A multi-connected air conditioning system

Abstract

The present invention discloses a multi-split air-conditioning system. For the problem that the capacity of the indoor unit exceeds the range of the outdoor unit capacity due to irregular installation and matching of indoor and outdoor units, incorrect setting of the indoor unit capacity, etc., and the outdoor unit cannot be detected according to normal logic, a technical means is adopted to shut down the specified indoor unit, and compare the changes in the outdoor unit operating parameters and / or the indoor unit operating parameters before and after the shutdown to determine whether there is an over-capacity situation. When there is an over-capacity situation, the degree of over-capacity is determined according to the changes in the indoor coil temperature before and after the shutdown of the specified indoor unit. According to different over-capacity levels, technical means are adopted to dynamically reduce the expansion valve opening corresponding to the indoor unit with a high cooling / heating degree, dynamically reduce the expansion valve opening of the indoor unit whose coil temperature deviates from the set threshold, shut down the corresponding expansion valve when the temperature control is shut down, and / or increase the upper limit of the compressor frequency to dynamically allocate the refrigerant flow of the indoor unit, thereby improving the cooling / heating effect of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to a multi-split air conditioning system. Background Art

[0002] A multi-split air conditioning system is a refrigeration / heat cycle system consisting of one or more outdoor units connected to several indoor units of the same or different capacities, which can directly provide treated air to one or several areas.

[0003] All indoor units in a multi-split air conditioning system are often not operated at the same time, and each indoor unit has obvious time-sharing characteristics. Therefore, in the design of a multi-split air conditioning system, the total capacity of the indoor unit and the capacity of the outdoor unit are usually designed to be within a deviation range; taking the design of the capacity deviation range of the indoor unit and the outdoor unit to be 75%-125% as an example, assuming that the capacity of the outdoor unit is 10 horsepower, the total capacity of the indoor unit is between 7.5 horsepower and 12.5 horsepower. Assuming that the user installs a 10-horsepower outdoor unit, 7 1-horsepower and 3 2-horsepower indoor units, the total capacity of the indoor unit is 7+3*2=13 horsepower, which exceeds the designed capacity deviation range, and the system will alarm and cannot operate normally. However, if the system has been installed, the possibility of disassembly is almost zero; in response to this problem, the manufacturer will adjust the capacity of the indoor unit to avoid the alarm range. For example, the capacity of one of the 2-horsepower indoor units is changed to 1 horsepower. At this time, the total capacity is 7+2*2+1=12 horsepower, so that the system alarm range can be avoided and the system operation can be maintained.

[0004] However, in this case, the system is already over-capacitated, which will affect the cooling / heating effect. A small-scale over-capacity will not cause users to notice, but a large-scale over-capacity will seriously reduce the cooling / heating effect of the air-conditioning system. Summary of the invention

[0005] The object of the present invention is to provide a multi-split air-conditioning system. When the capacity of the indoor unit exceeds the capacity range of the outdoor unit, the over-capacity situation is detected according to the operating parameters of the indoor and outdoor units, and the severity of the over-capacity is divided. Based on the severity of the over-capacity, without changing the installation structure, the operating capacity of the outdoor unit is allocated and the refrigerant flow of the indoor unit is controlled to solve the technical problem of poor cooling / heating effect of the air-conditioning system when over-capacity occurs.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] A multi-split air conditioning system is proposed, comprising:

[0008] At least one outdoor unit and multiple indoor units; each indoor unit is equipped with an expansion valve;

[0009] When the controller is configured so that the indoor unit capacity exceeds the outdoor unit capacity range and the outdoor unit cannot be detected, perform the following steps:

[0010] Over-allocation detection: shut down the specified indoor unit, and determine whether the system is over-allocated based on the changes in the operating parameters of the indoor units and / or outdoor units before and after shutdown;

[0011] Determination of over-allocation degree: When the system is over-allocated, compare the changes in the coil temperatures of each indoor unit before and after shutting down the specified indoor unit, and determine the degree of over-allocation based on the changes;

[0012] According to the degree of over-allocation, one or more of the following controls are selected to implement refrigerant redistribution: (1) Sort the indoor units by coil temperature at a set time interval, reduce the opening of the expansion valve of the indoor unit with a high degree of cooling / heating or close the expansion valve, and adjust the expansion valves of other indoor units according to the set value; (2) For indoor units that are turned on by temperature control, reduce the opening of the expansion valve of the indoor unit whose coil temperature deviates from the set threshold; (3) For indoor units that are turned off by temperature control, close their expansion valves; (4) Increase the upper limit of the compressor operating frequency.

[0013] Compared with the prior art, the advantages and positive effects of the air-conditioning system are as follows: for the multi-split air-conditioning system proposed in the present invention, for the problem that the capacity of the indoor unit exceeds the range of the outdoor unit capacity due to irregular installation and matching of the indoor and outdoor units, incorrect setting of the indoor unit capacity, etc., and the outdoor unit cannot be detected according to normal logic, a technical means of shutting down the designated indoor unit and comparing the changes in the outdoor unit operating parameters and / or the indoor unit operating parameters before and after the shutdown is used to determine whether there is an over-capacity situation. When there is an over-capacity situation, the degree of over-capacity is determined according to the changes in the indoor coil temperature before and after the shutdown of the designated indoor unit. For different degrees of over-capacity, technical means of dynamically reducing the expansion valve opening corresponding to the indoor unit with a high degree of cooling / heating, dynamically reducing the expansion valve opening of the indoor unit whose coil temperature deviates from the set threshold, shutting down the corresponding expansion valve when the temperature control is shut down, and / or increasing the upper limit of the compressor frequency are used to dynamically allocate the refrigerant flow of the indoor unit, thereby realizing intelligent allocation of the outdoor unit operating capacity under system over-capacity conditions and improving the cooling / heating effect of the system.

[0014] In some embodiments of the present invention, when the controller performs over-configuration detection, it includes: obtaining the first outdoor unit operating parameters and the first indoor unit operating parameters after the system operates stably in a designated mode; the designated mode is a cooling mode or a heating mode; turning off the first designated indoor unit, and obtaining the second outdoor unit operating parameters and the second indoor unit operating parameters after the system operates stably; comparing the first outdoor unit operating parameters and the second outdoor unit operating parameters, and comparing the first indoor unit operating parameters and the second indoor unit operating parameters; when the change of the outdoor unit operating parameters exceeds the first over-configuration threshold and the indoor unit operating parameters do not change, judging that the system is not over-configured; when the change of the outdoor unit operating parameters does not exceed the first over-configuration threshold, judging that the system is over-configured.

[0015] The outdoor unit operating parameters include high pressure, low pressure, exhaust temperature, suction temperature, etc., and the indoor unit operating parameters include coil temperature, outlet temperature, suction temperature, etc. For a multi-split air conditioning system, if the system is over-provisioned, the outdoor unit operating parameters are normal, but the indoor unit operating parameters will be affected by the over-provisioning and deviate from the set values. After the designated indoor unit is turned off, the outdoor unit operating parameters will not change significantly, but since the designated indoor unit is turned off, the operating effects of other indoor units will improve, so the indoor unit operating parameters will change; if the system is not over-provisioned, the indoor unit operating parameters will not be affected regardless of whether the designated indoor unit is turned off, but the outdoor unit operating parameters will change significantly. This embodiment achieves rapid detection of system over-provisioning by acquiring and comparing the outdoor unit operating parameters and indoor unit operating parameters acquired twice before and after the designated indoor unit is turned off.

[0016] In some embodiments of the present invention, the controller is further configured to: obtain the first indoor unit coil temperature after running in a specified mode until it is stable; and obtain the second indoor unit coil temperature after shutting down the first specified indoor unit system and running it until it is stable; when it is determined that the system is over-allocated, compare the first indoor unit coil temperature and the second indoor unit coil temperature, and determine the degree of system over-allocation based on changes in the indoor unit coil temperatures.

[0017] When the operating parameters of the outdoor unit do not change significantly before and after the designated indoor unit is shut down and the system is judged to be over-configured, the present invention further judges the degree of system over-configuration by comparing the degree of change in the temperature of the indoor unit coil before and after the designated indoor unit is shut down, so as to realize the judgment of the severity of the system over-configuration and provide an accurate basis for adjusting the over-configuration.

[0018] In some embodiments of the present invention, the controller is further configured to: when judging the degree of system over-provisioning based on the change in the indoor unit coil temperature, if the change in the indoor unit coil temperature does not exceed the second over-provisioning threshold, it is judged as low over-provisioning; if the change in the indoor unit coil temperature exceeds the second over-provisioning threshold, it is judged as high over-provisioning.

[0019] A second over-provisioning threshold is divided according to empirical values ​​or statistical values, and the system over-provisioning degree is divided into two levels: low over-provisioning and high over-provisioning, so as to judge the severity of the system over-provisioning and provide an accurate basis for adjusting the over-provisioning situation.

[0020] In some embodiments of the present invention, the controller is further configured to: shut down the third designated indoor unit when it is determined that the system is highly over-provisioned; obtain the third indoor unit coil temperature after the system runs to stability; compare the second indoor unit coil temperature with the third indoor unit coil temperature, and determine it as moderate over-provisioning when the change in the indoor unit coil temperature does not exceed the third over-provisioning threshold; and determine it as severe over-provisioning when the change in the indoor unit coil temperature exceeds the third over-provisioning threshold.

[0021] For high over-allocation conditions, the designated indoor unit is shut down again, and a third over-allocation threshold is divided according to empirical values ​​or statistical values. By comparing the change in the indoor unit coil temperature before and after shutting down the designated indoor unit with the third over-allocation threshold, the high over-allocation situation is subdivided into medium over-allocation and severe over-allocation, thereby realizing the judgment of the severity of the system over-allocation and providing an accurate basis for adjusting the over-allocation situation.

[0022] In some embodiments of the present invention, the controller is further configured to: shut down the second designated indoor unit when it is determined to be low over-provisioning; obtain the third outdoor unit operating parameters and the third indoor unit operating parameters after the system operation is stable; compare the second outdoor unit operating parameters and the third outdoor unit operating parameters, and compare the second indoor unit operating parameters and the third indoor unit operating parameters; confirm the determination of low over-provisioning when the changes in the outdoor unit operating parameters and the indoor unit operating parameters are within the set range, otherwise, judge the degree of system over-provisioning again based on the changes in the indoor unit coil temperature.

[0023] When the system over-provisioning situation is judged to be low over-provisioning, in order to avoid errors in judging the low over-provisioning situation due to fluctuations in system operating conditions, the low over-provisioning situation is analyzed and confirmed again by shutting down the second designated indoor unit and comparing the changes in the outdoor unit operating parameters and the indoor unit operating parameters before and after the shutdown.

[0024] In some embodiments of the present invention, when determining a low over-matching condition, the controller is configured to: 1) sort the indoor units by coil temperature at a set time interval: for the indoor unit with the highest cooling / heating degree, reduce the corresponding expansion valve opening by a first set percentage; for the indoor unit with the second highest cooling / heating degree, reduce the corresponding expansion valve opening by a second set percentage; 2) when there is no indoor unit temperature control shutdown, reduce the expansion valve opening of the indoor unit whose coil temperature deviates from the set threshold by a third percentage; 3) when the indoor unit temperature control shutdown occurs, close its corresponding expansion valve and stop the control of 1 and 2.

[0025] When the system is judged to be under low overcapacity, the system capacity is allocated under low overcapacity by combining the means of dynamically reducing the expansion valve opening of the indoor unit with the highest cooling / heating degree and dynamically reducing the expansion valve opening of the indoor unit whose coil temperature deviates from the set threshold, thereby ensuring the balance of indoor unit capacity. Under low overcapacity, when the outdoor unit is shut down by temperature control and the outdoor unit capacity is sufficient to meet the needs of the indoor unit, the expansion valve of the indoor unit that is shut down by temperature control will be closed, and the indoor units in the system will operate according to the set parameters.

[0026] In some embodiments of the present invention, when determining a moderate over-capacity, the controller is configured to: 1) sort the indoor units by coil temperature at a set time interval: for the indoor unit with the highest cooling / heating degree, reduce the corresponding expansion valve opening by a fourth set percentage; for the indoor unit with the second highest cooling / heating degree, reduce the corresponding expansion valve opening by a fifth set percentage; 2) when there is no indoor unit temperature control shutdown, reduce the expansion valve opening of the indoor unit whose coil temperature deviates from the set threshold by a sixth percentage; 3) increase the compressor frequency; 4) when the indoor unit temperature control shutdown occurs, close its corresponding expansion valve and stop the controls of 1, 2 and 3.

[0027] When the system is judged to be moderately over-capacitated, the system capacity is allocated in the case of moderate over-capacity and the capacity of the indoor units is balanced, by combining the means of dynamically reducing the expansion valve openings of the indoor units with the highest and second highest cooling / heating levels in different proportions, dynamically reducing the expansion valve openings of the indoor units whose coil temperatures deviate from the set threshold, and increasing the compressor frequency. In this way, the system capacity is balanced in the case of moderate over-capacity and the capacity of the indoor units is ensured. In the case of moderate over-capacity, when the outdoor unit is shut down by temperature control, the outdoor unit capacity can basically meet the needs of the indoor units. In the case of a temperature-controlled indoor unit, its expansion valve is closed and the indoor units in the system operate according to the set parameters.

[0028] In some embodiments of the present invention, when determining a severe over-allocation, the controller is configured to: 1) sort the indoor units by coil temperature at a set time interval: close the corresponding expansion valve of the indoor unit with the highest cooling / heating degree; reduce the opening of the corresponding expansion valve of the indoor unit with the second highest cooling / heating degree by the seventh set percentage; and adjust the speed of the indoor fan to the minimum; 2) for the indoor units that are turned on by temperature control, reduce the opening of the expansion valve of the indoor units whose coil temperatures deviate from the set threshold by an eighth percentage; 3) for the indoor units that are turned off by temperature control, close their expansion valves; and, sort the indoor units by coil temperature at a second set time interval, reduce the opening of the expansion valve corresponding to the indoor unit with the highest cooling / heating degree by a ninth percentage; 4) increase the compressor frequency; as mentioned above, 1 is not executed when 3 is executed, and 1 is executed when there is no indoor unit that is turned off by temperature control.

[0029] In the case of severe over-allocation, the controller is further configured to: 5) not execute 1, 2, 3 and 4 when the number of indoor units that are temperature-controlled and shut down exceeds the shutdown threshold.

[0030] When the system is judged to be severely over-provisioned, in the absence of temperature control shutdown, the system capacity is evenly distributed by dynamically reducing the expansion valve opening of the indoor units with the highest and second highest cooling / heating levels in different proportions, adjusting the speed of the indoor fan to the lowest gear, dynamically reducing the expansion valve opening of the indoor units whose coil temperatures deviate from the set threshold, and increasing the compressor frequency; in the presence of temperature control shutdown and the number of shutdowns does not exceed the shutdown threshold, the system capacity is evenly distributed by closing the expansion valve of the indoor unit with temperature control shutdown and dynamically reducing the expansion valve opening of the indoor unit with the highest cooling / heating level, dynamically reducing the expansion valve opening of the indoor unit whose coil temperatures deviate from the set threshold, and increasing the compressor frequency; in the presence of temperature control shutdown and the number of shutdowns exceeds the shutdown threshold, if the outdoor unit capacity is sufficient to meet the needs of the indoor units, the expansion valve of the indoor unit with temperature control shutdown is closed, and the indoor units of the system operate according to the set parameters.

[0031] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 A schematic diagram of the system architecture of the multi-split air conditioning system proposed by the present invention;

[0034] Figure 2 The following is a schematic diagram of the processing steps of the multi-split air conditioning system proposed by the present invention for the over-allocation of the system;

[0035] Figure 3 It is the room temperature curve for adjusting the system when the existing multi-split air conditioning system is over-allocated;

[0036] Figure 4 The room temperature curve of the multi-split air conditioning system of the present invention after processing the system over-allocation situation;

[0037] Figure 5 The following is a schematic diagram of the steps for detecting the over-provisioning of the system according to the first embodiment of the present invention;

[0038] Figure 6The following is a schematic diagram of the steps for analyzing the degree of over-provisioning of the system in the second embodiment of the present invention;

[0039] Figure 7 This is another step of analyzing the degree of over-provisioning by the system according to the third embodiment of the present invention;

[0040] Figure 8 This is another step of analyzing the degree of over-provisioning by the system according to the fourth embodiment of the present invention;

[0041] Fig. 9 It is a schematic diagram of the steps of implementing outdoor unit reallocation in the low over-allocation situation provided by the system in the fifth embodiment of the present invention;

[0042] Fig.10 It is a schematic diagram of the steps of implementing outdoor unit reallocation for a moderate over-allocation situation in the system according to the fifth embodiment of the present invention;

[0043] Fig.11 The figure is a schematic diagram of the steps of implementing outdoor unit reallocation in a system in a severe over-allocation situation according to the fifth embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0046] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0047] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0048] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0049] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0050] The multi-split air conditioning system provided in the present application performs the cooling / heating cycle of the air conditioner by using a compressor, a condenser, an expansion valve and an evaporator. The cooling / heating cycle includes a series of processes involving compression, condensation, expansion and evaporation to cool or heat the indoor space.

[0051] The low-temperature and low-pressure refrigerant enters the compressor, which compresses it into high-temperature and high-pressure refrigerant gas and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0052] The expansion valve expands the high-temperature and high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the low-temperature and low-pressure refrigerant gas to the compressor. The evaporator can achieve a cooling effect by utilizing the latent heat of evaporation of the refrigerant to exchange heat with the material to be cooled. In the entire cycle, the air conditioner can adjust the temperature of the indoor space.

[0053] The outdoor unit of the air conditioner refers to a portion of a cooling / heating cycle including a compressor and an outdoor heat exchanger, the indoor unit of the air conditioner includes an indoor heat exchanger, and an expansion valve may be provided in the indoor unit or the outdoor unit.

[0054] The indoor heat exchanger and the outdoor heat exchanger function as a condenser or an evaporator. When the indoor heat exchanger functions as a condenser, the air conditioner functions as a heater in a heating mode, and when the indoor heat exchanger functions as an evaporator, the air conditioner functions as a cooler in a cooling mode.

[0055] The present invention aims to provide a method for allocating system capacity according to different over-capacity levels, in order to address the situation in which the capacity of the indoor unit exceeds the capacity of the outdoor unit due to irregular installation and matching of the indoor and outdoor units, incorrect setting of the indoor unit capacity, and the outdoor unit cannot be detected according to normal logic. The method can detect whether there is an over-capacity situation, judge the degree of over-capacity when it exists, and provide system capacity allocation method according to different over-capacity levels, thereby realizing capacity over-capacity detection and fault-tolerant intelligent control, and solving the technical problem of poor effect when an over-capacity situation exists in a multi-split air-conditioning system.

[0056] like Figure 1 As shown, the multi-split air conditioning system proposed by the present invention comprises:

[0057] At least one outdoor unit 1 and a plurality of indoor units 2, each of which is equipped with an expansion valve (not shown in the figure).

[0058] The multi-split air conditioning system proposed in the present invention includes, but is not limited to, a controller of an outdoor unit, a central controller, a controller of an intelligent control terminal, a wired controller, etc. Figure 2 As shown, it is configured to perform the following steps:

[0059] S1. Over-provisioning detection: Shut down the designated indoor unit and determine whether the system is over-provisioning based on the changes in the operating parameters of the indoor units and outdoor units before and after shutdown.

[0060] If the system does not have an over-allocation situation, both the outdoor unit and the indoor unit can perform cooling / heating tasks according to the set parameters; if the system has an over-allocation situation, the outdoor unit performs the working conditions according to the set parameters. When all the indoor units are turned on and running, each indoor unit cannot be allocated enough capacity to achieve the effect required by the set parameters. However, if an indoor unit is turned off, the capacity of the outdoor unit can be more allocated to other indoor units, thereby improving the operating capacity of other indoor units. For this reason, the present invention adopts the method of shutting down the designated indoor unit, obtaining the system operating parameters before and after the designated indoor unit is shut down: including the operating parameters of the outdoor unit and the operating parameters of each indoor unit, and comparing and judging the operating parameters to analyze the system over-allocation situation.

[0061] S2. Determination of over-allocation degree: When the system is over-allocated, compare the changes in the coil temperatures of each indoor unit before and after shutting down the specified indoor unit, and determine the degree of over-allocation based on the changes.

[0062] The effect of cooling / heating is most directly reflected in the indoor unit coil temperature. When the system is judged to be over-allocated according to S1, the cooling / heating temperature of the indoor unit will definitely deviate from the requirements of the set parameters. For example, in cooling mode, the set parameters require the indoor temperature to reach 25ºC, but because the system allocation capacity is insufficient, the indoor unit coil temperature is not low enough and the indoor temperature cannot be reduced to 25ºC; when the designated indoor unit is turned off, the other indoor units can be allocated more capacity to implement cooling / heating, and the indoor unit coil temperature will decrease / increase. If the over-allocation is relatively minor, when the designated indoor unit is turned off, the coil temperature of the other indoor units will not change much. If the over-allocation is more serious, when the designated indoor unit is turned off, the coil temperature of the other indoor units will change significantly.

[0063] S3. Select one or more of the following controls to implement refrigerant redistribution according to the degree of over-allocation:

[0064] (1) Sort the indoor units by coil temperature at set time intervals to adjust the cooling / heating

[0065] The indoor unit with a higher degree of expansion reduces the opening of its expansion valve or closes the expansion valve, and the expansion valves of other indoor units are adjusted according to the set value.

[0066] That is, during the cooling / heating period of the system, the coil temperature of each indoor unit is dynamically detected, and the coil temperature is adjusted according to the coil temperature.

[0067] The indoor units are sorted according to the pipe temperature, and the indoor units with high cooling / heating degree are found. The opening of their expansion valves is adjusted according to the decreasing trend based on the original opening to reduce their refrigerant flow rate, thereby increasing the refrigerant flow rate of other indoor units, thereby achieving rapid cooling / heating.

[0068] Adjusting in a dynamic manner can prevent the same indoor unit from operating under the condition of reduced expansion valve opening for a long time, so that at the end of the set time interval, when it is sorted again and it is determined that it is not an indoor unit with a high degree of cooling / heating, the expansion valve will no longer be reduced but adjusted according to the normal opening, so that the cooling / heating temperature of the corresponding indoor unit will not deviate too far from the set parameters, but fluctuate around the set parameters.

[0069] (2) For indoor units that are turned on by temperature control, reduce the indoor units whose coil temperature deviates from the set threshold

[0070] expansion valve opening.

[0071] For indoor units in the temperature control on state, if the coil temperature deviates from the set threshold, the expansion

[0072] The expansion valve opening is adjusted to a decreasing trend on the original basis. For example, under cooling conditions, the threshold is set to 8 ºC. If the coil temperature is lower than 8 ºC, it means that the indoor unit refrigeration fully meets the user's needs, and the expansion valve opening can be appropriately adjusted to a decreasing trend.

[0073] In the present invention, the deviation from the set threshold is defined corresponding to the system operating condition, for example, in the cooling condition, it particularly refers to being lower than the set threshold, and in the heating condition, it particularly refers to being higher than the set threshold.

[0074] (3) For indoor units that are temperature-controlled and shut down, close their expansion valves.

[0075] For indoor units that are shut down by temperature control, their expansion valves are completely closed to distribute the refrigerant to the other indoor units to the greatest extent possible.

[0076] (4) Increase the upper limit of the compressor operating frequency.

[0077] When the system is developed and designed, a certain design margin is usually reserved to ensure reliable operation. Reducing the design margin in a small range will not affect the reliability of the system and can improve system performance. For example, the frequency will be limited when the current is too large, and the compressor frequency will be limited when the pressure is too high or too low. When the system is over-equipped, the upper limit of the compressor operating frequency can be appropriately increased to improve the operating capacity of each indoor unit.

[0078] In actual applications, when increasing the operating frequency of the compressor, the system's protection value for the compressor frequency limit must also be released. Usually, the degree of release of the protection value is lower than the amplitude of the compressor frequency increase. For example, the compressor frequency is increased by 5%, and the protection value is increased by 3%.

[0079] As described above, the present invention first analyzes the over-capacity situation of the system, determines the over-capacity degree when there is an over-capacity situation, and redistributes the capacity of the outdoor unit according to the over-capacity situation by combining one or more technical means, and finally realizes the intelligent control of capacity over-capacity detection and fault tolerance, so as to solve the problem of poor cooling / heating effect of the air-conditioning system under the over-capacity situation. Figure 3 As shown, when the solution proposed by the present invention is not used, the indoor temperature always fails to reach the set temperature, and the user experience is poor. Figure 4 As shown, after using the solution of the present invention, the room temperature curve fluctuates above and below the set temperature, achieving the effect of room temperature control in variable frequency control.

[0080] The following is a detailed description of the application of the solution proposed by the present invention in a multi-split air conditioning system with several specific embodiments.

[0081] Embodiment 1

[0082] This embodiment detects whether the multi-split air conditioning system is over-provisioned. Specifically, Figure 5 As shown, the following steps are included:

[0083] S51. Obtaining operating parameters of the first outdoor unit and the first indoor unit after stable operation in a designated mode; the designated mode is a cooling mode or a heating mode.

[0084] Taking the cooling mode as the designated mode as an example, after the cooling mode runs stably, the first outdoor operating parameter and the first indoor operating parameter are acquired.

[0085] The operating parameters of the outdoor unit include high pressure, low pressure, exhaust temperature, suction temperature, etc., and the operating parameters of the indoor unit include coil temperature, outlet temperature, suction temperature, etc.

[0086] S52: Turn off the first designated indoor unit, and obtain the operating parameters of the second outdoor unit and the second indoor unit after the system runs stably.

[0087] The first designated indoor unit may be one or more indoor units with the smallest or smaller capacity, for example. Trial and error is started with a small-capacity indoor unit. After shutting it down until the system runs stably, the operating parameters of the second outdoor unit and the second indoor unit are obtained.

[0088] S53: Compare the operating parameters of the first outdoor unit and the second outdoor unit, and compare the operating parameters of the first indoor unit and the second indoor unit.

[0089] The outdoor unit operating parameters and indoor unit operating parameters before and after shutting down the designated indoor unit are compared.

[0090] S54: When the change of the outdoor unit operating parameter exceeds the first over-allocation threshold and the indoor unit operating parameter does not change, determine that the system is not over-allocated.

[0091] If there is no over-provisioning in the system, the indoor unit operating parameters will not be affected regardless of whether the first designated indoor unit is turned off. On the contrary, the outdoor unit operating parameters will change significantly. This embodiment achieves rapid detection of the system over-provisioning by acquiring and comparing the outdoor unit operating parameters and the indoor unit operating parameters obtained twice before and after the first designated indoor unit is turned off.

[0092] S55: When the change of the outdoor unit operating parameter does not exceed the first over-provisioning threshold, determine that the system is over-provisioned.

[0093] For a multi-split air-conditioning system, if the system is over-provisioned, the operating parameters of the outdoor unit are normal, but the operating parameters of the indoor unit will be affected by the over-provisioning and deviate from the set values. After shutting down the first designated indoor unit, the operating parameters of the outdoor unit will not change significantly, but since the designated indoor unit is shut down, the operating effects of other indoor units will improve, so the operating parameters of the indoor unit will change.

[0094] By adopting the system over-capacity detection method provided in the present embodiment, the over-capacity of the indoor unit capacity in the multi-split air-conditioning system can be accurately detected, especially when the indoor unit capacity of the multi-split air-conditioning system exceeds the outdoor unit capacity range due to reasons such as irregular installation and matching of the indoor and outdoor units, incorrect setting of the indoor unit capacity, and the outdoor unit cannot be detected according to normal logic, the control logic provided in the present embodiment can also accurately detect whether the indoor unit and outdoor unit capacities match, thereby reducing the difficulty of detecting the system over-capacity.

[0095] Embodiment 2

[0096] When the system is judged to be over-capacitated based on the fact that the operating parameters of the outdoor unit have not changed significantly before and after the first designated indoor unit is shut down, this embodiment provides a method for analyzing the degree of over-capacity of a multi-split air-conditioning system to judge the degree of over-capacity of the system and provide an accurate basis for adjusting the over-capacity.

[0097] Specifically, Figure 6 As shown, including:

[0098] S61. Obtain the coil temperature of the first indoor unit after the indoor unit runs in a specified mode until it becomes stable.

[0099] Taking the cooling mode as an example, after the cooling mode runs stably, the first indoor unit coil temperature of each indoor unit is obtained.

[0100] S62: After the first designated indoor unit is turned off and the system runs stably, the coil temperature of the second indoor unit is obtained.

[0101] Turn off the first designated indoor unit until the system runs stably, and then obtain the coil temperature of each indoor unit again.

[0102] S63. When determining whether the system is over-allocated, compare the first indoor unit coil temperature with the second indoor unit coil temperature, and determine the degree of system over-allocation according to changes in the indoor unit coil temperatures.

[0103] In actual applications, the coil temperatures of each indoor unit obtained twice before and after are compared. When the coil temperature of at least one indoor unit changes significantly, it means that after shutting down an indoor unit, the indoor unit is allocated refrigerant sufficient to improve its cooling capacity, indicating that the system is over-allocated.

[0104] If the coil temperatures of all indoor units change, but the degree of change is not large, it means that before the first designated indoor unit is turned off, the system over-capacity is low, and after the first designated indoor unit is turned off, the refrigerant allocated to each indoor unit does not significantly improve its cooling capacity.

[0105] Embodiment 3

[0106] Based on the second embodiment, this embodiment further refines the degree of system over-provisioning, providing a more accurate basis for subsequent adjustments to the over-provisioning situation.

[0107] like Figure 7 As shown, this embodiment includes:

[0108] S71. Obtain the coil temperature of the first indoor unit after the unit runs in a specified mode until it becomes stable.

[0109] Still taking the cooling mode as an example, after the cooling mode runs stably, the first indoor unit coil temperature of each indoor unit is obtained.

[0110] S72: After the first designated indoor unit is turned off and the system runs stably, the coil temperature of the second indoor unit is obtained.

[0111] Turn off the first designated indoor unit until the system runs stably, and then obtain the coil temperature of each indoor unit again.

[0112] S73: Compare the first indoor unit coil temperature with the second indoor unit coil temperature, and determine the relationship between the change in the indoor unit coil temperature and the second over-allocation threshold.

[0113] The coil temperatures of each indoor unit obtained twice before and after are compared, and the change of the coil temperature of the indoor unit is compared with the second over-allocation threshold.

[0114] The second over-provisioning threshold is divided according to an empirical value or a statistical value, aiming to divide the degree of system over-provisioning into two levels, low over-provisioning and high over-provisioning, so as to judge the severity of system over-provisioning.

[0115] S74: The change in the indoor unit coil temperature does not exceed the second over-allocation threshold, and is determined to be low over-allocation.

[0116] S75: When the change in the indoor unit coil temperature exceeds the second over-allocation threshold, it is determined to be a high over-allocation.

[0117] In some embodiments of the present invention, when it is determined to be low over-provisioning, in order to avoid errors in judging the low over-provisioning situation due to fluctuations in system operating conditions, the low over-provisioning situation is analyzed and confirmed again by shutting down the second designated indoor unit and comparing the changes in the operating parameters of the outdoor unit and the indoor unit before and after the shutdown.

[0118] Specifically, Figure 7 As shown, including:

[0119] S76. Turn off the second designated indoor unit.

[0120] The second designated indoor unit is an indoor unit with a smaller capacity.

[0121] S77. After the system runs stably, obtain the operating parameters of the third outdoor unit and the third indoor unit, compare the operating parameters of the second outdoor unit and the third outdoor unit, and compare the operating parameters of the second indoor unit and the third indoor unit.

[0122] When the changes of the outdoor unit operating parameters and the indoor unit operating parameters are both within the set range, the low over-allocation determination is confirmed, otherwise, the process returns to step S71 to determine the system over-allocation degree again according to the change of the indoor unit coil temperature.

[0123] Embodiment 4

[0124] Based on the second embodiment, this embodiment proposes another method for dividing the degree of over-allocation, such as Figure 8 As shown, including:

[0125] S81. Obtain the coil temperature of the first indoor unit after the indoor unit runs in a specified mode until it becomes stable.

[0126] Still taking the cooling mode as an example, after the cooling mode runs stably, the first indoor unit coil temperature of each indoor unit is obtained.

[0127] S82: After the first designated indoor unit is turned off and the system runs stably, the coil temperature of the second indoor unit is obtained.

[0128] Turn off the first designated indoor unit until the system runs stably, and then obtain the coil temperature of each indoor unit again.

[0129] S83: Compare the first indoor unit coil temperature with the second indoor unit coil temperature, and determine the relationship between the change in the indoor unit coil temperature and the second over-allocation threshold.

[0130] The coil temperatures of each indoor unit obtained twice before and after are compared, and the change of the coil temperature of the indoor unit is compared with the second over-allocation threshold.

[0131] The second over-provisioning threshold is divided according to an empirical value or a statistical value, aiming to divide the degree of system over-provisioning into two levels, low over-provisioning and high over-provisioning, so as to judge the severity of system over-provisioning.

[0132] S84: The change in the indoor unit coil temperature does not exceed the second over-allocation threshold, and is determined to be low over-allocation.

[0133] S85: When the change in the indoor unit coil temperature exceeds the second over-allocation threshold, shut down the third designated indoor unit.

[0134] The third designated indoor unit selects an indoor unit with a slightly larger capacity, aiming to further divide the high over-allocation situation through significant changes in indoor and outdoor operating parameters.

[0135] S86. After the system runs to a stable state, the coil temperature of the third indoor unit is obtained.

[0136] S87: Compare the coil temperature of the second indoor unit and the coil temperature of the third indoor unit.

[0137] S88: When the change in the indoor unit coil temperature does not exceed the third over-allocation threshold, it is determined to be moderate over-allocation.

[0138] S89: When the change in the indoor unit coil temperature exceeds a third over-allocation threshold, it is determined to be severe over-allocation.

[0139] In this embodiment, for the high over-allocation condition, the designated indoor unit is shut down again, and a third over-allocation threshold is divided according to the empirical value or the statistical value. By comparing the change of the indoor unit coil temperature before and after shutting down the designated indoor unit with the third over-allocation threshold, the high over-allocation situation is subdivided into medium over-allocation degree and severe over-allocation degree, so as to judge the severity of the system over-allocation and provide an accurate basis for adjusting the over-allocation situation.

[0140] Embodiment 5

[0141] The present embodiment provides a control logic for reallocating the capacity / capacity of the outdoor unit under over-capacity conditions, including reallocation for low over-capacity conditions, reallocation for moderate over-capacity conditions, and reallocation for severe over-capacity conditions. When moderate over-capacity and severe over-capacity are not divided for high over-capacity conditions, one of the redistribution logics for moderate over-capacity or severe over-capacity given below may be selected for implementation, or any combination of the redistribution logics for moderate over-capacity and severe over-capacity may be selected for implementation.

[0142] Specifically, the redistribution control for low overallocation situations, such as Fig. 9 As shown, including:

[0143] S91. Sort the indoor units by coil temperature at a set time interval: for the indoor unit with the highest cooling / heating degree, reduce the corresponding expansion valve opening by a first set percentage; for the indoor unit with the second highest cooling / heating degree, reduce the corresponding expansion valve opening by a second set percentage.

[0144] For example, during the cooling / heating period of the system, the coil temperature of each indoor unit is obtained every ten minutes, and the indoor units are sorted based on the coil temperature to find the indoor unit with the highest cooling / heating degree.

[0145] For cooling, find the indoor units with the lowest and second lowest coil temperatures, and for heating, find the indoor units with the highest and second highest coil temperatures.

[0146] Taking cooling as an example, the opening of the expansion valve of the indoor unit with the lowest coil temperature is reduced according to the first set percentage, for example, the opening of the expansion valve is reduced to 90% of the current opening, and the opening of the expansion valve of the indoor unit with the second lowest coil temperature is reduced according to the second set percentage, for example, the opening of the expansion valve is reduced to 95% of the current opening.

[0147] After the indoor units are re-ordered based on the coil temperature at the set time interval, if the indoor units adjusted last time are no longer the ones with the lowest or second lowest coil temperature, the expansion valve opening is restored to normal control.

[0148] Through this technical means, the refrigerant flow of the indoor unit with a high cooling / heating degree is dynamically reduced, so that the refrigerant flow of other indoor units is increased, thereby achieving rapid cooling / heating. A small reduction in the refrigerant flow of the indoor unit with a high cooling / heating degree will not cause a significant decrease in its cooling / heating effect.

[0149] Since this operation is repeated at set time intervals, it is possible to avoid the same indoor unit from operating under the condition of reduced expansion valve opening for a long time, so that at the end of the set time interval, when it is once again sorted and determined that it is not an indoor unit with a high degree of cooling / heating, the expansion valve will no longer be reduced but adjusted according to the normal opening, so that the cooling / heating temperature of the corresponding indoor unit will not deviate too far from the set parameters, but will fluctuate around the set parameters.

[0150] S92: When no indoor unit is shut down for temperature control, reduce the opening of the expansion valve of the indoor unit whose coil temperature deviates from the set threshold by a third percentage.

[0151] When no indoor unit is shut down by temperature control, for all indoor units, the expansion valve opening of the indoor unit whose coil temperature deviates from the set threshold is reduced by a third percentage, for example, reduced to 95% of the current opening.

[0152] Taking the cooling condition as an example, when the threshold is set to 8 ºC, the coil temperature is lower than 8 ºC, indicating that the cooling effect of the indoor unit has met the user's needs. The expansion valve opening can be appropriately adjusted to a decreasing trend, and more refrigerant can be allocated to other indoor units while ensuring that the cooling effect is not significantly reduced.

[0153] In the embodiment of the present invention, the deviation from the set threshold is defined as follows: under cooling conditions, it particularly refers to a deviation below the set threshold, that is, the expansion valve opening of the indoor unit whose coil temperature is lower than the set threshold is reduced by a third percentage; under heating conditions, it particularly refers to a deviation above the set threshold, that is, the expansion valve opening of the indoor unit whose coil temperature is higher than the set threshold is reduced by a third percentage.

[0154] Similarly, this method also implements dynamic adjustment according to the set time interval. After each set time interval, if the indoor unit coil temperature that was last detected to have deviated from the set threshold approaches the set threshold, the expansion valve opening is restored to normal control.

[0155] Through this technical means, the refrigerant flow of the indoor unit whose cooling / heating coil temperature deviates from the set threshold is dynamically reduced, so that the refrigerant flow of other indoor units is increased, thereby achieving rapid cooling / heating. The refrigerant flow of the indoor unit with a high cooling / heating degree is slightly reduced without causing a significant decrease in its cooling / heating effect.

[0156] S93. When the indoor unit temperature control is turned off, close the corresponding expansion valve and stop the control of S91 and S92.

[0157] When the system is judged to be under low overcapacity, the system capacity is allocated under low overcapacity by combining the means of dynamically reducing the expansion valve opening of the indoor unit with the highest cooling / heating degree and dynamically reducing the expansion valve opening of the indoor unit whose coil temperature deviates from the set threshold, thereby ensuring the balance of indoor unit capacity. Under low overcapacity, when the outdoor unit is shut down by temperature control and the outdoor unit capacity is sufficient to meet the needs of the indoor unit, the expansion valve of the indoor unit that is shut down by temperature control will be closed, and the indoor units in the system will operate according to the set parameters.

[0158] Redistribution controls for moderate overallocation situations, such as Fig.10 As shown, including:

[0159] S101. Sort the indoor units by coil temperature at a set time interval: for the indoor unit with the highest cooling / heating degree, reduce the corresponding expansion valve opening by a fourth set percentage; for the indoor unit with the second highest cooling / heating degree, reduce the corresponding expansion valve opening by a fifth set percentage.

[0160] The content of the dynamic reallocation can refer to step S91 in the low over-allocation, which will not be described in detail here.

[0161] S102: When no indoor unit is shut down for temperature control, reducing the opening of the expansion valve of the indoor unit whose coil temperature deviates from the set threshold by a sixth percentage.

[0162] The content of the dynamic reallocation may refer to step S92 in the low over-allocation, which will not be described in detail here.

[0163] S103, increasing the compressor frequency;

[0164] When the system is developed and designed, a certain design margin is usually reserved to ensure reliable operation. Reducing the design margin in a small range will not affect the reliability of the system and can improve system performance. For example, the frequency will be limited when the current is too large, and the compressor frequency will be limited when the pressure is too high or too low. When the system is over-equipped, the upper limit of the compressor operating frequency can be appropriately increased to improve the operating capacity of each indoor unit.

[0165] In actual applications, when increasing the operating frequency of the compressor, the system's protection value for the compressor frequency limit must also be released. Usually, the degree of release of the protection value is lower than the amplitude of the compressor frequency increase. For example, the compressor frequency is increased by 5%, and the protection value is increased by 3%.

[0166] S104. When the indoor unit temperature control is turned off, close the corresponding expansion valve and stop the control of S101, S102 and S103.

[0167] When the system is judged to be moderately over-capacitated, the system capacity is allocated in the case of moderate over-capacity and the capacity of the indoor units is balanced, by combining the means of dynamically reducing the expansion valve openings of the indoor units with the highest and second highest cooling / heating levels in different proportions, dynamically reducing the expansion valve openings of the indoor units whose coil temperatures deviate from the set threshold, and increasing the compressor frequency. In this way, the system capacity is balanced in the case of moderate over-capacity and the capacity of the indoor units is ensured. In the case of moderate over-capacity, when the outdoor unit is shut down by temperature control, the outdoor unit capacity can basically meet the needs of the indoor units. In the case of a temperature-controlled indoor unit, its expansion valve is closed and the indoor units in the system operate according to the set parameters.

[0168] Redistribution control for severe overallocation situations, such as Fig.11 As shown, including:

[0169] S111. Sort the indoor units by coil temperature at a set time interval: close the corresponding expansion valve of the indoor unit with the highest cooling / heating degree; reduce the opening of the corresponding expansion valve of the indoor unit with the second highest cooling / heating degree by a seventh set percentage; and adjust the speed of the indoor fan to the minimum.

[0170] The content of the dynamic redistribution can refer to step S91 in low over-allocation and will not be elaborated here. For the case of severe over-allocation, while lowering the expansion valve of the indoor unit with the highest and second highest cooling / heating levels, the speed of its indoor fan is adjusted to the lowest gear to distribute the refrigerant to other indoor units as much as possible. In this case, the set time interval can be shortened and the frequency of dynamic adjustment can be increased to ensure that the adjusted indoor temperature does not fluctuate significantly.

[0171] S112. For the indoor units that are turned on by temperature control, the expansion valve opening of the indoor units whose coil temperatures deviate from the set threshold is reduced by an eighth percentage.

[0172] The content of the dynamic reallocation can refer to step S91 in the low over-allocation, which will not be described in detail here.

[0173] S113, for the indoor unit that is shut down by temperature control, close its expansion valve; and sort the indoor units by coil temperature according to the second set time interval, and reduce the expansion valve opening corresponding to the indoor unit with the highest cooling / heating degree by a ninth percentage.

[0174] In the case of severe over-allocation, not only is the expansion valve of the indoor unit that is shut down by temperature control closed, but the expansion valve opening of the indoor unit with the highest cooling / heating degree is also reduced in combination with dynamic redistribution.

[0175] This step and S111 are executed alternatively, that is, when S113 is executed, S111 is not executed, and when there is no indoor unit that is temperature-controlled and shut down, S111 is executed.

[0176] S114. Increase the compressor frequency.

[0177] In some embodiments of the present invention, when determining a severe over-allocation, before S112, a shutdown threshold is set to determine the number of indoor units that are shut down by temperature control. When the number of indoor units that are shut down by temperature control exceeds the shutdown threshold, S111, S112, S113 and S114 are not executed, and normal control is performed; when the number of indoor units that are shut down by temperature control does not exceed the shutdown threshold, the above S111 to S114 are executed.

[0178] The shutdown threshold is configured according to the actual situation of the system. When the number of indoor units is large, the shutdown threshold is large, and when the number of indoor units is small, the shutdown threshold is correspondingly small.

[0179] In this embodiment, when the system is determined to be severely over-capacitated, in the absence of temperature control shutdown, the system capacity is evenly distributed by dynamically reducing the expansion valve openings of the indoor units with the highest and second highest cooling / heating levels in different proportions, adjusting the speed of the indoor fan to the lowest gear, dynamically reducing the expansion valve openings of the indoor units whose coil temperatures deviate from the set threshold, and increasing the compressor frequency; in the presence of temperature control shutdown and the number of shutdowns does not exceed the shutdown threshold, the system capacity is evenly distributed by closing the expansion valves of the indoor units with temperature control shutdown and dynamically reducing the expansion valve openings of the indoor units with the highest cooling / heating levels, dynamically reducing the expansion valve openings of the indoor units whose coil temperatures deviate from the set threshold, and increasing the compressor frequency; in the presence of temperature control shutdown and the number of shutdowns exceeds the shutdown threshold, if the outdoor unit capacity is sufficient to meet the needs of the indoor units, the expansion valves of the indoor units with temperature control shutdown are closed, and the indoor units of the system operate according to the set parameters.

[0180] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0181] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A multi-split air conditioning system, comprising: At least one outdoor unit and multiple indoor units; Each indoor unit is equipped with an expansion valve; It is characterized by further comprising: When the controller is configured so that the indoor unit capacity exceeds the outdoor unit capacity range and the outdoor unit cannot be detected, perform the following steps: Over-allocation detection: Shut down the specified indoor unit and determine whether the system is over-allocated based on the changes in the operating parameters of the indoor units and / or outdoor units before and after shutdown; Determination of over-allocation degree: When the system is over-allocated, compare the changes in the coil temperatures of each indoor unit before and after shutting down the specified indoor unit, and determine the degree of over-allocation based on the changes; According to the degree of over-allocation, one or more of the following controls are selected to implement refrigerant redistribution: (1) Sort the indoor units by coil temperature at a set time interval, reduce the opening of the expansion valve of the indoor unit with a high degree of cooling / heating or close the expansion valve, and adjust the expansion valves of other indoor units according to the set value; (2) For indoor units that are turned on by temperature control, reduce the opening of the expansion valve of the indoor unit whose coil temperature deviates from the set threshold; (3) For indoor units that are turned off by temperature control, close their expansion valves; (4) Increase the upper limit of the compressor operating frequency.

2. The multi-split air conditioning system according to claim 1, characterized in that: When the controller performs over-allocation detection, it includes: After the specified mode is operated stably, the operating parameters of the first outdoor unit and the first indoor unit are obtained; the specified mode is a cooling mode or a heating mode; Turn off the first designated indoor unit, and obtain the operating parameters of the second outdoor unit and the second indoor unit after the system runs stably; Compare the operating parameters of the first outdoor unit and the second outdoor unit, and compare the operating parameters of the first indoor unit and the second indoor unit; when the change of the operating parameters of the outdoor unit exceeds the first over-allocation threshold and the operating parameters of the indoor unit do not change, judge that the system is not over-allocated; when the change of the operating parameters of the outdoor unit does not exceed the first over-allocation threshold, judge that the system is over-allocated.

3. The multi-split air conditioning system according to claim 2, characterized in that: The controller is also configured to: After running in a specified mode until stable, the first indoor unit coil temperature is obtained; and, After the first designated indoor unit system is turned off and runs to a stable state, the coil temperature of the second indoor unit is obtained; When it is determined that the system is over-provisioned, the first indoor unit coil temperature and the second indoor unit coil temperature are compared, and the degree of system over-provisioning is determined according to changes in the indoor unit coil temperatures.

4. The multi-split air conditioning system according to claim 3, characterized in that: The controller is also configured to: When judging the degree of system over-capacity based on the change of indoor unit coil temperature, If the change in the indoor unit coil temperature does not exceed the second over-allocation threshold, it is determined to be low over-allocation; If the change in the indoor unit coil temperature exceeds the second over-allocation threshold, it is determined to be a high over-allocation.

5. The multi-split air conditioning system according to claim 4, characterized in that: The controller is also configured to: When the system is judged to be highly over-allocated, the third designated indoor unit is turned off; After the system runs to stability, obtain the coil temperature of the third indoor unit; The second indoor unit coil temperature is compared with the third indoor unit coil temperature. When the change of the indoor unit coil temperature does not exceed the third over-provisioning threshold, it is determined to be moderate over-provisioning; when the change of the indoor unit coil temperature exceeds the third over-provisioning threshold, it is determined to be severe over-provisioning.

6. The multi-split air conditioning system according to claim 4, characterized in that: The controller is also configured to: When it is determined to be low over-allocation, the second designated indoor unit is turned off; After the system runs stably, the operating parameters of the third outdoor unit and the third indoor unit are obtained; Compare the operating parameters of the second outdoor unit and the third outdoor unit, and compare the operating parameters of the second indoor unit and the third indoor unit; when the changes in the operating parameters of the outdoor unit and the indoor unit are within the set range, confirm the judgment of low over-allocation, otherwise, judge the degree of system over-allocation again based on the change in the indoor unit coil temperature.

7. The multi-split air conditioning system according to claim 4 or 6, characterized in that: In the case of determining a low over-provision, the controller is configured to: 1) Sort the indoor units by coil temperature at a set time interval: for the indoor unit with the highest cooling / heating degree, reduce the corresponding expansion valve opening by a first set percentage; for the indoor unit with the second highest cooling / heating degree, reduce the corresponding expansion valve opening by a second set percentage; 2) when no indoor unit is shut down by temperature control, reducing the expansion valve opening of the indoor unit whose coil temperature deviates from the set threshold by a third percentage; 3) When the indoor unit temperature control is shut down, close the corresponding expansion valve and stop the control of 1 and 2.

8. The multi-split air conditioning system according to claim 5, characterized in that: In the case of determining moderate over-provisioning, the controller is configured to: 1) Sort the indoor units by coil temperature at a set time interval: for the indoor unit with the highest cooling / heating degree, reduce the corresponding expansion valve opening by the fourth set percentage; for the indoor unit with the second highest cooling / heating degree, reduce the corresponding expansion valve opening by the fifth set percentage; 2) when no indoor unit temperature control is turned off, reducing the expansion valve opening of the indoor unit whose coil temperature deviates from the set threshold by a sixth percentage; 3) Increase the compressor frequency; 4) When the indoor unit temperature control is shut down, close the corresponding expansion valve and stop the control of 1, 2 and 3.

9. The multi-split air conditioning system according to claim 5, characterized in that: In the case of severe over-provisioning, the controller is configured to: 1) Sort the indoor units by coil temperature at set time intervals: close the corresponding expansion valve of the indoor unit with the highest cooling / heating degree; reduce the opening of the corresponding expansion valve of the indoor unit with the second highest cooling / heating degree by the seventh set percentage; adjust the speed of the indoor fan to the minimum; 2) For indoor units that are turned on with temperature control, the expansion valve opening of the indoor units whose coil temperatures deviate from the set threshold is reduced by an eighth percentage; 3) For indoor units that are shut down by temperature control, close their expansion valves; and, sorting the indoor units by coil temperature at a second set time interval, and reducing the expansion valve opening corresponding to the indoor unit with the highest cooling / heating degree by a ninth percentage; 4) Increase the compressor frequency; In the above, when step 3 is executed, step 1 is not executed, and when there is no indoor unit that is temperature-controlled and shut down, step 1 is executed.

10. The multi-split air conditioning system according to claim 9, characterized in that: In the case of severe over-provisioning, the controller is further configured to: 5) When the number of indoor units that are shut down by temperature control exceeds the shutdown threshold, steps 1, 2, 3 and 4 are not executed.

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