, control the primary auxiliary circuit to open and control the secondary auxiliary circuit to close;

[0114] Step S520: Control the first expansion valve 320 to open to the minimum opening degree, and adjust the opening degree of the first expansion valve 320 according to the superheat of the first stage economizer so that the superheat of the first stage economizer reaches the superheat set value.

[0115] The superheat of the primary economizer is obtained by subtracting the inlet temperature of the primary auxiliary road from the outlet temperature of the primary auxiliary road.

[0116] Specifically, Level 2 energy demand corresponds to the medium energy demand stage described above, which means that the sum of the energy demand of all indoor units falls within the range of 50% to 90%. At this time, the sum of the energy demand of all indoor units is neither too high nor too low, and the multi-split system can only turn on Level 1 jet enthalpy enhancement to balance energy demand and energy efficiency. It should be noted that when the multi-split system is operating with the first-stage vapor injection enthalpy enhancement, the first-stage auxiliary circuit of the first-stage economizer 300 is open, while the second-stage auxiliary circuit of the second-stage economizer 400 is closed. Therefore, the first expansion valve 320 is open and operates at its minimum opening. Then, the first-stage economizer superheat of the first-stage economizer 300 is determined by subtracting the inlet temperature of the first-stage auxiliary circuit from the outlet temperature. The opening of the first expansion valve 320 is limited by using the first-stage economizer superheat and the superheat setpoint to ensure that the multi-split system outputs the optimal cooling capacity stably. This avoids the first expansion valve 320 opening being too large, which would result in excessive refrigerant flow, leading to ineffective heat exchange capacity of the evaporator and reduced compressor output capacity, thus reducing cooling capacity.

[0117] In the control method of the multi-unit system provided in some embodiments of the present invention, the energy demand level also includes a third level of energy demand, which is different from the first level of energy demand and also different from the second level of energy demand;

[0118] Step S230, which controls the opening status of the primary and secondary auxiliary roads according to the energy demand level, also includes:

[0119] When the multi-split air conditioning system is in the third energy demand state, the first-level auxiliary circuit and the second-level auxiliary circuit are shut down.

[0120] Specifically, the third level of energy demand can correspond to the low energy demand stage and the minimum energy demand stage described above. That is, the sum of the energy demand of all indoor units falls below 50%. At this time, the sum of the energy demand of all indoor units is low, and the multi-split system does not need to turn on the jet enthalpy enhancement. Therefore, the first-level auxiliary circuit and the second-level auxiliary circuit can be controlled to close, that is, the first solenoid valve 310 and the second solenoid valve 410 are controlled to close.

[0121] Reference Figure 6 In some embodiments of the present invention, the control method for a multi-unit air conditioning system further includes steps S610 to S620:

[0122] Step S610: Every first preset time interval, check whether all indoor units have reached the required temperature;

[0123] Step S620: When the number of indoor units reaching the temperature is greater than the preset value, adjust the operating frequency of the injection enthalpy compressor 100 according to the second adjustment rate, where the second adjustment rate is less than the first adjustment rate.

[0124] Specifically, when the difference between the indoor ambient temperature and the corresponding temperature setting value is less than the preset temperature value, the indoor unit reaches the set temperature.

[0125] Specifically, the first preset time interval between two adjacent detection time points for detecting whether all indoor units have reached the set temperature can be 15 minutes or 20 minutes. The indoor ambient temperature T is detected by the indoor unit's environmental detection sensor to see if it approaches the user's temperature set value Ts. When the difference between the indoor ambient temperature T and the corresponding temperature set value Ts is less than the preset temperature value, the indoor unit is determined to have reached the set temperature. When the number of indoor units that have reached the set temperature is less than 3, the compressor still adjusts the operating frequency of the enthalpy compressor 100 according to the first adjustment rate. When the number of indoor units that have reached the set temperature is greater than 3, the compressor adjusts to adjust the operating frequency of the enthalpy compressor 100 according to the second adjustment rate, so that the system's capacity output and the room temperature in each room can stabilize as quickly as possible. It should be noted that in step S220, the first frequency adjustment rate of the compressor corresponding to each energy demand level is as follows: 4Hz / 3s for the high energy demand stage, 3Hz / 3s for the medium energy demand stage, 2Hz / 3s for the low energy demand stage, and 1Hz / 3s for the minimum energy demand stage. In step S620, the second frequency adjustment rate of the compressor corresponding to each energy demand level is as follows: 4Hz / 5s for the high energy demand stage, 3Hz / 5s for the medium energy demand stage, 2Hz / 5s for the low energy demand stage, and 1Hz / 5s for the minimum energy demand stage. That is, when the number of indoor units reaching the set temperature exceeds the preset value, the frequency adjustment rate of the enthalpy-injecting compressor 100 is reduced, so that the system's capacity output and the room temperature in each room stabilize as quickly as possible.

[0126] Reference Figure 7 In the control method for a multi-split air conditioning system provided in some embodiments of the present invention, when the multi-split air conditioning system is in a level 2 energy demand condition, the control method further includes steps S710 to S720:

[0127] Step S710: When the number of indoor units reaching the temperature is less than or equal to the preset value for a second preset duration, control the opening of the first expansion valve 320 to maintain the position.

[0128] Step S720: Control the secondary auxiliary circuit to open, control the second expansion valve 420 to open to the minimum opening degree, and adjust the opening degree of the second expansion valve 420 according to the superheat of the secondary economizer so that the superheat of the secondary economizer reaches the superheat set value.

[0129] Understandably, when the multi-split system is in the second energy demand stage, the multi-split system can only activate the first-stage vapor injection enthalpy enhancement. At this time, if the time it takes for the number of indoor units reaching the temperature to be less than or equal to the preset value reaches the second preset duration, it indicates that the cooling and heating capacity under the first-stage vapor injection enthalpy enhancement state may be insufficient. At this time, the second-stage auxiliary circuit is opened, the second expansion valve 420 is opened, and the opening degree of the second expansion valve 420 is gradually adjusted to increase the cooling and heating capacity of the system.

[0130] Reference Figure 8 In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, when the time for all indoor units to reach the desired temperature reaches a third preset duration, the control method further includes steps S810 to S820:

[0131] Step S810: Close the secondary auxiliary road;

[0132] Step S820: Start timing and after the timing duration reaches the fourth preset duration, adjust the operating frequency of the spray enthalpy compressor 100 according to the indoor ambient temperature of the indoor unit.

[0133] In this embodiment, after all indoor units reach their temperature, in order to maintain a small fluctuation in room temperature, under the operating state of secondary enthalpy injection, the timer detects that the time for all indoor units to reach their temperature meets the third preset duration t', and then prioritizes closing the secondary enthalpy injection circuit / closing the secondary auxiliary circuit / closing the second solenoid valve 410. At the same time, the compressor continues to operate at its current operating frequency for a fourth preset duration t1. Then, the energy demand of the indoor units or the difference between the indoor ambient temperature T of each indoor unit and the corresponding temperature setpoint Ts is detected, and the compressor frequency is finely adjusted to maintain the room temperature.

[0134] In the control method for a multi-split air conditioning system provided in some embodiments of the present invention, when the multi-split air conditioning system is in a level 3 energy demand condition:

[0135] When the difference between the indoor ambient temperature of the indoor unit with energy demand and the corresponding temperature set value is greater than the preset temperature value for a period of time that reaches the fifth preset duration, the first-level auxiliary circuit will be opened.

[0136] The first expansion valve 320 is controlled to open to the minimum opening degree, and the opening degree of the first expansion valve 320 is adjusted according to the indoor ambient temperature so that the indoor ambient temperature reaches the corresponding temperature set value.

[0137] Understandably, when the multi-split system is in the third energy demand state, the multi-split system does not activate vapor injection enthalpy enhancement. At this time, if the difference between the indoor ambient temperature of the indoor unit with energy demand and the corresponding temperature set value is greater than the preset temperature value for a period of time exceeding the preset temperature value, it indicates that the cooling capacity may be insufficient when vapor injection enthalpy enhancement is not activated. In this case, the first-level auxiliary circuit is opened, the first expansion valve 320 is opened, and the opening degree of the first expansion valve 320 is gradually adjusted to increase the cooling capacity of the system.

[0138] In the control method of a multi-split air conditioning system provided in some embodiments of the present invention, when the time for all indoor units to reach the desired temperature reaches a sixth preset duration:

[0139] Control the closure of the primary auxiliary road;

[0140] Start timing and after the timing reaches the seventh preset time, adjust the operating frequency of the injection enthalpy compressor 100 according to the indoor ambient temperature of the indoor unit with energy demand.

[0141] In this embodiment, after all indoor units reach their set temperature, in order to reduce indoor temperature fluctuations and ensure stable system output, under the operating state with the first-stage enthalpy injection on, the timer detects that the time it takes for all indoor units to reach their set temperature meets the sixth preset duration t2, then the first-stage enthalpy injection circuit / first-stage auxiliary circuit / first solenoid valve 310 is closed, while the compressor continues to operate at its current operating frequency for a seventh preset duration t3. Then, the energy demand of the indoor units or the difference between the indoor ambient temperature T of each indoor unit and the corresponding temperature setpoint Ts is detected, and the compressor frequency is finely adjusted to maintain the room temperature.

[0142] In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, adjusting the opening degree of the first expansion valve 320 according to the superheat of the first-stage economizer includes:

[0143] The opening adjustment rate is determined based on the difference between the superheat value of the first-stage economizer and the superheat setpoint.

[0144] Increase the opening of the first expansion valve 320 according to the opening adjustment rate.

[0145] It is understandable that the opening adjustment rate of the first expansion valve 320 varies with the difference between the superheat of the first-stage economizer and the superheat set value. For example, the greater the difference between the superheat of the first-stage economizer and the superheat set value, the greater the opening adjustment rate. Determining the opening adjustment rate according to this strategy can make the opening adjustment of the first expansion valve 320 more reasonable and more conducive to the first-stage economizer superheat reaching the superheat set value quickly.

[0146] In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, adjusting the opening degree of the second expansion valve 420 according to the superheat of the secondary economizer includes:

[0147] The opening adjustment rate is determined based on the difference between the superheat value of the secondary economizer and the superheat setpoint.

[0148] Increase the opening of the second expansion valve 420 according to the opening adjustment rate.

[0149] It is understandable that the opening adjustment rate of the second expansion valve 420 changes with the difference between the superheat of the secondary economizer and the superheat set value. For example, the greater the difference between the superheat of the secondary economizer and the superheat set value, the greater the opening adjustment rate. Determining the opening adjustment rate according to this strategy can make the opening adjustment of the second expansion valve 42042 more reasonable and more conducive to the secondary economizer superheat reaching the superheat set value quickly.

[0150] In the control method of the multi-split air conditioning system provided in some embodiments of the present invention, adjusting the opening degree of the first expansion valve 320 according to the indoor ambient temperature includes:

[0151] The opening adjustment rate is determined based on the difference between the indoor ambient temperature and the corresponding temperature setting value;

[0152] Increase the opening of the first expansion valve 320 according to the opening adjustment rate.

[0153] It is understandable that the opening adjustment rate changes with the difference between the indoor ambient temperature and the temperature set value. For example, the greater the difference between the indoor ambient temperature and the temperature set value, the greater the opening adjustment rate. Determining the opening adjustment rate according to this strategy can make the opening adjustment of the second expansion valve 420 more reasonable and more conducive to the indoor ambient temperature quickly reaching the temperature set value.

[0154] The control method of the multi-unit air conditioning system provided in the embodiments of the present invention will be described in detail below with specific examples.

[0155] When the multi-split system starts up and receives a signal from the remote control, it first determines the operating mode of the multi-split system. If the multi-split system is operating in cooling or heating mode, it obtains the energy demand of all indoor units and then determines the energy demand level of the multi-split system based on the sum of the energy demands of all indoor units; otherwise, the multi-split system continues to operate according to the signal.

[0156] Scenario 1:

[0157] When the system detects a high energy demand phase, the compressor rises to a high frequency range according to the startup platform, with a frequency adjustment rate of 4Hz / 3s. After the compressor's operating frequency rises to the high frequency range corresponding to the high energy demand phase, the system activates the two-stage vapor injection enthalpy enhancement. The auxiliary circuits of the first-stage economizer 300 and the second-stage economizer 400 open simultaneously. The solenoid valves and expansion valves of the first-stage auxiliary circuit open or close simultaneously, as do the solenoid valves and expansion valves of the second-stage auxiliary circuit. Specifically, at this time, the first expansion valve 320 and the first solenoid valve 310 of the first-stage auxiliary circuit of the first-stage economizer 300 open. The first expansion valve 320 directly adjusts to the optimal step number Z, and the first-stage economizer 300 directly outputs according to the optimal superheat, accelerating the speed of the air conditioning system's output capacity.

[0158] The method for setting the optimal superheat Z of the first expansion valve 320 includes, but is not limited to, the following methods: based on the maximum heat exchange of the first-stage economizer 300, the optimal opening degree of the first expansion valve 320 is set by the temperature values ​​fed back by the sensor A at the inlet of the first-stage auxiliary circuit of the first-stage economizer and the sensor A' at the outlet of the first-stage auxiliary circuit of the first-stage economizer, so as to obtain the optimal superheat; based on the opening degree of the first expansion valve 320 obtained when the optimal capacity of the system is experimentally reviewed, the optimal superheat degree under this operating condition is set.

[0159] Additionally, at this time, the second expansion valve 420 and the second solenoid valve 410 of the secondary auxiliary circuit of the secondary economizer 400 are open. After the second expansion valve 420 is opened with a minimum step number X, the temperature value is detected by the sensor B at the inlet of the secondary auxiliary circuit of the secondary economizer and the sensor B' at the outlet of the secondary auxiliary circuit of the secondary economizer. The second expansion valve 420 is adjusted step number to continuously adjust the superheat SH2 of the secondary economizer. At this time, the superheat SH2 of the secondary economizer is an undefined value, the purpose of which is to adjust the output system of the secondary economizer 400 to the optimal capacity. The controller calculates the superheat SH2 of the secondary economizer every 20 seconds. When the superheat SH2 of the secondary economizer reaches the superheat setting range, the second expansion valve 420 maintains the current step number X' to control the refrigerant flow through the secondary economizer 400. Specifically, when the absolute value of the difference between the superheat setpoint SH2' and the superheat SH2 of the secondary economizer is greater than 5°C, the opening adjustment rate of the second expansion valve 420 is 2; when the absolute value of the difference between the superheat setpoint SH2' and the superheat SH2 of the secondary economizer is less than 5°C but greater than 2°C, the opening adjustment rate of the second expansion valve 420 is 1; when the absolute value of the difference between the superheat setpoint SH2' and the superheat SH2 of the secondary economizer is less than 2°C but greater than 0.5°C, the opening adjustment rate of the second expansion valve 420 is 0.5; when the absolute value of the difference between the superheat setpoint SH2' and the superheat SH2 of the secondary economizer is less than 0.5°C, it indicates that the superheat SH2 of the secondary economizer has reached the superheat setpoint range.

[0160] In addition, the system checks whether all indoor units have reached the set temperature. The first preset time interval between two adjacent detection points can be 15 minutes or 20 minutes. The indoor unit's environmental detection sensor detects whether the indoor ambient temperature T approaches the user's temperature set value Ts. When the difference between the indoor ambient temperature T and the corresponding temperature set value Ts is less than 0.5℃, the indoor unit is determined to have reached the set temperature. When fewer than 3 indoor units have reached the set temperature, the compressor continues to adjust the operating frequency of the enthalpy injection compressor 100 at 4Hz / 3s. When more than 3 indoor units have reached the set temperature, the compressor adjusts to adjust the operating frequency of the enthalpy injection compressor 100 at 4Hz / 5s, so that the system's capacity output and the room temperature in each room stabilize as quickly as possible.

[0161] Scenario 2:

[0162] When the system detects feedback indicating a medium energy demand stage, the compressor rises to the medium frequency range according to the startup platform, with a frequency adjustment rate of 3Hz / s. After the compressor frequency rises to the medium frequency range corresponding to the medium energy demand stage, the system activates the first-stage vapor injection enthalpy enhancement. The first expansion valve 320 and the first solenoid valve 310 of the first-stage economizer 300's first-stage auxiliary circuit open. After the first expansion valve 320 opens with a minimum step number Z', the temperature values ​​detected by the sensor A at the inlet and the sensor A' at the outlet of the first-stage auxiliary circuit are used to adjust the first expansion valve 320 step number to continuously adjust the superheat SH1 of the first-stage economizer. At this time, the superheat SH1 of the first-stage economizer is an undefined value, the purpose of which is to adjust the output system's optimal capacity of the first-stage economizer 300. The controller calculates the superheat SH1 of the first-stage economizer every 20 seconds. When the superheat SH1 of the first-stage economizer reaches the superheat set range, the first expansion valve 320 maintains the current step number Z1 to control the refrigerant flow through the first-stage economizer 300. Specifically, when the absolute value of the difference between the superheat setting value SH1' and the superheat value SH1 of the first-stage economizer is >5℃, the opening adjustment rate of the first expansion valve 320 is 2; when the absolute value of the difference between the superheat setting value SH1' and the superheat value SH1 of the first-stage economizer is less than 5℃ but greater than 2℃, the opening adjustment rate of the first expansion valve 320 is 1; when the absolute value of the difference between the superheat setting value SH1' and the superheat value SH1 of the first-stage economizer is less than 2℃ but greater than 0.5℃, the opening adjustment rate of the first expansion valve 320 is 0.5; when the absolute value of the difference between the superheat setting value SH1' and the superheat value SH1 of the first-stage economizer is less than 0.5℃, it indicates that the superheat value SH1 of the first-stage economizer has reached the superheat setting range.

[0163] In addition, the system checks whether all indoor units have reached the set temperature. The first preset time interval between two adjacent detection points can be 15 minutes or 20 minutes. The indoor unit's environmental detection sensor detects whether the indoor ambient temperature T approaches the user's temperature set value Ts. When the difference between the indoor ambient temperature T and the corresponding temperature set value Ts is less than 0.5℃, the indoor unit is determined to have reached the set temperature. When fewer than 3 indoor units have reached the set temperature, the compressor continues to adjust the operating frequency of the enthalpy injection compressor 100 at 3Hz / 3s. When more than 3 indoor units have reached the set temperature, the compressor adjusts to adjust the operating frequency of the enthalpy injection compressor 100 at 3Hz / 5s, so that the system's capacity output and the room temperature in each room stabilize as quickly as possible.

[0164] When the controller detects that fewer than 3 indoor units have reached the set temperature, and the timer has been continuously counting for more than time t, the first expansion valve 320 maintains its current step count Y and opens the auxiliary circuit of the secondary economizer 400 to perform secondary vapor injection and enthalpy enhancement on the compressor. At this time, the second solenoid valve 410 is energized and opens. After the second expansion valve 420 opens with the minimum step count X, the controller adjusts the step count of the second expansion valve 420 based on the temperature values ​​detected by the sensor B at the inlet and the sensor B' at the outlet of the secondary auxiliary circuit. The controller calculates the superheat SH2 of the secondary economizer every 20 seconds. When the superheat SH2 of the secondary economizer reaches the superheat setting range, the second expansion valve 420 maintains its current step count X1 to control the refrigerant flow through the secondary economizer 400. Specifically, when the absolute value of the difference between the superheat setpoint SH2' and the superheat SH2 of the secondary economizer is greater than 5°C, the opening adjustment rate of the second expansion valve 420 is 2; when the absolute value of the difference between the superheat setpoint SH2' and the superheat SH2 of the secondary economizer is less than 5°C but greater than 2°C, the opening adjustment rate of the second expansion valve 420 is 1; when the absolute value of the difference between the superheat setpoint SH2' and the superheat SH2 of the secondary economizer is less than 2°C but greater than 0.5°C, the opening adjustment rate of the second expansion valve 420 is 0.5; when the absolute value of the difference between the superheat setpoint SH2' and the superheat SH2 of the secondary economizer is less than 0.5°C, it indicates that the superheat SH2 of the secondary economizer has reached the superheat setpoint range.

[0165] At this time, following the operating mode of primary vapor injection enthalpy boosting main operation and secondary vapor injection enthalpy boosting auxiliary operation, the compressor is adjusted to a rate of 3Hz / 5s until the controller detects that more than 3 indoor units have reached the temperature. After all indoor units have reached the temperature, in order to maintain a small fluctuation in room temperature, under the operating state of secondary vapor injection enthalpy boosting, the timer detects that the stable operating time meets t', and then the secondary vapor injection enthalpy circuit is closed first / the second solenoid valve 410 is closed. At the same time, the compressor continues to operate at the current operating frequency t1. The controller continues to detect the energy demand of the indoor units or the difference between the indoor ambient temperature of each indoor unit and the set temperature, and then finely adjusts the compressor frequency to maintain the room temperature.

[0166] Scenario 3:

[0167] When the system detects a low energy demand phase, the compressor adjusts to a low frequency range according to the startup platform, with a frequency adjustment rate of 2Hz / 3s. The system does not activate the vapor injection enthalpy booster; the auxiliary circuits of the primary economizer (300 rpm) and the secondary economizer (400 rpm) are simultaneously closed, and the solenoid valves and expansion valves of both economizer auxiliary circuits are linked and closed. The system adjusts the expansion valve steps of each indoor unit according to the conventional linkage between exhaust temperature and compressor frequency. When the controller detects fewer than 3 indoor units reaching the required temperature, the compressor continues to adjust its frequency at 2Hz / 3s. When the controller detects more than 3 indoor units reaching the required temperature, the compressor adjusts its frequency to 2Hz / 5s, ensuring that the system's capacity output and room temperature stabilize as quickly as possible.

[0168] Scenario 4:

[0169] Multi-split air conditioning systems typically use large-displacement compressors. Due to the relatively high minimum operating frequency of these compressors (usually in the 16-24Hz range), even at lower frequencies, the system's cooling or heating capacity remains substantial. When users operate one or two indoor units, this can easily lead to excessively cold or hot indoor temperatures, affecting user comfort and increasing overall power consumption. Furthermore, large-displacement compressors vibrate significantly at lower frequencies, increasing the likelihood of abnormal noise, pipe breakage, leaks, and other customer complaints, thus impacting compressor lifespan. Therefore, this embodiment uses a small-displacement compressor in its multi-split system. This compressor can operate at a lower frequency, reducing energy loss, minimizing customer complaints, and extending compressor lifespan. This embodiment recommends that the small-displacement compressor's displacement be 70%-75% of the large-displacement compressor's displacement. Practical experience has shown that at this point, the minimum operating frequency of the small-displacement compressor can be as low as approximately 50% of that of the large-displacement compressor.

[0170] When a user operates one or both indoor units, and the system detects that the energy demand is at its minimum, the compressor rises to the minimum frequency range according to the startup platform, with a frequency adjustment rate of 1Hz / 3s. For indoor units with energy demand, the expansion valve step count is directly adjusted to the minimum step count. Simultaneously, the indoor unit with energy demand uses an ambient temperature sensor to detect whether the current indoor ambient temperature T1 is approaching the user's temperature setpoint Ts1. If the timer exceeds time ts and the indoor ambient temperature T1 still has not reached the user's temperature setpoint Ts1, the primary auxiliary circuit of the primary economizer 300 is activated to inject enthalpy into the compressor, rapidly outputting the energy demand, and the compressor frequency adjustment rate becomes 1Hz / 5s. At this time, when the first solenoid valve 310 opens, the first expansion valve 320 opens. After the first expansion valve 320 opens with the minimum step count Z', the indoor unit's ambient temperature sensor detects whether the indoor ambient temperature T1 is approaching the user's temperature setpoint Ts1, and adjusts the first expansion valve 320 step count accordingly. When |T1-Ts1|>5℃, the opening adjustment rate of the first expansion valve 320 is 2; when 5℃>|T1-Ts1|>2℃, the opening adjustment rate of the first expansion valve 320 is 1; when 2℃>|T1-Ts1|>0.5℃, the opening adjustment rate of the first expansion valve 320 is 0.5; when 0.5℃>|T1-Ts1|, the first expansion valve 320 maintains the current step number Y' to ensure that the system outputs the optimal cooling capacity stably.

[0171] When 0.5℃ > |T1-Ts1|, the controller determines that the temperature has been reached. In order to reduce indoor temperature fluctuations and ensure the system's stable output capability, the timer detects that the indoor temperature has been reached in time t2, and then closes the first-stage enthalpy injection circuit / closes the first solenoid valve 310. At the same time, the compressor continues to run at its current operating frequency for t3. The controller continues to detect the difference between the current indoor temperature of the unit with energy demand and the set temperature, and then finely adjusts the compressor frequency to maintain the room temperature.

[0172] Reference Figure 9 A second aspect of the present invention provides an operation control device 900, including a memory 920, a processor 910, and a computer program stored in the memory 920 and executable on the processor 910. The processor 910 executes the program to implement the control method of the first aspect embodiment described above, for example, executing... Figure 2 Method steps S210 to S230, Figure 4 Method steps S410 to S430, Figure 5 Method steps S510 to S520, Figure 6 Method steps S610 to S620, Figure 7 Method steps S710 to S720, Figure 8 Method steps S810 to S820.

[0173] Thirdly, embodiments of the present invention provide a multi-unit system, including the operation control device 900 as described in the second aspect embodiment above.

[0174] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer-executable instructions for causing a computer to perform the control method described in the first aspect of the invention, for example, executing... Figure 2 Method steps S210 to S230, Figure 4 Method steps S410 to S430, Figure 5 Method steps S510 to S520, Figure 6 Method steps S610 to S620, Figure 7 Method steps S710 to S720, Figure 8 Method steps S810 to S820.

[0175] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which may include computer storage media or non-transitory media and communication media or transient media. As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc DVD or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0176] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A control method for a multi-unit air conditioning system, characterized in that, The multi-split air conditioning system includes an enthalpy-injected compressor, a four-way valve, an outdoor heat exchanger, a primary economizer, a secondary economizer, and multiple indoor units. The enthalpy-injected compressor includes an exhaust port, an intake port, and an enthalpy-injection port. The primary economizer includes a primary main circuit and a primary auxiliary circuit. The secondary economizer includes a secondary main circuit and a secondary auxiliary circuit. The four-way valve is connected to the exhaust port, the outdoor heat exchanger, the intake port, and the multiple indoor units. The outdoor heat exchanger, the primary main circuit, and the secondary main circuit are connected sequentially. The secondary main circuit is connected to the multiple indoor units. The primary auxiliary circuit is connected to the enthalpy-injection port, and the secondary auxiliary circuit is connected to the intake port. The inlet of the primary auxiliary circuit is connected to the outlet of the primary main circuit via a first expansion valve, and the inlet of the secondary auxiliary circuit is connected to the outlet of the secondary main circuit via a second expansion valve. The method includes: The energy requirement level of the multi-split air conditioning system is determined based on the sum of the energy requirements of all the indoor units, and the energy requirement level includes Level 1 energy requirement. The operating frequency of the injection compressor is increased to the frequency range corresponding to the energy demand level according to a first adjustment rate corresponding to the energy demand level; While maintaining the operating frequency of the injection enthalpy compressor within the specified frequency range, the opening status of the primary auxiliary circuit and the secondary auxiliary circuit is controlled according to the energy demand level. The step of controlling the opening status of the primary auxiliary road and the secondary auxiliary road according to the energy demand level includes: When the multi-split air conditioning system is in the first-level energy demand state, control the first-level auxiliary circuit and the second-level auxiliary circuit to open; Control the first expansion valve to open to a first preset opening degree; The second expansion valve is controlled to open to the minimum opening degree, and the opening degree of the second expansion valve is adjusted according to the superheat of the secondary economizer so that the superheat of the secondary economizer reaches the superheat set value. The superheat of the secondary economizer is obtained by subtracting the inlet temperature of the secondary economizer from the outlet temperature of the secondary economizer.

2. The control method according to claim 1, characterized in that, The energy demand level also includes a secondary energy demand, which is different from the primary energy demand. The method of controlling the opening status of the primary auxiliary road and the secondary auxiliary road according to the energy demand level further includes: When the multi-split air conditioning system is in the secondary energy demand state, the primary auxiliary circuit is opened and the secondary auxiliary circuit is closed. The first expansion valve is controlled to open to the minimum opening degree, and the opening degree of the first expansion valve is adjusted according to the superheat of the first-stage economizer so that the superheat of the first-stage economizer reaches the superheat set value. The superheat of the primary economizer is obtained by subtracting the inlet temperature of the primary auxiliary circuit from the outlet temperature of the primary auxiliary circuit.

3. The control method according to claim 1, characterized in that, The energy demand level also includes a third level of energy demand, which is different from the first level of energy demand. The method of controlling the opening status of the primary auxiliary road and the secondary auxiliary road according to the energy demand level further includes: When the multi-unit system is in the third energy demand state, the first-level auxiliary circuit and the second-level auxiliary circuit are shut down.

4. The control method according to any one of claims 1 to 3, characterized in that, Also includes: Every first preset time interval, check whether all indoor units have reached the required temperature; When the number of indoor units reaching the set temperature exceeds a preset value, the operating frequency of the injection enthalpy compressor is adjusted according to a second adjustment rate, where the second adjustment rate is less than the first adjustment rate. Specifically, when the difference between the indoor ambient temperature of the indoor unit and the corresponding temperature setting value is less than the preset temperature value, the indoor unit reaches the set temperature.

5. The control method according to claim 2, characterized in that, When the multi-split air conditioning system is in the second-level energy demand condition: When the number of indoor units reaching the set temperature is less than or equal to a preset value for a second preset duration, the opening of the first expansion valve is controlled to remain constant. The secondary auxiliary circuit is controlled to open, the second expansion valve is controlled to open to the minimum opening degree, and the opening degree of the second expansion valve is adjusted according to the superheat degree of the secondary economizer so that the superheat degree of the secondary economizer reaches the superheat degree set value.

6. The control method according to claim 5, characterized in that, When all indoor units reach the desired temperature within the third preset time: Control the secondary auxiliary road to close; The timing begins and after the timing duration reaches the fourth preset duration, the operating frequency of the injection enthalpy compressor is adjusted according to the indoor ambient temperature of the indoor unit.

7. The control method according to claim 3, characterized in that, When the multi-split air conditioning system is in the third energy demand condition: When the difference between the indoor ambient temperature of the indoor unit with energy demand and the corresponding temperature setting value is greater than the preset temperature value for a period of time that reaches the fifth preset duration, the first-level auxiliary circuit is controlled to open. The first expansion valve is controlled to open to its minimum opening degree, and the opening degree of the first expansion valve is adjusted according to the indoor ambient temperature so that the indoor ambient temperature reaches the corresponding temperature set value.

8. The control method according to claim 7, characterized in that, When all indoor units reach the desired temperature within the sixth preset time: Control the primary auxiliary road to close; The timing begins and after the timing reaches the seventh preset duration, the operating frequency of the enthalpy compressor is adjusted according to the indoor ambient temperature of the indoor unit where energy is needed.

9. The control method according to claim 2, characterized in that, Adjusting the opening of the first expansion valve according to the superheat of the first-stage economizer includes: The opening adjustment rate is determined based on the difference between the superheat value of the first-stage economizer and the superheat setpoint. Increase the opening of the first expansion valve according to the opening adjustment rate.

10. The control method according to claim 5, characterized in that, The adjustment of the opening degree of the second expansion valve according to the superheat of the secondary economizer includes: The opening adjustment rate is determined based on the difference between the superheat value of the secondary economizer and the superheat setpoint. Increase the opening of the second expansion valve according to the opening adjustment rate.

11. The control method according to claim 7, characterized in that, Adjusting the opening degree of the first expansion valve according to the indoor ambient temperature includes: The opening adjustment rate is determined based on the difference between the indoor ambient temperature and the corresponding temperature set value. Increase the opening of the first expansion valve according to the opening adjustment rate.

12. An operation control device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the control method as described in any one of claims 1 to 11.

13. A multi-split air conditioning system, characterized in that, Includes the operation control device as described in claim 12.

14. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions for causing a computer to perform the control method as described in any one of claims 1 to 11.

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