Multi-connected variable frequency heat pump unit control method, device, equipment and storage medium

Abstract

The invention belongs to the technical field of electric appliances, and particularly relates to a multi-connected variable frequency heat pump unit control method and device, equipment and a storage medium. The method comprises the steps that the temperature difference between the actual temperature of a target medium and the set temperature of the target medium at the current moment is detected, and the target medium is the medium needing to be heated or cooled by the multi-connected variable frequency heat pump unit; calculating a target total frequency value of the multi-connected variable frequency heat pump unit according to the temperature difference; and according to the frequency difference value between the target total frequency value and the current actual total frequency value of the multi-connected variable frequency heat pump unit, the frequency of the heat pumps in the multi-connected variable frequency heat pump unit is adjusted. The target total frequency value of the multi-connected variable frequency heat pump unit is calculated according to the temperature difference, so that the heat exchange capacity of the heat pump unit meets the actual heat exchange requirement, and frequent start and stop of the heat pump unit are avoided; compared with the prior art, the frequency control is more accurate, the energy utilization efficiency is improved, and more energy is saved.

Description

Technical Field

[0001] The present application belongs to the field of electrical technology, and specifically relates to a control method, device, equipment, and storage medium for a multi-split variable frequency heat pump unit. Background Art

[0002] When variable frequency heat pumps are used in commercial scenarios, because the total load is relatively large, most of the time multiple heat pumps are installed in multiple connections for use.

[0003] During the heating or cooling process of a multi-split heat pump unit, if all heat pumps are started, the heat exchange capacity of all heat pumps working together often exceeds the actual demand, which will cause the multi-split heat pump unit to quickly reach the temperature and shut down. Soon, heating or cooling will be needed again. All heat pumps will start working and then quickly reach the temperature and shut down, which will cause the multi-split heat pump unit to start and stop frequently, which will not only waste energy but also accelerate the wear of the heat pump. In order to solve the problem of frequent start and stop of multi-split heat pump units, a method for multi-split units composed of fixed-frequency heat pumps is to determine the loading or unloading of the unit according to the control conditions, start a single heat pump in the unit when loading, and shut down a single heat pump in the unit when unloading.

[0004] However, when the above method is applied to a multi-split unit composed of variable frequency heat pumps, loading or unloading is completed only by starting or shutting down the heat pump, resulting in inaccurate frequency adjustment of the multi-split heat pump unit, which in turn leads to low energy utilization efficiency of the multi-split variable frequency heat pump unit. Summary of the invention

[0005] The present application provides a control method, device, equipment, and storage medium for a multi-split variable frequency heat pump unit to solve the technical problem that the prior art only completes loading or unloading by starting or shutting down the heat pump, resulting in inaccurate frequency adjustment of the multi-split heat pump unit, and further resulting in low energy utilization efficiency of the multi-split variable frequency heat pump unit.

[0006] In a first aspect, the present application provides a method for controlling a multi-split variable frequency heat pump unit, the method comprising:

[0007] Detecting the temperature difference between the actual temperature of the target medium at the current moment and the set temperature of the target medium, wherein the target medium is the medium to be heated or cooled by the multi-connected variable frequency heat pump unit;

[0008] Calculating a target total frequency value of the multi-connected variable frequency heat pump unit according to the temperature difference;

[0009] The frequency of the heat pump in the multi-split frequency conversion heat pump unit is adjusted according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split frequency conversion heat pump unit.

[0010] In the above-mentioned preferred technical solution of the multi-split variable frequency heat pump unit control method, the target total frequency value of the multi-split variable frequency heat pump unit is calculated according to the temperature difference, including:

[0011] Determine the capacity deviation value Δu of a single heat pump according to the temperature difference k ;

[0012] The total capacity deviation value of the unit is calculated according to the total capacity deviation value calculation formula of the unit. The total capacity deviation value calculation formula of the unit is: ΔU k =iΔu k

[0013] Among them, ΔU k is the total capacity deviation value of the unit, i is the number of heat pumps in the multi-split variable frequency heat pump unit that have not experienced shutdown failure or frequency limiting protection;

[0014] The target total frequency value is calculated according to the target total frequency value calculation formula, and the target total frequency value calculation formula is: U k =U k-1 +ΔU k

[0015] Among them, U k is the target total frequency value of the current cycle, U k-1 is the target total frequency value of the previous cycle.

[0016] In the above-mentioned preferred technical solution of the multi-frequency heat pump unit control method, the capacity deviation value Δu of a single heat pump is determined according to the temperature difference. k ,include:

[0017] The temperature difference change value is calculated according to the temperature difference change value calculation formula, and the temperature difference change value calculation formula is: ΔT=T k-1 -T k

[0018] Wherein, ΔT is the temperature difference change value, T k-1 is the temperature difference in the previous cycle, T k The temperature difference described in the current cycle;

[0019] The capacity deviation value of the single heat pump is determined according to the temperature difference change value and the temperature difference.

[0020] In the above-mentioned preferred technical solution of the multi-split variable frequency heat pump unit control method, the determining of the single heat pump capacity deviation value according to the temperature difference change value and the temperature difference comprises:

[0021] When the temperature difference change value remains unchanged, the greater the temperature difference, the greater the capacity deviation value of the single heat pump;

[0022] When the temperature difference remains unchanged, the smaller the temperature difference change value is, the larger the single heat pump capacity deviation value is.

[0023] In the above-mentioned preferred technical solution of the multi-split frequency conversion heat pump unit control method, the frequency of the heat pump in the multi-split frequency conversion heat pump unit is adjusted according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split frequency conversion heat pump unit, including:

[0024] If the target total frequency value is greater than the current actual total frequency value, the frequency difference is allocated to the multi-connected variable frequency heat pump unit according to a preset loading rule, wherein the preset loading rule includes:

[0025] Increasing the frequency of the heat pump currently in operation in the multi-split variable frequency heat pump unit by the frequency difference;

[0026] If the frequencies of the running heat pumps all reach the highest efficiency frequencies of the running heat pumps, and the current actual total frequency value still does not reach the target total frequency value, a first target heat pump is determined among the heat pumps that are not started in the multi-split variable frequency heat pump unit, and the frequency of the first target heat pump is adjusted according to the magnitude relationship between the frequency difference and the lowest operating frequency of the first target heat pump;

[0027] If all heat pumps in the multi-split variable frequency heat pump unit reach the highest efficiency frequency, and the current actual total frequency value still does not reach the target total frequency value, the frequency difference is allocated according to the frequencies of all heat pumps.

[0028] In the above-mentioned preferred technical solution of the multi-split variable frequency heat pump unit control method, the first target heat pump is determined among the heat pumps that are not started in the multi-split variable frequency heat pump unit, and the frequency of the first target heat pump is adjusted according to the magnitude relationship between the frequency difference and the minimum operating frequency of the first target heat pump, including:

[0029] Among the heat pumps that have not been started in the multi-split variable frequency heat pump unit, the heat pump with the shortest historical operating time is selected as the first target heat pump. At this time, if the frequency difference is less than the lowest operating frequency of the first target heat pump, the first target heat pump is not started; if the frequency difference is greater than or equal to the lowest operating frequency of the first target heat pump, the first target heat pump is started and the frequency of the first target heat pump is adjusted to the frequency difference.

[0030] In the above-mentioned preferred technical solution of the multi-split variable frequency heat pump unit control method, the frequency difference is distributed according to the frequencies of all heat pumps, including:

[0031] If the frequencies of all heat pumps in the multi-split variable frequency heat pump unit are different, the frequency difference will be allocated to the heat pump with the lowest frequency; if the frequencies of all heat pumps are the same, the frequency difference will be allocated to the heat pump with the shortest historical operating time; the upper limit of the frequency increase of all heat pumps is the maximum operating frequency of the heat pump.

[0032] In the above-mentioned preferred technical solution of the multi-split frequency conversion heat pump unit control method, the frequency of the heat pump in the multi-split frequency conversion heat pump unit is adjusted according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split frequency conversion heat pump unit, including:

[0033] If the target total frequency value is less than the current actual total frequency value, the frequency of the heat pump in the multi-split variable frequency heat pump unit is adjusted according to a preset load reduction rule, wherein the preset load reduction rule includes:

[0034] When the frequencies of all the running heat pumps of the multi-split variable frequency heat pump unit are higher than the maximum efficiency frequency, a second target heat pump is determined according to the frequencies of all the running heat pumps, and the frequency of the second target heat pump is reduced by the frequency difference;

[0035] If the frequencies of all the running heat pumps are reduced to the highest efficiency frequency, and the current actual total frequency value still does not reach the target total frequency value, then the heat pump with the longest historical operating time is selected from among all the running heat pumps as the third target heat pump;

[0036] According to the magnitude relationship between the third target heat pump minimum operating frequency and the frequency difference, the frequency of the third target heat pump is reduced by the frequency difference or the frequency of the third target heat pump is kept unchanged.

[0037] In the above-mentioned preferred technical solution of the multi-frequency variable-frequency heat pump unit control method, the second target heat pump is determined according to the frequency of all the running heat pumps, and the frequency of the second target heat pump is reduced by the frequency difference, including

[0038] If the frequencies of all the running heat pumps are the same, the heat pump with the longest historical operating time among all the running heat pumps is determined as the second target heat pump, and the frequency of the second target heat pump is reduced by the frequency difference;

[0039] If the frequencies of all the running heat pumps are different, the heat pump with the highest frequency among all the running heat pumps is determined as the second target heat pump, and the frequency of the second target heat pump is reduced by the frequency difference.

[0040] In the above-mentioned preferred technical solution of the multi-split variable frequency heat pump unit control method, reducing the frequency of the third target heat pump by the frequency difference or keeping the frequency of the third target heat pump unchanged according to the magnitude relationship between the third target heat pump minimum operating frequency and the frequency difference comprises:

[0041] If the frequency of the third target heat pump is lower than the minimum operating frequency of the third target heat pump after being reduced by the frequency difference and the frequency of the third target heat pump is not 0, the frequency of the third target heat pump is not reduced; otherwise, the frequency of the third target heat pump is reduced by the frequency difference, and the third target heat pump is turned off when the frequency of the third target heat pump drops to 0.

[0042] In the above-mentioned preferred technical solution of the multi-split variable frequency heat pump unit control method, the preset load reduction rule also includes:

[0043] If the heat pump in the multi-split variable frequency heat pump unit includes a plurality of compressors, the frequency of the compressor with the lowest frequency is preferentially reduced by the frequency difference.

[0044] In a second aspect, the present application provides a multi-split variable frequency heat pump unit control device, the device comprising:

[0045] A temperature difference detection module is used to detect the temperature difference between the actual temperature of the target medium at the current moment and the set temperature of the target medium, wherein the target medium is the medium to be heated or cooled by the multi-connected variable frequency heat pump unit;

[0046] A frequency calculation module, used to calculate a target total frequency value of the multi-connected variable frequency heat pump unit according to the temperature difference;

[0047] The frequency adjustment module is used to adjust the frequency of the heat pump in the multi-split frequency conversion heat pump unit according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split frequency conversion heat pump unit.

[0048] In a third aspect, the present application provides a multi-split variable frequency heat pump unit control device, the device comprising:

[0049] Memory, processor;

[0050] The memory is used to store computer programs;

[0051] The processor is used to execute the computer program stored in the memory to implement the above-mentioned multi-connected variable frequency heat pump unit control method.

[0052] In a fourth aspect, the present application provides a readable storage medium having a computer program stored thereon; the computer program is used to implement the above-mentioned multi-split variable frequency heat pump unit control method.

[0053] The control method, device, equipment, and storage medium of the multi-split variable frequency heat pump unit provided in the present application calculate the target total frequency value of the multi-split variable frequency heat pump unit according to the difference between the target medium set temperature and the current temperature, so that the heat exchange capacity of the multi-split variable frequency heat pump unit meets the actual heating or cooling demand, and avoids the frequent start and stop of the multi-split variable frequency heat pump unit. At the same time, the frequency of the heat pump in the multi-split variable frequency heat pump unit is adjusted according to the calculated target total frequency value. Compared with the existing solution of starting a single heat pump in the unit during loading and shutting down a single heat pump in the unit during load reduction, the frequency control is more precise, the energy utilization efficiency is improved, and more energy is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0055] Figure 1 This is a flow chart of a control method for a multi-split variable frequency heat pump unit provided in an embodiment of the present application;

[0056] Figure 2 It is a flow chart of a method for calculating a target total frequency value of a multi-split variable frequency heat pump unit according to a temperature difference provided in an embodiment of the present application;

[0057] Figure 3 It is a schematic diagram of a multi-connected variable frequency heat pump unit control device provided in an embodiment of the present application;

[0058] Figure 4 It is a schematic diagram of a multi-split variable frequency heat pump unit control device provided in an embodiment of the present application.

[0059] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0061] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in sequences other than those illustrated or described herein, for example.

[0062] In the embodiments of the present application, the words "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0063] For multi-split heat pump units, the idea of ​​avoiding frequent start and stop of the unit is to make the heat exchange capacity of the unit meet the actual heating or cooling needs. The operating frequency of the heat pump determines the heat exchange capacity of the compressor. Therefore, the multi-split heat pump unit can avoid frequent start and stop of the unit by controlling the total frequency of the unit's heat pump.

[0064] In a multi-split fixed-frequency heat pump unit, since the heat pumps are all fixed-frequency and cannot be adjusted, the total frequency of the unit can only be adjusted by starting or shutting down the heat pump, and the lowest operating frequency of a single heat pump is generally 40Hz, so the total frequency fluctuation of the unit will be very large, and it is difficult to accurately make the total frequency of the unit meet the actual total frequency required, resulting in energy waste. In addition, the startup process of the fixed-frequency heat pump is extremely power-consuming, further exacerbating the waste of energy.

[0065] Therefore, for a multi-split variable frequency heat pump unit, the technical concept of the present application to prevent the multi-split variable frequency heat pump unit from being frequently started and stopped is: the target total frequency value of the multi-split variable frequency heat pump unit is calculated according to the temperature difference between the target medium set temperature and the current temperature, and the frequency of the heat pump in the multi-split variable frequency heat pump unit is adjusted according to the frequency difference between the target total frequency value and the current actual total frequency value of the heat pump unit.

[0066] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0067] First, the nouns appearing in the embodiments of the present application are explained:

[0068] Minimum operating frequency: The lowest operating frequency that can be achieved when the heat pump is operating normally;

[0069] Maximum operating frequency: The highest operating frequency that can be achieved when the heat pump is operating normally;

[0070] Maximum efficiency frequency: The operating frequency with the highest efficiency when the heat pump is operating normally.

[0071] In a possible embodiment of the present application, a control method for a multi-split variable frequency heat pump unit is provided, which can be applied to a control unit of a multi-split variable frequency heat pump unit. Figure 1 is a flow chart of a control method for a multi-split variable frequency heat pump unit provided in an embodiment of the present application, such as Figure 1 As shown, the method includes:

[0072] S101, detecting the temperature difference between the actual temperature of the target medium at the current moment and the set temperature of the target medium, where the target medium is the medium to be heated or cooled by the multi-connected variable frequency heat pump unit;

[0073] In the present application, the target medium may be water or air, and the multi-split variable frequency heat pump unit may heat or cool the target medium, thereby regulating indoor temperature, providing hot and cold water, and the like.

[0074] To facilitate subsequent calculations, the temperature difference during heating is the target medium set temperature - the target medium actual temperature, and the temperature difference during cooling is the target medium actual temperature - the target medium set temperature.

[0075] S102, calculating a target total frequency value of the multi-connected variable frequency heat pump unit according to the temperature difference;

[0076] The optimal operating frequency for the multi-split variable frequency heat pump unit to adjust the actual temperature of the target medium to the set temperature is the target total frequency value, that is, when the multi-split variable frequency heat pump unit operates at the target total frequency value, the heat exchange capacity of the multi-split variable frequency heat pump unit can just adjust the temperature of the target medium to the user set temperature within an appropriate time. The target total frequency value is calculated based on the temperature difference between the actual temperature of the target medium and the set temperature of the target medium, which can avoid the problem of frequent start and stop of the multi-split variable frequency heat pump unit.

[0077] S103, adjusting the frequency of the heat pump in the multi-split variable frequency heat pump unit according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split variable frequency heat pump unit.

[0078] Specifically, when the target total frequency value is greater than the current actual total frequency value, the total frequency of the multi-split variable frequency heat pump unit is increased; when the target total frequency value is less than the current actual total frequency value, the total frequency of the multi-split variable frequency heat pump unit is reduced; the specific value of increase or decrease is determined according to the frequency difference; usually, the specific value of increase or decrease is equal to the frequency difference.

[0079] To facilitate subsequent calculations, when the target total frequency value is greater than the current actual total frequency value, the frequency difference is the target total frequency value - the current actual total frequency value; when the target total frequency value is less than the current actual total frequency value, the frequency difference is the current actual total frequency value - the target total frequency value.

[0080] Considering that the target medium temperature is not constant, a single execution of the above control steps cannot always maintain the target medium temperature at the set temperature. Optionally, steps S101 to S103 are repeated at intervals of a preset period. The preset period may be 30 seconds, and the present application does not limit the specific value of the preset period.

[0081] The technical effect of this embodiment is: the target total frequency value of the multi-split variable frequency heat pump unit is calculated according to the difference between the target medium set temperature and the current temperature, so that the heat exchange capacity of the multi-split variable frequency heat pump unit meets the actual heating or cooling demand, avoiding frequent start and stop of the multi-split variable frequency heat pump unit, and at the same time, according to the calculated target total frequency value, the frequency of the heat pump in the multi-split variable frequency heat pump unit is adjusted. Compared with the existing solution of starting a single heat pump in the unit during loading and shutting down a single heat pump in the unit during load reduction, the frequency control is more precise, the energy utilization efficiency is improved, and more energy-saving is achieved.

[0082] In a possible embodiment of the present application, a method for calculating a target total frequency value of a multi-split variable frequency heat pump unit according to a temperature difference is provided. Figure 2 : is a flow chart of a method for calculating a target total frequency value of a multi-split variable frequency heat pump unit according to a temperature difference provided in an embodiment of the present application, such as Figure 2 As shown, the method includes:

[0083] S201, determining a capacity deviation value of a single heat pump according to the temperature difference;

[0084] Specifically, the corresponding relationship between different temperature differences and the capacity deviation value of a single heat pump may be stored in the storage module of the control unit.

[0085] S202, calculating the total capacity deviation value of the unit according to the total capacity deviation value calculation formula of the unit;

[0086] Specifically, the calculation formula for the total capacity deviation value of the unit is: ΔU k =iΔu k

[0087] Among them, Δu k is the capacity deviation of a single heat pump, ΔU k is the total capacity deviation value of the unit, i is the number of heat pumps in the multi-split variable frequency heat pump unit that have not experienced shutdown failure or frequency limiting protection;

[0088] S203. Calculate the target total frequency value according to the target total frequency value calculation formula.

[0089] Specifically, the target total frequency value calculation formula is: U k =U k-1 +ΔU k

[0090] Among them, U k is the target total frequency value of the current cycle, U k-1 It is the target total frequency value of the previous cycle.

[0091] It should be noted that U k-1 It is the target total frequency value calculated by the target total frequency value calculation formula in the previous cycle, without considering the total frequency actually output by the multi-connected variable frequency heat pump unit. For example, the target total frequency value calculated in the previous cycle is 140Hz, and the total frequency value actually output by the unit is 130Hz, then U k-1 In addition, if the current cycle is the first cycle, U k-1 The frequency value is a preset value, that is, the first heat pump of the multi-split variable frequency heat pump unit first operates at the preset frequency value, and then repeatedly executes steps S101 to S103 at every preset period.

[0092] In a possible embodiment of the present application, the capacity deviation value Δu of a single heat pump is determined according to the temperature difference. k ,include:

[0093] The temperature difference change value is calculated according to the temperature difference change value calculation formula. The temperature difference change value calculation formula is: ΔT=T k-1 -T k

[0094] Where ΔT is the temperature difference change, T k-1 is the temperature difference of the previous cycle, T k is the temperature difference of the current cycle;

[0095] Determine the capacity deviation value of a single heat pump based on the temperature difference change value and temperature difference.

[0096] Optionally, the capacity deviation value of a single heat pump is determined according to the temperature difference change value and the temperature difference, including:

[0097] When the temperature difference change value remains unchanged, the greater the temperature difference, the greater the deviation value of the capacity of a single heat pump;

[0098] When the temperature difference remains unchanged, the smaller the temperature difference change value, the greater the deviation value of the single heat pump capacity.

[0099] It should be noted that: when the temperature difference change value remains unchanged, the larger the temperature difference, the faster the system needs to heat or cool, the higher the total frequency of the unit needs to be, and the larger the capacity deviation value of the single heat pump needs to be. On the contrary, the smaller the temperature difference is or becomes a negative value, the unit needs to continue to heat or cool the target to the set temperature or exceed the set temperature. At this time, the total frequency of the unit needs to be reduced, and the required single heat pump capacity deviation value is smaller, and it can be a negative value, thereby reducing the total frequency of the unit.

[0100] When the temperature difference remains unchanged, the smaller the temperature difference change value, the more it means that the heating or cooling capacity of the unit is insufficient and the total frequency of the unit needs to be increased, which requires a larger single heat pump capacity deviation value.

[0101] In practical applications, the temperature difference change value and the capacity deviation value of a single heat pump corresponding to the temperature difference can be determined according to the following table:

[0102] In a possible embodiment of the present application, the frequency of the heat pump in the multi-split variable frequency heat pump unit is adjusted according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split variable frequency heat pump unit, including:

[0103] If the target total frequency value is greater than the current actual total frequency value, the frequency difference is allocated to the multi-split variable frequency heat pump unit according to the preset loading rules. The preset loading rules include:

[0104] Rule 1: Increase the frequency of the running heat pump in the multi-split variable frequency heat pump unit by the frequency difference;

[0105] Rule 2: If the frequencies of all the running heat pumps have reached the highest efficiency frequencies of the running heat pumps, and the current actual total frequency value has not yet reached the target total frequency value, then a first target heat pump is determined among the heat pumps that have not been started in the multi-split variable frequency heat pump unit, and the frequency of the first target heat pump is adjusted according to the magnitude relationship between the frequency difference and the lowest operating frequency of the first target heat pump;

[0106] Optionally, determining a first target heat pump among the heat pumps that are not started in the multi-split variable frequency heat pump unit, and adjusting the frequency of the first target heat pump according to a magnitude relationship between the frequency difference and the lowest operating frequency of the first target heat pump, includes:

[0107] Among the heat pumps that have not been started in the multi-split variable frequency heat pump unit, the heat pump with the shortest historical operating time is selected as the first target heat pump. At this time, if the frequency difference is less than the lowest operating frequency of the first target heat pump, the first target heat pump is not started. If the frequency difference is greater than or equal to the lowest operating frequency of the first target heat pump, the first target heat pump is started and the frequency of the first target heat pump is adjusted to the frequency difference.

[0108] Rule 3: If all heat pumps in the multi-split variable frequency heat pump unit reach the highest efficiency frequency, and the current actual total frequency value still does not reach the target total frequency value, the frequency difference is allocated according to the frequencies of all heat pumps.

[0109] Optionally, a frequency difference is assigned to all heat pumps based on their frequencies, including:

[0110] If the frequencies of all heat pumps in a multi-split variable frequency heat pump unit are different, the frequency difference will be allocated to the heat pump with the lowest frequency. If the frequencies of all heat pumps are the same, the frequency difference will be allocated to the heat pump with the shortest historical operating time. The upper limit of the frequency increase of all heat pumps is the maximum operating frequency of the heat pump.

[0111] The following example illustrates the above loading rules:

[0112] A multi-split variable frequency heat pump unit includes two heat pumps, A and B. The capacities of the two heat pumps are as follows: model Target operating frequency Minimum operating frequency Maximum operating frequency Maximum efficiency frequency 60P 65Hz 40Hz 125Hz 90Hz

[0113] Among them, heat pump A has the shortest historical operating time.

[0114] During the loading process, when both heat pumps A and B are turned off, A is used as the first heat pump to be started. A starts and runs to the preset frequency value of 65Hz. During the subsequent loading process, the frequency of A increases (Rule 1);

[0115] When the frequency of A is increased to 90Hz, assuming that the target total frequency value is 120Hz, the frequencies of all the running heat pumps have reached the highest efficiency frequency of the running heat pumps, and the current actual total frequency value has not yet reached the target total frequency value, then the unstarted B is determined as the first target heat pump. At this time, the frequency difference is 120-90=30Hz, which is lower than the minimum operating frequency of B, so B is not started. When the target total frequency value is 130Hz and the frequency difference is 130-90=40Hz, the frequency difference is greater than the minimum operating frequency of B, and then B is started (Rule 2);

[0116] After B is started, A maintains 90Hz unchanged and B frequency increases. When both A and B reach 90Hz, if the current actual total frequency value has not yet reached the target total frequency value, for example, the target total frequency value is 181Hz, and A and B have the same frequency, A with the shortest historical running time is loaded first, and A is increased to 91Hz. When the target total frequency value is 182Hz, B has the lowest frequency, and B is increased to 91Hz until both A and B reach 125Hz. Even if the current actual total frequency value has not yet reached the target total frequency value, the total frequency value of the heat pump unit will no longer increase (Rule 3).

[0117] Through the above loading rules, the following technical effects can be achieved:

[0118] 1. Prioritize increasing the frequency of the running heat pump to the highest efficiency frequency to improve the energy efficiency ratio of the running heat pump;

[0119] 2. When the frequency difference is lower than the minimum operating frequency of the heat pump, the heat pump will not be started to avoid wasting the heat pump capacity;

[0120] 3. For the same frequency, the heat pump with the longest historical operation time is loaded first to ensure that the wear of all heat pumps in the unit is consistent after long-term operation;

[0121] 4. Different frequencies give priority to loading heat pumps with lower frequencies to keep the loads of all heat pumps in the unit consistent. This can also ensure that the wear of all heat pumps in the unit is consistent after long-term operation.

[0122] In a possible embodiment of the present application, the frequency of the heat pump in the multi-split variable frequency heat pump unit is adjusted according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split variable frequency heat pump unit, including:

[0123] If the target total frequency value is less than the current actual total frequency value, the frequency of the heat pump in the multi-split variable frequency heat pump unit is adjusted according to the preset load reduction rules. The preset load reduction rules include:

[0124] Rule 1: When the frequencies of all running heat pumps of the multi-split variable frequency heat pump unit are higher than the highest efficiency frequency, the second target heat pump is determined according to the frequencies of all running heat pumps, and the frequency of the second target heat pump is reduced by the frequency difference;

[0125] Optionally, a second target heat pump is determined according to the frequency of all running heat pumps, and the frequency of the second target heat pump is reduced by the frequency difference, including

[0126] If the frequencies of all the running heat pumps are the same, the heat pump with the longest historical operating time among all the running heat pumps is determined as the second target heat pump, and the frequency of the second target heat pump is reduced by the frequency difference;

[0127] If the frequencies of all the running heat pumps are different, the heat pump with the highest frequency among all the running heat pumps is determined as the second target heat pump, and the frequency of the second target heat pump is reduced by the frequency difference.

[0128] Rule 2:

[0129] If the frequencies of all running heat pumps are reduced to the highest efficiency frequency, and the current actual total frequency value still does not reach the target total frequency value, then the heat pump with the longest historical operating time is selected from all running heat pumps as the third target heat pump;

[0130] According to the magnitude relationship between the third target heat pump's lowest operating frequency and the frequency difference, the frequency of the third target heat pump is reduced by the frequency difference or the frequency of the third target heat pump is kept unchanged.

[0131] Optionally, according to the magnitude relationship between the minimum operating frequency of the third target heat pump and the frequency difference, reducing the frequency of the third target heat pump by the frequency difference or keeping the frequency of the third target heat pump unchanged comprises:

[0132] If the frequency of the third target heat pump is lower than the minimum operating frequency of the third target heat pump after being reduced by the frequency difference and the frequency of the third target heat pump is not 0, the frequency of the third target heat pump will not be reduced; otherwise, the frequency of the third target heat pump will be reduced by the frequency difference, and the third target heat pump will be turned off when the frequency of the third target heat pump drops to 0.

[0133] The following example illustrates the above load shedding rules:

[0134] A multi-split variable frequency heat pump unit includes two heat pumps, A and B. The capacities of the two heat pumps are as follows: model Target operating frequency Minimum operating frequency Maximum operating frequency Maximum efficiency frequency 60P 65Hz 40Hz 125Hz 90Hz

[0135] Among them, heat pump A has the shortest historical operating time.

[0136] When load shedding begins, both A and B run at 125Hz. A and B have the same frequency, and B has the longest historical running time. If the target total frequency is 249Hz, then B's frequency is first reduced to 124Hz. Afterwards, A and B have different frequencies, and A has the highest frequency. If the target total frequency is 248Hz, then A's frequency is reduced to 124Hz (Rule 1).

[0137] If both A and B are reduced to 90Hz, and the target total frequency value is 179Hz, then Rule 2 is executed, and B, which has the longest historical operating time, is determined as the third target heat pump, and the frequency of B is reduced to 89Hz, while the frequency of A remains unchanged. In the subsequent load shedding, the frequency of A remains unchanged, and the frequency of B gradually decreases. When the frequency of A is 90Hz and the frequency of B is 40Hz, if the target total frequency value is 120Hz, the frequency difference is 130Hz-120Hz=10Hz, and the frequency of B is reduced by 10Hz below its minimum operating frequency, the frequency of B remains unchanged, until the target total frequency value is 90Hz, the frequency difference is 130Hz-90Hz=40Hz, and the frequency of B is reduced by 40Hz to 0, then B is directly shut down. At this time, the running heat pump becomes A, and A is selected as the third target heat pump. If the load shedding continues, Rule 2 is repeated until all heat pumps are shut down.

[0138] Optionally, the preset load reduction rule also includes:

[0139] If the heat pump in the multi-split variable frequency heat pump unit includes multiple compressors, the frequency of the compressor with the lowest frequency will be preferentially reduced by the frequency difference.

[0140] Through the above load reduction rules, the following technical effects can be achieved:

[0141] 1. In rule 1, when the frequencies are the same, the unit with the longest historical operating time shall be given priority in load reduction, so that the degree of wear of the heat pumps of the unit after long-term operation is basically the same, and the frequency of all the running heat pumps of the unit shall be adjusted to the highest efficiency frequency first to improve the energy efficiency ratio of the running heat pumps;

[0142] Second, in rule 2, the heat pump with the longest historical operating time is preferentially reduced to shutdown, which can reduce the wear of the heat pump with the longest historical operating time. At the same time, if the frequency difference is lower than the lowest operating frequency of the third target heat pump and the third target heat pump frequency cannot be reduced to 0, the frequency of the third target heat pump will not be reduced to ensure sufficient heat exchange capacity of the unit. After the heat pump is shut down, if the heat exchange capacity is insufficient, the heat pump may need to be restarted. The restart process consumes a lot of power. The purpose of energy saving is achieved by reducing the number of heat pump shutdowns.

[0143] In a possible embodiment of the present application, a control device for a multi-split variable frequency heat pump unit is provided. Figure 3 Schematic diagram of a multi-split variable frequency heat pump unit control device provided in an embodiment of the present application, such as Figure 3 As shown, the device 30 includes: a temperature difference detection module 301, a frequency calculation module 302, and a frequency adjustment module 303;

[0144] The temperature difference detection module 301 is used to detect the temperature difference between the actual temperature of the target medium at the current moment and the set temperature of the target medium, where the target medium is the medium to be heated or cooled by the multi-connected variable frequency heat pump unit;

[0145] The frequency calculation module 302 is used to calculate the target total frequency value of the multi-split variable frequency heat pump unit according to the temperature difference;

[0146] The frequency adjustment module 303 is used to adjust the frequency of the heat pump in the multi-split frequency conversion heat pump unit according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split frequency conversion heat pump unit;

[0147] Optionally, the device 30 may further include a periodic control module, which is used to control the temperature difference detection module, the frequency calculation module, and the frequency adjustment module to perform functions at preset periodic intervals.

[0148] In a possible embodiment of the present application, a multi-split variable frequency heat pump unit control device is provided. Figure 4 Schematic diagram of a multi-split variable frequency heat pump unit control device provided in an embodiment of the present application, such as Figure 4 As shown, the device 40 includes:

[0149] Memory 401, processor 402, interactive interface 403, memory 401, processor 402, interactive interface 403 are connected via bus 403;

[0150] The memory 401 is used to store computer programs;

[0151] The processor 402 is used to execute the computer program stored in the memory 401 to implement the above-mentioned multi-connected variable frequency heat pump unit control method.

[0152] The specific implementation process of the processor 402 can be found in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0153] In the above Figure 4 In the illustrated embodiment, it should be understood that the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. A general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in the invention may be directly implemented as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor.

[0154] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (Non-volatile Memory, NVM), such as at least one disk memory.

[0155] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of this application is not limited to only one bus or type of bus.

[0156] In a possible embodiment of the present application, a readable storage medium is provided, on which a computer program is stored; the computer program is used to implement the above-mentioned multi-split variable frequency heat pump unit control method.

[0157] The computer-readable storage medium mentioned above can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0158] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0159] The division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, which may be electrical, mechanical or other forms.

[0160] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0161] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0162] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0163] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0164] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments, and the above embodiments are only used to illustrate the technical solution of the present application rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A control method for a multi-split frequency conversion heat pump unit, characterized in that: The method comprises: Detecting the temperature difference between the actual temperature of the target medium at the current moment and the set temperature of the target medium, wherein the target medium is the medium to be heated or cooled by the multi-connected variable frequency heat pump unit; Calculating a target total frequency value of the multi-connected variable frequency heat pump unit according to the temperature difference; The frequency of the heat pump in the multi-split frequency conversion heat pump unit is adjusted according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split frequency conversion heat pump unit.

2. The method according to claim 1, characterized in that The calculating the target total frequency value of the multi-connected variable frequency heat pump unit according to the temperature difference comprises: Determine the capacity deviation value Δu of a single heat pump according to the temperature difference k ; The total capacity deviation value of the unit is calculated according to the total capacity deviation value calculation formula of the unit. The total capacity deviation value calculation formula of the unit is: ΔU k =iΔu k Among them, ΔU k is the total capacity deviation value of the unit, i is the number of heat pumps in the multi-split variable frequency heat pump unit that have not experienced shutdown failure or frequency limiting protection; The target total frequency value is calculated according to the target total frequency value calculation formula, and the target total frequency value calculation formula is: U k =U k-1 +ΔU k Among them, U k is the target total frequency value of the current cycle, U k-1 is the target total frequency value of the previous cycle.

3. The method according to claim 2, characterized in that Determining the capacity deviation value Δu of a single heat pump according to the temperature difference k ,include: The temperature difference change value is calculated according to the temperature difference change value calculation formula, and the temperature difference change value calculation formula is: ΔT=T k-1 -T k Wherein, ΔT is the temperature difference change value, T k-1 is the temperature difference in the previous cycle, T k The temperature difference described in the current cycle; The capacity deviation value of the single heat pump is determined according to the temperature difference change value and the temperature difference.

4. The method according to claim 3, characterized in that The determining the single heat pump capacity deviation value according to the temperature difference change value and the temperature difference comprises: When the temperature difference change value remains unchanged, the greater the temperature difference, the greater the capacity deviation value of the single heat pump; When the temperature difference remains unchanged, the smaller the temperature difference change value is, the larger the single heat pump capacity deviation value is.

5. The method according to claim 1, characterized in that The step of adjusting the frequency of the heat pump in the multi-split frequency conversion heat pump unit according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split frequency conversion heat pump unit comprises: If the target total frequency value is greater than the current actual total frequency value, the frequency difference is allocated to the multi-connected variable frequency heat pump unit according to a preset loading rule, wherein the preset loading rule includes: Increasing the frequency of the heat pump currently in operation in the multi-split variable frequency heat pump unit by the frequency difference; If the frequencies of the running heat pumps all reach the highest efficiency frequencies of the running heat pumps, and the current actual total frequency value still does not reach the target total frequency value, a first target heat pump is determined among the heat pumps that are not started in the multi-split variable frequency heat pump unit, and the frequency of the first target heat pump is adjusted according to the magnitude relationship between the frequency difference and the lowest operating frequency of the first target heat pump; If all heat pumps in the multi-split variable frequency heat pump unit reach the highest efficiency frequency, and the current actual total frequency value still does not reach the target total frequency value, the frequency difference is allocated according to the frequencies of all heat pumps.

6. The method according to claim 5, characterized in that The determining of a first target heat pump among the heat pumps that are not started in the multi-split variable frequency heat pump unit, and adjusting the frequency of the first target heat pump according to a magnitude relationship between the frequency difference and the lowest operating frequency of the first target heat pump, comprises: Among the heat pumps that have not been started in the multi-split variable frequency heat pump unit, the heat pump with the shortest historical operating time is selected as the first target heat pump. At this time, if the frequency difference is less than the lowest operating frequency of the first target heat pump, the first target heat pump is not started; if the frequency difference is greater than or equal to the lowest operating frequency of the first target heat pump, the first target heat pump is started and the frequency of the first target heat pump is adjusted to the frequency difference.

7. The method according to claim 5, characterized in that The allocating the frequency difference according to the frequencies of all the heat pumps comprises: If the frequencies of all heat pumps in the multi-split variable frequency heat pump unit are different, the frequency difference will be allocated to the heat pump with the lowest frequency; if the frequencies of all heat pumps are the same, the frequency difference will be allocated to the heat pump with the shortest historical operating time; the upper limit of the frequency increase of all heat pumps is the maximum operating frequency of the heat pump.

8. The method according to claim 1, characterized in that The step of adjusting the frequency of the heat pump in the multi-split frequency conversion heat pump unit according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split frequency conversion heat pump unit comprises: If the target total frequency value is less than the current actual total frequency value, the frequency of the heat pump in the multi-connected variable frequency heat pump unit is adjusted according to a preset load reduction rule, wherein the preset load reduction rule includes: When the frequencies of all the running heat pumps of the multi-split variable frequency heat pump unit are higher than the maximum efficiency frequency, a second target heat pump is determined according to the frequencies of all the running heat pumps, and the frequency of the second target heat pump is reduced by the frequency difference; If the frequencies of all the running heat pumps are reduced to the highest efficiency frequency, and the current actual total frequency value still does not reach the target total frequency value, then the heat pump with the longest historical operating time is selected from among all the running heat pumps as the third target heat pump; According to the magnitude relationship between the third target heat pump minimum operating frequency and the frequency difference, the frequency of the third target heat pump is reduced by the frequency difference or the frequency of the third target heat pump is kept unchanged.

9. The method according to claim 8, characterized in that The step of determining a second target heat pump according to the frequencies of all the running heat pumps, and reducing the frequency of the second target heat pump by the frequency difference, includes: If the frequencies of all the running heat pumps are the same, the heat pump with the longest historical operating time among all the running heat pumps is determined as the second target heat pump, and the frequency of the second target heat pump is reduced by the frequency difference; If the frequencies of all the running heat pumps are different, the heat pump with the highest frequency among all the running heat pumps is determined as the second target heat pump, and the frequency of the second target heat pump is reduced by the frequency difference.

10. The method according to claim 8, characterized in that The reducing the frequency of the third target heat pump by the frequency difference or keeping the frequency of the third target heat pump unchanged according to the magnitude relationship between the third target heat pump minimum operating frequency and the frequency difference comprises: If the frequency of the third target heat pump is lower than the minimum operating frequency of the third target heat pump after being reduced by the frequency difference and the frequency of the third target heat pump is not 0, the frequency of the third target heat pump is not reduced; otherwise, the frequency of the third target heat pump is reduced by the frequency difference, and the third target heat pump is turned off when the frequency of the third target heat pump drops to 0.

11. The method according to claim 8, characterized in that The preset load reduction rules also include: If the heat pump in the multi-split variable frequency heat pump unit includes a plurality of compressors, the frequency of the compressor with the lowest frequency is preferentially reduced by the frequency difference.

12. A control device for a multi-split frequency conversion heat pump unit, characterized in that: The device comprises: A temperature difference detection module is used to detect the temperature difference between the actual temperature of the target medium at the current moment and the set temperature of the target medium, wherein the target medium is the medium to be heated or cooled by the multi-connected variable frequency heat pump unit; A frequency calculation module, used to calculate a target total frequency value of the multi-connected variable frequency heat pump unit according to the temperature difference; The frequency adjustment module is used to adjust the frequency of the heat pump in the multi-split frequency conversion heat pump unit according to the frequency difference between the target total frequency value and the current actual total frequency value of the multi-split frequency conversion heat pump unit.

13. A multi-split frequency conversion heat pump unit control device, characterized in that: The device comprises: Memory, processor; The memory is used to store computer programs; The processor is used to execute the computer program stored in the memory to implement the multi-split variable frequency heat pump unit control method as described in any one of claims 1 to 11.

14. A readable storage medium, characterized in that: The readable storage medium stores a computer program; the computer program is used to implement the control method of the multi-split variable frequency heat pump unit as described in any one of claims 1 to 11.

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