Control method, controller and multi-connected system of multi-connected system

Abstract

The application discloses a control method of a multi-connected system, a controller and the multi-connected system. The multi-connected system comprises an outdoor unit and multiple indoor units connected with the outdoor unit. The control method comprises the following steps: determining a load index of the indoor unit according to an indoor temperature detected by the indoor unit; determining a target evaporation temperature according to the load index; and adjusting a lower limit value of a running frequency of the compressor in a refrigeration mode according to the target evaporation temperature and an actual evaporation temperature of the indoor unit. In the embodiment of the application, the lowest running lower limit of the compressor can be relaxed, and the low-frequency performance of the compressor can be fully exerted.

Description

Technical Field

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

[0002] Multi-split air conditioning systems connect multiple indoor units. Due to the diverse operating requirements of different indoor units, the load demand range of current multi-split systems is quite large. To match the diverse operating range of loads, wide-range compressors are used in multi-split systems.

[0003] Currently, although wide-frequency compressors are used in multi-split air conditioning systems, their low-frequency stability and noise levels limit their operation. Under current control methods, the lowest frequency of these compressors can only be used in specific energy-saving modes, not in normal cooling modes. This prevents the full realization of the advantages of wide-frequency compressors in low-load scenarios. Consequently, multi-split air conditioning systems perform poorly in low-load conditions when running in normal cooling mode, with the compressor frequently starting and stopping, causing frequent fluctuations in indoor temperature, resulting in neither energy efficiency nor comfort. Summary of the Invention

[0004] This application provides a control method, controller, and multi-split air conditioning system, which can relax the minimum operating limit of the compressor and give full play to the low-frequency performance of the compressor.

[0005] In a first aspect, embodiments of this application provide a control method for a multi-split air conditioning system, the multi-split system including an outdoor unit and multiple indoor units connected to the outdoor unit; the control method includes:

[0006] The load index of the indoor unit is determined based on the indoor temperature detected by the indoor unit;

[0007] The target evaporation temperature is determined based on the load index.

[0008] The lower limit of the compressor's operating frequency in cooling mode is adjusted based on the target evaporation temperature and the actual evaporation temperature of the indoor unit.

[0009] In some embodiments, determining the target evaporation temperature based on the load index includes:

[0010] Determine the maximum load index among the load indices;

[0011] The target evaporation temperature for the current detection cycle is obtained based on the maximum load index and the target evaporation temperature of the previous detection cycle.

[0012] In some embodiments, adjusting the lower limit of the compressor's operating frequency in cooling mode based on the target evaporation temperature and the actual evaporation temperature of the indoor unit includes:

[0013] The temperature difference is determined based on the target evaporation temperature and the actual evaporation temperature of the indoor unit.

[0014] Adjust the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference.

[0015] In some embodiments, determining the temperature difference based on the target evaporation temperature and the actual evaporation temperature of the indoor unit includes:

[0016] Obtain the actual evaporation temperature of all indoor units corresponding to the current detection cycle, and determine the actual evaporation average value based on the actual evaporation temperature;

[0017] The temperature difference is determined based on the target evaporation temperature and the actual average evaporation value.

[0018] In some embodiments, before adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference, the method further includes:

[0019] The duration for which the temperature difference is greater than the preset temperature value is greater than a first duration, and the duration for which the compressor's current operating frequency is equal to the lower limit of the default operating frequency of the cooling mode is greater than a second duration, are determined.

[0020] or,

[0021] The duration for which the temperature difference is greater than a preset temperature value is greater than a first duration, and the duration for which the maximum load index in the load index is less than or equal to a first threshold is greater than a third duration.

[0022] In some embodiments, adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference includes:

[0023] Determine the frequency difference between the default lower limit of the energy-saving mode and the default lower limit of the cooling mode;

[0024] Based on the frequency difference, a correspondence is established between different temperature values ​​and the reduced operating frequency.

[0025] The operating frequency reduction value is determined based on the temperature difference and the corresponding relationship, and the default operating frequency lower limit value of the cooling mode is adjusted to reduce the operating frequency reduction value.

[0026] In some embodiments, the correspondence is a correspondence between different temperature ranges and the operating frequency reduction value; determining the operating frequency reduction value based on the temperature difference and the correspondence includes:

[0027] Based on the target temperature range into which the temperature difference falls, determine the corresponding downward adjustment value of the operating frequency for the target temperature range.

[0028] In some embodiments, the number of temperature intervals is determined by the value of the frequency difference, and the length of each temperature interval is equal to the difference between a first preset temperature value and a second preset temperature value divided by the number of temperature intervals.

[0029] In some embodiments, before adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference, the method further includes:

[0030] The high-pressure side pressure value and low-pressure side pressure value of the compressor are obtained, and the high-low pressure ratio value is determined based on the high-pressure side pressure value and the low-pressure side pressure value.

[0031] The duration for which the high-low pressure ratio is greater than the third threshold, the duration for which the temperature difference is greater than the preset temperature value is greater than the first duration, and the duration for which the current operating frequency is equal to the lower limit of the default operating frequency of the cooling mode is greater than the second duration are determined.

[0032] or,

[0033] The duration for which the high-low pressure ratio is greater than a third threshold, the duration for which the temperature difference is greater than the preset temperature value is greater than the first duration, and the duration for which the maximum load index is less than or equal to the first threshold is greater than the third duration are determined.

[0034] In some embodiments, after adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference, the method further includes:

[0035] When the multi-split system meets the exit conditions, the lower limit of the compressor's operating frequency in cooling mode is reset to the default lower limit of the operating frequency in cooling mode;

[0036] The exit conditions include at least one of the following:

[0037] The high-low pressure ratio is less than the fourth threshold, and the fourth threshold is less than or equal to the third threshold;

[0038] The cumulative running time when the current operating frequency is less than the fifth threshold is the fourth duration, and the fifth threshold is determined based on the safe operating frequency of the multi-unit system.

[0039] All indoor units are turned off.

[0040] In some embodiments, determining the load index of the indoor unit based on the indoor temperature detected by the indoor unit includes:

[0041] The temperature difference data of the indoor unit that is turned on within a preset time period is obtained. The temperature difference data is the difference between the indoor temperature of the corresponding indoor unit and the set temperature.

[0042] The load index of the indoor unit at the current moment is determined based on the temperature difference data.

[0043] In some embodiments, determining the load index of the indoor unit at the current moment based on the temperature difference data includes:

[0044] Determine the temperature difference function and weighting function within a preset time period. The temperature difference function represents the temperature difference data at different detection times within the preset time period, and the weighting function represents the weight value at different detection times within the preset time period.

[0045] The load index of the indoor unit at the current moment is determined based on the convolution integral result of the temperature difference function and the weighting function.

[0046] Secondly, embodiments of this application provide a controller, including at least one processor and a memory for communicatively connecting to the at least one processor; the memory stores instructions executable by the at least one processor, which, when executed by the at least one processor, enable the at least one processor to perform the control method for a multi-unit system as described in the first aspect.

[0047] Thirdly, embodiments of this application provide a multi-unit system, including the controller of the second aspect.

[0048] The control method, controller, and multi-split air conditioning system of this application embodiment have at least the following beneficial effects: The multi-split air conditioning system includes an outdoor unit and multiple indoor units connected to the outdoor unit. The multi-split air conditioning system collects the indoor temperature detected by the running indoor units and calculates the load index of the indoor units. By real-time monitoring of the operating status of the indoor units, the load demand of the indoor units is determined, and then the target evaporation temperature is determined according to the load index. Thus, the evaporation temperature during the operation of the indoor units can be determined based on the load demand of the indoor units, which facilitates the adjustment of the lower limit of the compressor operating frequency under different scenarios. Finally, the lower limit of the compressor operating frequency in cooling mode is adjusted according to the target evaporation temperature and the actual evaporation temperature of the indoor units, relaxing the minimum operating limit of the compressor, making the indoor temperature control more precise, and fully utilizing the low-frequency performance of the compressor while ensuring the reliability of the compressor. This embodiment effectively alleviates the problem of frequent shutdowns caused by insufficient compressor frequency reduction during low-load operation of multi-split air conditioning systems by determining key operating parameters such as the indoor unit's load index and target evaporation temperature. By determining the target evaporation temperature, indoor temperature control can be more precise, and the system can maximize the performance of the wide-frequency compressor, making the overall system more energy-efficient.

[0049] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description and the accompanying drawings. Attached Figure Description

[0050] Figure 1 This is a flowchart of a control method for a multi-unit air conditioning system provided in one embodiment of this application;

[0051] Figure 2 This is a flowchart for determining a target evaporation temperature provided in one embodiment of this application;

[0052] Figure 3 This is a flowchart illustrating the adjustment of the lower limit value of the compressor operating frequency based on the target evaporation temperature and the actual evaporation temperature, provided in one embodiment of this application.

[0053] Figure 4 This is a flowchart of determining a temperature difference value provided in one embodiment of this application;

[0054] Figure 5 This is a flowchart of a control method for a multi-unit air conditioning system provided in another embodiment of this application;

[0055] Figure 6 This is a flowchart illustrating the adjustment of the lower limit value of the compressor operating frequency based on the temperature difference, according to one embodiment of this application.

[0056] Figure 7 This is a flowchart of determining the down-adjustment value of the operating frequency provided in one embodiment of this application;

[0057] Figure 8 This is a flowchart of a control method for a multi-unit air conditioning system provided in another embodiment of this application;

[0058] Figure 9 This is a flowchart illustrating the resetting of the lower limit value according to one embodiment of this application;

[0059] Figure 10 This is a flowchart of determining the load index of an indoor unit provided in one embodiment of this application;

[0060] Figure 11 This is a flowchart of determining the load index of the indoor unit at the current moment based on temperature difference data, provided in one embodiment of this application;

[0061] Figure 12 This is an overall flowchart of the control method for a multi-unit system provided in an example of this application;

[0062] Figure 13 This is a schematic diagram of a controller provided in one embodiment of this application. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various implementations. Simultaneously, the steps or actions described in the method description can be rearranged or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0064] In the description of this application, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0065] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0066] Multi-split air conditioning systems connect multiple indoor units. Due to the diverse operating requirements of different indoor units, the load demand range of current multi-split systems is quite large. To match the diverse operating range of loads, wide-range compressors are used in multi-split systems.

[0067] Currently, although wide-frequency compressors are used in multi-split air conditioning systems, their low-frequency stability and noise levels limit their operation. Under current control methods, the lowest frequency of these compressors can only be used in specific energy-saving modes, not in normal cooling modes. This prevents the full realization of the advantages of wide-frequency compressors in low-load scenarios. Consequently, multi-split air conditioning systems perform poorly in low-load conditions when running in normal cooling mode, with the compressor frequently starting and stopping, causing frequent fluctuations in indoor temperature, resulting in neither energy efficiency nor comfort.

[0068] Based on this, this application provides a control method, controller, and multi-split air conditioning system. The multi-split air conditioning system includes an outdoor unit and multiple indoor units connected to the outdoor unit. The multi-split air conditioning system collects the indoor temperature detected by the running indoor units and calculates the load index of the indoor units. By real-time monitoring of the operating status of the indoor units, the load demand of the indoor units is determined, and then the target evaporation temperature is determined based on the load index. This allows the evaporation temperature during the operation of the indoor units to be determined based on the load demand of the indoor units, facilitating the adjustment of the lower limit of the compressor operating frequency under different scenarios. Finally, the lower limit of the compressor operating frequency in cooling mode is adjusted according to the target evaporation temperature and the actual evaporation temperature of the indoor units, relaxing the minimum operating limit of the compressor, making the indoor temperature control more precise, and fully utilizing the low-frequency performance of the compressor while ensuring the reliability of the compressor. This embodiment effectively alleviates the problem of frequent shutdowns caused by insufficient compressor frequency reduction during low-load operation of multi-split air conditioning systems by determining key operating parameters such as the indoor unit's load index and target evaporation temperature. By determining the target evaporation temperature, indoor temperature control can be more precise, and the system can maximize the performance of the wide-frequency compressor, making the overall system more energy-efficient.

[0069] The control method, controller, and multi-split air conditioning system are described below with reference to the accompanying drawings.

[0070] Reference Figure 1 As shown, Figure 1 This is a flowchart of a control method for a multi-unit air conditioning system provided in one embodiment of this application. The control method includes, but is not limited to, steps S101 to S103.

[0071] It should be noted that a multi-split system includes an outdoor unit and multiple indoor units connected to the outdoor unit. The multi-split system connects multiple indoor units through at least one outdoor unit. The outdoor unit is equipped with a compressor, which is connected to each indoor unit through refrigerant pipes. The multi-split system can achieve functions such as cooling and heating of the indoor units by controlling the operating status of the compressor and the flow direction of refrigerant in the refrigerant pipes.

[0072] Step S101: Determine the load index of the indoor unit based on the indoor temperature detected by the indoor unit.

[0073] In some embodiments, during the operation of a multi-split air conditioning system, the diverse operating needs of different indoor units result in a large load demand for the system. In order to fully utilize the compressor's performance in different scenarios, the multi-split air conditioning system in this embodiment first determines the load demand of the indoor unit, i.e., the load index, by detecting the indoor temperature of the corresponding room. The load index indicates the magnitude of the indoor unit's load demand. Then, based on the load index of each indoor unit, it determines how to adjust the lower limit of the compressor's operating frequency in cooling mode. By determining the load index of the indoor unit, it can respond more accurately to changes in indoor temperature, avoid energy waste and over-cooling or overheating, and improve energy efficiency and comfort.

[0074] Step S102: Determine the target evaporation temperature based on the load index.

[0075] In some embodiments, the load requirements of different indoor units in a multi-split air conditioning system may differ, resulting in a wide load operating range for the multi-split air conditioning system. Therefore, it is particularly important to fully utilize the performance of the compressor under different application scenarios. In this application embodiment, the target evaporation temperature of the multi-split air conditioning system is determined by the load index of the indoor unit, thereby obtaining the target temperature that the indoor unit needs to reach during the operation of the multi-split air conditioning system. This facilitates subsequent judgment on whether the lower limit of the compressor's operating frequency needs to be adjusted, ensuring that the multi-split air conditioning system can operate stably under load.

[0076] Step S103: Adjust the lower limit of the compressor's operating frequency in cooling mode according to the target evaporation temperature and the actual evaporation temperature of the indoor unit.

[0077] In some embodiments, the lowest frequency of the wide-frequency compressor can only be used in specific energy-saving modes and cannot be fully utilized in normal cooling modes. This prevents the wide-frequency compressor from fully leveraging its advantages in low-load scenarios, resulting in poor performance of multi-split systems in normal cooling modes under low-load conditions, with frequent compressor start-stops causing frequent fluctuations in indoor temperature. To avoid frequent compressor start-stops or fluctuating indoor temperatures, this application embodiment dynamically adjusts the compressor's operating frequency based on the actual evaporation temperature of the indoor unit. After determining the target evaporation temperature, the multi-split system adjusts the lower limit of the compressor's operating frequency in cooling mode according to the target evaporation temperature and the actual evaporation temperature of the indoor unit. This allows for dynamic adjustment of the compressor's operating frequency lower limit based on actual needs, enabling the system to respond more intelligently to actual load demands, resulting in more precise indoor temperature control, improved energy efficiency, reduced energy consumption, and maintenance of indoor environmental comfort. This approach ensures compressor reliability while fully utilizing the low-frequency performance of the wide-frequency compressor.

[0078] Reference Figure 2 As shown, Figure 2 This is a flowchart of determining a target evaporation temperature according to an embodiment of this application. It includes, but is not limited to, steps S201 to S202.

[0079] Step S201: Determine the maximum load index in the load index.

[0080] Step S202: Based on the maximum load index and the target evaporation temperature of the previous detection cycle, obtain the target evaporation temperature of the current detection cycle.

[0081] In steps S201 to S202 of some embodiments, during the process of determining the target evaporation temperature based on the load index, the load index is used to understand the current load demand of the multi-split system, and the load indices of all indoor units are compared to determine the maximum load index. Then, the target evaporation temperature of the previous detection cycle is determined, and the target evaporation temperature of the previous detection cycle is updated based on the maximum load index to determine the evaporation temperature that the compressor needs to reach in the current detection cycle. This ensures that the multi-split system can operate stably under load conditions, avoids overload or excessive operation, thereby extending the equipment life and improving the system performance, and ensuring the reliability of compressor operation.

[0082] Specifically, the target evaporation temperature can be updated using the following formula:

[0083] T2_target t =T2_target t-1 -C*max(LDI);

[0084] In this embodiment, the system target evaporation temperature T2_target at time t is updated and calculated every time interval. t `max(LDI)` represents the maximum value of the LDI calculated by all currently running indoor units, `C` is the adjustment coefficient, representing the adjustment range of the system's target evaporation temperature according to the load index, and `T2_target`. t-1 This is the target evaporation temperature for the previous testing cycle.

[0085] It is worth noting that T2_target in this embodiment has a preset upper and lower limit, for example, constrained between 7 and 18, so as to ensure the reliability of compressor operation and avoid overload or excessive operation.

[0086] It should be noted that the detection cycle in this embodiment can be set according to the user's needs. For example, the detection cycle can be to update the target evaporation temperature every hour, every two hours, every thirty minutes, etc. This embodiment does not impose any specific limitations.

[0087] Reference Figure 3 As shown, Figure 3 This is a flowchart illustrating an embodiment of the present application for adjusting the lower limit of the compressor operating frequency based on the target evaporation temperature and the actual evaporation temperature. The method includes, but is not limited to, steps S301 to S302.

[0088] Step S301: Determine the temperature difference based on the target evaporation temperature and the actual evaporation temperature of the indoor unit.

[0089] Step S302: Adjust the lower limit of the compressor's operating frequency in cooling mode according to the temperature difference.

[0090] In steps S301 to S302 of some embodiments, during the process of adjusting the lower limit of the compressor operating frequency, the actual evaporation temperature of the indoor unit in the multi-split system is obtained. Then, the temperature difference between the target evaporation temperature and the actual evaporation temperature of the indoor unit is determined, thereby reflecting the current operating status and performance of the multi-split system and ensuring that the system can operate effectively under different load conditions. Finally, the lower limit of the compressor operating frequency in cooling mode is adjusted according to the temperature difference to improve the stability and performance of the system. This avoids frequent temperature-reaching shutdowns caused by insufficient compressor minimum frequency lower limit, resulting in the inability to reduce the frequency. This makes indoor temperature control more accurate and avoids excessive system operation or unnecessary energy consumption.

[0091] Reference Figure 4 As shown, Figure 4 This is a flowchart illustrating the determination of a temperature difference value according to an embodiment of this application. It includes, but is not limited to, steps S401 to S402.

[0092] Step S401: Obtain the actual evaporation temperature of all indoor units corresponding to the current detection cycle, and determine the actual evaporation average value based on the actual evaporation temperature.

[0093] Step S402: Determine the temperature difference based on the target evaporation temperature and the actual average evaporation temperature.

[0094] In steps S401 to S402 of some embodiments, in the process of determining the temperature difference based on the target evaporation temperature and the actual evaporation temperature of the indoor unit, if only the actual evaporation temperature of a single indoor unit in the multi-split system is considered, it may lead to inaccurate indoor temperature control and affect the stable operation of the multi-split system. In this embodiment, the actual evaporation temperature of all indoor units corresponding to the current detection cycle is obtained, and the actual evaporation average value of all actual evaporation temperatures is determined. The actual evaporation average value takes into account the actual evaporation temperature of all indoor units in the system, not just the temperature of a single indoor unit. This can more accurately reflect the operating status and load demand of the entire system without being affected by abnormal fluctuations in the temperature of individual indoor units. Then, the target evaporation temperature and the actual evaporation average value are compared at each moment in the detection cycle to obtain the temperature difference value, thereby obtaining the performance of the multi-split system and reflecting the operating status of the multi-split system in the current detection cycle.

[0095] Specifically, the temperature difference can be expressed by the following formula:

[0096] △T2 = T2_target - T2_av;

[0097] Where T2_av is the actual average evaporation value, and T2_target is the target evaporation temperature.

[0098] Reference Figure 5 As shown, Figure 5 This is a flowchart of a control method for a multi-unit air conditioning system provided in another embodiment of this application. The method includes, but is not limited to, steps S501 to S502.

[0099] It should be noted that steps S501 to S502 occur before adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference.

[0100] Step S501: Determine that the duration for which the temperature difference is greater than the preset temperature value is greater than the first duration, and the duration for which the current operating frequency of the compressor is equal to the lower limit of the default operating frequency of the cooling mode is greater than the second duration.

[0101] Step S502: Determine that the duration of the temperature difference being greater than the preset temperature value is greater than the first duration, and the duration of the maximum load index in the load index being less than or equal to the first threshold is greater than the third duration.

[0102] In steps S501 to S502 of some embodiments, before adjusting the lower limit of the compressor's operating frequency in cooling mode, it is necessary to determine whether the current multi-split system needs to enter the process of adjusting the lower limit. If the current compressor's lowest frequency meets the requirements of normal cooling mode or more cooling modes, then it is not necessary to adjust the lower limit of the compressor's operating frequency. If the current compressor's lowest frequency does not meet the requirements of normal cooling mode, then it is necessary to dynamically adjust the lower limit of the compressor's operating frequency. Specifically, when it is determined that the duration of the temperature difference being greater than the preset temperature value is greater than the first duration, it indicates that the target evaporation temperature of the current multi-split system is significantly different from the actual evaporation temperature, and the indoor unit of the multi-split system is in this situation for a long time. Further judgment is needed to determine whether the multi-split system should enter the procedure of adjusting the lower limit. This embodiment will illustrate the following two situations.

[0103] In the first case, the compressor's operating frequency is determined. If the duration for which the compressor's current operating frequency is equal to the default operating frequency lower limit of the cooling mode is greater than the second duration, it indicates that the compressor's operating frequency lower limit is the default operating frequency lower limit of the cooling mode. However, the current default operating frequency lower limit of the cooling mode cannot solve the problem of frequent compressor start-stop. Therefore, it is necessary to enter the program to dynamically adjust the compressor's operating frequency lower limit, thereby relaxing the compressor's minimum operating limit.

[0104] In the second scenario, the load demand of the indoor unit is assessed. If the duration of the maximum load index in the load index being less than or equal to the first threshold is greater than the third duration, it indicates that the maximum load demand of the indoor unit is less than or equal to the first threshold. At this point, the program to adjust the lower limit of the compressor's operating frequency can be initiated, allowing the system to maximize the performance of the wide-frequency compressor and fully utilize its capabilities.

[0105] It should be noted that if the duration of the temperature difference being greater than the preset temperature value is greater than the first duration, the multi-split air conditioning system will enter the procedure of adjusting the lower limit of the compressor's operating frequency, provided any of the above conditions are met. In this embodiment, the first, second, and third durations can be set according to the user's needs or the historical operating parameters of the multi-split air conditioning system. Similarly, the preset temperature value and the first threshold can also be set according to the user's needs or the historical operating parameters of the multi-split air conditioning system. The first, second, and third durations can be the same or different; this embodiment does not impose specific restrictions.

[0106] In some embodiments, if the temperature difference is less than or equal to the preset temperature value, it indicates that the difference between the target evaporation temperature and the actual evaporation temperature of the current multi-split system is small, and there is no need to adjust the lower limit of the compressor's operating frequency; or, if the duration for which the temperature difference is greater than the preset temperature value is less than or equal to a first duration, it indicates that although the difference between the target evaporation temperature and the actual evaporation temperature of the current multi-split system is large, the duration for which the multi-split system maintains this state is short, that is, the state of the multi-split system may change, and in this case, there is also no need to adjust the lower limit of the compressor's operating frequency.

[0107] Reference Figure 6 As shown, Figure 6 This is a flowchart illustrating an embodiment of the present application for adjusting the lower limit of the compressor operating frequency based on the temperature difference. The method includes, but is not limited to, steps S601 to S603.

[0108] Step S601: Determine the frequency difference between the default lower limit of the energy-saving mode and the default lower limit of the cooling mode.

[0109] Step S602: Construct a correspondence between different temperature values ​​and the reduced operating frequency value based on the frequency difference.

[0110] Step S603: Determine the lower limit of the operating frequency based on the temperature difference and the corresponding relationship, and adjust the lower limit of the default operating frequency of the cooling mode to reduce the lower limit of the operating frequency.

[0111] In steps S601 to S603 of some embodiments, during the process of adjusting the lower limit of the compressor's operating frequency, since the compressor's lowest frequency can only be used in a specific energy-saving mode and cannot be fully opened for use in the normal cooling mode, the lower limit of the compressor's operating frequency differs between the energy-saving mode and the normal cooling mode. Therefore, the embodiments of the application need to determine the lower limit of the compressor's default operating frequency in the energy-saving mode and the lower limit of the default operating frequency in the cooling mode, and determine the frequency difference between the lower limit of the default operating frequency in the energy-saving mode and the lower limit of the default operating frequency in the cooling mode, thereby determining the frequency difference of the compressor in the two different modes. Then, based on the frequency difference, a correspondence between different temperature values ​​and the operating frequency reduction value is established. This allows for setting different compressor frequency operating limits in different scenarios, facilitating the relaxation of the compressor's minimum operating limit under different conditions. Finally, the operating frequency reduction value is determined based on the temperature difference and the correspondence, avoiding frequent start-stop of the compressor in different scenarios that would cause frequent fluctuations in indoor temperature. Adjusting the default operating frequency lower limit value of the cooling mode to reduce the operating frequency reduction value allows for flexible adjustment of the compressor's minimum operating limit under different scenarios and conditions, fully utilizing the compressor's low-frequency performance while ensuring compressor reliability.

[0112] Reference Figure 7 As shown, Figure 7 This is a flowchart illustrating the determination of a downgraded operating frequency value according to an embodiment of this application. The method includes, but is not limited to, step S701.

[0113] It should be noted that the correspondence is between different temperature ranges and the reduced operating frequency value, that is, each temperature range has its own corresponding reduced operating frequency value.

[0114] In some embodiments, the number of temperature intervals is determined by the value of the frequency difference. The length of each temperature interval is equal to the difference between the first preset temperature value and the second preset temperature value divided by the number of temperature intervals. That is, the length of the temperature interval can be expressed as DT2 = (first preset temperature value - second preset temperature value) / frequency difference, thereby realizing the multi-dimensional division of temperature intervals. This allows for setting corresponding operating frequency reduction values ​​for different temperature intervals, enabling flexible adjustment of the minimum operating limit value.

[0115] It should be noted that the first and second preset temperature values ​​can be set by the user according to their needs or the historical operating parameters of the multi-split system.

[0116] Step S701: Determine the downward adjustment value of the operating frequency corresponding to the target temperature range based on the temperature difference value falling into the target temperature range.

[0117] In some embodiments, the present application defines several temperature ranges, and each temperature range corresponds to its own operating frequency reduction value. In a multi-split air conditioning system, the compressor operates at different frequencies under different conditions. The present application determines the current temperature range of the compressor based on the target temperature range into which the temperature difference falls, and determines the operating frequency reduction value corresponding to the target temperature range. This enables the determination of the operating frequency reduction value of the compressor under specific conditions, avoiding the problem of frequent temperature-reaching shutdowns caused by insufficient compressor minimum frequency lower limit.

[0118] Reference Figure 8 As shown, Figure 8 This is a flowchart of a control method for a multi-unit air conditioning system provided in another embodiment of this application. The method includes, but is not limited to, steps S801 to S803.

[0119] It should be noted that steps S801 to S803 occur before adjusting the lower limit of the compressor's operating frequency in refrigeration mode based on the temperature difference.

[0120] Step S801: Obtain the high-pressure side pressure value and low-pressure side pressure value of the compressor, and determine the high-low pressure ratio value based on the high-pressure side pressure value and low-pressure side pressure value.

[0121] In some embodiments, before adjusting the lower limit of the compressor's operating frequency in cooling mode, the high-pressure measurement value and low-pressure test value of the multi-split system can be combined to determine whether the current multi-split system needs to enter the process of adjusting the lower limit. Specifically, in this embodiment, the high-pressure side pressure value and low-pressure side pressure value of the compressor are obtained, and the high-low pressure ratio is determined based on the high-pressure side pressure value and low-pressure side pressure value, thereby quickly determining the operating status of the multi-split system. In this embodiment, the high-low pressure ratio can reflect the current workload of the compressor.

[0122] Step S802: Determine that the duration for which the high-low pressure ratio is greater than the third threshold, the duration for which the temperature difference is greater than the preset temperature value is greater than the first duration, and the duration for which the current operating frequency is equal to the lower limit of the default operating frequency of the cooling mode is greater than the second duration.

[0123] In some embodiments, if the duration of the high-low pressure ratio being greater than a third threshold, the temperature difference being greater than a preset temperature value being greater than a first duration, and the duration of the current operating frequency being equal to the default operating frequency lower limit of the cooling mode being greater than a second duration, it indicates that the compressor's workload is large, the target evaporation temperature differs significantly from the actual evaporation temperature, and the current default operating frequency lower limit of the cooling mode cannot solve the problem of frequent compressor start-stop. Therefore, it is necessary to enter a program to dynamically adjust the compressor's operating frequency lower limit, thereby relaxing the compressor's minimum operating limit.

[0124] Step S803: Determine that the duration of the high-low pressure ratio being greater than the third threshold, the temperature difference being greater than the preset temperature value being greater than the first duration, and the duration of the maximum load index being less than or equal to the first threshold being greater than the third duration.

[0125] In some embodiments, if the duration of the high-low pressure ratio being greater than a third threshold, the temperature difference being greater than a preset temperature value being greater than a first duration, and the duration of the maximum load index being less than or equal to the first threshold being greater than a third duration, it indicates that the compressor's workload is large, the target evaporation temperature differs significantly from the actual evaporation temperature, and the maximum load requirement of the indoor unit is less than or equal to the first threshold. In this case, the program to adjust the lower limit of the compressor's operating frequency can be entered, so that the system can maximize the performance of the wide-frequency compressor and fully utilize its performance.

[0126] It should be noted that the first threshold and the third threshold in this embodiment can be set by the user according to the user's needs or the historical operating parameters of the multi-unit system.

[0127] Reference Figure 9 As shown, Figure 9 This is a flowchart illustrating the reset of the lower limit value according to an embodiment of this application. The method includes, but is not limited to, step S901.

[0128] It should be noted that step S901 occurs after adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference.

[0129] Step S901: When the multi-split system meets the exit conditions, reset the lower limit of the compressor's operating frequency in cooling mode to the default lower limit of the operating frequency in cooling mode.

[0130] In some embodiments, after adjusting the lower limit of the compressor's operating frequency in cooling mode, it is also determined whether the multi-split system has exited the program for adjusting the lower limit of the compressor's operating frequency in cooling mode, thereby reducing energy consumption. When the multi-split system meets the exit conditions, the lower limit of the compressor's operating frequency is reset, and the lower limit of the compressor's operating frequency in cooling mode is reset to the default lower limit of the operating frequency in cooling mode, ensuring that the compressor operates at an appropriate frequency after the exit conditions are met, which helps to avoid frequent start-stop of the compressor in cooling mode.

[0131] It should be noted that the exit conditions include one or more of the following: the high-low voltage ratio is less than the fourth threshold; the cumulative running time of the current operating frequency being less than the fifth threshold is the fourth duration; and all indoor units are turned off. The following is a detailed explanation of these three conditions.

[0132] In some embodiments, the high-low pressure ratio of the multi-split system is detected in real time. When the high-low pressure ratio is less than the fourth threshold, the program for adjusting the lower limit value is exited, and the lower limit value of the compressor's operating frequency in cooling mode is reset to the default operating frequency lower limit value of cooling mode. The fourth threshold is less than or equal to the third threshold, that is, there is a hysteresis between the fourth threshold and the third threshold, thereby avoiding control oscillation. The fourth threshold is the lowest pressure ratio within the noise tolerance range determined by previous experiments.

[0133] In some embodiments, if the cumulative running time when the current operating frequency is less than the fifth threshold is the fourth duration, it indicates that the current operating frequency of the compressor is too low, and the program for adjusting the lower limit needs to be exited. The lower limit of the compressor's operating frequency in cooling mode is then reset to the default lower limit of the operating frequency in cooling mode. The fifth threshold is determined based on the safe operating frequency of the multi-split system.

[0134] In some embodiments, if all indoor units are turned off, the lower limit of the compressor's operating frequency in cooling mode can be directly reset to the default lower limit of the operating frequency in cooling mode.

[0135] Reference Figure 10 As shown, Figure 10 This is a flowchart illustrating the determination of the load index of an indoor unit according to an embodiment of this application. The method includes, but is not limited to, steps S1001 to S1002.

[0136] Step S1001: Obtain the temperature difference data of the indoor unit that is turned on within a preset time period.

[0137] It should be noted that the temperature difference data is the difference between the indoor temperature of the corresponding indoor unit and the set temperature.

[0138] Step S1002: Determine the load index of the indoor unit at the current moment based on the temperature difference data.

[0139] In steps S1001 to S1002 of some embodiments, for any indoor unit, the indoor temperature changes over time during its operation. This embodiment records the difference between the indoor temperature detected by the activated indoor unit and the set temperature over a preset time period, i.e., temperature difference data. The larger the difference between the indoor temperature and the set temperature, the greater the current load demand of the indoor unit. Therefore, the load index at the current moment can be calculated based on the temperature difference data. To reflect the load changes of the indoor unit, the load index of the indoor unit at the current moment is calculated based on multiple temperature difference data within the preset time period. This load index reflects how the load of the indoor unit changes during its operation within the preset time period. According to control theory, the difference between the indoor temperature and the set temperature represents the control error of the system, which can be expressed as ε = T1 - T. set Where T1 is the indoor temperature, T set The load index is obtained by taking into account the change of control error over time to set the temperature. It can reflect the impact of the cumulative control error on the load index during past operation. The calculated load index reflects the system's ability to gradually and dynamically adjust the output of the corresponding set temperature.

[0140] Reference Figure 11 As shown, Figure 11 This is a flowchart illustrating how to determine the load index of an indoor unit at a given moment based on temperature difference data, according to one embodiment of this application. The method includes, but is not limited to, steps S2001 to S2002.

[0141] Step S2001: Determine the temperature difference function and weighting function within the preset time period.

[0142] It should be noted that the temperature difference function represents the temperature difference data at different detection times within the preset time period, and the weighting function represents the weight value at different detection times within the preset time period.

[0143] Step S2002: Determine the load index of the indoor unit at the current moment based on the convolution integral result of the temperature difference function and the weighting function.

[0144] In steps S2001 to S2002 of some embodiments, during the process of determining the load index of the indoor unit at the current moment based on the temperature difference data, the indoor unit detects the indoor temperature at certain time intervals. Therefore, the temperature difference data within the preset time period is also generated according to this time interval. To represent the change of temperature difference over time, embodiments of this application incorporate a temperature difference function, which can be expressed as ε(τ)=T1(τ)-T set (τ), where ε(τ) represents the dynamic change of the load, T1(τ) represents the indoor temperature at time τ, and T set (τ) represents the set temperature at time τ. The operating state of the indoor unit may remain constant or change within the preset time period. For example, the indoor unit may continuously maintain cooling within the preset time period, or it may switch between cooling and off states within the preset time period. That is, the cooling state is not continuous. Therefore, this embodiment incorporates a weighting function, which is used to calculate the load index through convolution with the temperature difference function. This allows the load index to reflect the impact of accumulated control errors on the load index during past operation. The specific calculation formula is as follows:

[0145]

[0146] Where LDI(τ) represents the load index, α t-τ Let α be the weighting function. t-τ The control error's indicative effect on the load decreases exponentially over time, while the integral represents the slow dynamic characteristics of the load. In this embodiment, its value range is set to 0 to 1, and the integral interval 0-t represents the preset time period from time 0 to time t. It is worth noting that different values ​​can be considered for the weighting function under different control scenarios. For example, in the operation of a multi-split air conditioning system under the same mode, the weight value can change continuously with operation, change in segments, or remain fixed. Furthermore, the weight value can be different in different modes, and the weight value can even be adaptively learned based on the historical operating data of the air conditioner. Examples are not listed here.

[0147] It is understandable that the load index expression in the convolutional form described above means that the calculation of the load index at each moment takes into account, to some extent, the impact of accumulated control errors during past operation. The degree of this impact can be determined by different weighting indices. During cooling operation, the load index value gradually decreases as the multi-split system's capacity outputs; the smaller the value, the lower the load demand of the corresponding indoor unit. Simultaneously, because the calculation of the load index considers time-series factors, its value can indicate different stages of cooling. For example, a value greater than 0 indicates a high-load cooling stage; a value less than 0 but greater than a certain value (e.g., -1) indicates a wall temperature reduction stage; and a value below a certain value indicates a low-load stage for maintaining room temperature.

[0148] To more clearly explain the control methods, controllers, and multi-split air conditioning systems described above, specific examples will be used below.

[0149] Example 1:

[0150] Reference Figure 12 , Figure 12 This is an overall flowchart of a control method for a multi-unit system provided in an example of this application.

[0151] In some embodiments, it is first assumed that the initial minimum compressor operating frequency of the multi-split system equipped with a wide-frequency compressor is Fmin0 in normal cooling mode and Fmin_eco in ECO cooling mode. The control method of the multi-split system is described in detail below.

[0152] Step S1: During the operation of the multi-split system, calculate and collect the load index (LDI_i) of the multiple indoor units currently in operation, where i represents the label of the different indoor units. A load index can be calculated for each indoor unit at any time after the system is started. The calculation method is as follows:

[0153] For a running indoor unit (denoted as the i-th indoor unit), the start-up time of this indoor unit is denoted as time i. Starting from time i, its control error is calculated at regular time intervals:

[0154] ε=T1-T set ;

[0155] Where T1 is the indoor temperature, T set To set the temperature.

[0156] At any time j, based on the control error ε(τ) at the current time and the load index at previous times, calculate the load index LDI(τ) from the start time to the current time according to the following formula.

[0157] In principle, the real-time load index is defined according to the following formula, which represents the convolution of the error function and the weighting function, and indicates an important characteristic of the load:

[0158] ε(τ)=T1(τ)-T set (τ);

[0159]

[0160] Where ε(τ) represents the dynamic difference between load and capacity; α t-τ The error indicates that its indicative effect on the load decreases exponentially over time; the integral expresses the slow dynamic characteristics of the load.

[0161] Under this convolution formula, the calculation of LDI(τ) at the current moment takes into account the decay of control error over time. For the assignment of α, different values ​​can be considered under different control scenarios. For example, during the operation of the system in the same mode, it can be continuously changing with the operation, or it can be segmented or fixed. In addition, the value of α can be different in different modes, and the value of α can even be adaptively learned based on the historical operation data of the air conditioner.

[0162] Essentially, the load index expression using convolutional methods aims to convey that the calculation of the load index at each moment takes into account, to some extent, the impact of accumulated control errors during past operation. The degree of this impact can be determined by different weighting indices. During cooling operation, this value gradually decreases as the air conditioning system's capacity outputs; the smaller the value, the lower the load demand of the corresponding indoor unit. Simultaneously, because the calculation method considers time-series factors, its value can indicate different stages of cooling. For example, a value greater than 0 indicates a high-load cooling stage; a value less than 0 but greater than a certain value (e.g., -1) indicates a wall temperature reduction stage; and a value below a certain value indicates a low-load stage for maintaining room temperature.

[0163] Step S2: Calculate the target operating evaporation temperature T2_target of the system based on the load index (LDI) of each indoor unit; and calculate the difference △T2 between the target T2 and the actual T2 based on the average value of the actual evaporation temperatures T2 of all currently operating indoor units.

[0164] Specifically, the difference ΔT2 between the target T2 and the actual T2 is calculated through the following two steps:

[0165] Step 1: According to the formula T2_target t =T2_target t-1 -C*max(LDI) updates the system target at time t every time interval, running T2_target. tWhere max(LDI) represents the maximum value of LDI calculated by all currently running internal machines, C is the adjustment coefficient, representing the adjustment range of the system target T2 according to the load index, and T2_target has preset upper and lower limits, such as needing to be constrained between 7 and 18.

[0166] Step 2: Calculate the average value T2_av of the actual evaporation temperature T2 of all currently running indoor units, and compare the difference ΔT2 = T2_target - T2_av between T2_target and T2_av at each time point.

[0167] In some embodiments, based on the calculated ΔT2, the current system compressor's actual operating frequency F_c, the current system's preset minimum operating frequency of the refrigeration compressor Fmin, and the current system high-low pressure ratio P_hl_rate, it is determined whether the current multi-split system has entered the "compressor minimum frequency lower limit relaxation" execution action.

[0168] Step S3: Determine whether the duration for which the difference △T2 is greater than the preset value 2 is greater than the preset value 3.

[0169] It should be noted that before determining whether the duration of the difference △T2 being greater than the preset value 2 is greater than the preset value 3, it is also possible to determine whether the ratio of the current high-voltage measurement value to the low-voltage measurement value P_hl_rate is greater than the preset value 1. If the ratio of the current high-voltage measurement value to the low-voltage measurement value P_hl_rate is greater than the preset value 1, then the determination in step S3 can be performed.

[0170] Step S4: The duration of the current operating frequency F_c = the system's initial minimum operating frequency Fmin0 is greater than the preset value 4.

[0171] Step S5: max(LDI) is less than or equal to the preset value 5, and the duration is greater than the preset value 6.

[0172] Step S6: When the duration of △T2 > preset value 2 is greater than the preset value 3, determine whether the multi-unit system satisfies either step S4 or step S5.

[0173] It should be noted that if the multi-split system does not meet steps S4 and S5, the compressor will be directly controlled to operate at the initial minimum frequency limit.

[0174] Step S7: When either step S4 or S5 is met, adjust the lower limit of the compressor's operating frequency in cooling mode.

[0175] In some embodiments, based on the difference ΔT2 between the measured evaporation temperature T2 and the calculated target evaporation temperature T2 of the multi-split system described above, the minimum operating frequency limit of the wide-frequency compressor in normal cooling mode is adjusted according to the following judgment conditions.

[0176] Assuming that the initial minimum compressor operating frequency of a multi-split system equipped with a wide-frequency compressor is Fmin0 in normal cooling mode and Fmin_eco in ECO cooling mode, then the lookup table dimension N is obtained by calculating N = Fmin0 - Fmin_eco, and the lookup interval of each column is DT2 = (preset value 7 - preset value 2) / N.

[0177] Table 1. Table of Operating Frequency Adjustment Values ​​Corresponding to the Range of △T2

[0178]

[0179] For example, the minimum operating frequency in normal cooling mode is 14 Hz, and the minimum operating frequency in ECO cooling mode is 8 Hz. The currently calculated system target T2 is 18 degrees, the current actual T2 of all indoor units is 16 degrees, the preset value 2 is 1, and the preset value 7 is 3. Then DT2 = (3-1) / 6 = 0.5. Following N = 6 dimensions, with each dimension having an interval of 0.5, and using the table lookup method as follows, ΔT2 = 2. According to the table lookup, the minimum frequency limit of the compressor is relaxed to Fmin = Fmin0 - 3 = 11 Hz. Therefore, the subsequent system control will be based on the latest compressor operating limit Fmin = 11 Hz.

[0180] Table 2. Table of Operating Frequency Adjustment Values ​​Corresponding to the Range of △T2

[0181]

[0182] Step S8: Determine whether the exit conditions of step S7 are met.

[0183] It should be noted that the exit conditions include, but are not limited to, at least one of the following:

[0184] Exit condition 1: Real-time detection of the high and low pressure ratio P_hl_rate of the system. When P_hl_rate < preset value 8 (where preset value 8 is the lowest pressure ratio within the noise tolerance range determined by previous experiments, and there is a hysteresis between preset value 8 and preset value 1 to avoid control oscillation), exit step 4 above and reset the system parameter Fmin to the initial minimum compressor operating frequency Fmin0 in normal cooling mode.

[0185] Exit condition 2: The actual operating frequency F_c of the compressor is lower than the preset value 9 and the cumulative operating time reaches the preset value 10.

[0186] Exit condition 3: When all indoor units are detected to be off, reset the system parameter Fmin to the initial minimum compressor operating frequency Fmin0 in normal cooling mode.

[0187] Step S9: When the exit condition in step S7 is met, reset the system parameter Fmin to the initial minimum compressor operating frequency Fmin0 in normal cooling mode.

[0188] In some embodiments, this application can relax the minimum operating limit of the compressor under specific conditions based on key system operating parameters such as indoor unit load demand and system high-low pressure ratio. This allows for full utilization of the low-frequency performance of the wide-frequency compressor while ensuring its reliability. This invention effectively alleviates the problem of frequent temperature-reaching shutdowns caused by insufficient compressor minimum frequency reduction during low-load operation, resulting in more precise indoor temperature control and maximizing the performance of the wide-frequency compressor, leading to greater overall system energy efficiency.

[0189] like Figure 13 As shown, Figure 13 This is a schematic diagram of a controller 1000 provided in one embodiment of this application.

[0190] The controller 1000 in this embodiment includes one or more processors 1001 and a memory 1002. Figure 13 The example uses a processor 1001 and a memory 1002.

[0191] Processor 1001 and memory 1002 can be connected via a bus or other means. Figure 13 Taking the example of a connection between China and Israel via a bus.

[0192] Memory 1002, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory 1002 may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory 1002 may optionally include memory 1002 remotely located relative to processor 1001, and these remote memories can be connected to controller 1000 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0193] Those skilled in the art will understand that Figure 13 The device structure shown does not constitute a limitation on the controller 1000 and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0194] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0195] The non-transient software program and instructions required to implement the control method of the multi-unit system in the above embodiments are stored in memory and executed by the processor, thus executing the above embodiments.

[0196] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network nodes. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0197] Furthermore, one embodiment of this application provides a computer-readable storage medium storing computer-executable instructions that are executed by a processor or controller 1000.

[0198] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0199] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0200] In the several embodiments provided in this application, it should be understood that the disclosed systems, instruments, and methods can be implemented in other ways. For example, the instrument embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between instruments or units may be electrical, mechanical, or other forms. Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, i.e., they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0201] It should also be understood that the various implementation methods provided in this application can be combined arbitrarily to achieve different technical effects.

[0202] The above is a detailed description of the preferred embodiments of this application. However, this application is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A control method for a multi-unit air conditioning system, characterized in that, The multi-split air conditioning system includes an outdoor unit and multiple indoor units connected to the outdoor unit; the control method includes: The load index of the indoor unit is determined based on the indoor temperature detected by the indoor unit; The target evaporation temperature is determined based on the load index. The lower limit of the compressor's operating frequency in cooling mode is adjusted based on the target evaporation temperature and the actual evaporation temperature of the indoor unit. The step of adjusting the lower limit of the compressor's operating frequency in cooling mode based on the target evaporation temperature and the actual evaporation temperature of the indoor unit includes: The temperature difference is determined based on the target evaporation temperature and the actual evaporation temperature of the indoor unit. Adjust the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference value; Before adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference, the method further includes: The high-pressure side pressure value and low-pressure side pressure value of the compressor are obtained, and the high-low pressure ratio value is determined based on the high-pressure side pressure value and the low-pressure side pressure value. The duration for which the high-low pressure ratio is greater than a third threshold, the duration for which the temperature difference is greater than a preset temperature value is greater than a first duration, and the duration for which the current operating frequency is equal to the lower limit of the default operating frequency of the cooling mode is greater than a second duration are determined. or, The duration for which the high-low pressure ratio is greater than a third threshold, the duration for which the temperature difference is greater than a preset temperature value is greater than a first duration, and the duration for which the maximum load index in the load index is less than or equal to the first threshold is greater than a third duration; After adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference, the method further includes: When the multi-split system meets the exit conditions, the lower limit of the compressor's operating frequency in cooling mode is reset to the default lower limit of the operating frequency in cooling mode; The exit conditions include at least one of the following: The high-low pressure ratio is less than the fourth threshold, and the fourth threshold is less than or equal to the third threshold; The cumulative running time when the current operating frequency is less than the fifth threshold is the fourth duration, and the fifth threshold is determined based on the safe operating frequency of the multi-unit system. All indoor units are turned off.

2. The control method according to claim 1, characterized in that, The step of determining the target evaporation temperature based on the load index includes: Determine the maximum load index among the load indices; The target evaporation temperature for the current detection cycle is obtained based on the maximum load index and the target evaporation temperature of the previous detection cycle.

3. The control method according to claim 1, characterized in that, Determining the temperature difference based on the target evaporation temperature and the actual evaporation temperature of the indoor unit includes: Obtain the actual evaporation temperature of all indoor units corresponding to the current detection cycle, and determine the actual evaporation average value based on the actual evaporation temperature; The temperature difference is determined based on the target evaporation temperature and the actual average evaporation value.

4. The control method according to claim 1, characterized in that, Before adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference, the method further includes: The duration for which the temperature difference is greater than the preset temperature value is greater than a first duration, and the duration for which the compressor's current operating frequency is equal to the lower limit of the default operating frequency of the cooling mode is greater than a second duration, are determined. or, The duration for which the temperature difference is greater than a preset temperature value is greater than a first duration, and the duration for which the maximum load index in the load index is less than or equal to a first threshold is greater than a third duration.

5. The control method according to claim 1, characterized in that, The step of adjusting the lower limit of the compressor's operating frequency in cooling mode based on the temperature difference includes: Determine the frequency difference between the default lower limit of the energy-saving mode and the default lower limit of the cooling mode; Based on the frequency difference, a correspondence is established between different temperature values ​​and the reduced operating frequency. The operating frequency reduction value is determined based on the temperature difference and the corresponding relationship, and the default operating frequency lower limit value of the cooling mode is adjusted to reduce the operating frequency reduction value.

6. The control method according to claim 5, characterized in that, The correspondence is the relationship between different temperature ranges and the reduced operating frequency value; The step of determining the operating frequency reduction value based on the temperature difference and the corresponding relationship includes: Based on the target temperature range into which the temperature difference falls, determine the corresponding downward adjustment value of the operating frequency for the target temperature range.

7. The control method according to claim 6, characterized in that, The number of temperature intervals is determined by the value of the frequency difference, and the length of each temperature interval is equal to the difference between the first preset temperature value and the second preset temperature value divided by the number of temperature intervals.

8. The control method according to claim 1, characterized in that, The step of determining the load index of the indoor unit based on the indoor temperature detected by the indoor unit includes: The temperature difference data of the indoor unit that is turned on within a preset time period is obtained. The temperature difference data is the difference between the indoor temperature of the corresponding indoor unit and the set temperature. The load index of the indoor unit at the current moment is determined based on the temperature difference data.

9. The control method according to claim 8, characterized in that, Determining the load index of the indoor unit at the current moment based on the temperature difference data includes: Determine the temperature difference function and weighting function within a preset time period. The temperature difference function represents the temperature difference data at different detection times within the preset time period, and the weighting function represents the weight value at different detection times within the preset time period. The load index of the indoor unit at the current moment is determined based on the convolution integral result of the temperature difference function and the weighting function.

10. A controller, characterized in that, It includes at least one processor and a memory for communicatively connecting to the at least one processor; the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the control method of the multi-unit system as described in any one of claims 1 to 9.

11. A multi-split air conditioning system, characterized in that, Includes the controller as described in claim 10.

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