Refrigeration device and control method for a refrigeration device

Abstract

The application provides a refrigeration device and a control method of the refrigeration device. The refrigeration device comprises a refrigeration system and a storage chamber. The refrigeration system supplies cold to the storage chamber. The refrigeration system comprises a variable frequency compressor, a condenser, a capillary tube and an evaporator connected in sequence. The refrigeration system further comprises a heat exchanger. The heat exchanger comprises high-temperature heat exchange pipes and low-temperature heat exchange pipes which are arranged in parallel and exchange heat with each other. The inlet of the high-temperature heat exchange pipes is connected with the condenser, and the outlet thereof is connected with the capillary tube. The inlet of the low-temperature heat exchange pipes is connected with the evaporator, and the outlet thereof is connected with the gas return port of the variable frequency compressor. The refrigeration system of the application exchanges heat through the high-temperature heat exchange pipes and the low-temperature heat exchange pipes, so that the refrigerant is first subjected to primary heat exchange and cooling before entering the evaporator, and is first subjected to heat exchange and heating before entering the variable frequency compressor. Therefore, the pressure between the outlet of the variable frequency compressor and the inlet of the capillary tube can be controlled within the range that can be borne by the variable frequency compressor when the refrigeration system is stably operated, and the low-temperature refrigeration below-40 DEG C can be realized.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment technology, and in particular to a refrigeration device and a control method for the refrigeration device. Background Technology

[0002] As people's living standards continue to improve, their requirements for food preservation and storage are also increasing. They are not only focusing on the preservation of refrigerated foods such as vegetables and fruits, but also paying attention to the preservation of frozen foods such as fish and meat. Research has shown that low-temperature environments below -40℃ play a crucial role in the preservation of frozen foods.

[0003] However, due to the low cooling temperature, when powered on, a large amount of refrigerant will converge to the condenser side, causing the condensing pressure on the condenser side to increase rapidly, while the evaporating pressure on the evaporator side to decrease rapidly. This results in a larger pressure difference on both sides of the compressor, an increase in system pressure, and even exceeds the pressure range that the compressor can withstand. Existing refrigeration systems are unable to achieve low-temperature refrigeration below -40°C. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a refrigeration device and a control method for the refrigeration device, thereby solving the problem that existing refrigeration systems are unable to achieve low-temperature refrigeration below -40°C.

[0005] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides a refrigeration device, including a refrigeration system and a storage compartment. The refrigeration system supplies cooling to the storage compartment. The refrigeration system includes a variable frequency compressor, a condenser, a capillary tube, and an evaporator connected in sequence. The refrigeration system also includes a heat exchanger, which includes a high-temperature heat exchange tube and a low-temperature heat exchange tube arranged in parallel and exchanging heat with each other. The inlet of the high-temperature heat exchange tube is connected to the condenser and its outlet is connected to the capillary tube. The inlet of the low-temperature heat exchange tube is connected to the evaporator and its outlet is connected to the return port of the variable frequency compressor.

[0006] To achieve one of the above-mentioned objectives, an embodiment of the present invention also provides a control method for a refrigeration device, employing the refrigeration device as described above. The control method includes: real-time monitoring of the temperature of the storage compartment and the inlet of the low-temperature heat exchange tube; obtaining the current value flowing through the variable frequency compressor; recording the time when the refrigeration device starts working as t1; recording the time when the temperature at the inlet of the low-temperature heat exchange tube drops to the same temperature as the storage compartment as t2; and recording Δt = t2 - t1; constructing a database, the database including multiple current values ​​and the corresponding Δt for each current value; extracting the minimum value of Δt from the database and recording its corresponding current value as I1; upon power-up, controlling the variable frequency compressor to start at a frequency F1; after running for a preset time Δt1, determining whether the current I flowing through the variable frequency compressor reaches I1; if not, controlling the frequency of the variable frequency compressor to increase by ΔF.

[0007] As a further improvement of one embodiment of the present invention, the control method further includes step S1: after controlling the frequency of the variable frequency compressor 1 to increase by ΔF, after a preset time Δt1, it is determined again whether the current I flowing through the variable frequency compressor reaches I1; if not, the frequency of the variable frequency compressor is increased by ΔF; step S1 is repeated until the current I flowing through the variable frequency compressor reaches I1.

[0008] As a further improvement of one embodiment of the present invention, the control method further includes step S2: after I reaches I1, after a preset time Δt2, it is determined whether the temperature Tr in the storage room has dropped to a preset temperature Tr0, where Tr0 = TTTtTT℃, and TTTt is the set temperature of the storage room; if not, after a preset time Δt2, it is determined again whether Tr has dropped to Tr0; step S2 is repeated until Tr drops to Tr0.

[0009] As a further improvement of one embodiment of the present invention, the control method further includes: after Tr drops to Tr0, determining whether I reaches the preset current I2; if I reaches the preset current I2, then controlling the frequency of the variable frequency compressor to remain unchanged.

[0010] As a further improvement of one embodiment of the present invention, the control method further includes: if I does not reach the preset current I2, then controlling the frequency of the variable frequency compressor to increase by ΔF successively until I reaches the preset current I2. The preset current I2 is the current flowing through the variable frequency compressor corresponding to the minimum evaporation temperature of the refrigeration device.

[0011] As a further improvement to one embodiment of the present invention, I2 <I1。

[0012] As a further improvement of one embodiment of the present invention, the control method further includes: if I reaches I3, then controlling the variable frequency compressor to stop, wherein I3>I1.

[0013] As a further improvement to one embodiment of the present invention, F1 = Fmin ~ FminT10Hz, ΔF = THz.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The refrigeration device and control method of the present invention have a simple refrigeration system structure and are easy to process. Through the heat exchange of high-temperature heat exchange tubes and low-temperature heat exchange tubes, the refrigerant is cooled down by heat exchange before entering the evaporator. On the other hand, the refrigerant is heated by heat exchange before entering the variable frequency compressor after leaving the evaporator. By making reasonable use of the heat exchange of the refrigeration system itself, the pressure between the outlet of the variable frequency compressor and the inlet of the capillary tube is controlled within the range that the variable frequency compressor can withstand during stable operation of the refrigeration system. This is conducive to achieving low-temperature refrigeration below -40℃ and can also significantly reduce energy consumption, which has great environmental significance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the refrigeration circuit according to an embodiment of the present invention;

[0016] Figure 2 This is a logic flowchart of a control method for a refrigeration device according to an embodiment of the present invention. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings.

[0018] In the various illustrations of this invention, for ease of illustration, certain dimensions of structures or parts may be enlarged relative to other structures or parts; therefore, only the basic structure of the subject matter of this invention is used to illustrate the invention.

[0019] It should be understood that although the terms first, second, etc., may be used in this document to describe various elements or structures, the objects being described should not be limited by these terms. These terms are only used to distinguish these objects from one another.

[0020] A refrigeration device provided in one embodiment of the present invention includes a cabinet and a door. The cabinet has a storage compartment, and the door is used to open or close the storage compartment. The refrigeration device also includes a refrigeration system disposed in the cabinet and supplying cooling to the storage compartment. Specifically, the refrigeration device can be configured as a freezer, refrigerator, etc., to meet the needs of different users and different application scenarios.

[0021] See Figure 1The refrigeration system includes a refrigeration circuit 100 and a refrigerant located within the refrigeration circuit 100. The refrigeration circuit 100 includes a variable frequency compressor 1, a condenser 2, a capillary tube 3, and an evaporator 4 connected in sequence. The refrigeration circuit 100 also includes a heat exchanger T, which includes a high-temperature heat exchange tube T1 and a low-temperature heat exchange tube T2 connected in parallel and exchanging heat with each other. The inlet of the high-temperature heat exchange tube T1 is connected to the condenser 2, and its outlet is connected to the capillary tube 3. The inlet of the low-temperature heat exchange tube T2 is connected to the outlet of the evaporator 4, and its outlet is connected to the return port of the variable frequency compressor 1. The high-temperature heat exchange tube T1 and the low-temperature heat exchange tube T2 are named for ease of distinction. Comparatively, the temperature of the refrigerant in the high-temperature heat exchange tube T1 is higher than the temperature of the refrigerant in the low-temperature heat exchange tube T2.

[0022] This refrigeration system has a simple structure and is easy to manufacture. Through heat exchange between the high-temperature heat exchange tube T1 and the low-temperature heat exchange tube T2, the refrigerant undergoes heat exchange and cooling before entering the evaporator 4. On the other hand, the refrigerant undergoes heat exchange and heating before entering the variable frequency compressor 1 after leaving the evaporator 4. By making reasonable use of the heat exchange within the refrigeration system itself, the pressure between the outlet of the variable frequency compressor 1 and the inlet of the capillary tube 3 is controlled within the range that the variable frequency compressor 1 can withstand during stable operation. This is beneficial for achieving low-temperature refrigeration below -40℃ and can also significantly reduce energy consumption, which has great environmental significance.

[0023] Specifically, the high-temperature heat exchange tube T1 and the low-temperature heat exchange tube T2 can be arranged side by side or wrapped together to achieve heat exchange.

[0024] Furthermore, the refrigeration device also includes a condenser fan located near the condenser 2, which can blow air to the condenser 2 to dissipate heat from the condenser 2.

[0025] Furthermore, the refrigeration circuit 100 also includes a dryer filter 6 located at the outlet of the condenser 2 to remove moisture and impurities mixed in the refrigerant. The outlet of the dryer filter 6 is connected to the high-temperature heat exchange tube T1.

[0026] Preferably, in this embodiment, the refrigerant includes a first working substance and a second working substance, wherein the mass percentage of the first working substance is 10-60%, the mass percentage of the second working substance is 40-90%, the first working substance is one of R170, R11TO, R23 or R14, and the second working substance is any one of R290, R600, R600a, R134a, R1234fy or R1234zT.

[0027] When the refrigerant, formed by mixing the two working fluids described above, is applied to the refrigeration system of this embodiment by adjusting the ratio of the two working fluids, it can not only meet the requirements of the refrigeration system for the amount of combustible refrigerant charged, but also achieve a temperature of -90℃ to -40℃ in the storage compartment of the refrigeration device, thus achieving a better preservation effect for frozen foods stored in the storage compartment. In practical applications, the mass percentage of the two working fluids can be adjusted according to the volume of the refrigeration device, the ambient temperature, and the application scenario to achieve the ideal preservation effect.

[0028] Preferably, the first working fluid is R170 or R11TO, and the second working fluid is any one of R290, R600, and R600a, with the first working fluid having a mass percentage of 20% to T0% and the second working fluid having a mass percentage of T0% to 80%. The binary refrigerant prepared in this way not only meets the temperature requirement of -90℃ to -40℃, but is also environmentally friendly and has significant environmental protection value.

[0029] Preferably, the first working refrigerant is R23 or R14, and the second working refrigerant is any one of R290, R600, and R600a. The mass percentage of the first working refrigerant is 10-40%, and the mass percentage of the second working refrigerant is 60-90%. The binary mixed refrigerant prepared in this way can not only meet the temperature requirement of -90℃ to -40℃, but also has flame retardant effect, improving the safety of the refrigeration system operation.

[0030] Preferably, the first working refrigerant is R170 or R11TO, and the second working refrigerant is any one of R134a, R1234fy, and R1234zT, with the first working refrigerant having a mass percentage of 10-40% and the second working refrigerant having a mass percentage of 60-90%. The resulting binary refrigerant mixture not only meets the temperature requirement of -90℃ to -40℃ but also exhibits flame-retardant properties, improving the safety of the refrigeration system operation.

[0031] Preferably, the first working refrigerant is R23 or R14, and the second working refrigerant is any one of R134a, R1234fy, and R1234zT. The mass percentage of the first working refrigerant is 20% to T0%, and the mass percentage of the second working refrigerant is T0% to 80%. The binary mixed refrigerant prepared in this way can not only meet the temperature requirement of -90℃ to -40℃, but also has flame retardant effect, improving the safety of the refrigeration system operation.

[0032] In other embodiments, the refrigerant may also be configured to include a low-temperature refrigerant, a medium-temperature refrigerant, and a high-temperature refrigerant, wherein the mass percentage of the low-temperature refrigerant is 20-40%, the mass percentage of the medium-temperature refrigerant is 20-40%, the mass percentage of the high-temperature refrigerant is 40-60%, the low-temperature refrigerant is any one of R23, R14, R170, and R11TO, the medium-temperature refrigerant is any one of R134a, R290, and R1270, and the high-temperature refrigerant is any one of R600 and R600a.

[0033] When the refrigerant, composed of the above three working fluids, is applied to the refrigeration system of this embodiment by adjusting the ratio of the three working fluids, it not only meets the requirements of the refrigeration system for the amount of combustible refrigerant to be charged, but also achieves a lower evaporation temperature and reduces evaporation pressure. Furthermore, its application in the aforementioned refrigeration system reduces the compressor's compression ratio, minimizing throttling and heat transfer losses, thereby improving refrigeration efficiency and performance. This allows the temperature inside the storage compartment of the refrigeration unit to reach -90℃ to -40℃, which is beneficial for preserving frozen foods such as meat and fish. Moreover, it reduces the technical requirements on the compressor. In practical applications, the mass percentage of the three working fluids can be adjusted according to the volume of the refrigeration unit, the ambient temperature, and the application scenario to achieve the desired preservation effect.

[0034] In this way, the refrigerant is compressed into a high-temperature, high-pressure refrigerant gas by the variable frequency compressor 1. The refrigerant gas enters the condenser 2 and condenses into a gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant enters the heat exchanger T and exchanges heat with the low-temperature heat exchanger T2 in the high-temperature heat exchanger tube T1 and is further condensed. Then, the refrigerant enters the capillary tube 3 for throttling and pressure reduction. Then, the refrigerant enters the evaporator 4 and exchanges heat to form a gas-liquid two-phase refrigerant, that is, the refrigerant is in a gas-liquid two-phase state at the outlet of the evaporator 4. This gas-liquid two-phase refrigerant passes through the low-temperature heat exchanger T2 and exchanges heat with the high-temperature heat exchanger T1, causing the refrigerant in the high-temperature heat exchanger T1 to cool down and condense. The refrigerant is in a gaseous state at the outlet of the low-temperature heat exchanger T2. Then, the refrigerant returns to the variable frequency compressor 1.

[0035] By applying the above-mentioned refrigerant to the refrigeration system of the present invention, the pressure of the pipeline between the variable frequency compressor 1 and the capillary tube 41 in the refrigeration circuit 100 after stable operation can be controlled to less than 1.6 MPa. This solves the problem of excessive pressure when the low-temperature refrigerant is used alone in the refrigeration system, reduces the requirements on the compressor, ensures the feasibility of the refrigeration system, and enables the refrigeration device to achieve a low-temperature storage environment of -90℃ to -40℃.

[0036] Furthermore, the temperature Tl of the refrigerant at the outlet of condenser 2 is greater than the ambient temperature Th, and the temperature difference between the two is ΔT = Tl - Th, where ΔT ≤ 3℃. In this embodiment, ΔT is below 3℃, which is much smaller than the 8℃ or lower in the prior art.

[0037] One embodiment of the present invention also provides a control method for a refrigeration device, which is implemented based on the above-described refrigeration device.

[0038] See Figure 2 Specifically, the control method includes:

[0039] The temperature of the storage room and the inlet of the low-temperature heat exchange tube T2 is monitored in real time, the current value flowing through the variable frequency compressor 1 is obtained, and the time when the refrigeration device starts to work is recorded as t1, and the time when the temperature of the inlet of the low-temperature heat exchange tube T2 drops to the same temperature as the storage room is recorded as t2. Δt = t2 - t1 is recorded.

[0040] Construct a database, which includes multiple current values ​​and the corresponding Δt for each current value;

[0041] Extract the minimum value of Δt from the database and record the corresponding current value as I1;

[0042] When powered on, control the variable frequency compressor 1 to start at frequency F1;

[0043] After running for a preset time △t1, determine whether the current I flowing through the variable frequency compressor 1 reaches I1;

[0044] If not, the frequency of the variable frequency compressor 1 is increased by ΔF.

[0045] In this way, when powered on, the temperature of the low-temperature heat exchange tube T2 can be reduced to the temperature of the storage chamber in the shortest possible time, so that the heat exchanger T can start to function in the shortest possible time, rapidly reducing the temperature of the refrigerant in the high-temperature heat exchange tube T1 and further condensing it. This helps to accelerate the reduction of condensation pressure, thereby reducing the pressure difference and refrigeration system pressure on both sides of the variable frequency compressor 1, preventing drastic changes in the exhaust temperature on both sides of the variable frequency compressor 1 that may even exceed its tolerable range, and thus extending the service life of the variable frequency compressor 1.

[0046] Preferably, Δt1 = 10 min, so that the heat exchanger T can start working as soon as possible.

[0047] Preferably, F1 = Fmin ~ FminT10Hz, ΔF = THz, where Fmin is the minimum set frequency of the variable frequency compressor 1. By starting the variable frequency compressor 1 at a lower frequency F1, the pressure on the variable frequency compressor 1 at power-on can be further reduced, and it is also beneficial for the subsequent frequency increase of the variable frequency compressor 1. ΔF = THz can prevent the frequency change of the variable frequency compressor 1 from being too large, which would lead to drastic changes in the discharge pressure, thereby preventing it from exceeding the tolerance range of the variable frequency compressor 1.

[0048] Furthermore, the control method further includes step S1:

[0049] After the frequency of the variable frequency compressor 1 is increased by ΔF, after a preset time Δt1, it is determined again whether the current I flowing through the variable frequency compressor 1 reaches I1.

[0050] If not, then the frequency of the variable frequency compressor 1 is increased by ΔF;

[0051] Repeat step S1 until the current I flowing through the variable frequency compressor 1 reaches I1. This allows the heat exchanger T to start working in the shortest possible time.

[0052] Furthermore, the control method further includes step S2:

[0053] After I reaches I1, after a preset time Δt2, it is determined whether the temperature Tr in the storage room has dropped to the preset temperature Tr0, where Tr0 = TTTtTT℃, and TTTt is the set temperature of the storage room;

[0054] If not, after a preset time Δt2, it is determined again whether Tr has dropped to Tr0;

[0055] Repeat step S2 until Tr drops to Tr0. This will lower the temperature of the storage room to just before it reaches the set temperature.

[0056] Furthermore, the control method further includes:

[0057] After Tr drops to Tr0, determine whether I has reached the preset current I2;

[0058] If I reaches the preset current I2, the frequency of the variable frequency compressor 1 will remain unchanged.

[0059] If I does not reach the preset current I2, the frequency of the variable frequency compressor is controlled to increase by ΔF successively until I reaches the preset current I2.

[0060] Wherein, the preset current I2 is the current flowing through the variable frequency compressor corresponding to the minimum evaporation temperature reached by the refrigeration device.

[0061] The minimum evaporation temperature that the refrigeration device can reach is determined during the design process. By pre-testing the current flowing through the variable frequency compressor 1 when the refrigeration device reaches the minimum evaporation temperature, and after the temperature Tr in the storage room drops to the preset temperature Tr0, the frequency of the variable frequency compressor 1 is adjusted to make the current reach I2, thereby controlling the refrigeration device to reach the minimum evaporation temperature and improving the refrigeration efficiency.

[0062] Among them, I2 <I1。

[0063] Furthermore, the control method further includes:

[0064] If I reaches I3, the variable frequency compressor 1 is controlled to stop, where I3 > I1. Here, I3 is the upper limit threshold of the current flowing through the variable frequency compressor 1. During the operation of the refrigeration device, the current is always controlled below I3 to prevent the temperature or pressure from exceeding the tolerance range of the refrigeration system.

[0065] Specifically, the variable frequency compressor 1 can be stopped for 30 minutes while the condenser fan continues to run.

[0066] Compared with the prior art, the refrigeration device and its control method provided by this invention have the following advantages: the refrigeration system has a simple structure and is easy to manufacture. Through the heat exchange of the high-temperature heat exchange tube T1 and the low-temperature heat exchange tube T2, the refrigerant undergoes heat exchange and cooling before entering the evaporator 4, and heat exchange and heating before entering the variable frequency compressor 1 after leaving the evaporator 4. This rationally utilizes the heat exchange of the refrigeration system itself, thereby controlling the pressure between the outlet of the variable frequency compressor 1 and the inlet of the capillary tube 3 within the range that the variable frequency compressor 1 can withstand during stable operation. This is beneficial for achieving low-temperature refrigeration below -40℃ and can also significantly reduce energy consumption, which has great environmental significance. Combined with the composition and ratio of the refrigerant, the refrigeration circuit 100 after stable operation can be located between the variable frequency compressor 1 and the capillary tube 3. The pressure in the pipes between pipes 41 is controlled to be less than 1.6 MPa, which solves the problem of excessive pressure when the low-temperature refrigerant is used alone in the refrigeration system, reduces the requirements on the compressor, and ensures the feasibility of the refrigeration system, thereby enabling the refrigeration device to achieve a low-temperature storage environment of -90℃ to -40℃. When powered on, the control method can reduce the temperature of the low-temperature heat exchange tube T2 to the temperature of the storage chamber in the shortest possible time, so that the heat exchanger T can start to work in the shortest possible time, rapidly reducing the temperature of the refrigerant in the high-temperature heat exchange tube T1 and further condensing it. This helps to accelerate the reduction of condensation pressure, thereby reducing the pressure difference on both sides of the variable frequency compressor 1 and the pressure of the refrigeration system, preventing drastic changes in the exhaust temperature on both sides of the variable frequency compressor 1 that may even exceed its tolerable range, and thus extending the service life of the variable frequency compressor 1.

[0067] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0068] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control method for a refrigeration device, characterized in that, The refrigeration device includes a refrigeration system and a storage compartment. The refrigeration system supplies cooling to the storage compartment. The refrigeration system includes a variable frequency compressor, a condenser, a capillary tube, and an evaporator connected in sequence. The refrigeration system also includes a heat exchanger, which includes a high-temperature heat exchange tube and a low-temperature heat exchange tube connected in parallel and exchanging heat with each other. The inlet of the high-temperature heat exchange tube is connected to the condenser, and its outlet is connected to the capillary tube. The inlet of the low-temperature heat exchange tube is connected to the evaporator, and its outlet is connected to the return port of the variable frequency compressor. The control method includes: The temperature of the storage room and the inlet of the low-temperature heat exchange tube are monitored in real time, the current value flowing through the variable frequency compressor is obtained, and the time when the refrigeration device starts to work is recorded as t1, and the time when the temperature of the inlet of the low-temperature heat exchange tube drops to the same temperature as the storage room is recorded as t2. Δt = t2 - t1 is recorded. Construct a database, which includes multiple current values ​​and the corresponding Δt for each current value; Extract the minimum value of Δt from the database and record the corresponding current value as I1; When powered on, the variable frequency compressor is controlled to start at frequency F1; After running for a preset time △t1, determine whether the current I flowing through the variable frequency compressor reaches I1; If not, then control the frequency of the variable frequency compressor to increase by ΔF; Step S1: After controlling the frequency of the variable frequency compressor to increase by ΔF, after a preset time Δt1, determine again whether the current I flowing through the variable frequency compressor has reached I1; if not, control the frequency of the variable frequency compressor to increase by ΔF. Repeat step S1 until the current I flowing through the variable frequency compressor reaches I1; Step S2: After I reaches I1, after a preset time Δt2, determine whether the temperature Tr in the storage room has dropped to the preset temperature Tr0, where Tr0 = Tset + 5℃, and Tset is the set temperature of the storage room; if not, after a preset time Δt2, determine again whether Tr has dropped to Tr0. Repeat step S2 until Tr drops to Tr0.

2. The control method for the refrigeration device according to claim 1, characterized in that, The control method further includes: After Tr drops to Tr0, determine whether I has reached the preset current I2; If I reaches the preset current I2, then the frequency of the variable frequency compressor is controlled to remain unchanged.

3. The control method for the refrigeration device according to claim 2, characterized in that, The control method further includes: If I does not reach the preset current I2, the frequency of the variable frequency compressor is controlled to increase by ΔF successively until I reaches the preset current I2.

4. The control method for the refrigeration device according to claim 2, characterized in that, The preset current I2 is the current flowing through the variable frequency compressor corresponding to the minimum evaporation temperature reached by the refrigeration device.

5. The control method for the refrigeration device according to claim 2, characterized in that, I2 <I1。 6. The control method for the refrigeration device according to claim 1, characterized in that, The control method further includes: If I reaches I3, then the variable frequency compressor is controlled to stop, where I3>I1.

7. The control method for the refrigeration device according to claim 1, characterized in that, F1 = Fmin ~ Fmin + 10Hz, where Fmin is the minimum set frequency of the variable frequency compressor, and ΔF = 5Hz.

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