Refrigerating system capable of adjusting supercooling degree and control method

Abstract

The invention discloses a refrigerating system capable of adjusting supercooling degree and a control method, and the method is characterized in that the pre-valve pressure adjustment and pre-valve supercooling degree adjustment are carried out on the combination of a main condenser and an auxiliary condenser by combining the judgment of the environment temperature and the refrigerating capacity, so that when the refrigerating equipment is in a relatively wide environment temperature range and is matched with batteries with different specifications, the refrigerating efficiency is improved. And the upstream supercooling degree can be accurately controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management systems, and in particular to a refrigeration system for adjusting supercooling and a control method. Background Art

[0002] Battery thermal management is the key to ensuring the continuous and safe operation of the battery system. Therefore, in the inspection of new energy battery products, it is essential to simulate the performance and reliability test when the battery thermal management state is consistent with the actual state. Direct cooling is a heat dissipation solution that takes into account both cooling efficiency and manufacturing cost, and is widely used in battery thermal management systems. However, there are differences in the thermal management systems corresponding to batteries of different specifications. In order to improve the test efficiency, a refrigeration device that can simulate the thermal management state of batteries of different specifications is needed.

[0003] The commonly used method of simulating battery thermal management is to maintain some cooling parameters of the refrigeration equipment consistent with the parameters of the thermal management refrigeration system that actually matches the battery, such as the valve front pressure and valve front subcooling under certain conditions. Therefore, when the refrigeration equipment is running, such parameters can be adjusted according to the set values. However, different battery cold plate specifications, ambient temperature and other factors will affect the stability of parameters such as the valve front pressure and valve front subcooling of the refrigeration equipment. Summary of the invention

[0004] In view of the above problems, the present invention proposes a refrigeration system and a control method for adjusting supercooling, which mainly solve the problems of the background technology.

[0005] To solve the above technical problems, the first aspect of the present invention proposes a refrigeration system for adjusting supercooling, comprising a main heat exchanger arranged at the output end of a compressor, at least two auxiliary heat exchangers arranged in parallel, and a battery cold plate, the main heat exchanger and the auxiliary heat exchanger are respectively provided with a main cooling fan and an auxiliary cooling fan, wherein a first pressure sensor and a first temperature sensor are provided at the output end of the main heat exchanger, a second pressure sensor and a second temperature sensor are provided at the input end of the electronic expansion valve, a third pressure sensor and a third temperature sensor are provided at the input end of the battery cold plate, a fourth pressure sensor and a fourth temperature sensor are provided at the output end of the battery cold plate, and an ambient temperature sensor is also provided at the condenser side.

[0006] A second aspect of the present invention provides a control method, which is applied to the above-mentioned refrigeration system for adjusting the degree of subcooling, and comprises the following steps:

[0007] S1, obtaining the ambient temperature value T output by the ambient temperature sensor 环 , when the ambient temperature is T 环 ≤Preset ambient temperature T 环1 When only one set of auxiliary heat exchangers is used for operation, when the ambient temperature value T环 >Preset ambient temperature T 环1 When two or more groups of the auxiliary heat exchangers are used to participate in the operation, the main cooling fan, the electronic expansion valve and the compressor are operated according to the preset maintenance time corresponding to each initial value;

[0008] S2, when the main cooling fan, the electronic expansion valve and the compressor reach their respective corresponding preset maintenance time, controlling the main cooling fan, the auxiliary cooling fan, the electronic expansion valve and the compressor to operate according to a preset control strategy;

[0009] S3, after the speed of the compressor reaches an initial value and is maintained for a second preset time, the current cooling capacity is estimated.

[0010] In S1, the solenoid valve corresponding to the auxiliary heat exchanger and the corresponding auxiliary cooling fan participating in the operation are opened.

[0011] In some embodiments, in S1, the speed of the main cooling fan runs at 50% of the maximum speed, the electronic expansion valve is 70% open, and after a first preset time, the speed of the compressor rises to 70% of the maximum speed, and then runs according to the preset maintenance time.

[0012] In some implementations, the first preset time is 15 seconds, and the second preset time is 2 minutes.

[0013] In some implementations, in S2, controlling the operation of the main cooling fan, the auxiliary cooling fan, the electronic expansion valve, and the compressor according to a preset control strategy includes:

[0014] S201, control of the compressor: the fourth pressure sensor obtains the battery cold plate outlet pressure P 出 , when the battery cold plate outlet pressure P 出 >Battery cold plate outlet pressure setting value + X, the compressor speed increases; when the battery cold plate outlet pressure P 出 <Battery cold plate outlet pressure setting value -X, the compressor speed decreases; when the battery cold plate outlet pressure setting value -X <Battery cold plate outlet pressure P 出 When the battery cold plate outlet pressure setting value is less than +X, the compressor speed remains unchanged, where X is the control accuracy;

[0015] S202, controlling the main cooling fan: the first pressure sensor obtains the condensing pressure P of the main condenser 凝 , when the main condenser condensation pressure P 凝 > valve front pressure setting value + Y, the speed of the main cooling fan increases; when the main condenser condensing pressure P 凝< the valve front pressure setting value -Y, the speed of the main cooling fan decreases; when the valve front pressure setting value -Y ≤ the main condenser condensing pressure P 凝 ≤ before-valve pressure setting value + Y, the speed of the main cooling fan decreases and remains unchanged, where Y is the control accuracy;

[0016] S203, controlling the auxiliary cooling fan: the second pressure sensor and the second temperature sensor respectively obtain the valve front pressure valve front pressure P 阀 and valve inlet temperature T 阀 , according to the valve inlet pressure P 阀 and valve inlet temperature T 阀 The subcooling degree before the valve is calculated. When the subcooling degree before the valve is greater than the setting value of the subcooling degree before the valve + Z, the speed of the auxiliary cooling fan decreases by the same amount; when the subcooling degree before the valve is less than the setting value of the subcooling degree before the valve - Z, the speed of the auxiliary cooling fan increases by the same amount; when the setting value of the subcooling degree before the valve - Z ≤ the subcooling degree before the valve ≤ the setting value of the subcooling degree before the valve + Z, the speed of the auxiliary cooling fan remains unchanged, wherein Z is the control accuracy;

[0017] S204, control of the electronic expansion valve: the fourth pressure sensor and the fourth temperature sensor respectively obtain the battery cold plate outlet pressure P 出 and battery cold plate outlet temperature T 出 , according to the battery cold plate outlet pressure P 出 and battery cold plate outlet temperature T 出 The superheat degree at the battery cold plate outlet is calculated. When the superheat degree at the battery cold plate outlet is greater than the battery cold plate outlet superheat setting value + A, the opening of the electronic expansion valve increases; when the superheat degree at the battery cold plate outlet is less than the battery cold plate outlet superheat setting value - A, the opening of the electronic expansion valve decreases; when the battery cold plate outlet superheat setting value - A ≤ the battery cold plate outlet superheat degree ≤ the battery cold plate outlet superheat setting value + A, the opening of the electronic expansion valve remains unchanged, wherein A is the control accuracy.

[0018] In some implementations, in S3, the current refrigeration capacity estimation process includes:

[0019] The third pressure sensor and the third temperature sensor respectively obtain the battery cold plate inlet pressure P 入 and the battery cold plate inlet temperature T 入 , according to the battery cold plate inlet pressure P 入 , the battery cold plate inlet temperature T 入 , and combined with the pre-stored corresponding relationship between the refrigerant temperature, pressure and enthalpy value, the battery cold plate inlet enthalpy value h1 is calculated; the fourth pressure sensor and the fourth temperature sensor respectively obtain the battery cold plate outlet pressure P 出 and battery cold plate outlet temperature T出 Similarly, the outlet enthalpy value h2 of the battery cold plate is obtained, and the refrigerant mass flow rate m is collected and obtained at the same time. The current cooling capacity Q is calculated according to the formula Q=m*(h1-h2).

[0020] In some embodiments, in S3, the cooling capacities Q1 and Q2 are preset, wherein Q1<Q2, and the number and value of Q1 and Q2 are adjusted according to the number of auxiliary heat exchangers actually designed, specifically including:

[0021] S301, when the cooling capacity Q is less than the preset cooling capacity Q1:

[0022] When the battery cold plate outlet superheat is detected to be less than the battery cold plate outlet superheat setting value - A for 30 consecutive seconds, the auxiliary heat exchanger of one group is shut down;

[0023] Alternatively, when it is detected that the battery cold plate outlet superheat is ≥ the battery cold plate outlet superheat setting value - A, the auxiliary heat exchangers of the two groups maintain the original parameters for operation;

[0024] S302, when the preset cooling capacity Q1≤cooling capacity Q≤preset cooling capacity Q2:

[0025] The auxiliary heat exchangers of the two groups are operated with original parameters;

[0026] S303, when the cooling capacity Q> the preset cooling capacity Q2:

[0027] When it is detected that the battery cold plate outlet superheat is less than the battery cold plate outlet superheat setting value - A, the auxiliary heat exchangers of the two groups maintain the original parameters for operation;

[0028] Alternatively, when the battery cold plate outlet superheat is detected to be ≥ the battery cold plate outlet superheat setting value - A for 30 consecutive seconds, the auxiliary heat exchangers of the two groups participate in the operation.

[0029] The beneficial effects of the present invention are as follows: by combining the determination of the ambient temperature and the cooling capacity, the pre-valve pressure and the pre-valve subcooling are adjusted for the combination of the main and auxiliary condensers, ensuring that the refrigeration equipment can accurately control the pre-valve subcooling in a wider ambient temperature range and when matching batteries of different specifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a three-dimensional diagram of a refrigeration system for adjusting supercooling disclosed in Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the content of the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, rather than all the contents.

[0032] Embodiment 1

[0033] This embodiment proposes a refrigeration system for adjusting the degree of supercooling, such as Figure 1 As shown, it includes a group of main heat exchangers 2 arranged at the output end of the compressor 1, at least two groups of auxiliary heat exchangers 8 and auxiliary heat exchangers 12 arranged in parallel, and a group of battery cold plates 22. The main heat exchanger 2, the auxiliary heat exchanger 8 and the auxiliary heat exchanger 12 are respectively provided with a main cooling fan 3, an auxiliary cooling fan 9 and an auxiliary cooling fan 13, wherein the output end of the main heat exchanger 2 is provided with a first pressure sensor 5 and a first temperature sensor 6, the input end of the electronic expansion valve 19 is provided with a second pressure sensor 17 and a second temperature sensor 18, the input end of the battery cold plate 22 (equivalent to the evaporator) is provided with a third pressure sensor 20 and a third temperature sensor 21, the output end of the battery cold plate 22 is provided with a fourth pressure sensor 23 and a fourth temperature sensor 24, and also includes an ambient temperature sensor 26 arranged on the condenser side.

[0034] The above are the differences between this embodiment and the prior art, and the remaining components of this refrigeration system can be set according to actual conditions. In one example, it also includes a first liquid storage tank 4 arranged after the main heat exchanger 2, the input end and output end of the auxiliary cooling fan 9 are respectively provided with a first solenoid valve 7 and a first non-return valve 10, the input end and output end of the auxiliary cooling fan 13 are respectively provided with a second solenoid valve 11 and a second non-return valve 14, the second pressure sensor 17 is respectively provided with a second liquid storage tank 15 and a flow meter 16, and the third liquid storage tank 25 is arranged after the fourth pressure sensor 23. The above-mentioned first liquid storage tank 4, second liquid storage tank 15 and third liquid storage tank 25 store refrigerant to ensure that the detected temperature and pressure are more stable.

[0035] Embodiment 2

[0036] This embodiment provides a control method, which is applied to the refrigeration system for adjusting the degree of subcooling described in the first embodiment, and includes the following steps:

[0037] S1, obtain the ambient temperature value T output by the ambient temperature sensor 26 环 , when the ambient temperature is T 环 ≤Preset ambient temperature T 环1 When only one set of auxiliary heat exchangers is used for operation, when the ambient temperature value T 环>Preset ambient temperature T 环1 When two or more auxiliary heat exchangers are used to participate in the operation, the main cooling fan 3, the electronic expansion valve 19 and the compressor 1 operate according to the preset maintenance time corresponding to each initial value.

[0038] In S1, the solenoid valves and corresponding auxiliary cooling fans of the auxiliary heat exchangers involved in the operation are turned on (the first solenoid valve 7 is turned on if one group is used, and the first solenoid valve 7 and the second solenoid valve 11 are turned on if two groups are used), and the auxiliary cooling fans (the auxiliary cooling fan 9 is turned on if one group is used, and the speed is set to R F2 If two groups are used, auxiliary cooling fans 9 and 13 are turned on, and the speeds are set to R F2 and R F3 The above initial value can be understood as the output state of each component before the equipment starts running. This state is selected according to the actual design specifications and test conditions of the system. It is not a fixed value. In one example, the speed of the main cooling fan 3 is 50% of the maximum speed R F1 The electronic expansion valve 19 is opened to 70% D, and after the first preset time (the first preset time can be set to 15s, the time value is for example, and the specific value can be selected according to the actual configuration), the speed of the compressor 1 rises to 70% of the maximum speed R Y Then it runs according to the preset maintenance time (the output values ​​of the above components are selected according to the actual design).

[0039] S2, when the main cooling fan 3, the electronic expansion valve 19 and the compressor 1 reach their respective corresponding preset maintenance time, the main cooling fan 3, the auxiliary cooling fans 9, 13, the electronic expansion valve 19 and the compressor 1 are controlled to operate according to the preset control strategy.

[0040] In one example, controlling the operation of the main cooling fan 3, the auxiliary cooling fans 9, 13, the electronic expansion valve 19 and the compressor 1 according to a preset control strategy includes:

[0041] S201, control of compressor 1: the fourth pressure sensor 23 obtains the battery cold plate outlet pressure P 出 , when the battery cold plate outlet pressure P 出 >Battery cold plate outlet pressure setting value + X, compressor 1 speed increases; when battery cold plate outlet pressure P 出 When the battery cold plate outlet pressure setting value is less than the battery cold plate outlet pressure setting value -X, the compressor 1 speed decreases; when the battery cold plate outlet pressure setting value -X is less than the battery cold plate outlet pressure P 出 When the battery cold plate outlet pressure is less than the set value + X, the speed of compressor 1 remains unchanged, where X is the control accuracy; 出 Affected by the speed of compressor 1, the battery cold plate outlet pressure P出 Maintain within ±X range.

[0042] S202, control of the main cooling fan 3: the first pressure sensor 5 obtains the main condenser condensation pressure P 凝 , when the main condenser condensation pressure P 凝 > valve pressure setting value + Y, the speed of main cooling fan 3 increases; when the main condenser condensing pressure P 凝 When the pressure before the valve is less than the setting value -Y, the speed of the main cooling fan 3 decreases; when the pressure before the valve is less than the setting value -Y ≤ the condensing pressure P of the main condenser 凝 ≤ the valve front pressure setting value + Y, the speed of the main cooling fan 3 decreases and remains unchanged, where Y is the control accuracy; due to the main condenser condensation pressure P 凝 Affected by the speed of the main cooling fan 3, the main condenser condensation pressure P 凝 Maintain within ±Y range.

[0043] S203, control of auxiliary cooling fans 9, 13: the second pressure sensor 17 and the second temperature sensor 18 respectively obtain the valve front pressure valve front pressure P 阀 and valve inlet temperature T 阀 , according to the valve inlet pressure P 阀 and valve inlet temperature T 阀 The subcooling degree before the valve is calculated. When the subcooling degree before the valve is greater than the setting value of the subcooling degree before the valve + Z, the speed of the auxiliary cooling fan (including the auxiliary cooling fan 13 and the auxiliary cooling fan 9) decreases by the same amount; when the subcooling degree before the valve is less than the setting value of the subcooling degree before the valve - Z, the speed of the auxiliary cooling fan (including the auxiliary cooling fan 13 and the auxiliary cooling fan 9) increases by the same amount; when the setting value of the subcooling degree before the valve - Z ≤ the subcooling degree before the valve ≤ the setting value of the subcooling degree before the valve + Z, the speed of the auxiliary cooling fan (including the auxiliary cooling fan 13 and the auxiliary cooling fan 9) remains unchanged, where Z is the control accuracy. It should be noted that when the second solenoid valve 11 is in the closed state, the auxiliary cooling fan 13 is closed and does not participate in the control. Since the subcooling degree before the valve is affected by the speed of the auxiliary cooling fan 13 and the auxiliary cooling fan 9, the speed of the cooling fan is adjusted to maintain the subcooling degree before the valve within the range of ± Z.

[0044] S204, control of the electronic expansion valve 19: the fourth pressure sensor 23 and the fourth temperature sensor 24 respectively obtain the battery cold plate outlet pressure P 出 and battery cold plate outlet temperature T 出 , according to the battery cold plate outlet pressure P 出 and battery cold plate outlet temperature T 出The battery cold plate outlet superheat is calculated. When the battery cold plate outlet superheat is greater than the battery cold plate outlet superheat setting value + A, the opening of the electronic expansion valve 19 increases; when the battery cold plate outlet superheat is less than the battery cold plate outlet superheat setting value - A, the opening of the electronic expansion valve 19 decreases; when the battery cold plate outlet superheat setting value - A ≤ battery cold plate outlet superheat ≤ battery cold plate outlet superheat setting value + A, the opening of the electronic expansion valve 19 remains unchanged, where A is the control accuracy. Since the battery cold plate outlet superheat is affected by the opening of the electronic expansion valve 19, the battery cold plate outlet superheat is maintained within the range of ± A by adjusting the opening of the electronic expansion valve 19.

[0045] S3, after the speed of the compressor 1 reaches the initial value and the maintenance time reaches the second preset time (the second preset time can be set to 2 minutes, and the time value is for example, and the specific value can be selected according to the actual configuration), the current cooling capacity is estimated.

[0046] Specifically, the current cooling capacity estimation process includes:

[0047] The third pressure sensor and the third temperature sensor respectively obtain the battery cold plate inlet pressure P 入 and the battery cold plate inlet temperature T 入 , according to the battery cold plate inlet pressure P 入 , Battery cold plate inlet temperature T 入 , and combined with the pre-stored corresponding relationship between the refrigerant temperature, pressure and enthalpy value, the battery cold plate inlet enthalpy value h1 is calculated; the fourth pressure sensor and the fourth temperature sensor respectively obtain the battery cold plate outlet pressure P 出 and battery cold plate outlet temperature T 出 Similarly, the outlet enthalpy value h2 of the battery cold plate is obtained, and the refrigerant mass flow rate m is collected and obtained at the same time. The current cooling capacity Q is calculated according to the formula Q=m*(h1-h2).

[0048] In S3, the cooling capacities Q1 and Q2 are preset, wherein Q1<Q2, and the number and value of Q1 and Q2 are adjusted according to the number of auxiliary heat exchangers actually designed. For example, in this embodiment, the auxiliary heat exchanger 8 and the auxiliary heat exchanger 12 are included, and the two auxiliary heat exchangers correspond to the preset cooling capacities Q1 and Q2 respectively, and the actual cooling capacity is selected according to the size of Q1 and Q2. Similarly, when the number of auxiliary condensers is three, the corresponding preset cooling capacities are Q1, Q2 and Q3, and the actual cooling capacity is selected according to the size of Q1 and Q2.

[0049] This system is based on auxiliary heat exchangers 8 and 12, and the specific control strategies include:

[0050] S301, when the cooling capacity Q is less than the preset cooling capacity Q1:

[0051] When the battery cold plate outlet superheat is detected to be less than the battery cold plate outlet superheat setting value - A for 30 consecutive seconds, one of the auxiliary heat exchangers will be shut down;

[0052] Alternatively, when it is detected that the battery cold plate outlet superheat is ≥ the battery cold plate outlet superheat setting value - A, the two groups of auxiliary heat exchangers maintain the original parameters for operation; to prevent the abnormal fluctuation of the detection data value in a short period of time when the detected cooling capacity is small, resulting in erroneous judgment, frequent switching of the auxiliary heat exchanger and large fluctuations in the system.

[0053] S302, when the preset cooling capacity Q1≤cooling capacity Q≤preset cooling capacity Q2:

[0054] The two groups of auxiliary heat exchangers maintain the original parameters for operation; in the system solution selection and design, when the actual cooling capacity is within this range, it is the middle output area corresponding to the control component selection, and there is a margin for adjusting the upper and lower outputs to avoid frequent switching of the auxiliary heat exchanger causing large fluctuations in the system.

[0055] S303, when the cooling capacity Q> the preset cooling capacity Q2:

[0056] When it is detected that the battery cold plate outlet superheat is less than the battery cold plate outlet superheat setting value - A, the auxiliary heat exchangers of the two groups maintain the original parameters for operation;

[0057] Alternatively, when the battery cold plate outlet superheat is detected to be ≥ the battery cold plate outlet superheat setting value - A for 30 consecutive seconds, the two groups of auxiliary heat exchangers will participate in the operation; to prevent the abnormal fluctuation of the detection data value in a short period of time from causing wrong judgment when the detected cooling capacity is too large, causing the auxiliary heat exchanger to switch frequently and cause large fluctuations in the system.

[0058] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A refrigeration system for adjusting subcooling, characterized in that: It includes a main heat exchanger arranged at the output end of the compressor, at least two auxiliary heat exchangers arranged in parallel, and a battery cold plate. The main heat exchanger and the auxiliary heat exchanger are respectively provided with a main cooling fan and an auxiliary cooling fan. The output end of the main heat exchanger is provided with a first pressure sensor and a first temperature sensor, the input end of the electronic expansion valve is provided with a second pressure sensor and a second temperature sensor, the input end of the battery cold plate is provided with a third pressure sensor and a third temperature sensor, the output end of the battery cold plate is provided with a fourth pressure sensor and a fourth temperature sensor, and also includes an ambient temperature sensor arranged on the condenser side.

2. A control method, applied to the refrigeration system for adjusting subcooling according to claim 1, characterized in that: The following steps are involved: S1, obtaining the ambient temperature value T output by the ambient temperature sensor 环 , when the ambient temperature is T 环 ≤Preset ambient temperature T 环1 When only one set of auxiliary heat exchangers is used for operation, when the ambient temperature value T 环 >Preset ambient temperature T 环1 When two or more groups of the auxiliary heat exchangers are used to participate in the operation, the main cooling fan, the electronic expansion valve and the compressor are operated according to the preset maintenance time corresponding to each initial value; S2, when the main cooling fan, the electronic expansion valve and the compressor reach their respective corresponding preset maintenance time, controlling the main cooling fan, the auxiliary cooling fan, the electronic expansion valve and the compressor to operate according to a preset control strategy; S3, after the speed of the compressor reaches an initial value and is maintained for a second preset time, the current cooling capacity is estimated.

3. The refrigeration system for adjusting subcooling according to claim 2, characterized in that: In S1, the solenoid valve corresponding to the auxiliary heat exchanger and the corresponding auxiliary cooling fan participating in the operation are opened.

4. The refrigeration system for adjusting subcooling according to claim 2, characterized in that: In S1, the main cooling fan runs at 50% of the maximum speed, the electronic expansion valve is 70% open, and after a first preset time, the compressor speed rises to 70% of the maximum speed and then runs according to the preset maintenance time.

5. The refrigeration system for adjusting subcooling according to claim 4, characterized in that: The first preset time is 15 seconds, and the second preset time is 2 minutes.

6. The refrigeration system for adjusting subcooling according to claim 2, characterized in that: In S2, controlling the operation of the main cooling fan, the auxiliary cooling fan, the electronic expansion valve and the compressor according to a preset control strategy includes: S201, control of the compressor: the fourth pressure sensor obtains the battery cold plate outlet pressure P 出 , when the battery cold plate outlet pressure P 出 >Battery cold plate outlet pressure setting value + X, the compressor speed increases; when the battery cold plate outlet pressure P 出 <Battery cold plate outlet pressure setting value -X, the compressor speed decreases; when the battery cold plate outlet pressure setting value -X <Battery cold plate outlet pressure P 出 When the battery cold plate outlet pressure setting value is less than +X, the compressor speed remains unchanged, where X is the control accuracy; S202, controlling the main cooling fan: the first pressure sensor obtains the condensing pressure P of the main condenser 凝 , when the main condenser condensation pressure P 凝 > valve front pressure setting value + Y, the speed of the main cooling fan increases; when the main condenser condensing pressure P 凝 < the valve front pressure setting value -Y, the speed of the main cooling fan decreases; when the valve front pressure setting value -Y ≤ the main condenser condensing pressure P 凝 ≤ before-valve pressure setting value + Y, the speed of the main cooling fan decreases and remains unchanged, where Y is the control accuracy; S203, controlling the auxiliary cooling fan: the second pressure sensor and the second temperature sensor respectively obtain the valve front pressure valve front pressure P 阀 and valve inlet temperature T 阀 , according to the valve inlet pressure P 阀 and valve inlet temperature T 阀 The subcooling degree before the valve is calculated. When the subcooling degree before the valve is greater than the setting value of the subcooling degree before the valve + Z, the speed of the auxiliary cooling fan decreases by the same amount; when the subcooling degree before the valve is less than the setting value of the subcooling degree before the valve - Z, the speed of the auxiliary cooling fan increases by the same amount; when the setting value of the subcooling degree before the valve - Z ≤ the subcooling degree before the valve ≤ the setting value of the subcooling degree before the valve + Z, the speed of the auxiliary cooling fan remains unchanged, wherein Z is the control accuracy; S204, control of the electronic expansion valve: the fourth pressure sensor and the fourth temperature sensor respectively obtain the battery cold plate outlet pressure P 出 and battery cold plate outlet temperature T 出 , according to the battery cold plate outlet pressure P 出 and battery cold plate outlet temperature T 出 The superheat degree at the battery cold plate outlet is calculated. When the superheat degree at the battery cold plate outlet is greater than the battery cold plate outlet superheat setting value + A, the opening of the electronic expansion valve increases; when the superheat degree at the battery cold plate outlet is less than the battery cold plate outlet superheat setting value - A, the opening of the electronic expansion valve decreases; when the battery cold plate outlet superheat setting value - A ≤ the battery cold plate outlet superheat degree ≤ the battery cold plate outlet superheat setting value + A, the opening of the electronic expansion valve remains unchanged, wherein A is the control accuracy.

7. The refrigeration system for adjusting subcooling according to claim 2, characterized in that: In S3, the current cooling capacity estimation process includes: The third pressure sensor and the third temperature sensor respectively obtain the battery cold plate inlet pressure P 入 and the battery cold plate inlet temperature T 入 , according to the battery cold plate inlet pressure P 入 , the battery cold plate inlet temperature T 入 , and combined with the pre-stored corresponding relationship between the refrigerant temperature, pressure and enthalpy value, the battery cold plate inlet enthalpy value h1 is calculated; the fourth pressure sensor and the fourth temperature sensor respectively obtain the battery cold plate outlet pressure P 出 and battery cold plate outlet temperature T 出 Similarly, the outlet enthalpy value h2 of the battery cold plate is obtained, and the refrigerant mass flow rate m is collected and obtained at the same time. The current cooling capacity Q is calculated according to the formula Q=m*(h1-h2).

8. The refrigeration system for adjusting subcooling according to claim 7, characterized in that: In S3, the cooling capacities Q1 and Q2 are preset, wherein Q1<Q2, and the number and value of Q1 and Q2 are adjusted according to the number of auxiliary heat exchangers actually designed, specifically including: S301, when the cooling capacity Q is less than the preset cooling capacity Q1: When the battery cold plate outlet superheat is detected to be less than the battery cold plate outlet superheat setting value - A for 30 consecutive seconds, the auxiliary heat exchanger of one group is shut down; Alternatively, when it is detected that the battery cold plate outlet superheat is ≥ the battery cold plate outlet superheat setting value - A, the auxiliary heat exchangers of the two groups maintain the original parameters for operation; S302, when the preset cooling capacity Q1≤cooling capacity Q≤preset cooling capacity Q2: The auxiliary heat exchangers of the two groups are operated with original parameters; S303, when the cooling capacity Q> the preset cooling capacity Q2: When it is detected that the battery cold plate outlet superheat is less than the battery cold plate outlet superheat setting value - A, the auxiliary heat exchangers of the two groups maintain the original parameters for operation; Alternatively, when the battery cold plate outlet superheat is detected to be ≥ the battery cold plate outlet superheat setting value - A for 30 consecutive seconds, the auxiliary heat exchangers of the two groups participate in the operation.

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