Energy-saving control method, controller and refrigerator of refrigerator

Abstract

This invention provides an energy-saving control method, controller, and refrigerator for a refrigerator, belonging to the field of refrigerator energy-saving control technology. The method includes: adjusting the compressor speed until the compressor's operating rate is within a first preset energy-saving range; after selectively activating one of the freezing branch, the refrigeration branch, or the variable-temperature branch, adjusting the opening of the electronic expansion valve in the activated branch according to the return gas temperature of the return gas pipe and the ambient temperature, and returning to the step of adjusting the compressor speed until the compressor's operating rate is within the first preset range and the difference between the return gas temperature and the ambient temperature is within a second preset range. The energy-saving control method of this invention enables the refrigerator to operate at the most energy-efficient compressor speed and refrigerant flow rate under all ambient temperatures.

Description

Technical Field

[0001] This invention relates to the field of refrigerator energy-saving control technology, and in particular to an energy-saving control method, controller and refrigerator for refrigerators. Background Technology

[0002] Against the backdrop of energy conservation and emission reduction, how to further reduce the power consumption of refrigerators has always been a challenge for the industry. Capillary tubes have the function of throttling and reducing pressure, preparing for evaporation. However, capillary tubes cannot actively regulate the refrigerant flow rate. The refrigerant flow rate mainly changes with the compressor speed, and is also affected by the ambient temperature and the refrigerator's heat load.

[0003] Electronic expansion valves are widely used in air conditioners due to their fast refrigerant control, high precision, wide adjustment range, and outstanding energy-saving and cooling effects. Currently, with improvements in the flow control precision and structural design of electronic expansion valves, it is becoming increasingly feasible to replace capillary tubes in refrigerators. This allows the electronic expansion valve to actively adjust the refrigerant flow and match the appropriate compressor speed, thereby reducing the refrigerator's power consumption, while maintaining the same refrigerant bubble layer and volume.

[0004] There is limited research on energy-saving control of refrigerator refrigeration systems equipped with electronic expansion valves in the existing technology. Therefore, how to achieve energy-saving control for refrigerators equipped with electronic expansion valves is an urgent problem to be solved. Summary of the Invention

[0005] One objective of the first aspect of this invention is to provide an energy-saving control method for a refrigerator, which enables the refrigerator to operate at the most energy-efficient compressor speed and refrigerant flow rate under all ambient temperatures.

[0006] A further objective of this invention is to provide a better way to preserve food.

[0007] A second aspect of the present invention is to provide a controller for implementing the energy-saving control method for the refrigerator described above.

[0008] A third aspect of the present invention is to provide a refrigerator including the controller described above.

[0009] Specifically, the present invention provides an energy-saving control method for a refrigerator. The refrigerator's refrigeration system includes a compressor, a condenser, a heat exchange tube, an evaporator branch, and a return pipe connected in series. The evaporator branch includes a freezing branch, a refrigeration branch, and a variable-temperature branch connected in parallel. The heat exchange tube exchanges heat with the return pipe. The freezing branch includes a first electronic expansion valve and a freezing evaporator connected in series. The refrigeration branch includes a second electronic expansion valve and a refrigeration evaporator connected in series. The variable-temperature branch includes a third electronic expansion valve and a variable-temperature evaporator connected in series. The method includes:

[0010] Adjust the speed of the compressor until the compressor's operating rate is within the first preset range for energy saving;

[0011] After selecting one of the refrigeration branch, the cold storage branch, or the variable temperature branch to be connected, the opening of the electronic expansion valve in the connected branch is adjusted according to the return gas temperature of the return gas pipe and the ambient temperature, and the process returns to the step of adjusting the speed of the compressor until the compressor's operating rate is within the first preset range and the difference between the return gas temperature and the ambient temperature is within the second preset range.

[0012] Optionally, the step of adjusting the compressor speed until the compressor's operating rate is within a first preset energy-saving range includes:

[0013] Determine whether the compressor's operating rate is greater than or equal to a first preset value and less than a second preset value, where the first preset value and the second preset value correspond to the lower limit and upper limit of the first preset interval, respectively.

[0014] If not, determine whether the compressor's operating rate is less than the first preset value;

[0015] When the compressor's operating rate is less than the first preset value, the compressor's speed is reduced, and the process returns to the step of determining whether the compressor's operating rate is greater than or equal to the first preset value and less than the second preset value.

[0016] When the compressor's operating rate is greater than or equal to the second preset value, the compressor's speed is increased, and the process returns to the step of determining whether the compressor's operating rate is greater than or equal to the first preset value and less than the second preset value.

[0017] Optionally, the step of adjusting the opening of the electronic expansion valve in the conductive branch according to the return gas temperature and ambient temperature of the return gas pipe includes:

[0018] Determine whether the difference between the return air temperature and the ambient temperature is greater than or equal to a third preset value and less than or equal to a fourth preset value, wherein the third preset value and the fourth preset value correspond to the lower limit and upper limit of the second preset interval, respectively;

[0019] If not, determine whether the difference between the return air temperature and the ambient temperature is less than the third preset value;

[0020] When the difference between the return gas temperature and the ambient temperature is less than the third preset value, the opening of the electronic expansion valve in the controlled branch is reduced, and the process returns to the step of determining whether the compressor's operating rate is greater than or equal to the first preset value and less than the second preset value.

[0021] Optionally, after determining whether the difference between the return air temperature and the ambient temperature is less than the third preset value, the method further includes:

[0022] When the difference between the return gas temperature and the ambient temperature is greater than the fourth preset value, the opening of the electronic expansion valve in the controlled branch increases, and the process returns to the step of determining whether the compressor's operating rate is greater than or equal to the first preset value and less than the second preset value.

[0023] Optionally, the first preset value is any value between 85% and 95%, and the second preset value is any value between 98% and 100%.

[0024] Optionally, the third preset value is any value between -3 and -1℃, and the fourth preset value is any value between 0 and 2℃.

[0025] Optionally, after selecting and activating the refrigeration branch, the cold storage branch, or the variable temperature branch, before adjusting the opening of the electronic expansion valve in the activated branch according to the return gas temperature of the return gas pipe and the ambient temperature, the method further includes:

[0026] The room temperature of the freezer compartment, refrigerator compartment, and variable temperature compartment of the refrigerator is detected;

[0027] The freezing branch, the refrigeration branch, and the variable temperature branch are activated sequentially according to the order in which the room temperature of the freezing compartment, the refrigeration compartment, and the variable temperature compartment reaches the corresponding start-up temperature.

[0028] Optionally, after the step of detecting the room temperature of the freezer compartment, refrigerator compartment, and variable temperature compartment of the refrigerator, the method further includes:

[0029] When the refrigeration compartment and the freezer compartment simultaneously reach their respective start-up temperatures, or when the refrigeration compartment and the variable temperature compartment simultaneously reach their respective start-up temperatures, the refrigeration branch is activated first.

[0030] In particular, the present invention also provides a controller comprising a memory and a processor, wherein the memory stores a control program, which, when executed by the processor, is used to implement the energy-saving control method for a refrigerator according to any of the preceding claims.

[0031] In particular, the present invention also provides a refrigerator including the controller described above.

[0032] According to an embodiment of the present invention, an energy-saving control method is provided. The method adjusts the compressor speed so that the compressor operating rate is within a first preset range of energy saving. After the operating rate is within the first preset range, when a certain branch is activated, the return gas temperature is adjusted by adjusting the opening of the electronic expansion valve on that branch so that the difference between the return gas temperature and the ambient temperature is within a second preset range, so that the refrigerator can operate at the most energy-efficient compressor speed and refrigerant flow rate under all climate ambient temperatures.

[0033] According to one embodiment of the present invention, when the compressor operating rate is too low or too high, the compressor operating rate is brought within an energy-saving range by correspondingly reducing or increasing the compressor speed.

[0034] According to one embodiment of the present invention, the purpose of adjusting the opening of each electronic expansion valve is to match the optimal flow rate of the refrigerator under different ambient temperatures and heat loads, and to determine whether the flow rate is in an optimal state by using the return gas temperature. The difference between the return gas temperature and the ambient temperature can be used to determine whether the refrigerant flow rate is appropriate, and the adjustment of the electronic expansion valves ensures that the refrigerant flow rate is in an energy-saving state.

[0035] According to one embodiment of the present invention, the activation priority of the refrigeration branch is set to the highest because the refrigeration temperature is relatively high, the food storage period is relatively short, and the food is more sensitive to temperature. Therefore, activating the refrigeration branch first can better preserve the food.

[0036] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0037] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0038] Figure 1 This is a flowchart of a refrigeration system corresponding to an energy-saving control method for a refrigerator according to an embodiment of the present invention;

[0039] Figure 2 This is a flowchart of an energy-saving control method for a refrigerator according to an embodiment of the present invention;

[0040] Figure 3 This is a flowchart of an energy-saving control method for a refrigerator according to another embodiment of the present invention;

[0041] Figure 4 This is a connection block diagram of the controller of a refrigerator according to an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the structure of a refrigerator according to an embodiment of the present invention. Detailed Implementation

[0043] In the description of this embodiment, it should be understood that the terms "inner", "outer", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0044] In the description of this embodiment, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0045] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature, that is, include one or more of that feature. When a feature "includes or contains" one or more of the features it encompasses, unless otherwise specifically stated, this indicates that other features are not excluded and may be further included.

[0046] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," and "coupling," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art should be able to understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0047] Furthermore, in the description of this embodiment, "above" or "below" the second feature can include direct contact between the first and second features, or it can include contact between the first and second features through another feature between them. That is, in the description of this embodiment, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "below" of the second feature can mean the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0048] Unless otherwise specified, all terms (including technical and scientific terms) used in the description of this embodiment have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0049] Figure 1 This is a flowchart of a refrigeration system corresponding to an energy-saving control method for a refrigerator according to an embodiment of the present invention. Figure 2 This is a flowchart of an energy-saving control method for a refrigerator according to an embodiment of the present invention. Figure 1 As shown, the refrigerator's refrigeration system includes a compressor 10, a condenser 20, a heat exchange tube 30, an evaporator branch, and a return pipe 50 connected in series. The evaporator branch includes a freezing branch, a refrigeration branch, and a variable-temperature branch connected in parallel. The heat exchange tube 30 exchanges heat with the return pipe 50. The freezing branch includes a first electronic expansion valve 41 and a freezing evaporator 42 connected in series. The refrigeration branch includes a second electronic expansion valve 43 and a refrigeration evaporator 44 connected in series. The variable-temperature branch includes a third electronic expansion valve 45 and a variable-temperature evaporator 46 connected in series. Here, the freezing evaporator 42 is located in the freezer compartment, the refrigeration evaporator 44 is located in the refrigerator compartment, and the variable-temperature evaporator 46 is located in the variable-temperature compartment. This refrigerator's refrigeration system uses electronic expansion valves and heat exchange tubes 30 to replace the combination of capillary tubes and electric valves in the prior art. The first electronic expansion valve 41, the second electronic expansion valve 43, and the third electronic expansion valve can be fixed behind the refrigerator's air duct and connected to their respective evaporators. The heat exchange tube 30 can be attached to the return pipe 50 so that the heat exchange tube 30 and the return pipe 50 can exchange heat. The heat exchange efficiency between the heat exchange tube 30 and the return pipe 50 is generally higher than that between the capillary tube and the return pipe 50. Therefore, in this embodiment, the heat exchange tube 30 is used to exchange heat, which can make the pre-cooling of the heat exchange tube 30 and the preheating of the return pipe 50 more complete, and reduce the waste of cold energy.

[0050] In this embodiment, the refrigeration system essentially separates the original capillary throttling and heat exchange functions. The electronic expansion valve is responsible for throttling, while the heat exchange tube 30 is responsible for heat exchange with the return pipe 50. Simultaneously, the electronic expansion valve can be completely closed, thus eliminating the need for an electric valve. By adjusting the opening of the electronic expansion valve, optimal flow rates can be matched to the refrigerator compartment, freezer compartment, and variable temperature compartment. This design not only regulates refrigerant flow and controls its on / off operation but also enhances heat exchange. By controlling the refrigerant flow and the compressor speed r through the electronic expansion valve, the refrigerator achieves the lowest possible power consumption.

[0051] like Figure 2 As shown, in one embodiment, the energy-saving control method for a refrigerator includes:

[0052] Step S100: Adjust the speed r of compressor 10 until the operating rate p of compressor 10 is within the first preset range of energy saving.

[0053] Step S100 can be performed after the refrigerator is running smoothly, giving the compressor 10 an initial speed, which can be an empirical value or a set value. In one embodiment, the first preset range can be set to [90, 100). Generally, the lower the compressor 10 speed r, the lower the average power, the higher the compressor 10 operating rate p, the smaller the temperature difference between different locations in the refrigerator compartment, the less heat loss in the evaporator compartment, and the lower the power consumption. Therefore, when adjusting the compressor 10, the principle is that the higher the operating rate p, the better, and it should be close to 100%.

[0054] In step S200, after selecting a refrigeration branch, a cold storage branch, or a variable temperature branch to be connected, the opening degree N of the electronic expansion valve in the connected branch is adjusted according to the return gas temperature Tc of the return gas pipe 50 and the ambient temperature Th, and the process returns to the step of adjusting the speed r of the compressor 10 until the operating rate p of the compressor 10 is within the first preset range and the difference between the return gas temperature Tc and the ambient temperature Th is within the second preset range.

[0055] It should be noted that in this embodiment, the order of adjusting the compressor 10's operating rate p and adjusting the return gas temperature Tc is not limited, as long as the compressor 10's operating rate p is ultimately within the first preset range and the difference between the return gas temperature Tc and the ambient temperature Th is within the second preset range.

[0056] The energy-saving control method of this embodiment adjusts the compressor speed r to make the compressor 10's operating rate p within the first preset range of energy saving. After the operating rate p is within the first preset range, when a certain branch is activated, the return gas temperature Tc is adjusted by adjusting the opening of the electronic expansion valve on that branch, so that the difference between the return gas temperature Tc and the ambient temperature Th is within the second preset range, so that the refrigerator can operate at the most energy-efficient compressor speed r and refrigerant flow rate under all climate ambient temperatures Th.

[0057] Figure 3 This is a flowchart of an energy-saving control method for a refrigerator according to another embodiment of the present invention. Figure 3 As shown, in one embodiment, step S100 includes:

[0058] Step S120: Determine whether the compressor 10's operating rate p is greater than or equal to the first preset value P1 and less than the second preset value P2. If not, proceed to step S140; if yes, proceed to step S200. The first preset value P1 and the second preset value P2 correspond to the lower limit and upper limit of the first preset interval, respectively.

[0059] In one embodiment, the first preset value P1 is any value between 85% and 95%, for example, the first preset value P1 is 85%, 90%, or 95%. The second preset value P2 is any value between 98% and 100%, for example, the second preset value P2 is 98%, 99%, or 100%.

[0060] Step S140: Determine whether the operating rate p of compressor 10 is less than the first preset value P1. If yes, proceed to step S160; otherwise, proceed to step S180.

[0061] Step S160: Control the speed r of compressor 10 to decrease, and return to the step of determining whether the operating rate p of compressor 10 is greater than or equal to the first preset value P1 and less than the second preset value P2, i.e., step S120.

[0062] In one embodiment, in step S160, the rotational speed r of the compressor 10 can be reduced to a first threshold, which can be 30-80 r / min, for example 30 r / min, 50 r / min or 80 r / min.

[0063] Step S180: Control the speed r of compressor 10 to increase, and return to the step of determining whether the start-up rate p of compressor 10 is greater than or equal to the first preset value P1 and less than the second preset value P2, i.e., step S120.

[0064] In one embodiment, in step S180, the rotational speed r of the compressor 10 can be increased to a second threshold, which can be 30-80 r / min, for example 30 r / min, 50 r / min or 80 r / min.

[0065] In this embodiment, when the operating rate p of the compressor 10 is too low or too high, the operating rate p of the compressor 10 is kept within the energy-saving range by correspondingly reducing the speed r of the compressor 10 or increasing the speed r of the compressor 10.

[0066] like Figure 3 As shown, in a further embodiment, step S200 includes

[0067] Step S210: Determine whether the difference between the return air temperature Tc and the ambient temperature Th is greater than or equal to the third preset value T1 and less than or equal to the fourth preset value T2. If not, proceed to step S220. The third preset value T1 and the fourth preset value T2 correspond to the lower limit and upper limit of the second preset interval, respectively.

[0068] In one embodiment, the third preset value T1 is any value from -3 to -1℃, for example, the third preset value T1 is -3℃, -2℃ or -1℃, and the fourth preset value T2 is any value from 0 to 2℃, for example, the fourth preset value T2 is 0℃, 1℃ or 2℃.

[0069] Step S220: Determine whether the difference between the return gas temperature Tc and the ambient temperature Th is less than the third preset value T1. If yes, proceed to step S240; otherwise, proceed to step S260.

[0070] Step S240: Decrease the opening degree N of the electronic expansion valve in the controlled branch, and return to the step of determining whether the start-up rate p of the compressor 10 is greater than or equal to the first preset value P1 and less than the second preset value P2, i.e., step S120.

[0071] Step S260: Increase the opening degree N of the electronic expansion valve in the controlled branch, and return to the step of judging whether the start-up rate p of the compressor 10 is greater than or equal to the first preset value P1 and less than the second preset value P2, i.e., step S120.

[0072] If the difference between the return gas temperature Tc and the ambient temperature Th is less than the third preset value T1, it indicates that the refrigerant flow is too large, resulting in excess cooling capacity and insufficient heat exchange with the return gas pipe 50. This causes the cooling capacity to flow back to the compressor 10, resulting in wasted cooling capacity. It also leads to failure of the anti-condensation test, with condensation occurring on the return gas pipe 50. When the difference between the return gas pipe 50 and the ambient temperature Th is greater than the fourth threshold, it indicates that the return gas temperature Tc is too high, and insufficient refrigerant causes overheating at the evaporator outlet.

[0073] The purpose of adjusting the opening of each electronic expansion valve in this embodiment is to match the optimal flow rate of the refrigerator under different ambient temperatures (Th) and different heat loads. The return gas temperature (Tc) is used to determine whether the flow rate is in an optimal state. The difference between the return gas temperature (Tc) and the ambient temperature (Th) can be used to determine whether the refrigerant flow rate is appropriate. The adjustment of the electronic expansion valves ensures that the refrigerant flow rate is in an energy-saving state.

[0074] In one embodiment, such as Figure 3 As shown, the procedure before step S200 also includes:

[0075] Step S192: Detect the room temperature of the freezer compartment, refrigerator compartment, and variable temperature compartment of the refrigerator.

[0076] Step S198: The freezing branch, the refrigeration branch, and the variable temperature branch are activated in sequence according to the order in which the room temperature of the freezer compartment, the refrigerator compartment, and the variable temperature compartment reaches the corresponding start-up temperature.

[0077] For example, if the refrigerator compartment reaches the refrigerator start-up temperature first, the refrigerator branch will be activated first, and the second electronic expansion valve 43 on the refrigerator branch will be adjusted accordingly. If the freezer compartment reaches the freezer start-up temperature first, the freezer branch will be activated first, and the first electronic expansion valve 41 on the freezer branch will be adjusted accordingly. The electronic expansion valves on the corresponding branches will be adjusted sequentially according to the time sequence in which the start-up temperatures are reached.

[0078] In a further embodiment, the method further includes the following steps before step S198:

[0079] Step S194: Determine if there is a situation where each room simultaneously reaches its respective start-up temperature. If yes, proceed to step S196; otherwise, proceed to step S198. The situation where each room simultaneously reaches its respective start-up temperature can be any two rooms simultaneously reaching their respective start-up temperatures, or it can be any three rooms simultaneously reaching their respective start-up temperatures.

[0080] Step S196: When the refrigerator compartment and the freezer compartment reach their respective start-up temperatures at the same time, or when the refrigerator compartment and the variable temperature compartment reach their respective start-up temperatures at the same time, the refrigerator branch is activated first.

[0081] If the freezer compartment and the variable temperature compartment reach their respective start-up temperatures simultaneously, either the freezer branch or the variable temperature branch can be activated first, without any restrictions.

[0082] In this embodiment, the activation priority of the refrigeration branch is set to the highest. This is because the refrigeration temperature is relatively high, the food storage period is relatively short, and the food is more sensitive to temperature. Therefore, activating the refrigeration branch first can better preserve the food.

[0083] Figure 4This is a connection block diagram of a refrigerator controller 100 according to an embodiment of the present invention. Figure 4 As shown, the present invention also provides a controller 100, which includes a memory 110 and a processor 120. The memory 110 stores a control program 122, which, when executed by the processor 120, is used to implement the energy-saving control method for a refrigerator in any of the above embodiments or combinations thereof. The processor 120 may be a central processing unit (CPU), a digital processing unit, etc. The processor 120 sends and receives data through a communication interface. The memory 110 is used to store the program executed by the processor 120. The memory 110 can be any medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, or it may be a combination of multiple memories 110. The above-described computational program can be downloaded from a computer-readable storage medium to a corresponding computing / processing device or downloaded to a computer or external storage device via a network (e.g., the Internet, a local area network, a wide area network, and / or a wireless network).

[0084] In this embodiment, the controller 100 adjusts the compressor 10 speed r so that the compressor 10's operating rate p is within the first preset range of energy saving. After the operating rate p is within the first preset range, when a certain branch is activated, the controller adjusts the opening of the electronic expansion valve on that branch to adjust the return gas temperature Tc, so that the difference between the return gas temperature Tc and the ambient temperature Th is within the second preset range. This allows the refrigerator to operate at the most energy-efficient compressor 10 speed r and refrigerant flow rate under all climate ambient temperatures Th.

[0085] Figure 5 This is a schematic diagram of the structure of a refrigerator 200 according to an embodiment of the present invention. Figure 5 As shown, the present invention also provides a refrigerator 200, which includes the controller described above.

[0086] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. An energy-saving control method for a refrigerator, wherein the refrigerator's refrigeration system comprises a compressor, a condenser, a heat exchange tube, an evaporator branch, and a return pipe connected in series, the evaporator branch comprising a freezing branch, a refrigeration branch, and a variable-temperature branch connected in parallel, the heat exchange tube exchanging heat with the return pipe, the freezing branch comprising a first electronic expansion valve and a freezing evaporator connected in series, the refrigeration branch comprising a second electronic expansion valve and a refrigeration evaporator connected in series, and the variable-temperature branch comprising a third electronic expansion valve and a variable-temperature evaporator connected in series, characterized in that, The method includes: Adjust the speed of the compressor until the compressor's operating rate is within the first preset range for energy saving; After selecting one of the refrigeration branch, the cold storage branch, or the variable temperature branch to be connected, the opening of the electronic expansion valve in the connected branch is adjusted according to the return gas temperature of the return gas pipe and the ambient temperature, and the process returns to the step of adjusting the speed of the compressor until the compressor's operating rate is within the first preset range and the difference between the return gas temperature and the ambient temperature is within the second preset range.

2. The energy-saving control method for a refrigerator according to claim 1, characterized in that, The step of adjusting the compressor speed until the compressor's operating rate is within a first preset energy-saving range includes: Determine whether the compressor's operating rate is greater than or equal to a first preset value and less than a second preset value, where the first preset value and the second preset value correspond to the lower limit and upper limit of the first preset interval, respectively. If not, determine whether the compressor's operating rate is less than the first preset value; When the compressor's operating rate is less than the first preset value, the compressor's speed is reduced, and the process returns to the step of determining whether the compressor's operating rate is greater than or equal to the first preset value and less than the second preset value. When the compressor's operating rate is greater than or equal to the second preset value, the compressor's speed is increased, and the process returns to the step of determining whether the compressor's operating rate is greater than or equal to the first preset value and less than the second preset value.

3. The energy-saving control method for a refrigerator according to claim 2, characterized in that, The steps for adjusting the opening of the electronic expansion valve in the conductive branch according to the return gas temperature and ambient temperature of the return gas pipe include: Determine whether the difference between the return air temperature and the ambient temperature is greater than or equal to a third preset value and less than or equal to a fourth preset value, wherein the third preset value and the fourth preset value correspond to the lower limit and upper limit of the second preset interval, respectively; If not, determine whether the difference between the return air temperature and the ambient temperature is less than the third preset value; When the difference between the return gas temperature and the ambient temperature is less than the third preset value, the opening of the electronic expansion valve in the controlled branch is reduced, and the process returns to the step of determining whether the compressor's operating rate is greater than or equal to the first preset value and less than the second preset value.

4. The energy-saving control method for a refrigerator according to claim 3, characterized in that, After determining whether the difference between the return air temperature and the ambient temperature is less than the third preset value, the method further includes: When the difference between the return gas temperature and the ambient temperature is greater than the fourth preset value, the opening of the electronic expansion valve in the controlled branch increases, and the process returns to the step of determining whether the compressor's operating rate is greater than or equal to the first preset value and less than the second preset value.

5. The energy-saving control method for a refrigerator according to claim 2, characterized in that, The first preset value is any value between 85% and 95%, and the second preset value is any value between 98% and 100%.

6. The energy-saving control method for a refrigerator according to claim 3, characterized in that, The third preset value is any value between -3 and -1℃, and the fourth preset value is any value between 0 and 2℃.

7. The energy-saving control method for a refrigerator according to any one of claims 1-6, characterized in that, Before the step of adjusting the opening of the electronic expansion valve in the activated branch according to the return gas temperature and ambient temperature after selecting and activating the refrigeration branch, the method further includes: The room temperature of the freezer compartment, refrigerator compartment, and variable temperature compartment of the refrigerator is detected; The freezing branch, the refrigeration branch, and the variable temperature branch are activated sequentially according to the order in which the room temperature of the freezing compartment, the refrigeration compartment, and the variable temperature compartment reaches the corresponding start-up temperature.

8. The energy-saving control method for a refrigerator according to claim 7, characterized in that, The step of detecting the room temperature of the freezer compartment, refrigerator compartment, and variable temperature compartment of the refrigerator further includes: When the refrigeration compartment and the freezer compartment simultaneously reach their respective start-up temperatures, or when the refrigeration compartment and the variable temperature compartment simultaneously reach their respective start-up temperatures, the refrigeration branch is activated first.

9. A controller, characterized in that, The controller includes a memory and a processor. The memory stores a control program, which, when executed by the processor, is used to implement the energy-saving control method for the refrigerator according to any one of claims 1-8.

10. A refrigerator, characterized in that, Includes the controller as described in claim 9.

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