Multi-link control method, multi-link and storage medium

Abstract

The present invention discloses a multi-split control method, a multi-split system and a storage medium. The multi-split control method includes: detecting the operating parameters of each turned-on outdoor unit; judging whether a refrigerant bias occurs in the multi-split system based on the operating parameters and analyzing the refrigerant amount of the turned-on outdoor unit; if a refrigerant bias occurs in the multi-split system or there are both refrigerant-deficient outdoor units and non-refrigerant-deficient outdoor units, a refrigerant adjustment action is performed. The operating mode of the multi-split system includes at least one of heating operation and cooling operation, and different operating modes are provided with corresponding refrigerant bias parameter conditions and / or refrigerant deficiency parameter conditions and / or refrigerant adjustment actions. During the operation of the multi-split system, the present invention promptly detects the imbalance of refrigerant distribution, balances the refrigerant distribution between the turned-on outdoor units through the refrigerant adjustment action, and each turned-on outdoor unit is in a better operating state, thereby improving the stability of the multi-split system.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-link systems, and in particular to a multi-link system control method, a multi-link system, and a storage medium. Background Art

[0002] Currently, most multi-split units on the market are modular multi-split units, that is, multiple outdoor units are installed in parallel. Although this installation method greatly reduces the labor and space costs of air-conditioning installation, since large and small modules are often installed in combination, not all outdoor units have the same capacity, or because of the influence of the installation environment, there is refrigerant deviation between the multi-split units, and the refrigerant deviation affects the performance and reliability of the unit. Therefore, the operating stability of traditional multi-split units still has much room for improvement.

[0003] When most modular multi-split units are installed in parallel, refrigerant imbalances can occur between the units due to factors such as the shape of the connecting manifolds, the position of the units, and even the flattening of the connecting pipes. For example, when a large-capacity unit and a small-capacity unit are operating at full load, both units receive the same amount of refrigerant. Or, when the same-capacity units are operating at the same load, the refrigerant amounts differ significantly. This can cause the unit with less refrigerant to operate in a refrigerant-deficient state, while the unit with more refrigerant to operate in a refrigerant-overload state. Regardless of whether this state is refrigerant-deficient or refrigerant-overloaded, the units will not function properly and may even be damaged.

[0004] In heating operation, multi-split units composed of outdoor units of different capacities are particularly prone to this type of problem, because the branch pipes connected in parallel between the outdoor units are all on the high-pressure side. At this time, the high pressure of each unit is consistent, so the amount of refrigerant allocated to each unit is similar. However, under the same load ratio, the suction volume of units of different capacities is inconsistent, while the amount of refrigerant allocated is indeed similar. This results in the low-pressure pressure of units with large suction volume being lower. In low-temperature environments such as winter, units with low low pressure are more prone to frost, and conventional heat pump units cannot operate simultaneously for defrosting and heating. Therefore, under high-load heating operation, due to the low low pressure and easy frost of some units, the entire system frequently enters the defrost state, seriously affecting the user experience. In addition, defrosting requires the compressor to run at a high frequency, resulting in energy waste. Summary of the Invention

[0005] In order to solve the defect of uneven refrigerant distribution in existing multi-split systems, the present invention proposes a multi-split control method, a multi-split system and a storage medium, so that each turned-on outdoor unit of the multi-split system can be allocated an appropriate amount of refrigerant, so that the turned-on outdoor units can perform better working performance and improve the operating stability of the multi-split system.

[0006] The technical solution adopted by the present invention is to design a multi-connection control method, including:

[0007] Check the operating parameters of each turned-on outdoor unit;

[0008] Determine whether refrigerant bias occurs in the multi-split system based on operating parameters and analyze the refrigerant volume of the turned-on outdoor units;

[0009] If refrigerant bias occurs in a multi-connected system or there are both refrigerant-deficient and non-refrigerant-deficient outdoor units, the refrigerant adjustment action will be performed.

[0010] Furthermore, the operation mode of the multi-split unit includes at least one of heating operation and cooling operation, and different operation modes are provided with corresponding refrigerant bias flow parameter conditions and / or refrigerant shortage parameter conditions and / or refrigerant adjustment actions.

[0011] In some embodiments, the multi-split system is in heating operation, and the refrigerant bias flow parameter condition is Td max -Td min ≥Heating set value, Td is the saturation temperature obtained by low pressure conversion, and the highest value among all the Td values ​​of the turned-on outdoor units is selected as Td max , the lowest value is taken as Td min ;

[0012] Judging whether refrigerant bias occurs in a multi-split system based on operating parameters includes:

[0013] Determine whether the multi-split unit meets the refrigerant bias flow parameter conditions;

[0014] If so, it is determined that the multi-split unit has refrigerant bias;

[0015] If not, determine whether there are both refrigerant-deficient outdoor units and refrigerant-free outdoor units.

[0016] In some embodiments, the VRF is in heating operation and the refrigerant shortage parameter conditions are Tp-Tg>Ts1, Tx-Td>Ts2, and Tw-Td>Ts3, where Tw is the outdoor ambient temperature, Tg is the saturation temperature obtained by high-pressure pressure conversion, Td is the saturation temperature obtained by low-pressure pressure conversion, Tp is the exhaust temperature, Tx is the suction temperature, and Ts1, Ts2, and Ts3 are all preset values;

[0017] The refrigerant quantity of the turned-on outdoor unit is analyzed based on the operating parameters, including:

[0018] Determine whether the turned-on outdoor unit has reached the refrigerant shortage parameter condition;

[0019] If so, the turned-on outdoor unit is marked as a refrigerant-deficient outdoor unit;

[0020] If not, the outdoor unit that has been turned on is marked as a non-refrigerant-deficient outdoor unit.

[0021] In some embodiments, a heating refrigerant balancing pipe is provided on the heating inlet side of the outdoor heat exchanger of each turned-on outdoor unit, a regulating valve is installed on the heating refrigerant balancing pipe, and the heating refrigerant balancing pipe is connected to the main liquid pipe of the multi-split unit;

[0022] When the multi-split system is in heating operation, the refrigerant adjustment actions include: calculating the standard value based on the low pressure values ​​of all turned on outdoor units, increasing the opening of the regulating valves of the turned on outdoor units with low pressure values ​​≤ the standard value, and closing the regulating valves of the turned on outdoor units with low pressure values ​​> the standard value.

[0023] Based on this embodiment, the change amount of each adjustment of the regulating valve=|(standard value-low pressure value of the external unit where the regulating valve is located)×β1|, where β1 is a proportional coefficient.

[0024] In some embodiments, the multi-split unit is in cooling operation, and the refrigerant bias flow parameter condition is Td max -Td min ≥ Cooling set value, Td is the saturation temperature obtained by low pressure conversion, and the highest value among all Td of the open outdoor units is selected as Td max , the lowest value is taken as Td min ;

[0025] Judging whether refrigerant bias occurs in a multi-split system based on operating parameters includes:

[0026] Determine whether the multi-split unit meets the refrigerant bias flow parameter conditions;

[0027] If so, it is determined that the multi-split unit has refrigerant bias;

[0028] If not, determine whether there are both refrigerant-deficient outdoor units and refrigerant-free outdoor units.

[0029] In some embodiments, the VRF is in cooling operation, and the refrigerant shortage parameter condition is Tp-Tg>Ts4, Tx-Td>Ts5, and Tg-Tw<Ts6, where Tw is the outdoor ambient temperature, Tg is the saturation temperature obtained by high-pressure pressure conversion, Td is the saturation temperature obtained by low-pressure pressure conversion, Tp is the exhaust temperature, Tx is the suction temperature, and Ts4, Ts5, and Ts6 are all preset values;

[0030] The refrigerant quantity of the turned-on outdoor unit is analyzed based on the operating parameters, including:

[0031] Determine whether the turned-on outdoor unit meets the refrigerant shortage parameter conditions;

[0032] If so, the turned-on outdoor unit is marked as a refrigerant-deficient outdoor unit;

[0033] If not, the outdoor unit that has been turned on is marked as a non-refrigerant-deficient outdoor unit.

[0034] In some embodiments, a refrigerant balancing pipe is provided on the suction side of the compressor of each turned-on outdoor unit, the refrigerant balancing pipe is equipped with an on-off valve, and the refrigerant balancing pipe is connected to the main gas pipe of the multi-split unit;

[0035] When the multi-split unit is in cooling operation, the refrigerant adjustment actions include: calculating the standard value based on the low pressure values ​​of all turned-on outdoor units, connecting the switch valves of the turned-on outdoor units with low pressure values ​​≤ the standard value, and closing the switch valves of the turned-on outdoor units with low pressure values ​​> the standard value.

[0036] In some embodiments, a heating refrigerant balancing pipe is provided on the heating inlet side of the outdoor heat exchanger of each turned-on outdoor unit, a regulating valve is installed on the heating refrigerant balancing pipe, and the heating refrigerant balancing pipes between the turned-on outdoor units are connected to each other;

[0037] When the multi-split system is in heating operation, the refrigerant adjustment operation includes: calculating the standard value based on the low pressure values ​​of all turned-on outdoor units, taking the outdoor units with insufficient refrigerant and the turned-on outdoor units with the standard value - low pressure value ≥ Ts7 as the demand outdoor units, and taking the turned-on outdoor units with the low pressure value greater than the standard value as the supply outdoor units, and Ts7 as the preset value;

[0038] Increase the opening of the regulating valves of the demand outdoor unit and the supply outdoor unit according to different proportions, so that the refrigerant of the supply outdoor unit is replenished into the demand outdoor unit through the heating refrigerant balancing pipe.

[0039] Based on this embodiment, the increase in the regulating valve of the demand outdoor unit each time = (standard value - low pressure value of the outdoor unit where the regulating valve is located) × β2, and the increase in the regulating valve of the supply outdoor unit each time = (low pressure value of the outdoor unit where the regulating valve is located - standard value) × β3, β2 and β3 are both proportional coefficients, and β2>β3.

[0040] In some embodiments, a refrigerant balancing pipe is provided on the suction side of the compressor of each turned-on outdoor unit, the refrigerant balancing pipe is equipped with an on-off valve, and the refrigerant balancing pipes between the turned-on outdoor units are connected to each other;

[0041] When the multi-split system is in cooling operation, the refrigerant adjustment actions include: calculating the standard value based on the low pressure values ​​of all turned-on outdoor units, connecting the outdoor units that are short of refrigerant, the turned-on outdoor units with standard value - low pressure value ≥ Ts8, and the switching valves with low pressure value > standard value, and Ts8 is the preset value.

[0042] Furthermore, the standard value is the median of the low pressure values ​​of all turned-on outdoor units.

[0043] Furthermore, before detecting the operating parameters of each turned-on outdoor unit, it is first determined whether the multi-split system has entered a stable operating state. If so, the operating parameters of each turned-on outdoor unit are detected.

[0044] Furthermore, after the multi-connected system enters the current operation mode and runs for a set time, it is determined that the multi-connected system enters a stable operation state.

[0045] The present invention also proposes a multi-split unit, comprising: a controller, at least two external units installed in parallel, and at least one internal unit, each external unit being connected to the internal unit via a main gas pipe and a main liquid pipe, and the controller executes the above-mentioned multi-split unit control method.

[0046] Furthermore, the outdoor unit is provided with a heating refrigerant balancing pipe and / or a cooling refrigerant balancing pipe, the heating refrigerant balancing pipe is connected to the main liquid pipe or the heating refrigerant balancing pipes between the outdoor units are connected to each other, and the cooling refrigerant balancing pipe is connected to the main gas pipe or the cooling refrigerant balancing pipes between the outdoor units are connected to each other.

[0047] The present invention also provides a storage medium, which is used to store a computer program. When the computer program is running, the multi-connection control method is executed.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. During the operation of the multi-split system, timely detect the imbalance of refrigerant distribution and balance the refrigerant distribution between the open outdoor units through refrigerant adjustment actions;

[0050] 2. Design corresponding parameter conditions and refrigerant adjustment actions according to different operating modes, accurately adjust the amount of refrigerant entering each turned-on outdoor unit, and effectively prevent uneven refrigerant distribution in multi-split systems;

[0051] 3. Compare the low pressure value of each turned-on outdoor unit with the standard value, and control the opening of the regulating valve of the refrigerant balancing pipe according to the comparison result, so as to ensure that each turned-on outdoor unit operates under the optimal refrigerant amount;

[0052] 4. The refrigerant balancing pipe of the outdoor unit is connected to the main pipe of the multi-split system. The refrigerant is replenished from the main pipe to the outdoor unit in poor condition, which is beneficial to the stability of the system.

[0053] 5. The refrigerant balancing pipes of the outdoor units are connected to each other, and the refrigerant is replenished from the outdoor unit in good condition to the outdoor unit in poor condition, which simplifies the pipe connection of the multi-split unit and saves engineering installation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The present invention is described in detail below with reference to the embodiments and accompanying drawings, in which:

[0055] Figure 1 This is a schematic diagram of the connection of an external unit of the present invention;

[0056] Figure 2 This is a schematic diagram of the connection of the refrigerant balancing pipe according to one embodiment of the present invention;

[0057] Figure 3 This is a schematic diagram of the connection of a refrigerant balancing pipe according to another embodiment of the present invention;

[0058] Figure 4 This is a schematic diagram of the process of entering the refrigerant regulation action during heating operation of the present invention;

[0059] Figure 5 This is a schematic diagram of the process of analyzing the amount of refrigerant in the outdoor unit during heating operation according to the present invention;

[0060] Figure 6 The present invention is based on the heating operation Figure 2 Schematic diagram of the refrigerant regulation process for the connection method;

[0061] Figure 7 The present invention is based on the heating operation Figure 3 Schematic diagram of the refrigerant regulation process for the connection method;

[0062] Figure 8 This is a schematic diagram of the process of entering the refrigerant adjustment action under refrigeration operation of the present invention;

[0063] Figure 9 This is a schematic diagram of the process of analyzing the amount of refrigerant in the external unit during refrigeration operation according to the present invention;

[0064] Figure 10 The present invention is based on the refrigeration operation Figure 2 Schematic diagram of the refrigerant regulation process for the connection method;

[0065] Figure 11 The present invention is based on the refrigeration operation Figure 3 Schematic diagram of the refrigerant regulation process for the connection method.

[0066] Figure numerals: 1, outdoor unit; 2, main air pipe; 3, main liquid pipe; 101, compressor; 102, outdoor heat exchanger; 103, four-way valve; 104, throttle valve; 105, gas-liquid separator; 106, air pipe; 107, liquid pipe; 108, heating refrigerant balancing pipe; 109, cooling refrigerant balancing pipe; 110, regulating valve; 111, switch valve; 112, subcooler. DETAILED DESCRIPTION

[0067] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0068] The multi-split control method proposed in the present invention can prevent the refrigerant in the outdoor unit from flowing sideways, so that each turned-on outdoor unit is allocated an appropriate amount of refrigerant to ensure the normal operation of each turned-on outdoor unit. Multi-split units include but are not limited to heat pump multi-split units. Conventional multi-split units have an outdoor unit and an indoor unit. The outdoor unit includes a plurality of outdoor units 1 installed in parallel, and the indoor unit includes a plurality of indoor units installed in parallel. Each indoor unit of the indoor unit is connected in parallel between the main gas pipe 2 and the main liquid pipe 3. Each outdoor unit 1 includes a compressor 101 and an outdoor heat exchanger 102, etc. Any outdoor unit 1 can independently circulate refrigerant with at least one indoor unit of the multi-split unit, and can also circulate refrigerant with at least one indoor unit together with other outdoor units.

[0069] like Figure 1 As shown, in some embodiments of the present invention, the operating modes of the multi-split unit include heating operation and cooling operation, and the outdoor unit 1 includes a compressor 101, a four-way valve 103, an outdoor heat exchanger 102, a throttle valve 104, and a gas-liquid separator 105, etc. The first end of the four-way valve 103 is connected to the exhaust port of the compressor 101, the second end is connected to one end of the outdoor heat exchanger 102, the third end is connected to the inlet of the gas-liquid separator 105, and the fourth end is connected to the main gas pipe 2 through the gas pipe 106, and the other end of the outdoor heat exchanger 102 is connected to the main liquid pipe 3 through the liquid pipe 107.

[0070] In order to achieve balanced regulation of the refrigerant amount, the outdoor unit 1 is provided with a heating refrigerant balancing pipe 108 and / or a cooling refrigerant balancing pipe 109 .

[0071] The function of the heating refrigerant balancing pipe 108 is to adjust the refrigerant amount of the external unit during the heating operation. One end of the heating refrigerant balancing pipe 108 is connected to the heating inlet side of the outdoor heat exchanger 102. The other end of the heating refrigerant balancing pipe 108 has two connection options: Figure 2 As shown, the first is connected to the main liquid pipe 3, and the refrigerant is added to the external unit 1 in a bad state from the main liquid pipe 3; Figure 3 As shown, the second method is not connected to the main liquid pipe 3. Instead, the heating refrigerant balancing pipes 108 between the outdoor units 1 are interconnected, and refrigerant is supplied from the outdoor unit 1 in good condition to the outdoor unit 1 in poor condition. Since the heating refrigerant balancing pipe 108 is connected to the heating inlet side of the outdoor heat exchanger 102, liquid refrigerant is supplied to the outdoor heat exchanger 102 during heating operation. Therefore, a regulating valve 110 is installed on the heating refrigerant balancing pipe 108. The opening of the regulating valve 110 is used to adjust the refrigerant flow rate of the outdoor unit 1. The regulating valve 110 can be an electronic expansion valve with a throttling function.

[0072] The function of the refrigeration refrigerant balancing pipe 109 is to adjust the amount of refrigerant to the external unit 1 during the refrigeration operation. One end of the refrigeration refrigerant balancing pipe 109 is connected to the suction side of the compressor 101. The other end of the refrigeration refrigerant balancing pipe 109 has two connection options: Figure 2As shown, the first is connected to the main gas pipe 2, and the refrigerant is added to the outdoor unit 1 in a bad state from the main gas pipe 2; Figure 3 As shown, the second type is not connected to the main gas pipe 2, and the refrigerant balancing pipes 109 between the outdoor units 1 are interconnected, and the refrigerant is supplied from the outdoor unit 1 in good condition to the outdoor unit 1 in poor condition. For the refrigerant balancing pipe 109, since it is connected to the suction side of the compressor 101, and the refrigerant fed into the suction side of the compressor 101 must be gaseous refrigerant, the refrigerant balancing pipe 109 is installed with a switch valve 111 that does not have a throttling function. The amount of refrigerant in the outdoor unit 1 is adjusted by opening or closing the switch valve 111, and the switch valve 111 can be a solenoid valve.

[0073] It should be understood that in specific applications, the refrigeration refrigerant balancing pipe 109 and / or the heating refrigerant balancing pipe 108 can be installed according to different application scenarios of the multi-split system. For example, if the working mode of the multi-split system is only cooling operation, the outdoor unit 1 is only provided with a refrigeration refrigerant balancing pipe 109; if the working mode of the multi-split system is only heating operation, the outdoor unit 1 is only provided with a heating refrigerant balancing pipe 108; if the working mode of the multi-split system includes cooling operation and heating operation, only the heating refrigerant balancing pipe 108 or only the refrigeration refrigerant balancing pipe 109 can be selected, but the preferred solution is that the outdoor unit 1 is provided with both a heating refrigerant balancing pipe 108 and a refrigeration refrigerant balancing pipe 109.

[0074] The design concept of the multi-split control method is to promptly detect the imbalance of refrigerant distribution during the operation of the multi-split system, and balance the refrigerant distribution between the turned-on outdoor units through refrigerant adjustment actions, so that the turned-on outdoor units all operate with a better refrigerant amount, thereby improving the stability of the multi-split system.

[0075] The implementation process of the multi-connection control method is described in detail below.

[0076] Check the operating parameters of each turned-on outdoor unit;

[0077] Determine whether refrigerant bias occurs in the multi-split system based on operating parameters and analyze the refrigerant volume of the turned-on outdoor units;

[0078] If refrigerant bias occurs in a multi-split system or there are both refrigerant-deficient and non-refrigerant-deficient outdoor units, it means that the refrigerant is unevenly distributed among the multi-split outdoor units. The outdoor units with less refrigerant are running in a refrigerant-deficient state or the outdoor units with more refrigerant are running in a refrigerant-excessive state, which will affect the working performance of the outdoor units. Therefore, refrigerant adjustment is required to balance the refrigerant distribution among the turned-on outdoor units.

[0079] It should be pointed out that the design principle of the simultaneous existence of refrigerant-deficient outdoor units and non-refrigerant-deficient outdoor units mentioned above is that if the multi-unit operation status is still acceptable, but all the turned-on outdoor units are refrigerant-deficient outdoor units, the operation status of each outdoor unit is not good. At this time, the refrigerant adjustment action will not only fail to improve the working performance of the outdoor unit, but may even aggravate the degree of refrigerant imbalance, and then cause the multi-unit to enter a poor operating state, resulting in more serious consequences. Therefore, when the multi-unit operation status is still acceptable, the refrigerant adjustment action must be performed when there are refrigerant-deficient outdoor units and non-refrigerant-deficient outdoor units at the same time.

[0080] Generally speaking, the operating modes of a multi-split unit include at least one of heating operation and cooling operation. In order to more accurately control the multi-split unit, corresponding refrigerant shortage parameter conditions and / or refrigerant bias parameter conditions and / or refrigerant adjustment actions are set for different operating modes. The judgment is made based on whether the operating parameters of the turned-on outdoor units meet the corresponding parameter conditions. Since the size of the operating parameters directly affects the accuracy of the judgment result, the preferred solution is to first determine whether the multi-split unit has entered a stable operating state before detecting the operating parameters of each turned-on outdoor unit. If so, the operating parameters of each turned-on outdoor unit are detected. If not, re-determine whether the multi-split unit has entered a stable operating state. There are many ways to determine whether the multi-split unit has entered a stable operating state. For example, in some embodiments of the present invention, after the multi-split unit enters the current operating mode and runs for a set time, it is determined that the multi-split unit has entered a stable operating state. The set time here can be 15 minutes or other values, which can be designed according to the specific model and usage requirements.

[0081] The following describes the parameters and refrigerant adjustment actions for heating and cooling operations respectively.

[0082] Heating operation

[0083] The operating parameters include but are not limited to Tw—outdoor ambient temperature, Tg—saturation temperature obtained by high pressure conversion, Td—saturation temperature obtained by low pressure conversion, Tp—exhaust temperature, and Tx—intake temperature.

[0084] The refrigerant shortage parameter condition for heating operation is Tp-Tg>Ts1 and Tx-Td>Ts2 and Tw-Td>Ts3. Ts1, Ts2 and Ts3 are all preset values. The design principle of the refrigerant shortage parameter condition is that under heating operation, the manifestation of refrigerant shortage in the outdoor unit is that the high pressure and low pressure are too low. In addition, the low-pressure side of the outdoor unit under heating operation is connected to the compressor, and the low pressure change is more obvious. The refrigerant bias flow parameter condition for heating operation is Td max -Td min ≥ Heating set value, select the highest value among all the Td of the turned on outdoor units as Td max , the lowest value is taken as Td minThe design principle of the refrigerant bias flow parameter condition is to determine whether the low pressure difference between the turned-on outdoor units is too large. If the low pressure difference is too large, it means that one of the outdoor units is in a bad state of lack of refrigerant.

[0085] like Figure 4 As shown, the multi-connection control method includes:

[0086] Step S100: The multi-unit machine starts hot operation and enters a stable operation state;

[0087] Step S101, detecting the Td of each turned-on outdoor unit;

[0088] Step S102: Determine whether Td max -Td min ≥ heating set value. If so, it means that the low pressure difference of the turned-on outdoor unit is large, and it is determined that refrigerant bias occurs in the multi-split system, and step S104 is executed. If not, it means that the low pressure difference of the turned-on outdoor unit is small, and step S103 is executed;

[0089] Step S103: Determine whether there are both refrigerant-deficient and non-refrigerant-deficient outdoor units. If so, it indicates that one of the outdoor units is operating in a refrigerant-deficient state, and execute step S104. If not, return to step S101.

[0090] Step S104: Entering the refrigerant adjustment action to balance the refrigerant distribution among the turned-on outdoor units.

[0091] It should be understood that determining whether refrigerant bias occurs in the multi-split system and analyzing the amount of refrigerant in the turned-on outdoor units are performed simultaneously or sequentially.

[0092] like Figure 5 As shown in the figure, the process of analyzing the refrigerant amount of the turned-on outdoor unit is as follows:

[0093] Step S100: The multi-unit machine starts hot operation and enters a stable operation state;

[0094] Step S101, detecting Tw, Tg, Td, Tp and Tx of each turned-on outdoor unit;

[0095] Step S102, determine whether Tp-Tg>Ts1 and Tx-Td>Ts2 and Tw-Td>Ts3. If so, it means that the high pressure and low pressure of the turned-on outdoor unit are too low, reaching the refrigerant deficiency parameter condition for heating operation, and the turned-on outdoor unit is marked as a refrigerant deficiency outdoor unit; if not, the refrigerant deficiency parameter condition for heating operation is not reached, and the turned-on outdoor unit is marked as a non-refrigerant deficiency outdoor unit.

[0096] like Figure 1 、 2As shown, in some embodiments of the present invention, a heating refrigerant balancing pipe 108 is provided on the heating inlet side of the outdoor heat exchanger 102 of each activated outdoor unit. The heating refrigerant balancing pipe 108 is equipped with a regulating valve 110, and the heating refrigerant balancing pipe 108 is connected to the main liquid pipe 3 of the multi-split system. Based on the connection method of the heating refrigerant balancing pipe 108, the refrigerant regulation operation during heating operation includes: calculating a standard value based on the low pressure values ​​of all activated outdoor units, increasing the opening of the regulating valve 110 of the activated outdoor units with a low pressure value ≤ the standard value, thereby increasing the amount of refrigerant flowing from the main liquid pipe 3 into the activated outdoor units with lower low pressure values, thereby increasing the refrigerant flow to these outdoor units; and closing the regulating valve 110 of the activated outdoor units with a low pressure value greater than the standard value, thereby reducing the amount of refrigerant flowing from the main liquid pipe 3 into the activated outdoor units with higher low pressure values, thereby reducing the refrigerant flow to these outdoor units.

[0097] The amount of change in each adjustment of the regulating valve 110 can be designed according to actual needs. The preferred solution is that the amount of change in each adjustment of the regulating valve = |(standard value - low pressure value of the outdoor unit where the regulating valve is located) × β1|, where β1 is the proportional coefficient. The lower the low pressure value of the outdoor unit where the regulating valve 110 is located, the greater the amount of change in the regulating valve 110, the faster the refrigerant distribution speed, and the better the regulation efficiency.

[0098] like Figure 6 As shown in the figure, a specific application example is used to illustrate the execution process of the refrigerant adjustment action:

[0099] Step S200: performing refrigerant adjustment operation;

[0100] Step S201: Detect the low voltage value of the turned-on outdoor unit and calculate the standard value;

[0101] Step S202: Select an outdoor unit that is turned on and has a low pressure value ≤ the standard value, and execute step S203; select an outdoor unit that is turned on and has a low pressure value greater than the standard value, and execute step S204;

[0102] Step S203, open the regulating valve, the increase in valve opening = (standard value - low pressure value of the external unit where the regulating valve is located) × β1;

[0103] Step S204: Determine whether the regulating valve is open. If not, maintain the closed state. If so, execute step S205.

[0104] Step S205 , the amount of reduction in valve body opening = (low pressure value of the external unit where the regulating valve is located - standard value) × β1.

[0105] like Figure 1 、 3As shown, in other embodiments of the present invention, a heating refrigerant balancing pipe 108 is provided on the heating inlet side of the outdoor heat exchanger 102 of each turned-on outdoor unit, the heating refrigerant balancing pipe 108 is installed with a regulating valve 110, and the heating refrigerant balancing pipes 108 between the turned-on outdoor units are connected to each other. Based on the connection method of the heating refrigerant balancing pipe 108, the refrigerant regulation action of the heating operation includes: calculating the standard value according to the low pressure values ​​of all turned on outdoor units, taking the refrigerant-deficient outdoor unit and the turned on outdoor unit with the standard value-low pressure value ≥ Ts7 as the demand outdoor unit, and taking the turned on outdoor unit with the low pressure value > standard value as the supply outdoor unit, and Ts7 is the preset value; increasing the opening of the regulating valve 110 of the demand outdoor unit and the supply outdoor unit according to different proportions, the opening of the regulating valve 110 of the demand outdoor unit is increased at a higher ratio, and the opening of the regulating valve 110 of the supply outdoor unit is increased at a smaller ratio, so that the refrigerant of the supply outdoor unit is replenished into the demand outdoor unit through the heating refrigerant balancing pipe 108, thereby reducing the amount of refrigerant in the supply outdoor unit and increasing the amount of refrigerant in the demand outdoor unit.

[0106] The amount of change in each adjustment of regulating valve 110 can be designed based on actual needs. A preferred solution is: the amount of increase in the regulating valve for the demand unit = (standard value - low pressure value of the unit where the regulating valve is located) × β2; the amount of increase in the regulating valve for the supply unit = (low pressure value of the unit where the regulating valve is located - standard value) × β3. β2 and β3 are both proportional coefficients, and β2 > β3. The lower the low pressure value of the unit where the regulating valve is located, the greater the amount of change in regulating valve 110, resulting in faster refrigerant distribution and improved regulation efficiency.

[0107] like Figure 7 As shown in the figure, a specific application example is used to illustrate the execution process of the refrigerant adjustment action:

[0108] Step S300: performing refrigerant adjustment operation;

[0109] Step S301: Detect the low voltage value of the turned-on outdoor unit and calculate the standard value;

[0110] Step S302: Select an outdoor unit that is short of refrigerant and an outdoor unit that is already turned on and has a standard value - low pressure value ≥ Ts7, and then execute step S303; select an outdoor unit that is already turned on and has a low pressure value greater than the standard value, and then execute step S304;

[0111] Step S303: Open the regulating valve, the increase in valve opening = (standard value - low pressure value of the external unit where the regulating valve is located) × β2;

[0112] Step S304: Open the regulating valve, and the increase in valve opening = (low pressure value of the external unit where the regulating valve is located - standard value) × β3.

[0113] Refrigeration operation

[0114] The operating parameters include but are not limited to Tw—outdoor ambient temperature, Tg—saturation temperature obtained by high pressure conversion, Td—saturation temperature obtained by low pressure conversion, Tp—exhaust temperature, and Tx—intake temperature.

[0115] The refrigerant shortage parameter condition for cooling operation is Tp-Tg>Ts4 and Tx-Td>Ts5 and Tg-Tw<Ts6. Ts4, Ts5 and Ts6 are all preset values. The design principle of the refrigerant shortage parameter condition is that under heating operation, the manifestation of refrigerant shortage in the outdoor unit is that the high pressure and low pressure are too low. In addition, the high pressure side of the outdoor unit is connected to the compressor under cooling operation, and the high pressure change is more obvious. The refrigerant bias flow parameter condition for cooling operation is Td max -Td min ≥ Cooling set value, Td is the saturation temperature obtained by low pressure conversion, and the highest value among all Td of the open outdoor units is selected as Td max , the lowest value is taken as Td min The design principle of the refrigerant bias flow parameter condition is to determine whether the low pressure difference between the turned-on outdoor units is too large. If the low pressure difference is too large, it means that one of the outdoor units is in a bad state of lack of refrigerant.

[0116] like Figure 8 As shown, the multi-connection control method includes:

[0117] Step S400: The multi-unit refrigeration system starts refrigeration and enters a stable operation state;

[0118] Step S401, detecting the Td of each turned-on outdoor unit;

[0119] Step S402: Determine whether Td max -Td min ≥ cooling set value. If so, it means that the low pressure difference of the turned-on outdoor unit is large, and it is determined that refrigerant bias occurs in the multi-split system, and step S404 is executed. If not, it means that the low pressure difference of the turned-on outdoor unit is small, and step S403 is executed;

[0120] Step S403: Determine whether there are both refrigerant-deficient outdoor units and non-refrigerant-deficient outdoor units. If so, it indicates that one outdoor unit is operating in a refrigerant-deficient state, and execute step S404. If not, return to step S401.

[0121] Step S404: Entering the refrigerant adjustment action to balance the refrigerant distribution among the turned-on outdoor units.

[0122] It should be understood that determining whether refrigerant bias occurs in the multi-split system and analyzing the amount of refrigerant in the turned-on outdoor units are performed simultaneously or sequentially.

[0123] like Figure 9 As shown in the figure, the process of analyzing the refrigerant amount of the turned-on outdoor unit is as follows:

[0124] Step S400: The multi-unit refrigeration system starts refrigeration and enters a stable operation state;

[0125] Step S401, detecting Tw, Tg, Td, Tp and Tx of each turned-on outdoor unit;

[0126] Step S402, determine whether Tp-Tg>Ts4 and Tx-Td>Ts5 and Tg-Tw<Ts6. If so, it means that the high pressure and low pressure of the turned-on outdoor unit are too low, reaching the refrigerant deficiency parameter condition for refrigeration operation, and the turned-on outdoor unit is marked as a refrigerant deficiency outdoor unit; if not, the refrigerant deficiency parameter condition for refrigeration operation is not reached, and the turned-on outdoor unit is marked as a non-refrigerant deficiency outdoor unit.

[0127] like Figure 1 、 2 As shown, in some embodiments of the present invention, a refrigerant balancing pipe 109 is provided on the suction side of the compressor 101 of each turned-on outdoor unit. The refrigerant balancing pipe 109 is equipped with an on-off valve 111, and the refrigerant balancing pipe 109 is connected to the main gas pipe 2 of the multi-split unit. Based on the connection method of the refrigerant balancing pipe 109, the refrigerant adjustment operation during cooling operation includes: calculating a standard value based on the low pressure values ​​of all turned-on outdoor units, closing the on-off valve 111 of the turned-on outdoor units with a low pressure value ≤ the standard value, thereby increasing the amount of refrigerant flowing from the main gas pipe 2 into the turned-on outdoor units with a lower low pressure value, thereby increasing the amount of refrigerant in these outdoor units; closing the on-off valve 111 of the turned-on outdoor units with a low pressure value greater than the standard value, thereby reducing the amount of refrigerant flowing from the main gas pipe 2 into the turned-on outdoor units with a higher low pressure value, thereby reducing the amount of refrigerant in these outdoor units.

[0128] like Figure 10 As shown in the figure, a specific application example is used to illustrate the execution process of the refrigerant adjustment action:

[0129] Step S500: performing refrigerant adjustment operation;

[0130] Step S501: Detect the low voltage value of the turned-on outdoor unit and calculate the standard value;

[0131] Step S502: Select an outdoor unit that is turned on and has a low pressure value ≤ the standard value, and execute step S503; select an outdoor unit that is turned on and has a low pressure value greater than the standard value, and execute step S504;

[0132] Step S503: Open the switch valve;

[0133] Step S504: determine whether the switch valve is open. If not, maintain the closed state. If so, execute step S505.

[0134] Step S505: close the switch valve.

[0135] like Figure 1 、 3 As shown, in other embodiments of the present invention, a refrigerant balancing pipe 109 is provided on the suction side of the compressor 101 of each turned-on outdoor unit, and the refrigerant balancing pipe 109 is installed with an on-off valve 111, and the refrigerant balancing pipes 109 between the turned-on outdoor units are interconnected. Based on the connection method of the refrigerant balancing pipe 109, the refrigerant adjustment action of the cooling operation includes: calculating a standard value based on the low pressure values ​​of all turned-on outdoor units, taking the refrigerant-deficient outdoor unit and the turned-on outdoor unit with the standard value - low pressure value ≥ Ts8 as the demand outdoor unit, Ts8 is a preset value, taking the turned-on outdoor unit with a low pressure value greater than the standard value as the supply outdoor unit, connecting the on-off valves 111 of the demand outdoor unit and the supply outdoor unit, so that the refrigerant of the supply outdoor unit is replenished into the demand outdoor unit through the refrigerant balancing pipe, thereby reducing the refrigerant amount of the supply outdoor unit and increasing the refrigerant amount of the demand outdoor unit.

[0136] like Figure 11 As shown in the figure, a specific application example is used to illustrate the execution process of the refrigerant adjustment action:

[0137] Step S600: performing refrigerant adjustment operation;

[0138] Step S601: Detect the low voltage value of the turned-on outdoor unit and calculate the standard value;

[0139] Step S602: Select an outdoor unit that is short of refrigerant, an outdoor unit that is already turned on and has a standard value - low pressure value ≥ Ts8, and an outdoor unit that is already turned on and has a low pressure value greater than the standard value, and execute step S603;

[0140] Step S603: Open the switch valve.

[0141] It should be pointed out that there are multiple ways to calculate the standard value mentioned above. In order to make the standard value more accurate, the preferred solution is to calculate the median of the low-pressure values ​​of all turned-on outdoor units. Since the median can truly reflect the normal low-pressure value of the current outdoor unit, the median is used as the standard value. If the low-pressure value of the turned-on outdoor unit is greater than or equal to the standard value, it means that its low-pressure value is equal to or higher than the normal low-pressure value of the current outdoor unit and the operating status is good. If the low-pressure value of the turned-on outdoor unit is less than the standard value, it means that the low-pressure value is less than the normal low-pressure value of the current outdoor unit and the operating status is poor. Of course, in actual applications, other methods can also be used to calculate the standard value, or the standard value can be designed as a fixed value, and the present invention does not impose any special restrictions on this.

[0142] It should be understood that the low pressure value mentioned above is the saturation temperature Td obtained by converting the low pressure, which generally refers to the saturation temperature corresponding to the pressure value detected by the low pressure sensor on the suction side of the compressor. The heating setting value mentioned above is 5°C, and the cooling setting value is 3°C. The cooling setting value is usually lower than the heating setting value. The setting value can be designed according to specific usage requirements, etc., and the present invention does not impose any special restrictions on this. β1 to β3 mentioned above are all proportional coefficients, β2>β3>β1. Since β1 is the refrigerant balancing pipe connected to the main pipe, the pressure difference between the main pipe and each outdoor unit is large. In order to prevent excessive refrigerant adjustment, the opening of the regulating valve should be adjusted at a smaller ratio, that is, β1 is the smallest. Since β2>β3 is the refrigerant balancing pipe connected to each other, the pressure difference between each outdoor unit is insufficient. In order to speed up the refrigerant adjustment speed, the opening of the regulating valve should be adjusted at a larger ratio. In some embodiments of the present invention, Ts1 and Ts4 are both 40°C, Ts2 is 5°C, Ts3 and Ts6 are both 10°C, Ts5 is 8°C, Ts7 is 3°C, and Ts8 is 2°C. This is because β1 is 10, β2 is 100, and β3 is 50. In actual applications, the set values, proportional coefficients, and preset values ​​can be designed according to the specific model and usage requirements, and the present invention does not impose any special limitations on this.

[0143] like Figure 2 、 3 As shown, the present invention also proposes a multi-split system, including: a controller, at least two outdoor units 1 installed in parallel, and at least one indoor unit, each outdoor unit 1 is connected to the indoor unit through a main air pipe 2 and a main liquid pipe 3, respectively. The controller executes the above-mentioned multi-split control method. When uneven refrigerant distribution occurs during the operation of the multi-split system, a timely and accurate judgment is made, and a refrigerant adjustment action is used to adjust the amount of refrigerant entering each turned-on outdoor unit, effectively preventing the problem of uneven refrigerant distribution in the turned-on outdoor units. Each turned-on outdoor unit is in a good operating state, thereby improving the stability of the multi-split system. The specific control logic has been introduced in detail above.

[0144] The present invention also provides a storage medium, which is used to store a computer program. When the computer program is running, the multi-connection control method is executed.

[0145] It should be noted that the terms used above are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. When the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof. The order of execution of actions, steps, etc. in the devices and methods shown in the specification and the drawings can be implemented in any order as long as there is no special explicit limitation on the order and as long as the output of the previous processing is not used in the subsequent processing. Similar sequential terms used for the convenience of description do not mean that they must be implemented in such an order.

[0146] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0147] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-connection control method, characterized in that: include: Check the operating parameters of each turned-on outdoor unit; Determining whether a refrigerant bias occurs in the multi-split system based on the operating parameters and analyzing the refrigerant amount of the turned-on outdoor unit; If the multi-split system has refrigerant bias or there are both refrigerant-deficient and non-refrigerant-deficient outdoor units, refrigerant adjustment is performed; Wherein, a heating refrigerant balancing pipe is provided on the heating inlet side of the outdoor heat exchanger of each of the outdoor units that has been turned on, the heating refrigerant balancing pipe is installed with a regulating valve, and the heating refrigerant balancing pipe is connected to the main liquid pipe of the multi-split unit; When the multi-split unit is in heating operation, the refrigerant regulation action includes: calculating a standard value based on the low pressure values ​​of all the turned-on outdoor units, increasing the opening of the regulating valves of the turned-on outdoor units whose low pressure values ​​are ≤ the standard value, and closing the regulating valves of the turned-on outdoor units whose low pressure values ​​are greater than the standard value.

2. The multi-connection control method according to claim 1, characterized in that: The amount of change in each adjustment of the regulating valve = |(standard value - low pressure value of the external unit where the regulating valve is located) × β1|, where β1 is a proportional coefficient.

3. A multi-connection control method, characterized in that: include: Check the operating parameters of each turned-on outdoor unit; Determining whether a refrigerant bias occurs in the multi-split system based on the operating parameters and analyzing the refrigerant amount of the turned-on outdoor unit; If the multi-split system has refrigerant bias or there are both refrigerant-deficient and non-refrigerant-deficient outdoor units, refrigerant adjustment is performed; Wherein, a heating refrigerant balancing pipe is provided on the heating inlet side of the outdoor heat exchanger of each of the turned-on outdoor units, the heating refrigerant balancing pipe is installed with a regulating valve, and the heating refrigerant balancing pipes between the turned-on outdoor units are connected to each other; When the multi-split unit is in heating operation, the refrigerant adjustment action includes: calculating a standard value based on the low pressure values ​​of all the turned-on outdoor units, taking the outdoor units lacking refrigerant and the turned-on outdoor units with a standard value - low pressure value ≥ Ts7 as the demand outdoor units, and taking the turned-on outdoor units with a low pressure value greater than the standard value as the supply outdoor units, where Ts7 is a preset value; The openings of the regulating valves of the demand outdoor unit and the supply outdoor unit are increased in different proportions, so that the refrigerant of the supply outdoor unit is replenished into the demand outdoor unit through the heating refrigerant balancing pipe.

4. The multi-connection control method according to claim 3, characterized in that: The amount of increase each time of the regulating valve of the demand outdoor unit = (standard value - low pressure value of the outdoor unit where the regulating valve is located) × β2, and the amount of increase each time of the regulating valve of the supply outdoor unit = (low pressure value of the outdoor unit where the regulating valve is located - standard value) × β3, β2 and β3 are both proportional coefficients, and β2>β3.

5. The multi-connection control method according to claim 1 or 3, characterized in that: When the multi-split unit is in heating operation, the refrigerant bias flow parameter condition is Td max -Td min ≥Heating set value, Td is the saturation temperature obtained by low pressure conversion, and the highest value among all the Td values ​​of the turned-on outdoor units is selected as Td max , the lowest value is taken as Td min ; Determining whether refrigerant bias occurs in the multi-split system according to the operating parameters includes: Determining whether the multi-split unit meets the refrigerant bias flow parameter condition; If yes, it is determined that the multi-split unit has refrigerant bias; If not, determine whether there are both refrigerant-deficient outdoor units and refrigerant-free outdoor units.

6. The multi-connection control method according to claim 1 or 3, characterized in that: When the multi-split unit is in heating operation, the refrigerant shortage parameter conditions are Tp-Tg>Ts1 and Tx-Td>Ts2 and Tw-Td>Ts3, where Tw is the outdoor ambient temperature, Tg is the saturation temperature obtained by high-pressure pressure conversion, Td is the saturation temperature obtained by low-pressure pressure conversion, Tp is the exhaust temperature, Tx is the suction temperature, and Ts1, Ts2 and Ts3 are all preset values; Analyzing the amount of refrigerant in the turned-on outdoor unit according to the operating parameters includes: Determining whether the turned-on outdoor unit meets the refrigerant shortage parameter condition; If so, the turned-on outdoor unit is marked as a refrigerant-deficient outdoor unit; If not, the turned-on outdoor unit is marked as a non-refrigerant-deficient outdoor unit.

7. A multi-connection control method, characterized in that: include: Check the operating parameters of each turned-on outdoor unit; Determining whether a refrigerant bias occurs in the multi-split system based on the operating parameters and analyzing the refrigerant amount of the turned-on outdoor unit; If the multi-split system has refrigerant bias or there are both refrigerant-deficient and non-refrigerant-deficient outdoor units, refrigerant adjustment is performed; Wherein, the suction side of the compressor of each turned-on outdoor unit is provided with a refrigeration refrigerant balancing pipe, the refrigeration refrigerant balancing pipe is installed with a switch valve, and the refrigeration refrigerant balancing pipe is connected to the main gas pipe of the multi-split unit; When the multi-split unit is in cooling operation, the refrigerant adjustment action includes: calculating a standard value based on the low pressure values ​​of all the turned-on outdoor units, connecting the switch valves of the turned-on outdoor units with low pressure values ​​≤ the standard value, and closing the switch valves of the turned-on outdoor units with low pressure values ​​> the standard value.

8. A multi-connection control method, characterized in that: include: Check the operating parameters of each turned-on outdoor unit; Determining whether a refrigerant bias occurs in the multi-split system based on the operating parameters and analyzing the refrigerant amount of the turned-on outdoor unit; If the multi-split system has refrigerant bias or there are both refrigerant-deficient and non-refrigerant-deficient outdoor units, refrigerant adjustment is performed; Wherein, a refrigeration refrigerant balancing pipe is provided on the suction side of the compressor of each of the turned-on outdoor units, the refrigeration refrigerant balancing pipe is installed with a switch valve, and the refrigeration refrigerant balancing pipes between the turned-on outdoor units are connected to each other; When the multi-split unit is in cooling operation, the refrigerant adjustment action includes: calculating a standard value based on the low pressure values ​​of all the turned-on outdoor units, connecting the refrigerant-deficient outdoor units, the turned-on outdoor units with standard value - low pressure value ≥ Ts8, and the switch valves with low pressure value > standard value, where Ts8 is a preset value.

9. The multi-connection control method according to claim 7 or 8, characterized in that: When the multi-split unit is in cooling operation, the refrigerant bias flow parameter condition is Td max -Td min ≥ Cooling set value, Td is the saturation temperature obtained by low pressure conversion, and the highest value among all Td of the open outdoor units is selected as Td max , the lowest value is taken as Td min ; Determining whether refrigerant bias occurs in the multi-split system according to the operating parameters includes: Determining whether the multi-split unit meets the refrigerant bias flow parameter condition; If yes, it is determined that the multi-split unit has refrigerant bias; If not, determine whether there are both refrigerant-deficient outdoor units and refrigerant-free outdoor units.

10. The multi-connection control method according to claim 7 or 8, characterized in that: When the multi-split unit is in cooling operation, the refrigerant shortage parameter condition is Tp-Tg>Ts4 and Tx-Td>Ts5 and Tg-Tw<Ts6, Tw is the outdoor ambient temperature, Tg is the saturation temperature obtained by high pressure conversion, Td is the saturation temperature obtained by low pressure conversion, Tp is the exhaust temperature, Tx is the suction temperature, and Ts4, Ts5 and Ts6 are all preset values; Analyzing the amount of refrigerant in the turned-on outdoor unit according to the operating parameters includes: Determining whether the turned-on outdoor unit meets the refrigerant shortage parameter condition; If so, the turned-on outdoor unit is marked as a refrigerant-deficient outdoor unit; If not, the turned-on outdoor unit is marked as a non-refrigerant-deficient outdoor unit.

11. The multi-connection control method according to any one of claims 1 to 4, 7 to 8, characterized in that: The standard value is the median of the low pressure values ​​of all the turned-on outdoor units.

12. The multi-connection control method according to claim 1, 3, 7 or 8, characterized in that: Before detecting the operating parameters of each turned-on outdoor unit, it is first determined whether the multi-split system has entered a stable operating state. If so, the operating parameters of each turned-on outdoor unit are detected.

13. The multi-connection control method according to claim 12, characterized in that: After the multi-connected system enters the current operation mode and runs for a set time, it is determined that the multi-connected system enters a stable operation state.

14. Multi-connection, including: A controller, at least two external units installed in parallel, and at least one internal unit, each of the external units being connected to the internal unit via a main gas pipe and a main liquid pipe, characterized in that the controller executes the multi-connected control method according to any one of claims 1 to 13.

15. The multi-split system according to claim 14, characterized in that: The outdoor unit is provided with a heating refrigerant balancing pipe and / or a cooling refrigerant balancing pipe. The heating refrigerant balancing pipe is connected to the main liquid pipe or the heating refrigerant balancing pipes between the outdoor units are connected to each other. The cooling refrigerant balancing pipe is connected to the main gas pipe or the cooling refrigerant balancing pipes between the outdoor units are connected to each other.

16. A storage medium for storing a computer program, characterized in that: When the computer program is executed, the multi-connection control method according to any one of claims 1 to 13 is executed.

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