Refrigeration system

Abstract

The refrigerating system comprises a compressor, a condenser, an evaporator, a buffer part and a controller, the buffer part is connected to the input end and the output end of the compressor through a first bypass pipeline and a second bypass pipeline, a first bypass valve is arranged on the first bypass pipeline, and a second bypass valve is arranged on the second bypass pipeline; the controller is used for acquiring related parameters of the compressor; related parameters are converted into a fuzzy set through a membership function, and reasoning calculation is conducted on the fuzzy set; performing defuzzification operation on the reasoning calculation result; controlling the opening degree of the first bypass valve and the opening degree of the second bypass valve according to the defuzzification operation result; the operation efficiency and stability of a refrigerating system of the air conditioning unit under different working conditions are improved, and high-voltage and low-voltage faults are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle air-conditioning equipment, and in particular, relates to a refrigeration system. Background Art

[0002] The air conditioning in the train provides a comfortable environment for passengers. As the vehicle travels and the surrounding weather changes, high-pressure failures in the refrigeration system will frequently occur. When the ambient temperature and load of traditional air-conditioning units change, it is difficult to achieve real-time and accurate regulation of the refrigerant flow, resulting in low system efficiency and prone to high-pressure or low-pressure failures. The refrigerant flow control in the air conditioner lacks intelligence and adaptability, and cannot meet modern high-efficiency and energy-saving needs. Summary of the invention

[0003] The object of the present invention is to provide a refrigeration system to solve the problems existing in the prior art of poor refrigerant flow regulation performance, high failure rate, and low intelligent degree of refrigerant flow control under different operating conditions in the refrigeration system of the existing air-conditioning unit.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0005] The present invention provides a refrigeration system, comprising:

[0006] compressor;

[0007] A condenser connected to the output end of the compressor through a refrigerant output pipeline;

[0008] an evaporator connected to the input end of the compressor via a refrigerant input pipeline;

[0009] a buffer element connected to the input end and the output end of the compressor through a first bypass pipeline and a second bypass pipeline, wherein the first bypass pipeline is provided with a first bypass valve, and the second bypass pipeline is provided with a second bypass valve;

[0010] A controller for:

[0011] Get the relevant parameters of the compressor;

[0012] Through the membership function, the relevant parameters are converted into fuzzy sets, and the fuzzy sets are inferred and calculated;

[0013] Performing defuzzification operation on the inference calculation result;

[0014] The openings of the first bypass valve and the second bypass valve are controlled according to the defuzzification operation result.

[0015] In some embodiments of the present application, a suction temperature sensor and a suction pressure sensor are provided at the input end of the compressor, which are used to detect the suction temperature Tsuction and the suction pressure Psuction, respectively.

[0016] In some embodiments of the present application, an exhaust temperature sensor and an exhaust pressure sensor are provided at the output end of the compressor, which are used to detect the exhaust temperature Trow and the exhaust pressure Prow, respectively.

[0017] In some embodiments of the present application, the compressor is also connected to an ammeter for detecting the current I of the compressor.

[0018] In some embodiments of the present application, the controller is connected to the intake temperature sensor, the intake pressure sensor, the exhaust temperature sensor, the exhaust pressure sensor, the ammeter, the first bypass valve and the second bypass valve, and the relevant parameters of the compressor include the intake temperature Tsuction, the intake pressure Psuction, the exhaust temperature Texhaust, the exhaust pressure Pexhaust, the current I and the ambient temperature Tring.

[0019] In some embodiments of the present application, one end of the first bypass pipeline is connected to the outlet of the buffer element, and the other end is connected to the refrigerant input pipeline between the compressor and the evaporator.

[0020] In some embodiments of the present application, one end of the second bypass pipeline is connected to the inlet of the buffer element, and the other end is connected to the refrigerant output pipeline between the compressor and the condenser.

[0021] In some embodiments of the present application, a gas-liquid separator is further provided between the evaporator and the compressor, and the second bypass pipeline is connected between the gas-liquid separator and the evaporator.

[0022] In some embodiments of the present application, a high-voltage protection switch is provided at the output end of the compressor, and a low-voltage protection switch is provided at the input end of the compressor.

[0023] In some embodiments of the present application, an expansion valve and a drying filter are further provided between the evaporator and the condenser.

[0024] Compared with the prior art, the advantages and positive effects of the present invention are:

[0025] The refrigeration system involved in the present application is provided with a cache element in parallel on the compressor, the cache element is connected to the input end of the compressor through a first bypass pipeline, and is connected to the output end of the compressor through a second bypass pipeline. The controller obtains relevant parameters of the compressor during the operation of the refrigeration system, and controls the opening of the first bypass valve and the second bypass valve through fuzzy calculation and defuzzification calculation to achieve precise control of the refrigerant flow rate. The refrigeration system can store part of the refrigerant output from the compressor in the cache element in a high-temperature environment to reduce the load on the high-pressure side; in a low-temperature environment, the controller controls the refrigerant in the cache element to be replenished from the input end of the compressor to the compressor to prevent low-pressure failure of the compressor, thereby improving the operating efficiency and stability of the refrigeration system of the air-conditioning unit under different working conditions and avoiding the occurrence of high-pressure and low-pressure failures.

[0026] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a system structure diagram of the refrigeration system proposed by the present invention;

[0029] Figure 2 It is a schematic diagram of the refrigerant flow state of the refrigeration system;

[0030] Figure 3 This is the controller connection diagram;

[0031] Figure 4 It is the control flow chart of the controller;

[0032] In the figure,

[0033] 100, compressor; 110, refrigerant input pipeline; 111, low-pressure protection switch; 120, refrigerant output pipeline; 121, high-pressure protection switch;

[0034] 200, condenser; 210, condensing fan;

[0035] 300, evaporator; 310, evaporation fan;

[0036] 400, cache element; 410, first bypass pipeline; 411, first bypass valve; 420, second bypass pipeline; 421, second bypass valve;

[0037] 500, gas-liquid separator;

[0038] 600, filter drier;

[0039] 700. Expansion valve. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0042] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0043] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0045] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0046] The present application proposes a refrigeration system, which includes a compressor 100, a condenser 200, an evaporator 300 and a buffer. The output end of the compressor 100 is connected to the condenser 200 through a refrigerant output pipeline 120, the input end of the compressor 100 is connected to the evaporator 300 through a refrigerant input pipeline 110, and the condenser 200 and the evaporator 300 are also connected through a refrigerant pipeline. The compressor 100, the condenser 200 and the evaporator 300 form a refrigerant circuit.

[0047] A condensing fan 210 is disposed next to the condenser 200 , and an evaporating fan 310 is disposed next to the evaporator 300 . The condensing fan 210 and the evaporating fan 310 are used to realize heat exchange between the condenser 200 and the evaporator 300 .

[0048] The buffer element 400 is connected to the input end of the compressor 100 through a first bypass line 410 , and is connected to the output end of the compressor 100 through a second bypass line 420 .

[0049] A first bypass valve 411 is provided on the first bypass line 410, and a second bypass valve 421 is provided on the second bypass line 420. The first bypass valve 411 and the second bypass valve 421 are respectively used to control the on-off of the first bypass line 410 and the second bypass line 420 to achieve regulation of the refrigerant participating in the refrigeration cycle in the refrigeration system.

[0050] The refrigeration system also includes a controller, which is used to:

[0051] Obtain relevant parameters of the compressor 100;

[0052] Through the membership function, the relevant parameters are converted into fuzzy sets, and the fuzzy sets are inferred and calculated; the inference calculation results are defuzzified;

[0053] The openings of the first bypass valve 411 and the second bypass valve 421 are controlled according to the defuzzification operation result.

[0054] Specifically, the relevant parameters of the compressor 100 include the suction temperature T 吸 , Suction pressure P 吸、 Exhaust temperature T 排 , Exhaust pressure P 排 , compressor current I and ambient temperature T 环 .

[0055] The input end of the compressor 100 is provided with an intake air temperature sensor and an intake air pressure sensor, which are used to detect the intake air temperature T 吸 and suction pressure P 吸 .

[0056] The output end of the compressor 100 is provided with an exhaust gas temperature sensor and an exhaust gas pressure sensor, which are used to detect the exhaust gas temperature T 排 and exhaust pressure P 排 .

[0057] The compressor 100 is also connected to an ammeter for detecting the current I of the compressor 100 .

[0058] The controller is connected to the suction temperature sensor, the suction pressure sensor, the exhaust temperature sensor, the exhaust pressure sensor, the ammeter, the first bypass valve 411 and the second bypass valve 421. The relevant parameters of the compressor 100 include the suction temperature T 吸 , Suction pressure P 吸 , Exhaust temperature T 排 , Exhaust pressure P 排 and the current I.

[0059] The specific process of the controller adjusting the first bypass valve 411 and the second bypass valve 421 according to the above-mentioned relevant parameters of the compressor 100 is described in detail below:

[0060] Fuzzy control is a control method that simulates the way human thinks. It formulates control strategies based on experience by expressing system variables as fuzzy sets, using fuzzy logic and fuzzy reasoning, including fuzzification, fuzzy rule reasoning, synthetic output membership functions and defuzzification.

[0061] 1. Fuzzification: Convert the input variables into membership in fuzzy sets.

[0062] 2. Rule reasoning: Based on the membership of fuzzy rules and input variables, the activation degree of the rules is calculated.

[0063] 3. Output membership function truncation: The membership function of the output variable is truncated according to the degree of activation.

[0064] 4. Synthesize output membership function: Combine the truncated output membership functions of all rules.

[0065] 1. Fuzzification

[0066] Fuzzification is the process of converting the precise input variables of the system into membership in a fuzzy set, which is the degree to which the variables belong to a certain fuzzy state.

[0067] It includes defining fuzzy sets of input variables and establishing membership functions.

[0068] Defining the fuzzy sets of input variables specifically refers to dividing the input variables into several fuzzy sets, such as (low, medium, high), according to the characteristics of the system.

[0069] Establishing a membership function means defining a membership function for each fuzzy set to describe the relationship between the variable value and the membership degree.

[0070] For each input variable, its membership in different fuzzy sets is calculated using membership functions.

[0071] 2. Fuzzy rule reasoning

[0072] The specification of fuzzy rules is to obtain the fuzzy set of output variables through fuzzy reasoning.

[0073] Each rule contains conditions and conclusions. The conditions are composed of fuzzy sets of input variables, and the conclusions are fuzzy sets of output variables.

[0074] Fuzzy rule reasoning includes calculating the activation degree of the rules and obtaining the fuzzy set of output variables.

[0075] For each rule, the minimum value of the membership of each input variable in its condition is calculated as the activation degree of the rule. The activation degree of the rule will affect the fuzzy set of the output variable, that is, the truncated output membership function.

[0076] 3. Synthetic output membership function

[0077] The synthetic output membership function is specifically realized by truncating the output membership function. The truncated output membership function is to truncate the membership function corresponding to the output variable according to the activation degree of the rule, which indicates the influence intensity of the rule on the output variable. Then, the output membership functions after truncating all the rules are merged to obtain the comprehensive fuzzy set of the output variable.

[0078] 4. Defuzzification:

[0079] Defuzzification is to convert the synthesized fuzzy output membership function into a specific control quantity to obtain the exact value of the output variable.

[0080] The methods used include centroid method, maximum membership method, etc. The centroid method (also called centroid method) is the most commonly used, which considers all possible output values ​​and their corresponding membership.

[0081] Centroid method formula:

[0082]

[0083] X: The value of the output variable.

[0084] μ(x): The membership degree of the composite membership function at x.

[0085] Calculation steps:

[0086] Calculate the numerator: For each value X in the range of the output variable, calculate X·μ(x) and integrate (or sum) over the entire range.

[0087] Calculate the denominator: For each value X in the range of the output variable, calculate (x), and integrate (or sum) over the entire range.

[0088] Calculate the output value: Divide the numerator by the denominator to get the exact value of the output variable.

[0089] For the refrigeration system involved in this application, the flow and pressure of the refrigerant are controlled by adjusting the opening of the high-pressure bypass valve and the low-pressure bypass valve, so that the system can operate efficiently and stably under different ambient temperatures and load conditions.

[0090] Related variables and ranges:

[0091] 1. Ambient temperature T 环 : 0℃~40℃;

[0092] 2. Compressor exhaust temperature T 排 : 90℃~120℃;

[0093] 3. Compressor suction temperature T 吸 :-5℃~15℃;

[0094] 4. High pressure side pressure P 高 : 1.6MPa~2.2MPa;

[0095] 5. Low pressure side pressure P 低 :0.2MPa~0.5MPa;6.Compressor current I:8A~16A.

[0096] Output variables and their scopes:

[0097] 1. High-pressure bypass valve opening: α 高 0%~100%;

[0098] 2. Low-pressure bypass valve opening α 低 :0%~100%.

[0099] Input variables and their membership functions:

[0100] The input variable is x, and its membership function y is:

[0101] The first membership function:

[0102]

[0103] The second membership function:

[0104]

[0105] The third membership function:

[0106]

[0107] Among them, X1 <X2<X3<X4

[0108] x is T 环 , T 排 , T 吸 , P 高 or P 低 .

[0109] μ1(y)μ2(y)μ3(y) are the membership functions of the corresponding range.

[0110] Specifically, the ambient temperature T 环 Fuzzy set: low temperature, medium temperature, high temperature;

[0111] Membership function definition:

[0112] Low temperature:

[0113]

[0114] Medium temperature:

[0115]

[0116] high temperature:

[0117]

[0118] Low temperature: When the ambient temperature is lower than or equal to 10℃, it is completely low temperature. Between 10℃ and 15℃, the membership degree decreases linearly from 1 to 0.

[0119] Medium temperature: between 10℃ and 15℃, the membership degree increases linearly from 0 to 1; between 15℃ and 25℃, the membership degree is 1; between 25℃ and 30℃, the membership degree decreases linearly from 1 to 0.

[0120] High temperature: When the ambient temperature is higher than 30℃, it is completely considered high temperature. Between 25℃ and 30℃, the degree of membership increases linearly from 0 to 1.

[0121] Compressor exhaust temperature T 排

[0122] Fuzzy set: Fuzzy set: low temperature, medium temperature, high temperature;

[0123] Membership function definition:

[0124] Low temperature:

[0125]

[0126] Medium temperature:

[0127]

[0128] high temperature:

[0129]

[0130] Low temperature: When T 排 When the temperature is less than or equal to 95℃, it is completely low temperature. Between 95℃ and 100℃, the degree of membership decreases linearly from 1 to 0.

[0131] Medium temperature: When T 排 Between 95℃ and 100℃, the membership degree increases linearly from 0 to 1; between 100℃ and 105℃, the membership degree is 1; between 105℃ and 110℃, the membership degree decreases linearly from 1 to 0.

[0132] High temperature: When T 排 When the temperature is higher than 110℃, it is completely high temperature. Between 105℃ and 110℃, the membership increases linearly from 0 to 1.

[0133] Compressor suction temperature:

[0134] Fuzzy set: low temperature, medium temperature, high temperature;

[0135] Membership function definition:

[0136] Low temperature:

[0137]

[0138] Medium temperature:

[0139]

[0140] high temperature:

[0141]

[0142] Low temperature: When T 排 When the temperature is less than or equal to 5℃, it is completely low temperature. Between 5℃ and 7.5℃, the degree of membership decreases linearly from 1 to 0.

[0143] Medium temperature: When T 排 Between 5℃ and 7.5℃, the membership degree increases linearly from 0 to 1; between 7.5℃ and 10℃, the membership degree is 1; between 10℃ and 12.5℃, the membership degree decreases linearly from 1 to 0.

[0144] High temperature: When T 排 When the temperature is higher than 12.5℃, it is completely considered high temperature. Between 10℃ and 12.5℃, the degree of membership increases linearly from 0 to 1.

[0145] Compressor 100 high pressure side pressure:

[0146] Fuzzy set: low pressure, medium pressure, high pressure;

[0147] Membership function definition:

[0148] Low Pressure:

[0149]

[0150] Medium Pressure:

[0151]

[0152] high pressure:

[0153]

[0154] Low pressure: When P 高 When it is less than or equal to 1.7Mpa, it is completely low pressure. Between 1.7Mpa and 1.8Mpa, the degree of membership decreases linearly from 1 to 0.

[0155] Medium pressure: When P 高 Between 1.7Mpa and 1.8Mpa, the degree of membership increases linearly from 0 to 1; between 1.8Mpa and 1.9Mpa, the degree of membership is 1; between 1.9Mpa and 2.0Mpa, the degree of membership decreases linearly from 1 to 0.

[0156] High pressure: When P 高 When the pressure is higher than 2.0Mpa, it is completely high pressure. Between 1.9Mpa and 2.0Mpa, the degree of membership increases linearly from 0 to 1.

[0157] Compressor 100 low pressure side pressure:

[0158] Fuzzy set: low pressure, medium pressure, high pressure;

[0159] Membership function definition:

[0160] Low Pressure:

[0161]

[0162] Medium Pressure:

[0163]

[0164] high pressure:

[0165]

[0166] Low pressure: When P 低 When it is less than or equal to 0.25Mpa, it is completely low pressure. Between 0.25Mpa and 0.3Mpa, the degree of membership decreases linearly from 1 to 0.

[0167] Medium pressure: When P 低 Between 0.25Mpa and 0.3Mpa, the degree of membership increases linearly from 0 to 1; between 0.3Mpa and 0.325Mpa, the degree of membership is 1; between 0.325Mpa and 0.35Mpa, the degree of membership decreases linearly from 1 to 0.

[0168] High pressure: When P 低 When the pressure is higher than 0.35Mpa, it is completely high pressure. Between 0.325Mpa and 0.35Mpa, the degree of membership increases linearly from 0 to 1.

[0169] Compressor current:

[0170] Fuzzy sets: low load, medium load, high load;

[0171] Low load:

[0172]

[0173] Medium Pressure:

[0174]

[0175] high pressure:

[0176]

[0177] Low load: When I is less than or equal to 10A, it is completely low load. Between 0.25Mpa and 0.3Mpa, the degree of membership decreases linearly from 1 to 0.

[0178] Medium load: When I is between 10A and 12A, the membership increases linearly from 0 to 1; between 12A and 13A, the membership is 1; between 13A and 14A, the membership decreases linearly from 1 to 0.

[0179] High load: When I is greater than 14A, it is completely high load. Between 13A and 14A, the membership increases linearly from 0 to 1.

[0180] Output variables and their membership functions

[0181] Bypass valve opening membership function:

[0182] Fuzzy sets: small opening, medium opening, large opening.

[0183] Membership function definition:

[0184] Small opening:

[0185]

[0186] Medium opening:

[0187]

[0188] Wide opening:

[0189]

[0190] When the valve opening is less than or equal to 20%, it is completely a small opening; between 20% and 30%, the membership degree decreases linearly from 1 to 0.

[0191] Between 20% and 50%, the degree of membership increases linearly from 0 to 1; between 50% and 70%, the degree of membership is 1; between 70% and 80%, the degree of membership decreases linearly from 1 to 0.

[0192] When the valve opening is greater than 80%, it is completely a large opening; between 70% and 80%, the membership degree increases linearly from 0 to 1.

[0193] Fuzzy rules

[0194] High pressure bypass valve control rules:

[0195] 1. Rule H1:

[0196] If T 环 is high temperature, T 排 is high temperature, P 高 is high pressure, I is high load, then the high pressure bypass valve opening α 高 It’s a big opening.

[0197] When the ambient temperature, exhaust temperature, high-pressure side pressure and compressor 100 load are all high, it is necessary to increase the opening of the high-pressure bypass valve to reduce the system pressure and temperature.

[0198] 2. Rule H2:

[0199] If T 环 is medium temperature, T 排 is medium temperature, P 高 is medium pressure, I is medium load, then the high pressure bypass valve opening α 高 It is the middle opening.

[0200] Under moderate conditions, keep the high pressure bypass valve at a moderate opening.

[0201] 3. Rule H3:

[0202] If T 环 is low temperature, T 排 is low temperature, P 高 is low pressure, I is low load, then the high pressure bypass valve opening α 高 It is a small opening.

[0203] Under low load conditions, bypass is reduced to maintain system efficiency.

[0204] 4. Rule H4:

[0205] If T 环 is high temperature, T 排 is high temperature, P 高 is medium pressure, I is high load, then the high pressure bypass valve opening α 高 It’s a big opening.

[0206] 5. Rule H5:

[0207] If T 环 is medium temperature, T 排 is medium temperature, P 高 is high pressure, I is high load, then the high pressure bypass valve opening α 高 It’s a big opening.

[0208] Low pressure bypass valve control rules:

[0209] 1. Rule L1:

[0210] If T 环 is low temperature, T 吸 is low temperature, P 低 is low pressure, I is low load, then the low pressure bypass valve opening α 低 It’s a big opening.

[0211] Under low temperature, low pressure and low load conditions, the opening of the low pressure bypass valve is increased to improve the refrigeration effect of the evaporator 300 .

[0212] 2. Rule L2:

[0213] If T 环 is medium temperature, T 吸 is medium temperature, P 低 is medium pressure, I is medium load, then the low pressure bypass valve opening α 低 It is the middle opening.

[0214] 3. Rule L3:

[0215] If T 环 is high temperature, T 吸 is high temperature, P 低 is high pressure, I is high load, then the low pressure bypass valve opening α 低 It is a small opening.

[0216] Under high temperature, high pressure and high load conditions, the bypass is reduced and the flow rate of the refrigerant through the evaporator 300 is increased.

[0217] 4. Rule L4:

[0218] If T 环 is medium temperature, T 吸 is medium temperature, P 低 is high pressure, I is medium load, then the low pressure bypass valve opening α 低 It is a small opening.

[0219] 5. Rule L5:

[0220] If T 环 is low temperature, T 吸 is low temperature, P 低 is medium pressure, I is low load, then the low pressure bypass valve opening α 低 It’s a big opening.

[0221] According to the above calculation method,

[0222] 1. Ambient temperature T 环 =28℃;

[0223] 2. Compressor exhaust temperature T 排 =108℃;

[0224] 3. Compressor suction temperature T 吸 =9℃;

[0225] 4. High pressure side pressure P 高 =1.92MPa;

[0226] 5. Low pressure side pressure P 低 =0.33MPa;

[0227] 6. Compressor current I = 13.5A.

[0228] For T 环 =28°C, its corresponding low temperature membership is 0, medium temperature membership is 0.4, high temperature membership is 0.6, and the ambient temperature 28° belongs to both medium temperature (membership 0.4) and high temperature (membership 0.6).

[0229] For T 排 =108°C, its corresponding low temperature membership is 0, medium temperature membership is 0.4, high temperature membership is 0.6, and the compressor exhaust temperature of 108° belongs to both medium temperature (membership 0.4) and high temperature (membership 0.6).

[0230] For T 吸 =9°C, its corresponding low temperature membership is 0, medium temperature membership is 0.4, and high temperature membership is 0.6. The compressor suction temperature of 9° belongs to both medium temperature (membership 0.4) and high temperature (membership 0.6).

[0231] For P 高 =1.92MPa, its corresponding low pressure membership is 0, medium pressure membership is 0.8, high pressure membership is 0.2, and the high pressure side pressure 1.92MPa belongs to both medium pressure (membership 0.8) and high pressure (membership 0.2).

[0232] For P 低 =0.33MPa, its corresponding low pressure membership is 0, medium pressure membership is 0.8, high pressure membership is 0.2, and the low pressure side pressure 0.33MPa belongs to both medium pressure (membership 0.8) and high pressure (membership 0.2).

[0233] For I=13.5A, the corresponding low load membership is 0, the medium load membership is 0.5, and the high load membership is 0.5. The compressor current 13.5A belongs to both medium load (membership 0.5) and high load (membership 0.5).

[0234] Rule Evaluation:

[0235] High Pressure Bypass Valve Rule Assessment:

[0236] Rule H1:

[0237] Conditional membership:

[0238] μ 高 (T 环 )=0.6

[0239] μ 高 (T 排 )=0.6

[0240] μ 高 (P高 )=0.2

[0241] μ 高 (I) = 0.5;

[0242] Activation level H1 =min(0.6, 0.6, 0.2, 0.5) = 0.2

[0243] Rule H2:

[0244] Conditional membership:

[0245] μ 中 (T 环 )=0.4

[0246] μ 中 (T 排 )=0.4

[0247] μ 中 (P 高 )=0.8

[0248] μ 中 (I) = 0.5;

[0249] Activation level H2 =min(0.4, 0.4, 0.8, 0.5) = 0.4

[0250] Rule H4:

[0251] Conditional membership:

[0252] μ 高 (T 环 )=0.6

[0253] μ 高 (T 排 )=0.6

[0254] μ 中 (P 高 )=0.8

[0255] μ 高 (I) = 0.5;

[0256] Activation level H4 =min(0.6, 0.6, 0.8, 0.5) = 0.5

[0257] Rule H5:

[0258] Conditional membership:

[0259] μ 中 (T 环 )=0.4

[0260] μ 中 (T 排 )=0.4

[0261] μ 高 (P 高 )=0.2

[0262] μ 中 (I) = 0.5;

[0263] Activation level H5 =min(0.4, 0.4, 0.4, 0.5) = 0.2

[0264] Low Pressure Bypass Valve Rule Assessment:

[0265] Rule L2:

[0266] Conditional membership:

[0267] μ 中 (T 环 )=0.4

[0268] μ 中 (T 吸 )=0.4

[0269] μ 中 (P 低 )=0.8

[0270] μ 中 (I) = 0.5;

[0271] Activation level L2 =min(0.4, 0.4, 0.8, 0.5) = 0.4

[0272] Rule L3:

[0273] Conditional membership:

[0274] μ 高 (T 环 )=0.6

[0275] μ 高 (T 吸 )=0.6

[0276] μ 高 (P 低 )=0.2

[0277] μ 高 (I) = 0.5;

[0278] Activation level L3 =min(0.6, 0.6, 0.2, 0.5) = 0.2

[0279] Rule L4:

[0280] Conditional membership:

[0281] μ 中 (T 环 )=0.4

[0282] μ 中 (T 吸 )=0.4

[0283] μ 高 (P 低 )=0.2

[0284] μ 中 (I) = 0.5;

[0285] Activation level L4 =min(0.4, 0.4, 0.4, 0.5) = 0.2

[0286] The output membership function cutoffs of the high-pressure bypass valve and the low-pressure bypass valve are obtained according to the activation degree, and the output membership functions are synthesized.

[0287] Defuzzification

[0288] Calculate the specific value of the output variable by the centroid method.

[0289]

[0290] Calculation of high pressure bypass valve opening:

[0291] Interval division:

[0292] α 高 ∈[20%,30%]: membership increases from 0 to 0.4

[0293] α 高 ∈[30%,50%]: membership is 0.4

[0294] α 高 ∈[50%,70%]: membership decreases from 0.4 to 0

[0295] α 高 ∈[70%,80%]: membership increases from 0 to 0.5

[0296] α 高 ∈[80%,100%]: membership is 0.5;

[0297] Calculate the denominator: D = D1 + D2 + D3 + D4 + D5 = 5 + 8 + 4 + 2.5 + 10 = 29.5

[0298] Calculate the denominator:

[0299] N=N1+N2+N3+N4+N5=133.33+320+220+187.5+900=1760.83;

[0300] High pressure bypass valve opening:

[0301] Calculation of low pressure bypass valve opening:

[0302] α 低 ∈[0%,20%]: membership degree is 0.2

[0303] α 低 ∈[20%,30%]: The membership degree is between 0.2 and 0.4, whichever is greater

[0304] α 低 ∈[30%,50%]: the membership degree is 0.4;

[0305] Calculate the denominator: D = D1 + D2 + D3 = 4 + 4 + 8 = 16

[0306] Calculate the numerator: D = N1 + N2 + N3 = 40 + 100 + 320 = 460;

[0307] Low pressure bypass valve opening:

[0308] The high-pressure bypass valve opening is approximately 59.7%.

[0309] This indicates that under the current operating conditions, a moderate refrigerant bypass is required on the high-pressure side to reduce the system pressure and temperature, protect the compressor 100 and improve the system efficiency.

[0310] The low-pressure bypass valve opening is approximately 28.75%.

[0311] This indicates that a smaller bypass volume is required on the low-pressure side to maintain the cooling effect of the evaporator 300 and ensure indoor temperature control.

[0312] The ambient temperature is high (28°C) and the system load is heavy, so the opening of the high-pressure bypass valve needs to be appropriately increased.

[0313] The low-pressure bypass valve maintains a relatively small opening to ensure that sufficient refrigerant passes through the evaporator 300 to meet the refrigeration demand.

[0314] The specific calculation of fuzzy calculation and defuzzification is existing technology. The focus of this application is to use the above calculation method to intelligently control the opening of the high-pressure bypass valve and the low-pressure bypass valve based on the structure of the refrigeration system to improve the operating stability of the unit and reduce the failure rate.

[0315] In some embodiments of the present application, one end of the first bypass line 410 is connected to the outlet of the buffer element 400 , and the other end is connected to the refrigerant input line 110 between the compressor 100 and the evaporator 300 .

[0316] One end of the second bypass pipeline 420 is connected to the inlet of the buffer element 400 , and the other end is connected to the refrigerant output pipeline 120 between the compressor 100 and the condenser 200 .

[0317] A gas-liquid separator 500 is further provided between the evaporator 300 and the compressor 100 , and the second bypass line 420 is connected between the gas-liquid separator 500 and the evaporator 300 .

[0318] A high-voltage protection switch 121 is provided at the output end of the compressor 100 , and a low-voltage protection switch 111 is provided at the input end of the compressor 100 .

[0319] When the refrigerant pressure in the air-conditioning system is too high, the high-pressure protection switch 121 will automatically disconnect the circuit to stop the compressor 100, thereby preventing the compressor 100 from being overloaded and damaged.

[0320] The low-pressure protection switch 111 monitors the refrigerant pressure at the input end of the compressor 100. When the pressure is lower than a set value, the low-pressure protection switch 111 automatically starts the refrigeration cycle; when the pressure reaches the set value, the switch automatically stops the refrigeration cycle.

[0321] An expansion valve 700 and a drying filter 600 are also provided between the evaporator 300 and the condenser 200. The drying filter 600 plays a role in filtering impurities and improving the purity of the refrigerant.

[0322] The controller obtains relevant parameters of the compressor 100 during the operation of the refrigeration system, and controls the opening of the first bypass valve 411 and the second bypass valve 421 through fuzzy calculations and defuzzification calculations to achieve precise control of the refrigerant flow rate. The refrigeration system can store part of the refrigerant output from the compressor 100 in the buffer element 400 in a high-temperature environment to reduce the load on the high-pressure side; in a low-temperature environment, the controller controls the refrigerant in the buffer element 400 to be replenished from the input end of the compressor 100 to the compressor 100 to prevent low-pressure failure of the compressor 100, thereby improving the operating efficiency and stability of the refrigeration system of the air-conditioning unit under different working conditions and avoiding the occurrence of high-pressure and low-pressure failures.

Claims

1. A refrigeration system, characterized in that: include: compressor; A condenser connected to the output end of the compressor through a refrigerant output pipeline; an evaporator connected to the input end of the compressor via a refrigerant input pipeline; a buffer element connected to the input end and the output end of the compressor through a first bypass pipeline and a second bypass pipeline, wherein the first bypass pipeline is provided with a first bypass valve, and the second bypass pipeline is provided with a second bypass valve; A controller for: Get the relevant parameters of the compressor; Through the membership function, the relevant parameters are converted into fuzzy sets, and the fuzzy sets are inferred and calculated; Performing defuzzification operation on the inference calculation result; The openings of the first bypass valve and the second bypass valve are controlled according to the defuzzification operation result.

2. The refrigeration system according to claim 1, characterized in that: The input end of the compressor is provided with an intake air temperature sensor and an intake air pressure sensor, which are used to detect the intake air temperature T 吸 and suction pressure P 吸 .

3. The refrigeration system according to claim 2, characterized in that: The output end of the compressor is provided with an exhaust temperature sensor and an exhaust pressure sensor, which are used to detect the exhaust temperature T 排 and exhaust pressure P 排 .

4. The refrigeration system according to claim 3, characterized in that: The compressor is also connected to an ammeter for detecting the current I of the compressor.

5. The refrigeration system according to claim 4, characterized in that: The controller is connected to the intake temperature sensor, the intake pressure sensor, the exhaust temperature sensor, the exhaust pressure sensor, the ammeter, the first bypass valve and the second bypass valve. The relevant parameters of the compressor include the intake temperature T 吸 , the suction pressure P 吸 , the exhaust temperature T 排 , the exhaust pressure P 排 , the current I and the ambient temperature T 环 .

6. The refrigeration system according to claim 1, characterized in that: One end of the first bypass pipeline is connected to the outlet of the buffer element, and the other end is connected to the refrigerant input pipeline between the compressor and the evaporator.

7. The refrigeration system according to claim 1, characterized in that: One end of the second bypass pipeline is connected to the inlet of the buffer element, and the other end is connected to the refrigerant output pipeline between the compressor and the condenser.

8. The refrigeration system according to claim 7, characterized in that: A gas-liquid separator is further provided between the evaporator and the compressor, and the second bypass pipeline is connected between the gas-liquid separator and the evaporator.

9. The refrigeration system according to claim 1, characterized in that: The output end of the compressor is provided with a high-voltage protection switch, and the input end of the compressor is provided with a low-voltage protection switch.

10. The refrigeration system according to claim 1, characterized in that: An expansion valve and a drying filter are also arranged between the evaporator and the condenser.

Images