Multi-split system

Abstract

The multi-split system comprises an outdoor unit and at least two indoor units, the outdoor unit comprises an outdoor temperature detection module, and when the indoor units operate in a refrigeration mode, refrigeration load parameters of rooms corresponding to the indoor units are determined; the expected indoor temperature at each moment is determined; according to the refrigeration load parameter, the difference between the indoor temperature at the current moment and the expected indoor temperature, the difference between the outdoor temperature and the indoor temperature and the control period, the real-time demand load is determined; and determining the target evaporation temperature according to the real-time demand load, and determining the compressor frequency according to the target evaporation temperature. The frequency of the compressor can be matched with the real-time demand load, the under-regulation problem of a large-load and small-temperature-difference scene and the over-regulation problem of a small-load and large-temperature-difference scene are solved, the air conditioner capacity is matched with the building load, room temperature fluctuation is reduced in medium and small loads, power consumption increase caused by frequent starting and stopping is avoided, and the indoor unit capacity is improved in the large load; the room temperature change speed is accelerated; and the user comfort is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the air conditioning technical field, and particularly to a multi-connected system. BACKGROUND

[0002] The system control target of the current multi-connected central air conditioner is usually the difference between the set temperature and the return air temperature, which will be used as a key reference for the compressor frequency, the evaporation temperature, the superheat degree and the like in the control system. However, since the temperature difference can only reflect the target room temperature state, the actual output control target of the multi-connected central air conditioner system is the building load, and the temperature difference is only an important parameter in the air heat load item of the building load, and cannot fully reflect the state of the item, and the description of the "quantity" in the item is missing, and in the building load, the heat leakage load, the solar radiation load and the internal disturbance load are also important factors. Therefore, using the "temperature difference" as the control target alone is easy to cause the problems of small temperature difference and large load under-regulation, large temperature difference and small load over-regulation, and room temperature fluctuation of medium load, and also causes the problems of frequent start and stop of the unit, low energy efficiency, poor user experience and the like.

[0003] The above information disclosed in this BACKGROUND section is only for increasing the understanding of the background of the present application, and therefore, it can include information that does not constitute prior art that is already known in the art. SUMMARY

[0004] The present application provides a multi-connected system, which solves the technical problem of using the temperature difference as the control target of the existing multi-connected air conditioner, which is easy to cause the problems of small temperature difference and large load under-regulation, large temperature difference and small load over-regulation, and room temperature fluctuation of medium load.

[0005] To achieve the above-mentioned application purposes, the present application adopts the following technical solutions:

[0006] A multi-connected system includes an outdoor unit and at least two indoor units, the outdoor unit includes an outdoor temperature detection module, and when the indoor unit operates in a cooling mode:

[0007] A cooling load parameter of a room corresponding to the indoor unit is determined;

[0008] An expected indoor temperature at each moment is determined;

[0009] A real-time demand load is determined according to the cooling load parameter, the difference between the indoor temperature and the expected indoor temperature at the current moment, the difference between the outdoor temperature and the indoor temperature, and a control period;

[0010] A target evaporation temperature is determined according to the real-time demand load, and a compressor frequency is determined according to the target evaporation temperature.

[0011] In some embodiments of the present application, the cooling load parameter is a built-in parameter of the multi-connected system, and / or the cooling load parameter is determined through self-learning.

[0012] The data obtained during the complete cooling process are: the total cooling time is greater than the set time; the initial indoor temperature difference between indoor and outdoor temperatures is lower than the set temperature difference; the indoor temperature change within a specific time period is higher than the first set difference; and the final indoor temperature difference between indoor and set temperatures is lower than the second set difference. These data are used as learning data.

[0013] Obtain the real-time capability Qe of the indoor unit;

[0014] The cooling load parameters a, b, and c are determined by solving the load characteristic model based on the real-time capacity Qe of the indoor unit and the learning data. The load characteristic model is Qe = Qn = a × (difference between indoor temperature and set temperature) + b × (difference between outdoor temperature and indoor temperature) × learning time step + c × learning time step.

[0015] In some embodiments of this application, the real-time demand load Q r_n = a × (difference between indoor temperature and desired indoor temperature at time n) + b × (difference between outdoor temperature and indoor temperature at time n) × control period + c × control period.

[0016] In some embodiments of this application, the desired indoor temperature at each moment is determined based on the difference between the indoor temperature and the set temperature, the equipment capability characteristics, and the time elapsed since the cooling process was performed.

[0017] In some embodiments of this application, the real-time load demand Q of each indoor unit is obtained. r_n Calculate the target evaporation temperature for each indoor unit.

[0018]

[0019] Among them, f sh f sc For each indoor unit, the subcooling and superheating characteristic parameters are: m cs n cs The characteristic parameters of the sensible heat capacity of the indoor unit; m cl n cl T represents the characteristic parameter of the indoor mechanism's latent heat capacity; i The indoor temperature for each indoor unit; T ld The dew point temperature corresponding to the return air temperature of each indoor unit.

[0020] In some embodiments of this application, the target evaporation temperature is the minimum or average value of the target evaporation temperatures of all indoor units.

[0021] In some embodiments of this application, the compressor frequency is determined based on compressor parameters, the capacity of all indoor units, and the target evaporation temperature.

[0022] In some embodiments of this application, the rotational speed of the indoor fan is determined based on the real-time demand load, and the rotational speed of the indoor fan is determined based on the ratio of the maximum rotational speed of the indoor fan, the real-time demand load, and the capacity characteristic coefficient of the indoor unit.

[0023] In some embodiments of this application, the indoor unit includes an indoor expansion valve. The initial opening of the indoor expansion valve is determined based on the maximum opening of the indoor expansion valve and the ratio of the current capacity value of the indoor unit to the sum of the capacities of all indoor units. The superheat value of the indoor unit is determined. When the superheat value is lower than the set value, the opening of the indoor expansion valve remains unchanged. When the superheat value is higher than the set value, the opening of the indoor expansion valve is reduced.

[0024] In some embodiments of this application, the reduction in the opening of the indoor expansion valve is determined based on the difference between the superheat difference and the superheat difference at two consecutive times, and the superheat correction coefficient.

[0025] Compared with existing technologies, the advantages and positive effects of this invention are as follows: A multi-split air conditioning system includes an outdoor unit and at least two indoor units. The outdoor unit includes an outdoor temperature detection module. When the indoor unit is operating in cooling mode, the following are achieved: the cooling load parameters of the corresponding room are determined; the desired indoor temperature at each moment is determined; the real-time demand load is determined based on the cooling load parameters, the difference between the current indoor temperature and the desired indoor temperature, the difference between the outdoor temperature and the indoor temperature, and the control cycle; the target evaporation temperature is determined based on the real-time demand load; and the compressor frequency is determined based on the target evaporation temperature. Therefore, this invention uses the real-time demand load of the room as the control element of the multi-split air conditioning system, enabling the operating state of the multi-split air conditioning system to match the real-time demand load. This solves the under-adjustment problem in scenarios with large loads and small temperature differences, and the over-adjustment problem in scenarios with small loads and large temperature differences. It ensures that the air conditioning capacity matches the building load, reduces room temperature fluctuations and avoids increased power consumption due to frequent start-stop cycles under small and medium loads, and enhances the capacity of the indoor units under large loads, accelerating the rate of room temperature change and improving user comfort. Under load-following technology, various energy-saving controls can be implemented according to user needs, while improving system operational reliability, achieving energy saving and efficiency improvement, and enhancing user comfort.

[0026] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1This is a schematic diagram of the refrigerant circulation in the cooling mode of a multi-split system according to an embodiment;

[0029] Figure 2 This is a flowchart illustrating the determination of cooling load parameters for a multi-split system cooling mode according to an embodiment.

[0030] Figure 3 A flowchart illustrating the process of obtaining historical operating data of indoor units that can be used for model learning in the cooling mode of a multi-split system according to an embodiment;

[0031] Figure 4 This is a control flowchart of a multi-split air conditioning system in cooling mode according to an embodiment;

[0032] Figure 5 This is a flowchart illustrating the adjustment of compressor frequency, indoor fan speed, and indoor expansion valve in the cooling mode of a multi-split air conditioning system according to an embodiment.

[0033] Figure 6 This is a schematic diagram of the refrigerant circulation in the heating mode of a multi-split air conditioning system according to an embodiment;

[0034] Figure 7 This is a flowchart illustrating the determination of cooling load parameters for the heating mode of a multi-split air conditioning system according to an embodiment.

[0035] Figure 8 This is a flowchart illustrating the self-learning of cooling load parameters in heating mode of a multi-split system according to an embodiment.

[0036] Figure 9 This is a control flowchart of a multi-split air conditioning system in heating mode according to an embodiment;

[0037] Figure 10 This is a flowchart illustrating the adjustment of compressor frequency, indoor fan speed, and indoor expansion valve in the heating mode of a multi-split system according to an embodiment.

[0038] In the diagram, 1 is the compressor; 4 is the four-way valve; 5 is the outdoor heat exchanger; and 6 is the outdoor expansion valve.

[0039] 18-1, First indoor heat exchanger; 19-1, First indoor expansion valve;

[0040] 18-2, Second indoor heat exchanger; 19-2, Second indoor expansion valve;

[0041] 18-3, Third indoor heat exchanger; 19-3, Third indoor expansion valve. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0044] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0045] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0046] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0047] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0048] The multi-split air conditioning system disclosed in this application executes the refrigeration cycle of an air conditioner by using a compressor, condenser, throttling device, and evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation to cool or heat an indoor space.

[0049] Low-temperature, low-pressure refrigerant enters the compressor, which compresses it into a high-temperature, 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.

[0050] The throttling device expands the high-temperature, high-pressure liquid refrigerant that condenses in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the expanded refrigerant in the throttling device, returning the low-temperature, low-pressure refrigerant gas to the compressor. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout the cycle, the air conditioner regulates the temperature of the indoor space.

[0051] The outdoor unit of a multi-split air conditioning system refers to the part of the refrigeration cycle that includes the compressor and the outdoor heat exchanger. The throttling device is located in the outdoor unit.

[0052] The indoor unit of a multi-split system includes an indoor heat exchanger. The multi-split system includes at least two indoor units, and each indoor unit is equipped with an indoor expansion valve. The capacity of the indoor unit is adjusted by regulating the opening of the indoor expansion valve.

[0053] The indoor and outdoor heat exchangers function as either condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner functions as a heater in heating mode; when the indoor heat exchanger is used as an evaporator, the air conditioner functions as a cooler in cooling mode.

[0054] A multi-split air conditioning system includes an outdoor unit and at least two indoor units. The outdoor unit includes a compressor and an outdoor heat exchanger, and each indoor unit includes an indoor heat exchanger and an indoor expansion valve.

[0055] Figure 1 This is a schematic diagram of the refrigerant circulation in a multi-unit refrigeration system. Figure 1 In the example, the multi-split system includes an outdoor unit and a first indoor unit, a second indoor unit, and a third indoor unit. The outdoor unit is connected to the first indoor unit, the second indoor unit, and the third indoor unit through a connection pipe to form a multi-split system.

[0056] The outdoor unit is equipped with a compressor 1, an outdoor heat exchanger 5, an outdoor expansion valve 6, and a four-way valve 4. The operating capacity of the indoor unit can be adjusted by regulating the operating frequency of the compressor 1.

[0057] The outdoor unit is also equipped with an outdoor temperature detection module to detect the outdoor temperature T. a .

[0058] The first indoor unit is equipped with a first indoor heat exchanger 18-1, a first indoor expansion valve 19-1 and a first indoor fan (not shown in the figure). The operating capacity of the first indoor unit can be adjusted by adjusting the opening of the first indoor expansion valve 19-1 and / or the speed of the first indoor fan.

[0059] The first indoor unit includes a first indoor ambient temperature detection module d1, a first indoor unit liquid pipe temperature detection module c1, and a first indoor unit gas pipe temperature detection module b1.

[0060] The second indoor unit is equipped with a second indoor heat exchanger 18-2, a second indoor expansion valve 19-2, and a second indoor fan (not shown in the figure). The operating capacity of the second indoor unit can be adjusted by adjusting the opening of the second indoor expansion valve 19-2 and / or the speed of the second indoor fan.

[0061] The second indoor unit includes a second indoor ambient temperature detection module d2, a second indoor unit liquid pipe temperature detection module c2, and a second indoor unit gas pipe temperature detection module b2.

[0062] The third indoor unit is equipped with a third indoor heat exchanger 18-3, a third indoor expansion valve 19-3, and a third indoor fan (not shown in the figure). The operating capacity of the third indoor unit can be adjusted by adjusting the opening of the third indoor expansion valve 19-3 and / or the speed of the third indoor fan.

[0063] The third indoor unit includes a third indoor ambient temperature detection module d3, a third indoor unit liquid pipe temperature detection module c3, and a third indoor unit gas pipe temperature detection module b3.

[0064] The indoor ambient temperature detection module is used to detect the indoor temperature T. i .

[0065] All indoor units include a set temperature acquisition module.

[0066] The set temperature acquisition module is used to acquire the indoor set temperature T. s .

[0067] When a multi-split air conditioner is running in cooling mode in the indoor unit:

[0068] Determine the cooling load parameters a, b, and c for the room corresponding to the indoor unit;

[0069] Determine the desired indoor temperature T at each moment. exp_n ;

[0070] Based on the cooling load parameters and the current indoor temperature T i(n) With the desired indoor temperature T exp_n Difference between outdoor and outdoor temperatures T a(n) With indoor temperature T i(n) The difference and control cycle determine the real-time demand load Q. r_n ;

[0071] Based on real-time demand load Q r_n Determine the target evaporation temperature, and then determine the compressor frequency H based on the target evaporation temperature.

[0072] In some embodiments, based on real-time demand load Q r_n Determine the rotational speed F of the indoor fan.

[0073] In some embodiments, the initial opening degree of the indoor expansion valve is determined, the superheat of the indoor unit is determined, and the opening degree of the indoor expansion valve is adjusted according to the superheat.

[0074] The system uses a capacity measurement algorithm that can operate in multi-split indoor units to learn the load characteristics of a given target building and uses the building's demand load as the control target of the control system.

[0075] After obtaining the load characteristic parameters of the target building, a load model is established, and the evaporation temperature and superheat of the system's important control targets are directly calculated based on the demand load, thereby controlling the compressor frequency and indoor fan speed. The indoor unit's electronic expansion valve serves as a supplementary control item.

[0076] By controlling the multi-split air conditioning system according to real-time load demand, the problems of under-adjustment in high-load, low-temperature-difference scenarios and over-adjustment in low-load, high-temperature-difference scenarios are solved. This ensures that the air conditioning capacity matches the building load, reducing room temperature fluctuations and avoiding increased power consumption due to frequent start-stop cycles under low to medium loads, while enhancing indoor unit capacity and accelerating room temperature changes to improve user comfort under high loads. Under load-following technology, various energy-saving controls can be implemented according to user needs, while improving system reliability, achieving energy efficiency, and enhancing user comfort.

[0077] Step 1: Determine the cooling load parameters of the room corresponding to the indoor unit:

[0078] In some embodiments, the method for determining the cooling load parameters a, b, and c of the room corresponding to the indoor unit is as follows: the cooling load parameters are built-in parameters of the multi-split unit and can be read directly.

[0079] In some embodiments, the method for determining the cooling load parameters a, b, and c of the room corresponding to the indoor unit is as follows: more accurate cooling load parameters of the room are determined by self-learning from historical data.

[0080] In some embodiments, it is determined whether the multi-split air conditioning system is being powered on for the first time. If it is, the built-in cooling load parameters a0, b0, and c0 of the multi-split system are read and used to control the system. If it is not the first time, it is necessary to determine whether self-learning is required for this operation. If the cooling self-learning conditions are met, self-learning is performed to determine the cooling load parameters, and the learned cooling load parameters are used to control the multi-split system. In subsequent startup processes, it is determined whether self-learning is required for this operation. If not, the cooling load parameters determined by the previous self-learning are used for control; if so, self-learning is performed to determine the cooling load parameters, and the learned cooling load parameters are used to control the multi-split system.

[0081] exist Figure 2 In the example, the process for determining the cooling load parameters using the cooling mode is as follows:

[0082] S1, Begin.

[0083] S2. Determine if this is the first time the device is powered on. If yes, proceed to step S3; otherwise, proceed to step S4.

[0084] S3. Read the built-in cooling load parameters a0, b0, and c0 of the multi-split unit as the cooling load parameters.

[0085] S4. Determine whether the cooling self-learning conditions are met. If not, proceed to step S5. If yes, proceed to step S6.

[0086] S5. Obtain the cooling load parameters from the last startup.

[0087] S6. Perform self-learning to determine the cooling load parameters after learning.

[0088] Based on the indoor unit capacity Q of a multi-split air conditioning system e The indoor unit will be able to perform its Q function in real time when it is in a balanced state. e Considered room load Q n The building load characteristics model should include at least three components: indoor air heat storage load, wall and window heat leakage load, and equipment and occupant internal disturbance load.

[0089] Among these, the air heat storage load is related to the room size and the difference between the set temperature and the initial temperature; the wall and window heat leakage load is mainly related to the building's insulation and the indoor-outdoor temperature difference; and the equipment and occupant disturbance load is related to the usage scenario. A numerical model of the load can be established based on the actual composition of the building load, by obtaining the real-time operating capacity Q of the indoor units. e The model learns the building load characteristics by treating the actual building load as the building's actual load. The learning process requires selecting a complete cooling process, and using the operational data during this process, the building load characteristic parameters in the load model are determined, ultimately forming a load characteristic model for the target building.

[0090] After the load characteristic model is established, the future outdoor ambient temperature, indoor temperature, and set temperature can be input into the model to determine the future room demand load. The system operating parameters can then be adjusted based on the demand load and the expected control objectives.

[0091] The self-learning process of cooling load parameters is as follows:

[0092] The data obtained during the complete cooling process are: the total cooling time is greater than the set time Ymin; the initial indoor temperature and outdoor temperature difference is lower than the set temperature difference; the indoor temperature change within a specific time is higher than the first set difference; and the final indoor temperature and set temperature difference is lower than the set difference. These data are used as learning data.

[0093] Q: Real-time capability of obtaining indoor unit e ;

[0094] Based on the real-time capabilities of the indoor unit and the learning data, the load characteristic model is solved to determine the cooling load parameters a, b, and c. The load characteristic model is Q. e =Q n = a × (difference between indoor temperature and set temperature) + b × (difference between outdoor temperature and indoor temperature) × learning time step + c × learning time step.

[0095] The load characteristic model is: Q n =a×(T) i -T s )+b×(T a -T i )×t+c×t.

[0096] In the above formula:

[0097] Q n Building load, kW;

[0098] a, b, c: Cooling load parameters, dimensionless units;

[0099] T i Indoor temperature, °C;

[0100] Ts : Set temperature, °C;

[0101] T a Outdoor temperature, °C;

[0102] t: learning time step, min.

[0103] In some embodiments, self-learning of cooling load parameters is performed only if the following three conditions are met:

[0104] Condition 1: The indoor unit has not undergone any learning process since it was turned on this time;

[0105] Condition 2: The time elapsed since the last learning session ended is greater than m hours;

[0106] Condition 3: Obtain historical operating data of the indoor unit that can be used for model learning: that is, screen the quality of historical data of the indoor unit. When the historical process to be learned is a complete cooling process, the model learning step is only executed when a data segment meets the following conditions: the total cooling time is greater than Ymin, the initial room temperature is similar to the outdoor ambient temperature, the change in indoor temperature within a specific time is higher than the first set difference, and the final difference between the indoor temperature and the set temperature is lower than the second set difference.

[0107] exist Figure 3 In the example, the method for obtaining historical operating data of the indoor unit that can be used for model learning is as follows:

[0108] S1, Begin.

[0109] S2. Select the indoor unit's refrigerated operating period for the purpose of learning, and obtain the operating parameters for that period: operating time tn, indoor temperature T. i Outdoor temperature T a and set temperature T s .

[0110] S3. Determine if the runtime tn is greater than or equal to the set runtime Ymin. If yes, proceed to step S4; otherwise, proceed to step S2.

[0111] S4, |Initial indoor temperature vs. outdoor temperature difference| is lower than the set temperature difference, |T i0 -T a0 If |≤k℃, proceed to step S5; otherwise, proceed to step S2.

[0112] S5. Within a specific time period, the indoor temperature change exceeds a first preset difference. If yes, proceed to step S6; otherwise, proceed to step S2. The first preset difference is, for example, 0.5℃.

[0113] S6. If the final indoor temperature is the same as the set temperature, proceed to step S7; otherwise, proceed to step S2.

[0114] S7. Obtain the real-time performance capability of the indoor unit during this runtime period. e Indoor temperature T i Outdoor temperature T a Set temperature T s And the learning time step t.

[0115] Indoor unit real-time performance capability Q e It is a function related to the structural parameters, heat transfer coefficient, superheat, subcooling, and evaporation temperature of the indoor unit heat exchanger, and can be calculated using existing technology:

[0116] Q e =f(S) str K i SH i SC i T e ).

[0117] In the above formula:

[0118] S str Indoor heat exchanger structural parameters;

[0119] K i : The heat transfer coefficient of the indoor heat exchanger under current operating conditions;

[0120] SH i : Superheat at the outlet of the indoor heat exchanger, °C;

[0121] SC i : Inlet subcooling of indoor heat exchanger, °C;

[0122] T e : Evaporation temperature of indoor heat exchanger, °C.

[0123] The real-time performance capability of the indoor unit during this period (Q) e Assuming the actual load Q of the room n .

[0124] Select at least three time points from the historical operating periods of the indoor unit for model learning, input the operating data of the indoor unit equipment at the above time points into the building load characteristic model, and establish equations to solve for the building load characteristic parameters a, b, and c.

[0125] Step 2: Setting the Real-Time Target Temperature

[0126] The desired indoor temperature at each moment is used as the real-time target temperature. The desired indoor temperature at each moment is determined based on the difference between the indoor temperature and the set temperature, the equipment capacity characteristics, and the time already spent in the cooling process.

[0127] The desired indoor temperature T at each moment is determined based on the temperature drop curve. exp_n .

[0128] The optimal temperature drop curve for the cooling process is calculated and set from the start of operation of the multi-split air conditioning system. The temperature drop curve represents the desired indoor temperature T at each moment. exp_n This is used to calculate the demand load of the target room. The formula for calculating the curve is shown below:

[0129] In the above formula,

[0130] α, β, γ, and θ are temperature characteristic constants;

[0131] τ n The value at the current moment since the start of the cooling process, h;

[0132] T i(n-1) Let be the indoor temperature at time n-1, in °C;

[0133] T i0 The initial indoor temperature, in °C;

[0134] T s The set temperature is ℃.

[0135] The optimal temperature drop curve controls the indoor temperature to drop rapidly in the first half to quickly reach a comfortable temperature, and then drops slowly in the second half to avoid over-adjustment.

[0136] In the optimal temperature decrease curve, the target temperature value T at the initial moment. exp_0 Take the initial indoor temperature T i0 The value; when the actual indoor temperature T i From the start of the cooling process, the initial temperature reached is the set temperature T. s When they are equal, make T in Always equal to T s .

[0137] The optimal temperature drop curve will gradually bring the room temperature to the set temperature in a gentle, approximate manner. Over time, the expected temperature change at each step is related to the expected temperature difference at the initial moment and the expected temperature difference at the current moment.

[0138] The third step is to determine the real-time demand load Q. r_n .

[0139] Based on the cooling load parameters and the current indoor temperature T i(n) The difference T from the desired indoor temperature exp_n Outdoor temperature T a(n) With indoor temperature T i(n) The difference and control cycle determine the real-time demand load Q. r_n .

[0140] Real-time demand load Qr_n = a × (difference between indoor temperature and desired indoor temperature at time n) + b × (difference between outdoor temperature and indoor temperature at time n) × control period + c × control period.

[0141] After confirming the cooling load parameters a, b, and c and the real-time desired indoor temperature, it is necessary to calculate the "real-time demand load Q" of the target indoor unit. r_n The calculation formula is as follows:

[0142] Q r_n =a×(T) i(n) -T exp_n )+b×(T a(n) -T i(n) )×t+c×t.

[0143] In the above formula:

[0144] Q r_n Real-time demand load, kW;

[0145] a, b, c: Cooling load parameters, dimensionless units;

[0146] T i(n) : Indoor temperature at time n, in °C;

[0147] T exp_n : The expected indoor temperature at time n, in °C;

[0148] T a(n) Outdoor ambient temperature, °C;

[0149] t: control cycle, h.

[0150] Step 4: Load following control.

[0151] After determining the real-time demand load, the control objective of the multi-split unit is controlled according to the real-time demand load to achieve load following control.

[0152] exist Figure 4 In the example, the load follower control process is as follows:

[0153] S1. Power on.

[0154] S2. Obtain cooling load parameters.

[0155] S3. Real-time target temperature setting: Acquires indoor temperature, outdoor temperature, and set temperature; calculates the desired indoor temperature T at each moment based on the optimal temperature drop curve. exp_n .

[0156] S4, Set the indoor temperature T i(n) Expected indoor temperature T exp_n Outdoor temperature T a(n)Input cooling load parameters into the load characteristic model to calculate the real-time demand load Q. r_n .

[0157] S5. Calculate and control the control objectives of the multi-split air conditioner based on real-time demand load.

[0158] S6. Is the device powered off? If yes, proceed to step S7; otherwise, proceed to step S3.

[0159] S7, Power off.

[0160] The building load following control of multi-split air conditioning systems mainly targets evaporation temperature control and air volume control. These control objectives are mainly achieved through compressor frequency control, indoor unit electronic expansion valve opening control, and indoor unit fan speed control.

[0161] The main logic of load following control is to make the real-time load demand value directly equal to the real-time generating capacity value of the indoor unit, thus achieving load following control. After obtaining the real-time load demand value from the third step, the target evaporation temperature is determined, and the compressor operating frequency is determined based on the target evaporation temperature. The indoor fan speed is determined based on the real-time load demand, and the initial opening of the indoor expansion valve is determined. The opening of the indoor expansion valve is adjusted based on the superheat, thereby precisely regulating the compressor frequency, indoor fan speed, and indoor expansion valve opening.

[0162] Obtain the real-time load demand Q for each indoor unit r_n Calculate the target evaporation temperature for each indoor unit.

[0163]

[0164] Among them, f sh f sc For each indoor unit, the subcooling and superheating characteristic parameters are: m cs n cs The characteristic parameters of the sensible heat capacity of the indoor unit; m cl n cl T represents the characteristic parameter of the indoor mechanism's latent heat capacity; i The indoor temperature for each indoor unit is given in °C; T. ld The dew point temperature, in °C, corresponds to the return air temperature of each indoor unit.

[0165] The above calculation method takes into account the evaporation temperature at which the indoor unit heat exchanger may exert its sensible heat capacity and latent heat capacity under cooling conditions.

[0166] The target evaporation temperature is the minimum or average of the target evaporation temperatures of all indoor units.

[0167] In some embodiments, when the user selects a high comfort scenario, the target evaporation temperature T of the multi-split system is... e0_iThis is recorded as the minimum target evaporation temperature of all indoor units in the system.

[0168] In some embodiments, when the user selects a high-performance scenario, the target evaporation temperature T of the multi-split system is... e0_i This is recorded as the average of the target evaporation temperatures of all indoor units in the system.

[0169] The target evaporation temperature T of the multi-split air conditioning system e0_i Determine the actual operating frequency Hi of the compressor.

[0170] In some embodiments, the compressor frequency is determined based on compressor parameters, the capacity of all indoor units, and the target evaporation temperature.

[0171] The compressor frequency at time i

[0172] In the above formula, S1 is a characteristic parameter of the compressor, a constant, which is related to the compressor model;

[0173] S2 is the compressor frequency correction factor, a constant, which is related to the indoor unit model;

[0174] V HP_j Let be the capacity characteristic coefficient of the j-th indoor unit in the system, a constant, which is related to the capacity and model of the indoor unit.

[0175] The indoor fan speed is determined based on the real-time demand load, and the indoor fan speed is determined based on the ratio of the maximum indoor fan speed, the real-time demand load, and the capacity characteristic coefficient of the indoor unit.

[0176] Rotation speed of the indoor fan at time i

[0177] In the above formula: Q r_n The load requirement for each indoor unit, in kWh;

[0178] F max : Maximum speed of the fan, rpm;

[0179] Fo sh Fan speed and superheat correction parameters;

[0180] Fo Te Fan speed and evaporation temperature correction parameters;

[0181] V HP_j : The capacity characteristic coefficient of the j-th indoor unit in the system, a constant, which is related to the capacity and model of the indoor unit;

[0182] a is a constant, for example: a = 28.

[0183] The fan, as the main auxiliary adjustment component, is set to stepless speed regulation. The fan speed is calculated based on the ratio of the real-time demand load to the indoor unit capacity characteristic coefficient. In addition, correction terms for superheat and evaporation temperature are added.

[0184] The indoor unit includes an indoor expansion valve. The initial opening of the indoor expansion valve is determined based on the maximum opening of the indoor expansion valve and the ratio of the current capacity of the indoor unit to the total capacity of all indoor units.

[0185] Initial opening value of the electronic expansion valve for each indoor unit

[0186] In the above formula:

[0187] EXV max : Maximum opening value of the indoor electronic expansion valve.

[0188] VO j : Capacity of the j-th indoor unit, in HP.

[0189] The total capacity of the indoor units in the system, in HP.

[0190] C b One-to-one mode correction parameter, dimensionless parameter, related to specific function selection options.

[0191] Calculate the superheat value SH of the indoor unit i When the superheat value is lower than the set value, the opening of the indoor expansion valve remains unchanged; when the superheat value is higher than the set value, the opening of the indoor expansion valve is reduced.

[0192] The amount of reduction in the opening of the indoor expansion valve is determined based on the difference between the superheat difference and the superheat difference at two consecutive times, and the superheat correction coefficient.

[0193] In some embodiments, the value is set to 0.

[0194] Determine the superheat value (SH) of the indoor unit. i If the superheat value SH i If ≤0, then maintain the opening value EXV of the indoor expansion valve. i Unchanged; if the superheat value SH i If the value is greater than 0, then reduce the opening degree EXV of the electronic expansion valve of the indoor unit. i If the value is given, then the electronic expansion valve opening value EXV at the next moment will be... i(n+1) The calculation method is as follows:

[0195] ΔSH i(n) =SH i(n) -SH i(n-1) .

[0196] In the above formula: r1, r2, C SH : Superheat iteration correction coefficient, a constant, which is related to the indoor unit model;

[0197] SH i(n) : The superheat at the indoor unit outlet at time n.

[0198] exist Figure 5 In the example, the process of controlling the multi-split air conditioning system is as follows:

[0199] S1, Begin.

[0200] S2. Obtain system operating status parameters.

[0201] S3. Calculate the real-time load demand Q for each indoor unit. r_n .

[0202] S4. Calculate the target evaporation temperature T for each indoor unit based on real-time demand load. e_i .

[0203] S5. Calculate the target evaporation temperature T of the multi-split air conditioning system. eo_i .

[0204] S6. Calculate the initial opening of the indoor expansion valve based on the target evaporation temperature T. eo_i Calculate the compressor frequency and indoor fan speed. Control the compressor frequency, indoor expansion valve opening, and indoor fan speed.

[0205] S7. Determine the indoor superheat value SH i If the value is ≤0, proceed to step S9; otherwise, proceed to step S8.

[0206] S8. Reduce the opening of the indoor expansion valve. Proceed to step S10.

[0207] S9. Keep the opening of the indoor expansion valve unchanged. Proceed to step S10.

[0208] S10. Is the device powered off? If yes, proceed to step S11; otherwise, proceed to step S2.

[0209] S11, Power off.

[0210] Figure 6 This is a schematic diagram of the refrigerant circulation in a multi-unit thermal mode. Figure 6 In the example, the multi-split system includes an outdoor unit and a first indoor unit, a second indoor unit, and a third indoor unit. The outdoor unit is connected to the first indoor unit, the second indoor unit, and the third indoor unit through a connection pipe to form a multi-split system.

[0211] The outdoor unit is equipped with a compressor 1, an outdoor heat exchanger 5, an outdoor expansion valve 6, and a four-way valve 4. The operating capacity of the indoor unit can be adjusted by regulating the operating frequency of the compressor 1.

[0212] The outdoor unit is also equipped with an outdoor temperature detection module to detect the outdoor temperature T. a .

[0213] The first indoor unit is equipped with a first indoor heat exchanger 18-1, a first outdoor expansion valve 19-1, and a first indoor fan (not shown in the figure). The operating capacity of the first indoor unit can be adjusted by adjusting the opening of the first outdoor expansion valve 19-1 and / or the speed of the first indoor fan.

[0214] The first indoor unit includes a first indoor ambient temperature detection module d1, a first indoor unit liquid pipe temperature detection module c1, and a first indoor unit gas pipe temperature detection module b1.

[0215] The second indoor unit is equipped with a second indoor heat exchanger 18-2, a second outdoor expansion valve 19-2, and a second indoor fan (not shown in the figure). The operating capacity of the second indoor unit can be adjusted by adjusting the opening of the second outdoor expansion valve 19-2 and / or the speed of the second indoor fan.

[0216] The second indoor unit includes a second indoor ambient temperature detection module d2, a second indoor unit liquid pipe temperature detection module c2, and a second indoor unit gas pipe temperature detection module b2.

[0217] The third indoor unit is equipped with a third indoor heat exchanger 18-3, a third outdoor expansion valve 19-3, and a third indoor fan (not shown in the figure). The operating capacity of the third indoor unit can be adjusted by adjusting the opening of the third outdoor expansion valve 19-3 and / or the speed of the third indoor fan.

[0218] The third indoor unit includes a third indoor ambient temperature detection module d3, a third indoor unit liquid pipe temperature detection module c3, and a third indoor unit gas pipe temperature detection module b3.

[0219] The indoor ambient temperature detection module is used to detect the indoor temperature T. i .

[0220] All indoor units include a set temperature acquisition module.

[0221] The set temperature acquisition module is used to acquire the indoor set temperature T. s .

[0222] When a multi-split air conditioner is running in heating mode on the indoor unit:

[0223] Determine the heating load parameters a, b, and c for the room corresponding to the indoor unit;

[0224] Determine the desired indoor temperature T at each moment. exp_n ;

[0225] Based on the heating load parameters and the desired indoor temperature T at the current moment exp_n With indoor temperature T i(n) Difference in indoor temperature T i(n) With outdoor temperature T a(n) The difference and control cycle determine the real-time demand load Q. r_n ;

[0226] Based on real-time demand load Q r_n Determine the target condensing temperature, and then determine the compressor frequency H based on the target condensing temperature.

[0227] In some embodiments, based on real-time demand load Q r_n Determine the rotational speed F of the indoor fan.

[0228] In some embodiments, the initial opening degree of the outdoor expansion valve is determined, the subcooling degree of the indoor unit is determined, and the opening degree of the outdoor expansion valve is adjusted according to the subcooling degree.

[0229] The system uses a capacity measurement algorithm that can operate in multi-split indoor units to learn the load characteristics of a given target building and uses the building's demand load as the control target of the control system.

[0230] After obtaining the load characteristic parameters of the target building, a load model is established, and the important control targets of the multi-split system under heating conditions, such as condensing temperature and subcooling, are directly calculated based on the demand load. This allows for the control of compressor frequency and indoor fan speed, with the outdoor unit's electronic expansion valve serving as a supplementary control item.

[0231] By controlling the multi-split air conditioning system according to real-time load demand, the problems of under-adjustment in high-load, low-temperature-difference scenarios and over-adjustment in low-load, high-temperature-difference scenarios are solved. This ensures that the air conditioning capacity matches the building load, reducing room temperature fluctuations and avoiding increased power consumption due to frequent start-stop cycles under low to medium loads, while enhancing indoor unit capacity and accelerating room temperature changes to improve user comfort under high loads. Under load-following technology, various energy-saving controls can be implemented according to user needs, while improving system reliability, achieving energy efficiency, and enhancing user comfort.

[0232] Step 1: Determine the heating load parameters of the room corresponding to the indoor unit:

[0233] In some embodiments, the method for determining the heating load parameters a, b, and c of the room corresponding to the indoor unit is as follows: the heating load parameters are built-in parameters of the multi-split air conditioner and can be read directly.

[0234] In some embodiments, the method for determining the heating load parameters a, b, and c of the room corresponding to the indoor unit is to determine more accurate heating load parameters of the room through self-learning based on historical data.

[0235] In some embodiments, it is determined whether the multi-split system is being powered on for the first time. If it is, the built-in heating load parameters a0, b0, and c0 of the multi-split system are read and used to control the system. If it is not the first time being powered on, it is necessary to determine whether self-learning is required for this operation. If the conditions for heating self-learning are met, self-learning is performed to determine the heating load parameters, and the multi-split system is controlled using the learned heating load parameters. In subsequent startup processes, it is determined whether self-learning is required for this operation. If not, the heating load parameters determined by the previous self-learning are used for control; if so, self-learning is performed to determine the heating load parameters, and the multi-split system is controlled using the learned heating load parameters.

[0236] exist Figure 7 In the example, the process for determining the heating load parameters in the heating mode is as follows:

[0237] S1, Begin.

[0238] S2. Determine if this is the first time the device is powered on. If yes, proceed to step S3; otherwise, proceed to step S4.

[0239] S3. Read the built-in heating load parameters a0, b0, and c0 of the multi-split unit as heating load parameters.

[0240] S4. Determine whether the heating self-learning conditions are met. If not, proceed to step S5. If yes, proceed to step S6.

[0241] S5. Obtain the heating load parameters from the last startup.

[0242] S6. Perform self-learning to determine the heating load parameters after learning.

[0243] Based on the indoor unit capacity Q of a multi-split air conditioning system e The indoor unit will be able to perform its Q function in real time when it is in a balanced state. e The building load characteristics are learned by treating the room load Qn as a factor. The building load characteristic model includes at least three parts: indoor air heat storage load, wall and window heat leakage load, and equipment and personnel internal disturbance load.

[0244] Among these, the air heat storage load is related to the room size and the difference between the set temperature and the initial temperature; the wall and window heat leakage load is mainly related to the building's insulation and the indoor-outdoor temperature difference; and the equipment and occupant disturbance load is related to the usage scenario. A numerical model of the load can be established based on the actual composition of the building load, by obtaining the real-time operating capacity Q of the indoor units.e The model learns the building load characteristics by treating the actual building load as the building's actual load. The learning process requires selecting a complete greenhouse process, and using the operational data during this process, the building load characteristic parameters in the load model are determined, ultimately forming a load characteristic model for the target building.

[0245] After the load characteristic model is established, the future outdoor ambient temperature, indoor temperature, and set temperature can be input into the model to determine the future room demand load. The system operating parameters can then be adjusted based on the demand load and the expected control objectives.

[0246] The self-learning process of heating load parameters is as follows:

[0247] The data obtained during the complete heating process are: the total heating time is greater than the set time Ymin; the initial indoor temperature and outdoor temperature difference is lower than the set temperature difference; the indoor temperature change within a specific time is higher than the first set difference; and the final indoor temperature and set temperature difference is lower than the set difference. These data are used as learning data.

[0248] Q: Real-time capability of obtaining indoor unit e ;

[0249] Based on the real-time capabilities of the indoor unit and the learning data, the load characteristic model is solved to determine the heating load parameters a, b, and c. The load characteristic model is Q. e =Q n = a × (difference between set temperature and indoor temperature) + b × (difference between indoor temperature and outdoor temperature) × learning time step - c × learning time step.

[0250] The load characteristic model is: Q n =a×(T) s -T i )+b×(T i -T i )×tc×t.

[0251] In the above formula:

[0252] Q n Building load, kW;

[0253] a, b, c: Heating load parameters, dimensionless units;

[0254] T i Indoor temperature, °C;

[0255] T s : Set temperature, °C;

[0256] T a Outdoor temperature, °C;

[0257] t: The time step of the learning process, in min.

[0258] In some embodiments, self-learning of heating load parameters is performed only if the following three conditions are met:

[0259] Condition 1: The indoor unit has not undergone any learning process since it was turned on this time;

[0260] Condition 2: The time elapsed since the last learning session ended is greater than m hours;

[0261] Condition 3: Obtain historical operating data of the indoor unit that can be used for model learning: that is, screen the quality of historical data of the indoor unit. When the historical process to be learned is a complete heating process, the model learning step will be executed only when a piece of data meets the following conditions: the total heating time is greater than Ymin, the initial room temperature is similar to the outdoor ambient temperature, the change in indoor temperature within a specific time is higher than the first set difference, and the difference between the final set temperature and the indoor temperature is lower than the second set difference.

[0262] exist Figure 8 In the example, the method for obtaining historical operating data of the indoor unit that can be used for model learning is as follows:

[0263] S1, Begin.

[0264] S2. Select the indoor thermal operation period to be used for learning, and obtain the operating parameters during this period: operating time tn, indoor temperature T. i Outdoor temperature T a and set temperature T s .

[0265] S3. Determine if the runtime tn is greater than or equal to the set runtime Ymin. If yes, proceed to step S4; otherwise, proceed to step S2.

[0266] S4, |Initial indoor temperature vs. outdoor temperature difference| is lower than the set temperature difference, |T i0 -T a0 If |≤k℃, proceed to step S5; otherwise, proceed to step S2.

[0267] S5. Within a specific time period, the indoor temperature change exceeds a first preset difference value. If yes, proceed to step S6; otherwise, proceed to step S2. The first preset difference value is, for example, 0.7℃.

[0268] S6. If the final indoor temperature is the same as the set temperature, proceed to step S7; otherwise, proceed to step S2.

[0269] S7. Obtain the real-time performance capability of the indoor unit during this runtime period. e Indoor temperature T i Outdoor temperature T a Set temperature T s And the time step t of the learning process.

[0270] Indoor unit real-time performance capability Q e It is a function related to the structural parameters, heat transfer coefficient, superheat, subcooling, and condensing temperature of the indoor unit heat exchanger, and can be calculated using existing technology:

[0271] Q e =f(S) str K i SH i SC i T c ).

[0272] In the above formula:

[0273] S str Indoor heat exchanger structural parameters;

[0274] K i : The heat transfer coefficient of the indoor heat exchanger under current operating conditions;

[0275] SH i : Inlet superheat of indoor heat exchanger, °C;

[0276] SC i : Subcooling degree at the outlet of the indoor heat exchanger, °C;

[0277] T c : Indoor heat exchanger condensing temperature, °C.

[0278] The real-time performance capability of the indoor unit during this period (Q) e Assuming the actual load Q of the room n .

[0279] Select at least three time points from the historical operating periods of the indoor unit for model learning, input the operating data of the indoor unit equipment at the above time points into the building load characteristic model, and establish equations to solve for the building load characteristic parameters a, b, and c.

[0280] Step 2: Setting the Real-Time Target Temperature

[0281] The desired indoor temperature at each moment is used as the real-time target temperature. The desired indoor temperature at each moment is determined based on the difference between the set temperature and the indoor temperature, the equipment's capacity characteristics, and the time elapsed during the heating process.

[0282] The desired indoor temperature T at each moment is determined based on the temperature rise curve. exp_n .

[0283] The optimal temperature rise curve for the heating process is calculated and set from the start of operation of the multi-split air conditioning system. The temperature rise curve represents the desired indoor temperature T at each moment. exp_nThis is used to calculate the demand load of the target room. The formula for calculating the curve is shown below:

[0284]

[0285] In the above formula,

[0286] α, β, γ, and θ are temperature characteristic constants;

[0287] τ n The value at the current moment when the self-heating process begins, h;

[0288] T i(n-1) Let be the indoor temperature at time n-1, in °C;

[0289] T i0 The initial indoor temperature, in °C;

[0290] T s The set temperature is ℃.

[0291] The optimal temperature rise curve controls the indoor temperature to drop rapidly in the first half to quickly reach a comfortable temperature, and then drops slowly in the second half to avoid over-adjustment.

[0292] In the optimal temperature rise curve, the target temperature value T at the initial moment is... exp_0 Take the initial indoor temperature T i0 The value; when the actual indoor temperature T i The heating process begins when the temperature reaches the set temperature T for the first time. s When they are equal, make T in Always equal to T s .

[0293] The optimal temperature rise curve will gradually bring the room temperature to the set temperature in a gentle, approximate manner. As time progresses, the expected temperature change at each step is related to the expected temperature difference at the initial moment and the expected temperature difference at the current moment.

[0294] The third step is to determine the real-time demand load Q. r_n .

[0295] Based on the difference T between the heating load parameters and the desired indoor temperature at the current moment. exp_n With indoor temperature T i(n) Indoor temperature T i(n) With outdoor temperature T a(n) The difference and control cycle determine the real-time demand load Q. r_n .

[0296] Real-time demand load Q r_n= a × (difference between desired indoor temperature and actual indoor temperature at time n) + b × (difference between indoor temperature and outdoor temperature at time n) × control period - c × control period.

[0297] After confirming the heating load parameters a, b, and c and the real-time desired indoor temperature, it is necessary to calculate the "real-time demand load Q" of the target indoor unit. r_n The calculation formula is as follows:

[0298] Q r_n =a×(T) exp_n -T i(n) )+b×(T i(n) -T a(n) )×tc×t.

[0299] In the above formula:

[0300] Q r_n Real-time demand load, kW;

[0301] a, b, c: Heating load parameters, dimensionless units;

[0302] T i(n) : Indoor temperature at time n, in °C;

[0303] T exp_n : The expected indoor temperature at time n, in °C;

[0304] T a(n) Outdoor ambient temperature, °C;

[0305] t: control cycle, h.

[0306] Step 4: Load following control.

[0307] After determining the real-time demand load, the control objective of the multi-split unit is controlled according to the real-time demand load to achieve load following control.

[0308] exist Figure 9 In the example, the load follower control process is as follows:

[0309] S1. Power on.

[0310] S2. Obtain heating load parameters.

[0311] S3. Real-time target temperature setting: Acquires indoor temperature, outdoor temperature, and set temperature; calculates the desired indoor temperature T at each moment based on the optimal temperature rise curve. exp_n .

[0312] S4, Set the indoor temperature T i(n) Expected indoor temperature T exp_n Outdoor temperature T a(n)Input heating load parameters into the load characteristic model to calculate the real-time demand load Q. r_n .

[0313] S5. Calculate and control the control objectives of the multi-split air conditioner based on real-time demand load.

[0314] S6. Is the device powered off? If yes, proceed to step S7; otherwise, proceed to step S3.

[0315] S7, Power off.

[0316] The building load following control of multi-split air conditioning systems mainly targets condensing temperature control and air volume control. These control objectives are primarily achieved through compressor frequency control, outdoor expansion valve opening control, and indoor unit fan speed control.

[0317] The main logic of load following control is to ensure that the real-time load demand value is directly equal to the real-time generating capacity value of the indoor unit, thus achieving load following control. After obtaining the real-time load demand value from step three, the target condensing temperature is determined, and the compressor operating frequency is determined based on the target condensing temperature. The indoor fan speed is determined based on the real-time load demand, and the compressor frequency and indoor fan speed are precisely adjusted. The initial opening of the outdoor expansion valve is determined, and the opening of the outdoor expansion valve is adjusted based on the subcooling, thus fine-tuning the multi-split system.

[0318] Obtain the real-time load demand Q for each indoor unit r_n Calculate the target condensing temperature for each indoor unit.

[0319]

[0320] Among them, f sh f sc For each indoor unit, the subcooling and superheating characteristic parameters are: m cs n cs T represents the characteristic parameter of the indoor mechanical heating sensible heat capacity; i The indoor temperature for each indoor unit.

[0321] The above calculation method takes into account the condensing temperature of the indoor unit heat exchanger when it may exert its sensible heat capacity under heating conditions.

[0322] The target condensing temperature is the maximum or average value of the target condensing temperatures of all indoor units.

[0323] In some embodiments, when the user selects a high comfort scenario, the target condensing temperature T of the multi-split system is... c0_i This is recorded as the maximum target condensing temperature of all indoor units in the system.

[0324] In some embodiments, when the user selects a high-performance scenario, the target condensing temperature T of the multi-split system is... c0_iThis is recorded as the average of the target condensing temperatures of all indoor units in the system.

[0325] The target condensing temperature T of the multi-split air conditioning system c0_i Determine the actual operating frequency Hi of the compressor.

[0326] In some embodiments, the compressor frequency is determined based on compressor parameters, the capacity of all indoor units, and the target condensing temperature.

[0327] The compressor frequency at time i

[0328] In the above formula, S1 is a characteristic parameter of the compressor, a constant, which is related to the compressor model;

[0329] S2 is the compressor frequency correction factor, a constant, which is related to the indoor unit model;

[0330] V HP_j Let be the capacity characteristic coefficient of the j-th indoor unit in the system, a constant, which is related to the capacity and model of the indoor unit.

[0331] The indoor fan speed is determined based on the real-time demand load, and the indoor fan speed is determined based on the ratio of the maximum indoor fan speed, the real-time demand load, and the capacity characteristic coefficient of the indoor unit.

[0332] Rotation speed of the indoor fan at time i

[0333] In the above formula: Q r_n The load requirement for each indoor unit, in kWh;

[0334] F max : Maximum speed of the fan, rpm;

[0335] Fo sh Fan speed subcooling correction parameters;

[0336] Fo T c: Fan speed and condensing temperature correction parameters;

[0337] V HP_j : The capacity characteristic coefficient of the j-th indoor unit in the system, a constant, which is related to the capacity and model of the indoor unit;

[0338] a is a constant, for example: a = 28.

[0339] The fan, as the main auxiliary adjustment component, is set to continuously variable speed. The fan speed is calculated based on the ratio of the real-time demand load to the indoor unit capacity characteristic coefficient. In addition, correction terms for subcooling and condensing temperature are added.

[0340] The outdoor unit includes an outdoor expansion valve 6. The initial opening of the outdoor expansion valve 6 is determined based on the maximum opening of the outdoor expansion valve 6, the capacity of the indoor unit when it is turned on, and the ratio of the capacity of the indoor unit to the sum of the capacities of all indoor units.

[0341] Initial opening value of each outdoor electronic expansion valve

[0342] In the above formula:

[0343] EXO max : Maximum opening value of the outdoor expansion valve.

[0344] The sum of the capacities of the indoor units that are powered on and running in the system, in HP.

[0345] —The total capacity of indoor units in the system, in HP.

[0346] C b —Mode correction parameter, a dimensionless parameter, related to specific function selection options.

[0347] Calculate the subcooling degree T of the indoor unit sc_i When the subcooling is lower than the target condensing temperature, reduce the opening of the outdoor expansion valve. When the subcooling is lower than the target condensing temperature, reduce the opening of the outdoor expansion valve. When the subcooling is equal to the target condensing temperature, keep the opening of the indoor expansion valve unchanged. When the subcooling is higher than the target condensing temperature, increase the opening of the outdoor expansion valve.

[0348] The amount of reduction in the opening of the outdoor expansion valve is determined based on the difference between the subcooling difference and the subcooling difference at two consecutive times, and the subcooling correction coefficient.

[0349] Determine the subcooling degree (Tsc) of the indoor unit i With the target condensation temperature T sco The relationship, if the supercooling Tsc i <T sco Then reduce the outdoor expansion valve opening value EVO; if the subcooling Tsc i =T sco Then keep the outdoor expansion valve opening value (EVO) unchanged; if Tsc i >T sco If so, increase the outdoor expansion valve opening value EVO.

[0350] T sco The numerical value range is [8, 15]℃.

[0351] The electronic expansion valve opening value (EVO) at the next moment i(n+1) The calculation method is as follows:

[0352] ΔSCi(n) =SC i(n) -SC i(n-1) .

[0353] In the above formula: r1, r2, C SH Subcooling correction coefficient, a constant, is related to the indoor unit model;

[0354] SC i(n) : Subcooling at the indoor unit outlet at time n.

[0355] exist Figure 10 In the example, the process of controlling the multi-split air conditioning system is as follows:

[0356] S1, Begin.

[0357] S2. Obtain system operating status parameters.

[0358] S3. Calculate the real-time load demand Q for each indoor unit. r_n .

[0359] S4. Calculate the target condensing temperature T for each indoor unit based on real-time demand load. c_i .

[0360] S5. Calculate the target condensing temperature T of the multi-split air conditioning system. co_i .

[0361] S6. Calculate the initial opening of the outdoor expansion valve, based on the target condensing temperature T. co_i Calculate the compressor frequency and indoor fan speed. Control the compressor frequency, outdoor expansion valve opening, and indoor fan speed.

[0362] S7. Determine the indoor subcooling value Tsc i With the target condensation temperature T sco The relationship in Tsc i >T sco At that time, proceed to step S8, in Tsc i =T sco Then, proceed to step S9, in Tsc i <T sco Then proceed to step S10.

[0363] S8. Increase the opening of the outdoor expansion valve. Proceed to step S11.

[0364] S9. Keep the outdoor expansion valve opening unchanged. Proceed to step S11.

[0365] S10. Reduce the opening of the outdoor expansion valve while keeping it unchanged. Proceed to step S11.

[0366] S11. Is the device powered off? If yes, proceed to step S12; otherwise, proceed to step S2.

[0367] S12, Power off.

[0368] Multi-split air conditioning systems adjust the control method of the compressor and expansion valve based on the actual load demand of the building, which can match the air conditioning capacity with the actual load of the building and solve the problems of over- or under-utilization of indoor unit capacity.

[0369] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0370] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A multi-split air conditioning system, comprising an outdoor unit and at least two indoor units, wherein the outdoor unit includes an outdoor temperature detection module, characterized in that, When the indoor unit is running in cooling mode: Determine the cooling load parameters of the room corresponding to the indoor unit; Determine the desired indoor temperature at each moment; The real-time demand load is determined based on the cooling load parameters, the difference between the current indoor temperature and the desired indoor temperature, the difference between the outdoor temperature and the indoor temperature, and the control cycle. The target evaporation temperature is determined based on the real-time demand load, and the compressor frequency is determined based on the target evaporation temperature.

2. The multi-unit air conditioning system according to claim 1, characterized in that, The cooling load parameters are built-in parameters of the multi-split air conditioning system, and / or the cooling load parameters are determined through self-learning: The data obtained during the complete cooling process are: the total cooling time is greater than the set time; the initial indoor temperature difference between indoor and outdoor temperatures is lower than the set temperature difference; the indoor temperature change within a specific time period is higher than the first set difference; and the final indoor temperature difference between indoor and set temperatures is lower than the second set difference. These data are used as learning data. Obtain the real-time capability Qe of the indoor unit; The cooling load parameters a, b, and c are determined by solving the load characteristic model based on the real-time capacity Qe of the indoor unit and the learning data. The load characteristic model is Qe = Qn = a × (difference between indoor temperature and set temperature) + b × (difference between outdoor temperature and indoor temperature) × learning time step + c × learning time step.

3. The multi-unit air conditioning system according to claim 2, characterized in that, The real-time demand load Q r _n = a × (difference between indoor temperature and desired indoor temperature at time n) + b × (difference between outdoor temperature and indoor temperature at time n) × control period + c × control period.

4. The multi-unit air conditioning system according to claim 1, characterized in that, The desired indoor temperature at each moment is determined based on the difference between the indoor temperature and the set temperature, the equipment's capacity characteristics, and the time elapsed since the cooling process began.

5. The multi-unit air conditioning system according to claim 1, characterized in that, Obtain the real-time load demand Q for each indoor unit r_n Calculate the target evaporation temperature for each indoor unit. Among them, f sh f sc For each indoor unit, the subcooling and superheating characteristic parameters are: m cs n cs The characteristic parameters of the indoor unit's cooling and sensible heating capacity; m cl n cl T represents the characteristic parameter of the indoor mechanism's latent heat capacity; i The indoor temperature for each indoor unit; T ld The dew point temperature corresponding to the return air temperature of each indoor unit.

6. The multi-unit air conditioning system according to claim 5, characterized in that, The target evaporation temperature is the minimum or average of the target evaporation temperatures of all indoor units.

7. The multi-unit air conditioning system according to claim 1, characterized in that, The compressor frequency is determined based on the compressor parameters, the capacity of all indoor units, and the target evaporation temperature.

8. The multi-split air conditioning system according to any one of claims 1-7, characterized in that, The indoor fan speed is determined based on the real-time demand load, and the indoor fan speed is determined based on the ratio of the maximum indoor fan speed, the real-time demand load, and the capacity characteristic coefficient of the indoor unit.

9. The multi-split air conditioning system according to any one of claims 1-7, characterized in that, The indoor unit includes an indoor expansion valve. The initial opening of the indoor expansion valve is determined based on the maximum opening of the indoor expansion valve and the ratio of the current capacity of the indoor unit to the total capacity of all indoor units. The superheat value of the indoor unit is determined. When the superheat value is lower than the set value, the opening of the indoor expansion valve remains unchanged. When the superheat value is higher than the set value, the opening of the indoor expansion valve is reduced.

10. The multi-unit air conditioning system according to claim 9, characterized in that, The amount of reduction in the opening of the indoor expansion valve is determined based on the difference between the superheat difference and the superheat difference at two consecutive times, and the superheat correction coefficient.

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