A high-reliability detection method for the temperature and pressure of an air compressor

Abstract

The present invention provides a method for detecting the temperature and pressure of an air compressor with high reliability. By using the intake pressure, the final exhaust pressure, the total compression ratio, and the intake temperature, the size of the first-stage exhaust temperature is calculated, and temperature calculation models for the air side and the coolant side are established. The first-order inertia link is used to describe its dynamic characteristics, and the first law of thermodynamics for an open system is used for description. After an accurate model is obtained through training based on experimental data; when it is detected that the temperature sensor or the pressure sensor fails, the system can automatically adjust, and the exhaust temperature and exhaust pressure of each stage of the air compressor are calculated in real time according to the established model, ensuring the efficient operation of the air compressor system.

Description

Technical Field

[0001] The present invention relates to the field of air compressor inverters, and particularly to a method for detecting the temperature and pressure of an air compressor with high reliability. Background Art

[0002] An air compressor is a commonly used device. To ensure the normal operation of the air compressor, it is necessary to monitor its operating data, including pressure, temperature, flow rate, voltage, etc. These parameters have a direct impact on the operating state and performance of the air compressor. The air compressor pressure refers to the pressure exerted in the compressed air. A reasonable pressure can ensure the normal operation of the air compressor system and also save energy. The exhaust temperature of the air compressor is one of the important indicators for evaluating its operating state. An exhaust temperature within a certain range not only helps to maintain the performance of the air compressor but also prevents potential equipment failures. An excessively high exhaust temperature may cause lubricating oil deterioration, increased equipment wear, and even safety accidents such as fires. Therefore, timely and accurate detection of the exhaust pressure and exhaust temperature is of great significance for ensuring the safe operation of the air compressor.

[0003] Currently, the detection of the air compressor exhaust pressure and exhaust temperature is usually achieved through pressure sensors and temperature sensors. In the actual working environment of the air compressor, due to various complex situations such as the long-term operation of the air compressor and the high-temperature working environment, it is very likely that its temperature sensor or pressure sensor will be damaged. Moreover, temperature and pressure affect each other. When one of them fails, it is very likely that the air compressor system will malfunction and cannot operate normally, resulting in huge economic and energy losses. Summary of the Invention

[0004] To solve the above problems, the present invention proposes a method for detecting the temperature and pressure of an air compressor with high reliability. When it is detected that the temperature sensor or pressure sensor fails, the exhaust temperature of the air compressor is calculated by establishing dynamic models of the air side and the coolant side, and then the exhaust pressure is deduced based on the exhaust temperature to achieve automatic adjustment of the system and ensure the efficient operation of the air compressor system.

[0005] A method for detecting the temperature and pressure of an air compressor with high reliability provided by the present invention includes the following steps:

[0006] Step S1, determining the primary intake pressure of the air compressor , the final exhaust pressure , the total compression ratio , the primary intake temperature ;

[0007] Among them, the total compression ratio The calculation formula is:

[0008] ,

[0009] Among them, is the total compression ratio, is the final exhaust pressure, is the primary intake pressure.

[0010] Step S2: Calculate the theoretical compression ratio of each stage of the multi-stage air compressor based on the minimum compression power consumption theory , n = 1, 2, 3, 4, …, n is a natural number starting from 1, where the theoretical compression ratio of each stage The calculation formula is:

[0011] ,

[0012] Among them, is the theoretical compression ratio of each stage, and n is a natural number starting from 1.

[0013] In the actual design process, to improve the volumetric efficiency of the air compressor, the actual compression ratio of the primary stage is smaller than the theoretical compression ratio of the primary stage . Therefore, the theoretical compression ratio of the primary stage is corrected to obtain the actual compression ratio of the primary stage . Similarly, the actual compression ratio of each stage can be obtained.

[0014] Step S3: Calculate the primary exhaust pressure according to the actual compression ratio of the primary stage and the primary intake pressure of the multi-stage air compressor, and calculate the primary exhaust temperature according to the primary intake temperature .

[0015] Among them, the calculation formula for the primary exhaust pressure is:

[0016] ,

[0017] Among them, is the primary exhaust pressure, is the actual compression ratio of the primary stage;

[0018] The calculation formula for the primary exhaust temperature is:

[0019] ,

[0020] Among them, is the primary exhaust temperature, is the primary intake temperature, and q is the adiabatic index of temperature.

[0021] Step S4, at time k, establish the dynamic temperature detection models for the air side and the coolant side respectively. For the air side:

[0022] ,

[0023] where, is the specific heat at constant pressure of the gas, is the mass of the gas flowing into the cooler at time k, is the gas temperature when flowing into the cooler at time k, is the gas temperature when flowing out of the cooler at time k, is the heat transfer amount between both sides of the cooler at time k, is the specific heat at constant volume of the gas, is the mass of the gas in the cooler at time k, is the gas temperature in the cooler at time k, d is the differential operator, and t is the time.

[0024] For the coolant side:

[0025] ,

[0026] ,

[0027] ,

[0028] where, is the specific heat capacity of the coolant, is the mass of the coolant flowing into the cooler at time k, is the coolant temperature when flowing into the cooler at time k, is the coolant temperature when flowing out of the cooler at time k, is the mass of the coolant in the cooler at time k, is the coolant temperature in the cooler at time k, is the heat transfer coefficient, is the heat transfer area, is the difference between the gas temperature when flowing out of the cooler at time k and the coolant temperature when flowing out of the cooler at time k.

[0029] After establishing the dynamic models for the air side and the coolant side, collect n groups of real-time data including mass and gas temperature when flowing in and out of the cooler. n is a natural number starting from 1. After fitting , and , , by solving the differential equation, an accurate model for the gas side and the coolant side can be trained to calculate the temperatures of the gas and the coolant at any time.

[0030] Step S5: Determine the fault status of the temperature sensor and the pressure sensor. If the temperature sensor fails, go to step S6; if the pressure sensor fails, go to step S7.

[0031] Step S6: When the temperature sensor fails, starting from time k + 2, use the trained air-side dynamic model and coolant-side dynamic model to estimate the size of the exhaust temperature after each stage of compression and the temperatures of the gas and coolant at any time during the cooling process. The specific process is as follows:

[0032] The first-stage exhaust temperature can be calculated from the first-stage intake temperature and the gas type :

[0033] ,

[0034] During the cooling stage, according to the air-side dynamic model and coolant-side dynamic model in step S4, the gas temperature and coolant temperature in the cooler at any time and any stage can be calculated.

[0035] Step S7: When the pressure sensor fails, starting from time k + 2, reverse-infer the size of the gas pressure after compression based on the size of the exhaust temperature after each stage of compression detected by the temperature detector.

[0036] The specific process is as follows:

[0037] According to the exhaust temperature calculation formula for each stage of the compression part:

[0038] ,

[0039] The exhaust pressure calculation formula for each stage of the compression part:

[0040] ,

[0041] where, is the exhaust temperature at the nth stage, is the intake temperature at the nth stage, is the actual compression ratio at the nth stage, q is the temperature adiabatic index, is the exhaust pressure at the nth stage, is the intake pressure at the nth stage, and n is a natural number starting from 1.

[0042] Based on the first-stage intake temperature and the size of the first-stage exhaust temperature detected by the temperature detector , reverse-infer the actual compression ratio at the first stage , and obtain the first-stage exhaust pressure from the calculation formula of the first-stage exhaust pressure in S3 , and so on for the second-stage compression and subsequent stages of compression. Based on the detected size of the exhaust temperature at each stage, reverse-infer the actual compression ratio at each stage The intake pressure at each stage is equal to the exhaust pressure of the previous stage. From the calculation formula for the exhaust pressure at each stage of the compression section, the exhaust pressure at each stage can be calculated accordingly.

[0043] Furthermore, the actual compression ratio of the first stage The calculation formula is:

[0044] ,

[0045] where is the actual compression ratio of the first stage, is the theoretical compression ratio of the first stage.

[0046] According to the total compression ratio of the multi-stage air compressor and the equal-pressure ratio theory, the actual compression ratios of other stages are also corrected accordingly. The actual compression ratio The calculation formula is:

[0047] ,

[0048] where is the actual compression ratio of the nth stage, is the total compression ratio. In this formula, n is set as a natural number starting from 2.

[0049] Furthermore, the judgment conditions for the fault state of the temperature sensor are as follows:

[0050] Set the temperature threshold a and set a dead zone interval based on the temperature threshold a where φ is the fault tolerance range of the temperature threshold; record the air temperature detected by the temperature sensor at time k and the air temperature detected at time k + 1 ; calculate the gas temperatures at time k and time k + 1 according to the air-side dynamic model established in step S4 , 。

[0051] When the gas temperatures recorded by the temperature sensor at time k and the gas temperatures at time k + 1 , meet the following conditions, it is diagnosed that the temperature sensor has a fault;

[0052] ,

[0053] and ,

[0054] and from time k to time k + 1 A mutation occurs;

[0055] where is the temperature calculated by the air - side dynamic model and the coolant - side dynamic model at time k, is the air temperature recorded by the temperature sensor at time k, a is the temperature threshold, and φ is the temperature threshold tolerance range, is the temperature calculated by the air - side dynamic model and the coolant - side dynamic model at time k + 1, is the air temperature recorded by the temperature sensor at time k + 1, is the empty set symbol, is the intersection symbol, is the square bracket.

[0056] Furthermore, the judgment conditions for the pressure sensor fault state are as follows:

[0057] Set the pressure threshold b, and set the dead - zone interval on the basis of the pressure threshold b, where is the pressure threshold tolerance range; record the magnitudes of the exhaust pressures at each stage detected by the pressure sensor at time k and the magnitudes of the exhaust pressures at each stage detected at time k + 1 .

[0058] When the pressure recorded by the pressure sensor at time k and the pressure at time k + 1 satisfy the following conditions, it is diagnosed that the pressure sensor has a fault:

[0059] ,

[0060] and ,

[0061] and from time k to time k + 1 a mutation occurs;

[0062] where is the pressure recorded by the pressure sensor at time k, is the pressure recorded by the pressure sensor at time k + 1, b is the pressure threshold, is the pressure threshold tolerance range.

[0063] The technical effect of the present invention is as follows:

[0064] 1. The established dynamic temperature - calculation models for the air - side and the coolant - side are accurate, realizing redundant fault - tolerant control of temperature and pressure;

[0065] 2. The system can automatically adjust to ensure the efficient operation of the air compressor system. Description of the Drawings

[0066] Figure 1 It is a flowchart of the algorithm steps provided by the present invention;

[0067] Figure 2 It is a flowchart of temperature detection and judgment provided by the present invention;

[0068] Figure 3 It is a flowchart of pressure detection and judgment provided by the present invention. Detailed Embodiment

[0069] The following is only the preferred embodiment of the present invention. The present invention will be further described in detail below in conjunction with the drawings and specific embodiments, so as to facilitate those skilled in the art to understand the present invention. It should be noted that for those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims without departing from the principle of the present invention, all inventions and creations using the concept of the present invention are within the scope of protection.

[0070] Figure 1 It is a flowchart of the method steps provided by the present invention. As Figure 1 shown, a method for detecting the temperature and pressure of a highly reliable air compressor includes the following steps:

[0071] Step S1, determine the primary intake pressure of the air compressor , the final exhaust pressure , the total compression ratio , the primary intake temperature ;

[0072] Among them, the formula for calculating the total compression ratio is:

[0073] ,

[0074] Among them, is the total compression ratio, is the final exhaust pressure, is the primary intake pressure.

[0075] Step S2, calculate the theoretical compression ratio of each stage of the multi-stage air compressor based on the minimum compression power consumption theory , n = 1, 2, 3, 4,..., n is a natural number starting from 1. Among them, the formula for calculating the theoretical compression ratio of each stage is:

[0076] ,

[0077] Among them, is the theoretical compression ratio at all levels, and n is a natural number starting from 1.

[0078] In the actual design process, to improve the volumetric efficiency of the air compressor, the actual compression ratio of the first stage is smaller than the theoretical compression ratio of the first stage Therefore, the theoretical compression ratio of the first stage is corrected to obtain the actual compression ratio of the first stage Similarly, the actual compression ratios at all levels can be obtained.

[0079] Among them, the actual compression ratio of the first stage The calculation formula is:

[0080] ,

[0081] where is the actual compression ratio of the first stage, is the theoretical compression ratio of the first stage.

[0082] According to the total compression ratio of the multi-stage air compressor and the equal-pressure ratio theory, the actual compression ratios of other stages are also corrected accordingly. The actual compression ratio of each stage The calculation formula is:

[0083] ,

[0084] where is the actual compression ratio of the nth stage, is the total compression ratio. In this formula, n is set as a natural number starting from 2.

[0085] Step S3, according to the actual compression ratio of the first stage , the first-stage intake pressure of the multi-stage air compressor, calculate the first-stage discharge pressure , and calculate the first-stage discharge temperature according to the first-stage intake temperature .

[0086] Among them, the first-stage discharge pressure The calculation formula is:

[0087] ,

[0088] where is the first-stage discharge pressure, is the actual compression ratio of the first stage;

[0089] The first-stage discharge temperature The calculation formula is:

[0090] ,

[0091] Among them, is the primary exhaust temperature, is the primary inlet temperature, and q is the temperature adiabatic index.

[0092] Step S4: At time k, establish the dynamic temperature detection models for both the air side and the coolant side. For the air side:

[0093] ,

[0094] Among them, is the specific heat at constant pressure of the gas, is the mass of the gas flowing into the cooler at time k, is the gas temperature when flowing into the cooler at time k, is the gas temperature when flowing out of the cooler at time k, is the heat transfer amount between both sides of the cooler at time k, is the specific heat at constant volume of the gas, is the mass of the gas in the cooler at time k, is the gas temperature in the cooler at time k, d is the differential operator, and t is the time.

[0095] For the coolant side:

[0096] ,

[0097] ,

[0098] ,

[0099] Among them, is the specific heat capacity of the coolant, is the mass of the coolant flowing into the cooler at time k, is the coolant temperature when flowing into the cooler at time k, is the coolant temperature when flowing out of the cooler at time k, is the mass of the coolant in the cooler at time k, is the coolant temperature in the cooler at time k, is the heat transfer coefficient, is the heat transfer area, is the difference between the gas temperature when flowing out of the cooler at time k and the coolant temperature when flowing out of the cooler at time k.

[0100] After establishing the dynamic models for both the air side and the coolant side, collect n groups of real-time data including mass and gas temperatures when flowing in and out of the cooler. n is a natural number starting from 1, and fit , and , After that, by solving the differential equation, an accurate model of the gas side and the coolant side can be trained to calculate the temperatures of the gas and the coolant at any time.

[0101] Step S5: Determine the fault status of the temperature sensor and the pressure sensor. If the temperature sensor fails, go to step S6; if the pressure sensor fails, go to step S7. Figure 2 This is the flowchart for temperature detection and judgment provided by the present invention. As Figure 2 shown, the judgment conditions for the fault status of the temperature sensor are as follows:

[0102] Set the temperature threshold a, and set a dead zone interval based on the temperature threshold a , where φ is the temperature threshold tolerance range; record the air temperature detected by the temperature sensor at time k and the air temperature detected at time k + 1 ; Calculate the gas temperatures at time k and time k + 1 according to the air side dynamic model established in step S4 , ;

[0103] When the gas temperatures recorded by the temperature sensor at time k and the gas temperatures at time k + 1 , meet the following conditions, it is diagnosed that the temperature sensor has failed;

[0104] ,

[0105] and ,

[0106] and there is a mutation from time k to time k + 1 ;

[0107] Among them, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k, is the air temperature recorded by the temperature sensor at time k, a is the temperature threshold, φ is the temperature threshold tolerance range, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k + 1, is the air temperature recorded by the temperature sensor at time k + 1, is the empty set symbol, is the intersection symbol, is the square bracket.

[0108] Figure 3The flowchart for pressure detection and judgment provided by the present invention is as follows Figure 3 As shown, the judgment conditions for the failure state of the pressure sensor are as follows:

[0109] Set the pressure threshold b, and set a dead zone interval based on the pressure threshold b , where is the fault tolerance range of the pressure threshold; record the magnitudes of the exhaust pressures at each stage detected by the pressure sensor at time k and the magnitudes of the exhaust pressures at each stage detected at time k + 1 ;

[0110] When the pressure recorded by the pressure sensor at time k and the pressure at time k + 1 and the pressure threshold b, the pressure threshold fault tolerance range meet the following conditions, it is diagnosed that the pressure sensor has failed:

[0111] ,

[0112] and ,

[0113] and from time k to time k + 1 there is a mutation;

[0114] wherein, is the pressure recorded by the pressure sensor at time k, is the pressure recorded by the pressure sensor at time k + 1, b is the pressure threshold, is the pressure threshold fault tolerance range.

[0115] Step S6, when the temperature sensor fails, starting from time k + 2, use the trained air-side dynamic model and coolant-side dynamic model to estimate the magnitudes of the exhaust temperatures after compression at each stage and the temperatures of the gas and coolant at any time during the cooling process. The specific process is as follows:

[0116] The first-stage exhaust temperature can be calculated from the first-stage intake temperature and the gas type :

[0117] ,

[0118] In the cooling stage, according to the air-side dynamic model and coolant-side dynamic model in Step S4, the gas temperature and coolant temperature in the cooler at any time and at any stage can be calculated.

[0119] Step S7, when the pressure sensor fails, starting from time k + 2, calculate the magnitude of the gas pressure after compression by back-inference based on the magnitudes of the exhaust temperatures after compression at each stage detected by the temperature detector.

[0120] The specific process is as follows:

[0121] According to the calculation formulas for the exhaust gas temperature at each stage of the compression part:

[0122] ,

[0123] The calculation formulas for the exhaust gas pressure at each stage of the compression part:

[0124] ,

[0125] Among them, is the exhaust gas temperature at the nth stage, is the intake air temperature at the nth stage, is the actual compression ratio at the nth stage, and q is the adiabatic index of temperature, is the exhaust gas pressure at the nth stage, is the intake air pressure at the nth stage, and n is a natural number starting from 1.

[0126] According to the intake air temperature at the first stage and the magnitude of the exhaust gas temperature at the first stage detected by the temperature detector , the actual compression ratio at the first stage is inversely deduced. From the calculation formula of the exhaust gas pressure at the first stage in S3, the exhaust gas pressure at the first stage is obtained. For the second-stage compression and subsequent stages of compression, by analogy, according to the magnitude of the exhaust gas temperature detected at each stage, the actual compression ratio at each stage is inversely deduced. The intake air pressure at each stage is equal to the exhaust gas pressure of the previous stage. From the calculation formulas for the exhaust gas pressure at each stage of the compression part, the exhaust gas pressure at each stage can be calculated.

[0127] Next, according to the design requirements of engineering practice, the performance indicators of a two-stage air compressor are formulated, and the above method is practiced with simulated data. The specific content is as follows:

[0128] The intake air pressure is 0.1 MPa, and the exhaust gas pressure is 2 MPa.

[0129] According to steps S1 to S3, it can be known that , , , , .

[0130] The intake air temperature is taken as the actual atmospheric temperature during the test, .

[0131] The air-side parameters and coolant-side parameters at time k are shown in Table 1 and Table 2:

[0132] Table 1 Air-side parameters at time k

[0133]

[0134] Table 2 Coolant side parameters at time k

[0135]

[0136] Fitting the heat transfer coefficient .

[0137] The temperature calculation formula of gas and coolant at any time is obtained by calculating the differential equation:

[0138] ,

[0139] Air side dynamic equation: ,

[0140] Coolant side dynamic equation: ,

[0141] Will Substituting the air side dynamic equation and the coolant side dynamic equation into the two equations in parallel, we can get two differential equations:

[0142] ,

[0143] ,

[0144] Finally, the Runge-Kutta method is used to program a numerical solution to determine the temperature of the gas and coolant at any time.

[0145] By detecting the temperature of the temperature sensor and the pressure sensor, it is determined whether the sensor is faulty at a certain moment. If the temperature sensor fails, the temperature at any moment can be solved by adding the model. If the pressure sensor fails, the gas pressure after compression can be inferred based on the exhaust temperature after each stage of compression detected by the temperature detector.

[0146] Although the specific implementation of the invention is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A highly reliable air compressor temperature and pressure detection method, characterized in that: The following steps are involved: Step S1, determining the first-stage air intake pressure of the air compressor , Final exhaust pressure , total compression ratio , first stage inlet temperature ; Among them, the total compression ratio The calculation formula is: ， in, is the overall compression ratio, is the final exhaust pressure, is the first stage intake pressure; Step S2, calculating the theoretical compression ratio of each stage of the multi-stage air compressor based on the minimum compression power consumption theory , n=1,2,3,4,…, n is a natural number starting from 1, where the theoretical compression ratio of each level is The calculation formula is: ， in, is the theoretical compression ratio at each level, and n is a natural number starting from 1; In the actual design process, in order to improve the volumetric efficiency of the air compressor, the actual compression ratio of the first stage is The first-stage theoretical compression ratio Small, so the first-stage theoretical compression ratio Correction is performed to obtain the actual compression ratio of the first stage Similarly, the actual compression ratio of each level can be obtained ; Step S3, based on the actual compression ratio of the first level , Multi-stage air compressor first stage inlet pressure Calculate the first stage exhaust pressure , according to the first-stage intake air temperature Calculate the primary exhaust temperature ; Among them, the first-stage exhaust pressure The calculation formula is: ， in, is the first-stage exhaust pressure, is the actual compression ratio of the first stage; First stage exhaust temperature The calculation formula is: ， in, is the first-stage exhaust temperature, is the first-stage inlet temperature, q is the temperature adiabatic index; Step S4, at time k, establish temperature detection dynamic models for the air side and the coolant side, respectively. For the air side: ， in, is the constant pressure specific heat of the gas, is the mass of gas flowing into the cooler at time k, is the gas temperature when it flows into the cooler at time k, is the gas temperature when it flows out of the cooler at time k, is the heat transfer on both sides of the cooler at time k, is the specific heat at constant volume of the gas, is the mass of gas in the cooler at time k, is the gas temperature in the cooler at time k, d is the differential operator, and t is the time; Coolant side: ， ， ， in, is the specific heat capacity of the coolant, is the mass of coolant flowing into the cooler at time k, is the coolant temperature when it flows into the cooler at time k, is the coolant temperature when it flows out of the cooler at time k, is the mass of coolant in the cooler at time k, is the temperature of the coolant in the cooler at time k, is the heat transfer coefficient, is the heat exchange area, is the difference between the gas temperature when it flows out of the cooler at time k and the coolant temperature when it flows out of the cooler at time k; After the dynamic models of the air side and the coolant side are established, n sets of real-time data including mass and gas temperature when entering and leaving the cooler are collected, where n is a natural number starting from 1. , and , After that, by solving the differential equations, the accurate models of the gas side and the coolant side can be trained to calculate the temperature of the gas and coolant at any time; Step S5, judging the fault status of the temperature sensor and the pressure sensor. If the temperature sensor fails, the process goes to step S6; if the pressure sensor fails, the process goes to step S7; Step S6, when the temperature sensor fails, the trained air-side dynamic model and coolant-side dynamic model are used to estimate the exhaust temperature after each stage of compression and the temperature of the gas and coolant at any time during the cooling process starting from time k+2. The specific process is as follows: The first stage exhaust temperature can be calculated from the first stage inlet temperature and gas type : ， In the cooling stage, the air side dynamic model and the coolant side dynamic model described in step S4 can calculate the gas temperature and the coolant temperature in the cooler at any time and any level; Step S7, when the pressure sensor fails, the pressure of the compressed gas is inferred from the exhaust temperature of each level after compression detected by the temperature detector starting from time k+2. The specific process is as follows: According to the exhaust temperature calculation formula of each stage of the compression part: ， The calculation formula for exhaust pressure at each stage of compression is: ， in, is the n-stage exhaust temperature, is the n-stage intake temperature, is the actual compression ratio of level n, q is the temperature adiabatic index, is the n-stage exhaust pressure, is the n-stage intake pressure, where n is a natural number starting from 1; According to the first-stage intake air temperature The temperature detector detects the primary exhaust temperature , reverse the actual compression ratio of the first stage , the first-stage exhaust pressure in S3 The calculation formula is used to obtain the first-stage exhaust pressure. The second-stage compression and subsequent compression levels are analogous. According to the detected exhaust temperature of each level, the actual compression ratio of each level is inferred. The intake pressure of each stage is equal to the exhaust pressure of the previous stage. The exhaust pressure of each stage can be calculated based on the exhaust pressure calculation formula of the compression part.

2. A high-reliability air compressor temperature and pressure detection method according to claim 1, characterized in that: In step S2, the first-level actual compression ratio The calculation formula is: ， in, is the actual compression ratio of the first stage, is the first-level theoretical compression ratio; According to the total compression ratio of the multi-stage air compressor According to the isobaric ratio theory, the actual compression ratios of other levels are also corrected accordingly. The calculation formula is: ， in, is the actual compression ratio of level n, is the total compression ratio. In this formula, n is set to a natural number starting from 2.

3. A high-reliability air compressor temperature and pressure detection method according to claim 1, characterized in that: In step S5, the temperature sensor fault state judgment condition is as follows: Set temperature threshold a Set the dead zone interval based on temperature threshold a Where φ is the temperature threshold tolerance range; record the air temperature detected by the temperature sensor at time k And the air temperature detected at time k+1 ; Calculate the gas temperature at time k and time k+1 according to the air side dynamic model established in step S4 , ; When the temperature sensor records the gas temperature at time k and the gas temperature at time k+1 Calculate the temperature at time k and time k+1 with the air side dynamic model , When the following conditions are met, the temperature sensor is diagnosed as faulty; ， and , And from time k At time k+1 Mutation occurs; in, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k, is the air temperature recorded by the temperature sensor at time k, a is the temperature threshold, φ is the temperature threshold tolerance range, is the temperature calculated by the air side dynamic model and the coolant side dynamic model at time k+1, is the air temperature recorded by the temperature sensor at time k+1, is the empty set symbol, is the intersection symbol, For square brackets.

4. A high-reliability air compressor temperature and pressure detection method according to claim 1, characterized in that: In step S5, the pressure sensor fault state judgment condition is as follows: Set the pressure threshold b, and set the dead zone interval based on the pressure threshold b ,in is the pressure threshold tolerance range; records the exhaust pressures of each level detected by the pressure sensor at time k And the exhaust pressure of each level detected at time k+1 ; When the pressure sensor records the pressure at time k And the pressure at k+1 and pressure threshold b, pressure threshold tolerance range The pressure sensor is diagnosed as faulty when the following conditions are met: ， and , And from time k At time k+1 Mutation occurs; in, is the pressure recorded by the pressure sensor at time k, is the pressure recorded by the pressure sensor at time k+1, b is the pressure threshold, is the pressure threshold tolerance range.

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