Cabinet-level terminal cooling system and control method for data center

Abstract

The present invention relates to a cabinet-level terminal cooling system and control method for a data center, wherein the cooling system includes a first temperature sensor, a second temperature sensor, a pressure sensor, a main control module, a sub-control module, an electronic expansion valve, and an evaporator. The first temperature sensor is used to detect the refrigerant temperature at the evaporator outlet. The pressure sensor is used to detect the refrigerant pressure at the evaporator outlet. The second temperature sensor is used to detect the cabinet outlet air temperature. The control method is based on the cascade PID control principle, adjusts the evaporator outlet superheat by the opening of the electronic expansion valve, and controls the cabinet outlet air temperature with the superheat as an intermediate variable, thereby achieving precise control of the cabinet outlet air temperature, solving the problems of uneven cooling capacity distribution and excessive power usage efficiency (PUE) at the end of the data center, and can also solve the problem of compressor failure caused by excessive or low superheat at the evaporator outlet.

Description

Technical Field

[0001] The present invention relates to the technical field of energy-saving cooling for data centers, and in particular to a cabinet-level terminal cooling system and a control method for a data center. Background Art

[0002] In recent years, the information economy, exemplified by big data and cloud computing, has rapidly developed, leading to an ever-increasing scale of data center construction. Data centers house a large number of servers and storage devices, which are characterized by high heat dissipation density, long heat dissipation times, and strict requirements for ambient temperature and humidity. To ensure stable operation of servers and other equipment within data centers, data centers require year-round cooling and precise temperature control. Data centers often utilize computer room-level cooling systems, which typically employ underfloor air supply. This approach is significantly constrained by computer room space and, due to the long air supply distances, can lead to frequent mixing of hot and cold airflows and localized hotspots within the computer room. Compared to computer room-level cooling systems, cabinet-level cooling systems absorb heat locally within each cabinet, preventing mixing of hot and cold airflows and effectively alleviating localized hotspots. This cooling approach is ideally suited to the large-scale and high-heat density characteristics of today's data centers.

[0003] The terminal of the traditional cabinet-level cooling system needs to be equipped with a variable frequency fan to ensure that the terminal outlet air temperature meets the design requirements. However, the installation of a large number of variable frequency fans not only increases the complexity of the system, but also increases the difficulty of controlling the system. It is worth noting that in order to ensure the stable operation of the cabinet-level cooling system and prevent compressor liquid hammer, the terminal of the cabinet-level cooling system is often equipped with an electronic expansion valve to regulate the refrigerant flow, thereby ensuring that the refrigerant at the terminal evaporator outlet has a certain degree of superheat. However, this control method with superheat as a single target value cannot directly and accurately control the outlet air temperature of the data center cabinet, thereby affecting the cooling effect of the system and the service life of the electronic equipment inside the server. Therefore, it is necessary to propose a method for the coordinated control of the superheat of the refrigerant at the evaporator outlet and the cabinet outlet air temperature. Summary of the Invention

[0004] (1) Technical issues to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a cabinet-level terminal cooling system and control method for a data center, which solves the technical problems that the traditional cabinet-level cooling system has high system complexity and high control difficulty due to the configuration of a large number of variable frequency fans, and the control method that uses the evaporator outlet superheat as a single target value, which makes it impossible to directly and accurately regulate the air outlet temperature of the data center cabinet.

[0006] (2) Technical solution

[0007] In order to achieve the above objectives, the main technical solutions adopted by the present invention include:

[0008] In a first aspect, the present invention provides a cabinet-level terminal cooling system for a data center, comprising a first temperature sensor, a second temperature sensor, a pressure sensor, a main control module, a secondary control module, an electronic expansion valve, and an evaporator; the first temperature sensor is used to detect the refrigerant temperature at the evaporator outlet; the pressure sensor is used to detect the refrigerant pressure at the evaporator outlet; and the second temperature sensor is used to detect the cabinet outlet air temperature.

[0009] The first temperature sensor and the pressure sensor are both connected to the auxiliary control module via signal lines; the second temperature sensor is connected to the main control module via a signal line; the electronic expansion valve is connected to the auxiliary control module;

[0010] The main control module and the sub-control module constitute a cascade PID control, which adjusts the evaporator outlet superheat by the valve opening of the electronic expansion valve, and controls the cabinet outlet air temperature with the evaporator outlet superheat as an intermediate variable. The cabinet-level terminal cooling system controls the cabinet outlet air temperature and the evaporator outlet superheat within a desired range.

[0011] The cabinet-level terminal cooling system proposed in this invention for data centers uses the evaporator outlet superheat and cabinet outlet air temperature as target values. This system not only achieves precise control of the cabinet outlet air temperature, but also takes into account the evaporator outlet superheat. By keeping the evaporator outlet superheat within the permitted range of the data center air conditioning system, it effectively prevents compressor liquid hammer caused by low evaporator outlet superheat, but also avoids problems such as excessive compressor exhaust temperature caused by excessive evaporator outlet superheat.

[0012] Optionally, the input quantity of the main control module includes a cabinet outlet air temperature setting value and a cabinet outlet air temperature measurement value measured by the second temperature sensor, and the output quantity of the main control module is an evaporator outlet superheat setting value.

[0013] Optionally, the input quantity of the sub-control module includes the evaporator outlet superheat set value, the evaporator outlet refrigerant temperature measurement value measured by the first temperature sensor, and the evaporator outlet refrigerant pressure measurement value measured by the pressure sensor, and the output quantity of the sub-control module is the electronic expansion valve opening value.

[0014] Optionally, the electronic expansion valve is installed at the inlet pipe of the evaporator; the first temperature sensor and the pressure sensor are both installed at the outlet of the evaporator, and the second temperature sensor is installed at the air outlet of the cabinet.

[0015] In a second aspect, the present invention provides a control method for a cabinet-level terminal cooling system for a data center, the control method comprising:

[0016] Step S1: the main control module first calculates the evaporator outlet superheat value based on the difference between the cabinet outlet air temperature measurement value and the cabinet outlet air temperature setting value, then determines the evaporator outlet superheat setting value according to the evaporator outlet superheat value calculation value, and finally outputs the evaporator outlet superheat setting value to the sub-control module;

[0017] Step S2: The sub-control module first calculates the saturation temperature corresponding to the evaporator outlet refrigerant pressure, then calculates the evaporator outlet superheat measurement value based on the evaporator outlet refrigerant temperature measurement value and the saturation temperature, and finally calculates the electronic expansion valve opening value based on the difference between the evaporator outlet superheat measurement value and the evaporator outlet superheat set value.

[0018] The proposed control method for a cabinet-level terminal cooling system in a data center is based on the cascade PID control principle and is suitable for controlled processes with significant hysteresis. It controls the cabinet outlet air temperature by adjusting the opening of the electronic expansion valve while also taking into account the evaporator outlet superheat. This control method eliminates the need for fan control and can provide cooling on demand based on the cooling requirements of different cabinets, thereby achieving precise control of the cabinet outlet air temperature and significantly reducing the cost and complexity of the control system.

[0019] Optionally, in step S1, the evaporator outlet superheat value is calculated using formula ①:

[0020]

[0021] Among them, K P Represents the main control module proportional coefficient, T i represents the integral time constant of the main control module, e(t) represents the difference between the measured cabinet outlet air temperature and the set cabinet outlet air temperature, and u(t) is the calculated value of the evaporator outlet superheat.

[0022] Optionally, the main control module is provided with a superheat upper threshold and a superheat lower threshold; in step S1, determining the evaporator outlet superheat setting value according to the evaporator outlet superheat calculated value includes:

[0023] When the calculated superheat value at the evaporator outlet is higher than the superheat upper limit threshold, the superheat setting value at the evaporator outlet is set to the superheat upper limit threshold;

[0024] When the calculated superheat value at the evaporator outlet is lower than the superheat lower limit threshold, the evaporator outlet superheat set value is set to the superheat lower limit threshold;

[0025] When the calculated superheat value at the evaporator outlet is between the superheat lower limit threshold and the superheat upper limit threshold, the evaporator outlet superheat set value is set to the calculated superheat value at the evaporator outlet.

[0026] Optionally, in step S2, the saturation temperature corresponding to the refrigerant pressure at the evaporator outlet is calculated by fitting formula ②:

[0027] T s =f(P) ②

[0028] The fitting formula is obtained based on the physical parameters of different refrigerants, where P represents the measured value of the refrigerant pressure at the evaporator outlet, T s Represents the refrigerant saturation temperature corresponding to the evaporator outlet refrigerant pressure P.

[0029] Optionally, in step S2, the measured value of superheat at the evaporator outlet is calculated using formula ③:

[0030] SH sensor =T1–T s ③

[0031] In the formula ③, T1 represents the measured value of the refrigerant temperature at the evaporator outlet, T s Represents the refrigerant saturation temperature corresponding to the evaporator outlet refrigerant pressure P.

[0032] Optionally, in step S2, the opening value of the electronic expansion valve is calculated using formula ④:

[0033]

[0034] In the formula ④, K P1 Represents the proportional coefficient of the auxiliary control module, T i1 Represents the integral time constant of the sub-control module, T D1 represents the differential time constant of the sub-control module, n(t) represents the difference between the measured value of the evaporator outlet superheat and the set value of the evaporator outlet superheat, and m(t) is the opening value of the electronic expansion valve.

[0035] (3) Beneficial effects

[0036] The beneficial effects of the present invention are:

[0037] (1) The cabinet-level terminal cooling system for data centers proposed in this invention uses the evaporator outlet superheat and the cabinet outlet air temperature as target values. While achieving direct and precise control of the cabinet outlet air temperature, it also takes into account the evaporator outlet superheat. Furthermore, the evaporator outlet superheat is controlled within the permitted range of the data center air conditioning system. This effectively prevents compressor liquid hammer caused by low evaporator outlet superheat, and avoids problems such as excessive compressor exhaust temperature caused by excessive evaporator outlet superheat.

[0038] (2) The control method for the cabinet-level terminal cooling system for a data center proposed in this invention is based on the cascade PID control principle. The evaporator outlet superheat is adjusted by the opening of the electronic expansion valve, and the cabinet outlet air temperature is controlled using the evaporator outlet superheat as an intermediate variable. This control method can directly and accurately adjust the cabinet outlet air temperature, solving the problems of uneven cooling capacity distribution and excessive power usage efficiency (PUE) at the cabinet-level terminal in the data center. This effectively reduces the energy consumption of the cooling system terminal while taking into account the cooling capacity requirements of the data center.

[0039] (3) The control method proposed in the present invention controls the superheat at the evaporator outlet within a desired range during the control process, which can solve the problem of compressor failure caused by excessive or low superheat at the evaporator outlet, thereby improving the stability of the refrigeration system.

[0040] (4) The control method proposed in the present invention does not need to consider controlling the fan. It takes the evaporator outlet superheat and the cabinet outlet air temperature as the target value. It can provide cooling on demand according to the cooling requirements of different cabinets, thereby achieving direct and precise control of the cabinet outlet air temperature, significantly reducing the complexity and control difficulty of the cabinet-level terminal cooling system, thereby reducing the cost of the control system.

[0041] (5) The control method proposed in the present invention is suitable for controlled processes with obvious hysteresis. Through cascade PID control, the adjustment accuracy and adjustment speed are improved, and the temperature control effect of the air-conditioning system is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic structural diagram of a cabinet-level terminal cooling system for a data center according to the present invention;

[0043] Figure 2 This is a control principle diagram of a cabinet-level terminal cooling system for a data center according to the present invention;

[0044] Figure 3 This is a control flow chart of the cabinet-level terminal cooling system for a data center according to the present invention.

[0045] [Description of Reference Numerals]

[0046] 1: First temperature sensor; 2: Second temperature sensor; 3: Pressure sensor; 4: Main control module; 5: Sub-control module; 6: Electronic expansion valve; 7: Evaporator. DETAILED DESCRIPTION

[0047] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Instead, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0048] Reference Figure 1 The present invention proposes a cabinet-level terminal cooling system for a data center, comprising a first temperature sensor 1, a second temperature sensor 2, a pressure sensor 3, a main control module 4, a sub-control module 5, an electronic expansion valve 6, and an evaporator 7. The electronic expansion valve 6 is installed in the inlet pipe of the evaporator 7. The first temperature sensor 1 is installed at the evaporator outlet, close to the evaporator outlet pipe, and is used to detect the refrigerant temperature at the outlet of the evaporator 7. The pressure sensor 3 is installed at the evaporator outlet and is used to detect the refrigerant pressure at the outlet of the evaporator 7. The second temperature sensor 2 is installed at the cabinet air outlet and is used to detect the cabinet outlet air temperature.

[0049] The main control module 4 and the sub-control module 5 are both built into the programmable logic controller (PLC). The sub-control module 5 is connected to the main control module 4 via a signal line and receives the evaporator outlet superheat setting value output by the main control module 4.

[0050] The first temperature sensor 1 and the pressure sensor 3 are both connected to the secondary control module 5 via signal lines. The second temperature sensor 2 is connected to the main control module 4 via a signal line.

[0051] The valve body of the electronic expansion valve 6 is equipped with a coil, which is connected to the auxiliary control module 5 and is used to receive the opening value of the electronic expansion valve output by the auxiliary control module 5 .

[0052] Figure 2 The control principle of the cabinet-level terminal cooling system for a data center of the present invention is shown. The main control module 4 and the sub-control module 5 constitute a cascade PID control, which adjusts the evaporator outlet superheat by the valve opening of the electronic expansion valve, and controls the cabinet outlet air temperature with the evaporator outlet superheat as the intermediate variable, so as to control the cabinet outlet air temperature and the evaporator outlet superheat within the desired range. The present invention does not specifically limit the type of PID controller. According to the actual application situation, the main control module 4 and the sub-control module 5 can adopt a PI controller, a PD controller or a PID controller. Among them, P, I, and D are abbreviations for Proportion, Integral, and Differential, respectively.

[0053] The control variables of the main control module 4 and the sub-control module 5 include two types of variables: input and output.

[0054] The input quantity of the main control module 4 includes the cabinet outlet temperature setting value T set and the cabinet outlet air temperature measurement value T detected by the second temperature sensor 2 sensor , the output is the evaporator outlet superheat setting value SH set .

[0055] The input of the auxiliary control module 5 is the evaporator outlet superheat setting value SH output by the main control module 4 set , the evaporator outlet refrigerant temperature measurement value T1 detected by the first temperature sensor 1, and the evaporator outlet refrigerant pressure measurement value P detected by the pressure sensor 3, the output is the electronic expansion valve opening value C.

[0056] The cabinet-level terminal cooling system for data centers proposed in this paper utilizes the cascade PID control principle, using the evaporator outlet superheat and cabinet outlet air temperature as target values. This system not only precisely controls the cabinet outlet air temperature but also takes into account the evaporator outlet superheat. By keeping the evaporator outlet superheat within the permitted range of the data center air conditioning system, it effectively prevents compressor liquid hammer caused by low evaporator outlet superheat, but also avoids problems such as excessive compressor exhaust temperature caused by excessive evaporator outlet superheat.

[0057] Figure 3 The control flow of the cabinet-level terminal cooling system for a data center of the present invention is shown. To better understand the control flow of the present invention, as an example, the main control module 4 adopts a PI controller, which can reduce or eliminate steady-state errors and calculate the evaporator outlet superheat set value SH set The auxiliary control module 5 adopts a PID controller. The opening of the electronic expansion valve should change in real time to achieve accurate control of the cabinet air outlet temperature. Therefore, the auxiliary control module 5 adopts a PID control method that fluctuates over time to ensure high regulation quality.

[0058] The control method of the cabinet-level terminal cooling system for a data center of the present invention comprises the following steps:

[0059] Step S1: The main control module 4 first calculates the cabinet outlet air temperature T according to formula ①. sensor The cabinet outlet temperature setting value T set The evaporator outlet superheat calculated value is calculated based on the difference between the calculated value and the superheat upper limit threshold and the superheat lower limit threshold, and the evaporator outlet superheat set value is determined according to the relationship between the evaporator outlet superheat calculated value and the superheat upper limit threshold and the superheat lower limit threshold, and the evaporator outlet superheat set value is output to the sub-control module 5.

[0060] The specific process is as follows:

[0061] The main control module 4 first calculates the evaporator outlet superheat value using formula ①.

[0062]

[0063] In the above formula ①, K P Represents the main control module proportional coefficient, T i represents the integral time constant of the main control module, and e(t) represents the measured value of the cabinet outlet temperature T sensor The cabinet outlet temperature setting value T set The difference between the two, u(t) is the output signal, that is, the calculated value of the superheat at the evaporator outlet.

[0064] To prevent compressor liquid hammer caused by low evaporator outlet superheat, a lower superheat threshold is set in the main control module 4. To prevent problems such as excessive compressor exhaust temperature caused by excessive evaporator outlet superheat, an upper superheat threshold is set in the main control module 4. In engineering applications, the upper and lower superheat thresholds can be customized based on actual operating conditions and needs, ensuring a balance between system stability and energy efficiency.

[0065] If the superheat value calculated according to formula ① is higher than the upper superheat threshold, the evaporator outlet superheat setting value SH set Set as the upper superheat threshold; if it is lower than the lower superheat threshold, the evaporator outlet superheat setting value SH set Set as the lower superheat threshold; if the calculated superheat value is between the lower superheat threshold and the upper superheat threshold, the evaporator outlet superheat setting value SH set Set to the calculated superheat value.

[0066] Step S2: The sub-control module 5 first calculates the saturation temperature T corresponding to the refrigerant pressure P at the evaporator outlet by fitting formula ② s Then, according to formula ③, the measured value of the refrigerant temperature at the evaporator outlet T1 and the saturation temperature T s Calculate the evaporator outlet superheat measurement value SH sensor Finally, according to formula ④ based on the evaporator outlet superheat measurement value SH sensor and the evaporator outlet superheat setting value SH set The difference between the two is used to calculate the opening value C of the electronic expansion valve.

[0067] The specific process is as follows:

[0068] First, the sub-control module 5 calculates the saturation temperature T corresponding to the refrigerant pressure P at the evaporator outlet through formula ② s .

[0069] T s =f(P) ②

[0070] The above formula ② is a fitting formula, which is obtained based on the physical parameters of different refrigerants. Among them, P represents the measured value of the refrigerant pressure at the evaporator outlet, T s Represents the refrigerant saturation temperature corresponding to the evaporator outlet refrigerant pressure P.

[0071] Taking R410A as the refrigerant as an example, the pressure design condition of the refrigerant in the evaporator is set to 0-5MPa. According to the physical properties of the refrigerant R410A, the following fitting formula is obtained:

[0072] T s =-0.148P 6 +2.507P 5 -16.926P 4 +58.438P 3 -112.070P 2 +136.930P-60.955 Then, the sub-control module 5 calculates the evaporator outlet superheat measurement value SH through formula ③ sensor .

[0073] SH sensor =T1–T s ③

[0074] In the above formula ③, T1 represents the measured value of the refrigerant temperature at the evaporator outlet, T s Represents the refrigerant saturation temperature corresponding to the evaporator outlet refrigerant pressure P.

[0075] Finally, the auxiliary control module 5 calculates the electronic expansion valve opening value C through formula ④.

[0076]

[0077] In the above formula ④, K P1 Represents the proportional coefficient of the auxiliary control module, T i1 Represents the integral time constant of the sub-control module, T D1 represents the differential time constant of the auxiliary control module, and n(t) represents the measured value of superheat at the evaporator outlet SH sensor and the evaporator outlet superheat setting value SH set The difference between them, m(t) is the output signal, that is, the opening value C of the electronic expansion valve.

[0078] By varying the valve opening of the electronic expansion valve 6 through the aforementioned control process, the present invention can simultaneously control the cabinet air outlet temperature and the evaporator outlet superheat within a desired range. In engineering applications, this desired range can be customized based on actual operating conditions and requirements to ensure efficient and stable system operation while also maximizing energy efficiency.

[0079] The control method for a cabinet-level terminal cooling system for a data center proposed in this invention is based on the principle of cascade PID control. The evaporator outlet superheat is adjusted by the opening of an electronic expansion valve, and the cabinet outlet air temperature is controlled using the evaporator outlet superheat as an intermediate variable. This control method enables direct and precise regulation of the cabinet outlet air temperature, addressing the problems of uneven cooling capacity distribution and excessively high power usage efficiency (PUE) at the cabinet-level terminal in data centers. This effectively reduces energy consumption at the end of the cooling system while meeting the cooling needs of the data center. During the control process, the evaporator outlet superheat is kept within a desired range, addressing compressor failures caused by excessively high or low evaporator outlet superheat, thereby improving the stability of the cooling system. Furthermore, the control method of this invention uses the evaporator outlet superheat and the cabinet outlet air temperature as target values, providing cooling on demand based on the cooling needs of different cabinets without requiring fan control. This significantly reduces the complexity and control difficulty of the cabinet-level terminal cooling system, thereby reducing the cost of the control system. The control method of this invention is suitable for controlled processes with significant hysteresis. Through cascade PID control, it improves regulation accuracy and speed, significantly enhancing the temperature control effectiveness of the air conditioning system.

[0080] It should be noted that the PI parameters of the main control module 4 and the PID parameters of the sub-control module 5 can be adjusted by using the attenuation curve method, the critical proportionality method or the traditional parameter tuning method such as the self-tuning module in the control module. Parameter tuning refers to determining the specific values of the proportional coefficient, integral time constant and differential time constant in the controller according to the characteristics of the controlled process to achieve the best control effect. Specifically in this embodiment, that is, the PI controller parameter K in the above formula ① is P and T i , and the PID controller parameter K in formula ④ P1 、T i1 and T D1 Perform parameter tuning.

[0081] Although the cabinet-level terminal cooling system and control method proposed in this embodiment are applied to a data center for exemplary purposes, those skilled in the art will appreciate that the cabinet-level terminal cooling system and control method of the present invention can also be used for cabinet-level air-conditioning systems in other non-data center application scenarios.

[0082] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0083] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0084] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0085] In the description of this specification, the terms "one embodiment", "some embodiments", "embodiments", "examples", "specific examples" or "some examples" refer to the specific features, structures, materials or characteristics described in conjunction with the embodiment or example and included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0086] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A cabinet-level terminal cooling system for a data center, comprising a first temperature sensor (1), a second temperature sensor (2), a pressure sensor (3), a main control module (4), a secondary control module (5), an electronic expansion valve (6), and an evaporator (7); The main control module (4) and the auxiliary control module (5) constitute a cascade PID control; The input quantity of the main control module (4) includes the cabinet outlet air temperature setting value and the cabinet outlet air temperature measurement value measured by the second temperature sensor (2), and the output quantity is the evaporator outlet superheat setting value; The main control module (4) calculates the evaporator outlet superheat calculated value based on the difference between the cabinet outlet air temperature measurement value and the cabinet outlet air temperature set value; then determines the evaporator outlet superheat set value based on the evaporator outlet superheat calculated value; the main control module (4) is provided with a superheat upper limit threshold and a superheat lower limit threshold, and the evaporator outlet superheat set value is between the superheat upper limit threshold and the superheat lower limit threshold; The input quantity of the auxiliary control module (5) includes the evaporator outlet superheat setting value, the evaporator outlet refrigerant temperature measurement value measured by the first temperature sensor (1), and the evaporator outlet refrigerant pressure measurement value measured by the pressure sensor (3), and the output quantity of the auxiliary control module (5) is the electronic expansion valve opening value; The evaporator outlet superheat is adjusted by the valve opening of the electronic expansion valve (6), and the cabinet outlet air temperature is controlled with the evaporator outlet superheat as an intermediate variable. The cabinet-level terminal cooling system controls the cabinet outlet air temperature and the evaporator outlet superheat within a desired range.

2. The cabinet-level terminal cooling system for a data center according to claim 1, wherein: When the calculated superheat value at the evaporator outlet is higher than the superheat upper limit threshold, the superheat setting value at the evaporator outlet is set to the superheat upper limit threshold; When the calculated superheat value at the evaporator outlet is lower than the superheat lower limit threshold, the evaporator outlet superheat set value is set to the superheat lower limit threshold; When the calculated superheat value at the evaporator outlet is between the superheat lower limit threshold and the superheat upper limit threshold, the evaporator outlet superheat set value is set to the calculated superheat value at the evaporator outlet.

3. The cabinet-level terminal cooling system for a data center according to claim 1, wherein: The first temperature sensor (1), the pressure sensor (3) and the electronic expansion valve (6) are all connected to the auxiliary control module (5); the second temperature sensor (2) is connected to the main control module (4).

4. The cabinet-level terminal cooling system for a data center according to claim 1, wherein: The electronic expansion valve (6) is installed on the inlet pipeline of the evaporator (7); the first temperature sensor (1) and the pressure sensor (3) are both installed at the outlet of the evaporator (7), and the second temperature sensor (2) is installed at the air outlet of the cabinet.

5. A control method for a cabinet-level terminal cooling system for a data center, wherein the control method is applied to the cabinet-level terminal cooling system for a data center according to any one of claims 1 to 4, characterized in that: The control method includes: Step S1: the main control module (4) first calculates the evaporator outlet superheat calculated value based on the difference between the cabinet outlet air temperature measurement value and the cabinet outlet air temperature set value, then determines the evaporator outlet superheat set value based on the evaporator outlet superheat calculated value, and finally outputs the evaporator outlet superheat set value to the auxiliary control module (5); Step S2: The sub-control module (5) first calculates the saturation temperature corresponding to the refrigerant pressure at the evaporator outlet, then calculates the evaporator outlet superheat measurement value based on the evaporator outlet refrigerant temperature measurement value and the saturation temperature, and finally calculates the electronic expansion valve opening value based on the difference between the evaporator outlet superheat measurement value and the evaporator outlet superheat set value.

6. The control method for a cabinet-level terminal cooling system for a data center according to claim 5, wherein: In step S1, the superheat value at the evaporator outlet is calculated using formula ①: Among them, K P Represents the main control module proportional coefficient, T i represents the integral time constant of the main control module, e(t) represents the difference between the measured cabinet outlet air temperature and the set cabinet outlet air temperature, and u(t) is the calculated value of the evaporator outlet superheat.

7. The control method for a cabinet-level terminal cooling system for a data center according to claim 5, wherein: In step S1, determining the evaporator outlet superheat setting value according to the evaporator outlet superheat calculation value includes: When the calculated superheat value at the evaporator outlet is higher than the superheat upper limit threshold, the superheat setting value at the evaporator outlet is set to the superheat upper limit threshold; When the calculated superheat value at the evaporator outlet is lower than the superheat lower limit threshold, the evaporator outlet superheat set value is set to the superheat lower limit threshold; When the calculated superheat value at the evaporator outlet is between the superheat lower limit threshold and the superheat upper limit threshold, the evaporator outlet superheat set value is set to the calculated superheat value at the evaporator outlet.

8. The control method for a cabinet-level terminal cooling system for a data center according to claim 5, wherein: In step S2, the saturation temperature corresponding to the refrigerant pressure at the evaporator outlet is calculated by fitting formula ②: T s =f(P)② The fitting formula is obtained based on the physical parameters of different refrigerants, where P represents the measured value of the refrigerant pressure at the evaporator outlet, T s Represents the refrigerant saturation temperature corresponding to the evaporator outlet refrigerant pressure P.

9. The control method for a cabinet-level terminal cooling system for a data center according to claim 8, wherein: In step S2, the measured value of the superheat at the evaporator outlet is calculated using formula ③: SH sensor =T1–T s ③ In the above formula ③, T1 represents the measured value of the refrigerant temperature at the evaporator outlet, T s Represents the refrigerant saturation temperature corresponding to the evaporator outlet refrigerant pressure P.

10. The control method for a cabinet-level terminal cooling system for a data center according to claim 9, wherein: In step S2, the opening value of the electronic expansion valve is calculated by formula ④: In the formula ④, K P1 Represents the proportional coefficient of the auxiliary control module, T i1 Represents the integral time constant of the sub-control module, T D1 represents the differential time constant of the sub-control module, n(t) represents the difference between the measured value of the evaporator outlet superheat and the set value of the evaporator outlet superheat, and m(t) is the opening value of the electronic expansion valve.

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