Control system and control method for realizing combustion tail gas recirculation of internal combustion engine

Abstract

The invention discloses a combustion optimization control method for a methanol pure oxygen combustion tail gas recirculation internal combustion engine. The method comprises the following steps: acquiring engine operation parameters; calculating the current combustion efficiency and emission level; determining a control error; calculating an adjustment amount by using a multivariable adaptive control algorithm and executing the adjustment amount; and the adjusted engine performance is monitored and cyclically optimized. According to the method, multiple parameters are monitored in real time by adopting a high-precision sensor, a multivariable mathematical model is constructed through a PI D control algorithm, and adaptive control calculation is introduced. A comprehensive performance index function F is also defined, and factors such as combustion efficiency, equivalence ratio, temperature, emission and fuel consumption are considered for optimizing the EGR rate. Efficient, clean and economical operation of the methanol pure oxygen combustion internal combustion engine is achieved, the combustion efficiency is improved, emission control and fuel economy are improved, and intelligence and self-adaptability of a control system are enhanced.

Description

Technical Field

[0001] The present invention relates to engine power control technology, and in particular to a control system and a control method for realizing combustion exhaust gas recirculation of an internal combustion engine. Background Art

[0002] With the improvement of environmental protection awareness and the transformation of energy structure, methanol as a clean alternative fuel is receiving more and more attention. Methanol pure oxygen combustion internal combustion engine has become a research hotspot due to its high efficiency and low emission characteristics. However, traditional methanol pure oxygen combustion engine still faces some challenges in practical application, mainly including:

[0003] Unstable combustion efficiency, fuel economy needs to be improved, and control methods are complex: Since the physical and chemical properties of methanol are different from those of traditional fuels, it is difficult to maintain optimal combustion efficiency under different operating conditions. While ensuring performance, how to maximize fuel utilization remains an important issue. Traditional single-parameter control methods are difficult to cope with the multivariable and strongly coupled characteristics of methanol pure oxygen combustion, so the control methods are relatively backward, especially the control methods for combustion exhaust gas recirculation are even more backward. Summary of the invention

[0004] The object of the present invention is to provide a control system and a control method for realizing exhaust gas recirculation of an internal combustion engine, which solves the above-mentioned technical problems pointed out in the prior art.

[0005] The present invention provides a combustion optimization control system for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine, comprising:

[0006] Multiple sensors are used to collect engine operating parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow, oxygen flow and exhaust gas composition; based on the engine operating parameters, calculate the current actual combustion efficiency, and then detect and obtain the actual nitrogen oxide emission concentration;

[0007] The central control unit is used to set the target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target , calculate the error of the control variable; under the preset condition of limiting the methanol flow, use the multivariable adaptive control algorithm to calculate the adjustment amount of the methanol flow, oxygen flow and combustion chamber temperature; under the preset condition of not limiting the methanol flow, use the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node to calculate the adjustment amount of the valve opening; execute the adjustment amount and adjust the corresponding control device actuator; the control device actuator includes a switch valve and a pump, a flow valve and a combustion temperature controller;

[0008] The combustion optimization control system of the methanol pure oxygen combustion exhaust gas recirculation internal combustion engine also includes: a high-precision thermocouple, a piezoresistive pressure sensor, a Coriolis mass flowmeter and an infrared spectrometer;

[0009] The high-precision thermocouple is used to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber and calculate the average temperature as the combustion chamber temperature;

[0010] The piezoresistive pressure sensor is used to measure the combustion chamber pressure and obtain the combustion chamber pressure;

[0011] The Coriolis mass flowmeter is used to measure the methanol flow rate and the oxygen flow rate respectively;

[0012] The infrared spectrometer is used for real-time analysis of exhaust gas components.

[0013] Accordingly, the present invention also provides a combustion optimization control method for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine, which uses a combustion optimization control system for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine to implement control processing, including the following steps:

[0014] S1. Collect engine operating parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow rate, oxygen flow rate and exhaust gas composition;

[0015] S2. Calculating the current actual combustion efficiency based on the engine operating parameters, and then detecting and obtaining the actual nitrogen oxide emission concentration;

[0016] S3, according to the preset target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target , calculate the error of the control variable;

[0017] S4. Under the preset condition of limiting the methanol flow rate, use a multivariable adaptive control algorithm to calculate the adjustment amount of the methanol flow rate, oxygen flow rate and combustion chamber temperature; under the preset condition of not limiting the methanol flow rate, use the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node to calculate the adjustment amount of the valve opening; execute the adjustment amount and adjust the corresponding control device actuator; the control device actuator includes a switch valve and a pump, a flow valve and a combustion temperature controller.

[0018] Preferably, as an implementable embodiment, the operating parameters collected in step S1 also include:

[0019] S11, using a high-precision thermocouple to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber and calculate the average temperature as the combustion chamber temperature;

[0020] S12, measuring the combustion chamber pressure using a piezoresistive pressure sensor to obtain the combustion chamber pressure;

[0021] S13, using a Coriolis mass flowmeter to measure the methanol flow rate and the oxygen flow rate respectively;

[0022] S14. Analyze the exhaust gas components in real time by using an infrared spectrometer to obtain exhaust gas component analysis results.

[0023] Preferably, as an implementable embodiment, the method for calculating the combustion efficiency in step S2 includes:

[0024] S21. Calculate theoretical thermal efficiency based on combustion chamber temperature and combustion chamber pressure;

[0025] S22, calculating the current actual air-fuel ratio using the detection ratio of the methanol flow rate and the oxygen flow rate; and then calculating the corrected current air-fuel ratio based on the current actual air-fuel ratio, the preset ideal air-fuel ratio and the adjustment parameters;

[0026] Corrected current air-fuel ratio

[0027] Among them: AFR 实际 : The actual air-fuel ratio calculated in step S22;

[0028] AFR 理想 : ideal air-fuel ratio;

[0029] σ: represents a tuning parameter;

[0030] S23, calculating the proportion of incompletely burned fuel according to the exhaust gas composition analysis result;

[0031] S24, outputting the actual combustion efficiency by comprehensively calculating the theoretical thermal efficiency, the corrected current air-fuel ratio, and the proportion of fuel that is not completely burned, to obtain the actual combustion efficiency.

[0032] The calculation formula for actual combustion efficiency is: 实际( =η 理论( ·k 空燃比( 1-r 末完全燃烧 ;

[0033] η 实际 : The actual combustion efficiency finally calculated;

[0034] η 理论 : Theoretical thermal efficiency;

[0035] k 空燃比 : Corrected current air-fuel ratio k 空燃比 ;

[0036] r 末完全燃烧 : Indicates the proportion of fuel that is not completely burned.

[0037] Preferably, as an implementation scheme, step S3 is based on the preset target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target , calculate the error of the control variable; the step S4 uses a multivariable adaptive control algorithm to calculate the adjustment amount of methanol flow, oxygen flow and combustion chamber temperature, including the following steps:

[0038] S41, implement PID control algorithm for each control variable to build a multivariable mathematical model, the control variable includes methanol flow rate u m , oxygen flow u o , combustion chamber temperature u T ;

[0039] The calculation formula of the multivariate mathematical model is:

[0040]

[0041] Among them, i∈m,o,T, respectively represent the methanol flow rate, oxygen flow rate and combustion chamber temperature;

[0042] S42, performing adaptive control calculation on the multivariable mathematical model:

[0043]

[0044]

[0045]

[0046] Among them, K p，i (t+1) is the value of the proportional gain of the ith controlled variable (such as methanol flow, oxygen flow or combustion chamber temperature) at time t+1. It is used to control the response of the system to the current error.

[0047] K i，i (t+1) is the value of the integral gain (lntegral Gain) of the i-th control variable at time t+1t+1t+1. The integral gain is used to eliminate steady-state errors, that is, to adjust the output by accumulating past errors.

[0048] K d，i (t+1) is the value of the derivative gain of the ith control variable at time t+1. The derivative gain is used to predict future error changes and help reduce the overshoot of the system;

[0049] α p , α i , α d are their respective learning rates, and E is the preset threshold index of the comprehensive performance of fuel saving;

[0050] Then they are the partial derivatives of the performance index E with respect to the proportional gain, integral gain and differential gain respectively;

[0051] S43, obtain the current demand input instruction, analyze the current demand input instruction, obtain the setting target combustion chamber temperature T target and target nitrogen oxide emission concentration u o，target And the target methanol flow rate u m，target Instruction information; record the current methanol flow u m (t), oxygen flow u o (t) and combustion chamber temperature u T (t); then calculate the error of the current control variable based on the current record information and instruction information:

[0052] e m =u m,target -u m (t);

[0053] e o =u o，target -u o (t);

[0054] e T =T target -u T (t);

[0055] Obtain the coupling effect dynamics G of each built-in control variable of the system: the coupling effect matrix G of each built-in control variable of the system is as follows:

[0056]

[0057] S44, input the error of the control variable into the coupling effect matrix G, and then calculate the increment of each control variable to adjust the control variable (i.e., the control increment Δu of the output methanol flow rate) m and the control increment Δu of oxygen flow o and the control increment Δu of the combustion chamber temperature T ), adjust the control variables by the increment of each control variable and record the current methanol flow u m (t), oxygen flow u o (t) and combustion chamber temperature u T (t) Perform a sum operation to obtain and update the control variable of the next control timing node:

[0058] u m (t+1)=u m (t)+Δu m ;

[0059] u o (t+1)=u o (t)+Δu o ;

[0060] u T (t+1)=u T (t)+Δu T .

[0061] When executing the current methanol flow to update the control variable of the next control timing node, real-time judgment u m Is (t+1) greater than the maximum methanol flow rate u? m，max ; if u m (t+1)> Maximum methanol flow rate u m，max , then u m (t+1) = Maximum methanol flow rate u m，max .

[0062] Preferably, as an implementable embodiment, after step S44, the following steps are further included:

[0063] Further determining whether an unrestricted methanol flow comprehensive control operation instruction is received, and if a restricted methanol flow comprehensive control operation instruction is received, setting a comprehensive performance index function F;

[0064] A comprehensive performance index function F is set; and the optimal control parameters of the exhaust gas recirculation rate EGR at the next control timing node are solved by maximizing the comprehensive performance index function F.

[0065] The embodiment of the present invention provides a control system and control method for realizing exhaust gas recirculation of an internal combustion engine, which has the following technical effects:

[0066] In specific applications, the present invention collects multiple key operating parameters including combustion chamber temperature, pressure, methanol flow, oxygen flow and tail gas composition. The present invention uses PID control algorithm to construct a multivariable mathematical model and introduces adaptive control calculation. This method can effectively handle the complexity and strong coupling characteristics of the methanol pure oxygen combustion process, and improve the adaptability and accuracy of the control system.

[0067] At the same time, a comprehensive control mode is also set. When the comprehensive control mode is used, by introducing the comprehensive performance index function F, the present invention simultaneously considers multiple factors such as combustion efficiency, equivalence ratio, combustion chamber temperature, nitrogen oxide emissions and fuel consumption. This method effectively balances the needs of emission control and fuel economy. By finding the optimal EGR rate through an optimization algorithm (such as a gradient descent method), the present invention fully utilizes the potential of exhaust gas recirculation technology in a methanol pure oxygen combustion engine, and further improves the performance and emission control capability of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 Schematic diagram of the overall control architecture for implementing a combustion exhaust gas recirculation control system for an internal combustion engine;

[0069] Figure 2 A flow chart of a method for controlling the recirculation of combustion exhaust gas for an internal combustion engine;

[0070] Reference numerals: sensor 10 ; central control unit 20 ; human-machine interaction interface 30 . DETAILED DESCRIPTION

[0071] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0072] To facilitate understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings.

[0073] Example 1: See Figure 1 The present invention provides a control system for realizing exhaust gas recirculation of an internal combustion engine, comprising:

[0074] A plurality of sensors 10 are used to collect engine operating parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow rate, oxygen flow rate and exhaust gas composition; based on the engine operating parameters, calculate the current actual combustion efficiency, and then detect and obtain the actual nitrogen oxide emission concentration;

[0075] The central control unit 20 is used to set the target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target, calculate the error of the control variable; under the preset condition of limiting the methanol flow, use the multivariable adaptive control algorithm to calculate the adjustment amount of the methanol flow, oxygen flow and combustion chamber temperature; under the preset condition of not limiting the methanol flow, use the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node to calculate the adjustment amount of the valve opening; execute the adjustment amount and adjust the corresponding control device actuator; the control device actuator includes a switch valve and a pump, a flow valve and a combustion temperature controller;

[0076] The human-machine interaction interface 30 is used to display the system operation status and receive operation instructions.

[0077] The combustion optimization control system of the methanol pure oxygen combustion exhaust gas recirculation internal combustion engine also includes: a high-precision thermocouple, a piezoresistive pressure sensor, a Coriolis mass flowmeter and an infrared spectrometer;

[0078] The high-precision thermocouple is used to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber and calculate the average temperature as the combustion chamber temperature;

[0079] The piezoresistive pressure sensor is used to measure the combustion chamber pressure and obtain the combustion chamber pressure;

[0080] The Coriolis mass flowmeter is used to measure the methanol flow rate and the oxygen flow rate respectively;

[0081] The infrared spectrometer is used for real-time analysis of exhaust gas components.

[0082] The present invention adopts PID control algorithm to construct a multivariable mathematical model and introduces adaptive control calculation. This method can effectively handle the complexity and strong coupling characteristics in the methanol pure oxygen combustion process and improve the adaptability and accuracy of the control system.

[0083] At the same time, comprehensive control evaluation parameters are introduced to set the comprehensive performance index function F, and the optimal EGR rate in the comprehensive performance index function F is found through an optimization algorithm (such as a gradient descent method). The present invention gives full play to the potential of exhaust gas recirculation technology in a methanol pure oxygen combustion engine, and further improves the performance and emission control capability of the engine.

[0084] Therefore, the present invention adopts a cyclic optimization method, by continuously monitoring the adjusted engine performance and returning to the parameter collection step, to achieve continuous optimization and self-adjustment of the control system. The control system of the present invention can dynamically adjust the target parameters according to the current demand input command, such as setting the target combustion chamber temperature and target nitrogen oxide emissions, so as to adapt to different working conditions and environmental changes.

[0085] The present invention effectively solves the main problems faced by traditional methanol pure oxygen combustion internal combustion engines, achieves stable improvement in combustion efficiency, effective control of emissions, improvement in fuel economy, and enhanced intelligence and adaptability of the control system. This comprehensive optimization method provides a strong guarantee for the efficient, clean and economical operation of methanol pure oxygen combustion exhaust gas recirculation internal combustion engines.

[0086] The internal combustion engine mentioned in the embodiment of the present invention adopts a multivariable adaptive control algorithm to calculate the adjustment amount of methanol flow, oxygen flow and exhaust gas recirculation rate; at the same time, the control system is adjusted according to the feedback of the temperature sensor data, and finally the engine reaches the optimal state. For details, see Example 2.

[0087] Embodiment 2

[0088] See also Figure 2 Embodiment 2 of the present invention provides a combustion optimization control method for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine, comprising the following steps:

[0089] S1. Collect engine operating parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow rate, oxygen flow rate and exhaust gas composition;

[0090] S2. Calculating the current actual combustion efficiency based on the engine operating parameters, and then detecting and obtaining the actual nitrogen oxide emission concentration;

[0091] S3, according to the preset target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target , calculate the error of the control variable;

[0092] S4, under the preset condition of limiting the methanol flow rate, using a multivariable adaptive control algorithm, calculating the adjustment amount of the methanol flow rate, the oxygen flow rate and the combustion chamber temperature; under the preset condition of not limiting the methanol flow rate, using the optimal control parameter of the exhaust gas recirculation rate EGR of the next control timing node to calculate the adjustment amount of the valve opening; executing the adjustment amount, adjusting the corresponding control device actuator; the control device actuator includes a switch valve and a pump and a flow valve and a combustion temperature controller;

[0093] Preferably, as an implementable embodiment, the operating parameters collected in step S1 also include:

[0094] S11, using a high-precision thermocouple to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber and calculate the average temperature as the combustion chamber temperature;

[0095] S12, measuring the combustion chamber pressure using a piezoresistive pressure sensor to obtain the combustion chamber pressure;

[0096] S13, using a Coriolis mass flowmeter to measure the methanol flow rate and the oxygen flow rate respectively;

[0097] S14. Analyze the exhaust gas components in real time by using an infrared spectrometer to obtain exhaust gas component analysis results.

[0098] The exhaust gas components are analyzed in real time by an infrared spectrometer to obtain exhaust gas component analysis results (assuming that there are three exhaust gas component analysis results, namely CO, CO2 and O2 and their respective concentrations).

[0099] Preferably, as an implementable embodiment, the method for calculating the combustion efficiency in step S2 includes:

[0100] S21. Calculate theoretical thermal efficiency based on combustion chamber temperature and combustion chamber pressure;

[0101] S22, calculating the current actual air-fuel ratio using the detection ratio of the methanol flow rate and the oxygen flow rate; and then calculating the corrected current air-fuel ratio based on the current actual air-fuel ratio, the preset ideal air-fuel ratio and the adjustment parameters;

[0102] Corrected current air-fuel ratio

[0103] Among them: AFR 实际 : The actual air-fuel ratio calculated in step S22;

[0104] AFR 理想 : ideal air-fuel ratio;

[0105] σ: represents a tuning parameter;

[0106] S23, calculating the proportion of incompletely burned fuel according to the exhaust gas composition analysis result;

[0107] S24, comprehensively calculating the above parameters, namely the theoretical thermal efficiency, the corrected current air-fuel ratio and the proportion of incompletely burned fuel, to output the actual combustion efficiency and obtain the actual combustion efficiency.

[0108] The actual combustion efficiency is calculated as: 实际( =η 理论( ·k 空燃比( 1-r 末完全燃烧 ;

[0109] η 实际 : The actual combustion efficiency finally calculated;

[0110] η 理论 : Theoretical thermal efficiency;

[0111] k 空燃比: Corrected current air-fuel ratio k 空燃比 ;

[0112] r 末完全燃烧 : Indicates the proportion of fuel that is not completely burned.

[0113] S combines the above parameters to specifically refer to the comprehensive use of the theoretical thermal efficiency, the corrected current air-fuel ratio and the proportion of incompletely burned fuel to calculate the output of the actual combustion efficiency.

[0114] In the specific technical solution of this embodiment, during the execution of step S23, the proportion of incompletely burned fuel is calculated according to the exhaust gas component analysis result, specifically:

[0115] Example: Calculating the proportion of fuel that is not completely burned

[0116] Assume that this technical solution conducts a combustion test and obtains the following exhaust gas composition analysis results (also possible):

[0117] CO (nitric oxide) concentration: 1000ppm;

[0118] CO2 (carbon dioxide) concentration: 12%;

[0119] O2 (oxygen) concentration: 3%;

[0120] Explanation: The reason why the technical solution of the embodiment of the present application allows the exhaust gas (for example: CO2) to be recycled is that research has found that it has the following technical effects: methanol and pure oxygen are mixed and burned in the cylinder to generate high-temperature carbon dioxide and water vapor. When the high-temperature carbon dioxide and water vapor are input as circulating gas media, they will be mixed with oxygen to reduce the concentration of pure oxygen, thereby ensuring the volume of gas entering the engine cylinder (that is, by mixing high-temperature carbon dioxide and water vapor with oxygen, the concentration of oxygen entering the cylinder can be reduced. This is because carbon dioxide and water vapor occupy a part of the volume, reducing the volume ratio of pure oxygen. Although the oxygen concentration is reduced, the total volume of gas entering the engine cylinder can be ensured to remain unchanged or increase appropriately by recycling the exhaust gas. This can maintain the power output of the engine).

[0121] On the other hand, by recycling the high-temperature tail gas (such as CO2) after the combustion, that is, these high-temperature gases can be used as circulating gas medium. The utilization rate of fuel can be further improved. On the other hand, recycling tail gas can reduce carbon dioxide emissions because part of the carbon dioxide is reused instead of being directly discharged into the atmosphere.

[0122] 1. First calculate the theoretical incompletely burned fuel ratio:

[0123] The proportion of incompletely burned fuel can usually be estimated by the concentration of CO and CO2. The following formula can be used for this technical solution:

[0124]

[0125] in:

[0126] C CO is the CO concentration (ppm).

[0127] is the CO2 concentration (expressed in ppm).

[0128] 2.Convert concentration units:

[0129] First, this technical solution needs to convert the CO2 concentration into ppm:

[0130]

[0131] 3. Calculate the proportion of fuel that is not completely burned

[0132] Substituting the concentration into the formula:

[0133] r 末完全燃烧 =10001000+120000=1000121000≈0.00826;

[0134] 4. Convert to percentage:

[0135] Convert ratio to percentage: r 末完全燃烧 ≈0.826%;

[0136] From the above examples, it can be seen that by analyzing the exhaust gas composition to obtain the exhaust gas composition analysis result, and then continuing to perform the software calculation operation, the present application example obtains that the proportion of incompletely burned fuel is about 0.826%. This value can be used for further combustion efficiency calculation and optimization.

[0137] Explanation: In the specific technical solution of the embodiment of the present application, due to

[0138] The calculation formula for actual combustion efficiency is: 实际( =η 理论( ·k 空燃比( 1-r 末完全燃烧 ;

[0139] Variable description of the above calculation formula:

[0140] η 实际 : The actual combustion efficiency finally calculated.

[0141] η 理论 : Theoretical thermal efficiency calculated in step S21.

[0142] k 空燃比 : The data calculated based on the correction coefficient of the current air-fuel ratio, that is, the corrected current air-fuel ratio k 空燃比 .

[0143] r 末完全燃烧 : Indicates the proportion of fuel that is not completely burned.

[0144] Specific implementation process description: 理论 Calculated by combustion chamber temperature and combustion chamber pressure; the corrected current air-fuel ratio is k 空燃比 , is calculated based on the correction coefficient of the current air-fuel ratio and the preset ideal air-fuel ratio and adjustment parameter output. The calculation formula is:

[0145] Corrected current air-fuel ratio

[0146] Among them: AFR 实际 : The current air-fuel ratio calculated in step S22. AFR 理想 : ideal air-fuel ratio (usually about 1.5 for methanol). σ: represents an adjustment parameter (for example, it can be 0.2). 末完全燃烧 : The proportion of incompletely burned fuel calculated in step S23.

[0147] During the execution of the above step S24, n 实际( =η 理论( ·k 空燃比( 1-r 末完全燃烧 The above processing process refers to the theoretical efficiency, the influence of the corrected air-fuel ratio, and the efficiency loss caused by incomplete combustion. Through this information processing process, the embodiment of the present application obtains a more accurate estimate of the actual combustion efficiency.

[0148] Preferably, as an implementation scheme, step S3 is based on the preset target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target , calculate the error of the control variable; the step S4 uses a multivariable adaptive control algorithm to calculate the adjustment amount of methanol flow, oxygen flow and combustion chamber temperature, including the following steps:

[0149] S41, implement PID control algorithm for each control variable to build a multivariable mathematical model, the control variable includes methanol flow rate u m , oxygen flow u o , combustion chamber temperature u T ;

[0150] The calculation formula of the multivariate mathematical model is:

[0151]

[0152] Among them, i∈m,o,T, respectively represent the methanol flow rate, oxygen flow rate and combustion chamber temperature;

[0153] S42, performing adaptive control calculation on the multivariable mathematical model:

[0154]

[0155]

[0156]

[0157] Among them, K p,i (t+1) is the value of the proportional gain of the ith controlled variable (such as methanol flow, oxygen flow or combustion chamber temperature) at time t+1. It is used to control the response of the system to the current error.

[0158] K i,i (t+1) is the value of the integral gain of the i-th control variable at time t+1t+1t+1. The integral gain is used to eliminate steady-state errors, that is, to adjust the output by accumulating past errors.

[0159] K d,i (t+1 is the value of the derivative gain of the ith control variable at time t+1. The derivative gain is used to predict future error changes and help reduce the overshoot of the system;

[0160] α p ,α i ,α d are their respective learning rates, and E is the preset threshold index of the comprehensive performance of fuel saving;

[0161] α p : The learning rate of the proportional gain. It controls the adjustment amplitude of the proportional gain during the update process, affecting the speed and stability of system convergence.

[0162] ai: Learning rate of integral gain. It controls the adjustment amplitude of integral gain during the update process and affects the improvement speed of steady-state performance.

[0163] ad: learning rate of the differential gain. It controls the adjustment amplitude of the differential gain during the update process and affects the sensitivity to the change of error.

[0164] E is the preset threshold indicator of the comprehensive performance of fuel saving. It is an objective function to measure the performance of the system, and the update of PID parameters will be based on the gradient information of this indicator.

[0165] Then they are the partial derivatives of the performance index E with respect to the proportional gain, integral gain and differential gain respectively;

[0166] S43, obtain the current demand input instruction, analyze the current demand input instruction, obtain the setting target combustion chamber temperature T targe t and target nitrogen oxide emission concentration u o，target And the target methanol flow rate u m，target Instruction information; record the current methanol flow u m (t), oxygen flow u o (t) and combustion chamber temperature u T (t); then calculate the error of the current control variable based on the current record information and instruction information:

[0167] e m =u m，target -u m (t);

[0168] e o =u o，target -u o (t);

[0169] e T =T target -u T (t);

[0170] Obtain the coupling effect dynamics G of each built-in control variable of the system: the coupling effect matrix G of each built-in control variable of the system is as follows:

[0171]

[0172] S44, input the error of the control variable into the coupling effect matrix G, and then calculate the increment of each control variable to adjust the control variable (i.e., the control increment Δu of the output methanol flow rate) m and the control increment Δu of oxygen flow o and the control increment Δu of the combustion chamber temperature T ), adjust the control variables by the increment of each control variable and record the current methanol flow u m (t), oxygen flow u o (t) and combustion chamber temperature u T (t) Perform a sum operation to obtain and update the control variable of the next control timing node:

[0173] u m(t+1)=u m (t)+Δu m ;

[0174] u o (t+1)=u o (t)+Δu o ;

[0175] u T (t+1)=u T (t)+Δu T .

[0176] When executing the current methanol flow to update the control variable of the next control timing node, real-time judgment u m Is (t+1) greater than the maximum methanol flow rate u? m,max ; if u m (t+1)> Maximum methanol flow rate u m,max , then u m (t+1) = Maximum methanol flow rate u m，max .

[0177] In the above execution process, sensor data acquisition, that is, obtaining data from temperature sensors, pressure sensors, flow sensors, etc. Then the above error calculation is performed: the difference between the actual value and the set target value is calculated. The control amount that needs to be adjusted (i.e. the control increment Δu of the methanol flow) is calculated according to the control algorithm. m and the control increment Δu of oxygen flow o and the control increment Δu of the combustion chamber temperature T ). Finally, the execution control is implemented: that is, the control is implemented by adjusting the actuators such as valves and pumps.

[0178] For example: Assume that in the above example, there is a methanol-burning internal combustion engine, and the goal is to optimize its operating performance so that it can achieve the best combustion efficiency and emission control under specific load conditions. Here is how to apply the above solution to this case:

[0179] Get the current demand input command, analyze the current demand input command, and obtain the set target combustion chamber temperature T target and target nitrogen oxide emissions NO x，target And the target methanol flow rate u m,target The command information and setting of methanol flow rate u m,max The maximum value of

[0180] In the initial state, record the current methanol flow u m (t), oxygen flow u o (t) and combustion chamber temperature u T (t). Calculate the current error: e m =um,target -u m (t); e o =u o,target -u o (t); e T =T target -u T (t);

[0181] Calculate the current multivariable control error, and output the control increment Δu of the methanol flow rate according to the current multivariable control error and the coupling effect matrix G of each control variable built into the system. m and the control increment Δu of oxygen flow o and the control increment Δu of the combustion chamber temperature T : Calculate Δu using the coupling effect of each control variable built into the system m , Δu o , Δu T For example, assuming that the coupling effect dynamics G of each control variable built into the system is known, calculate the required control increment. Where G is the 3x3 system built-in parameter factor coupling matrix.

[0182] According to the calculation, the incremental adjustment control variable of the next control timing node (i.e. the next control moment) is obtained: m (t+1)=u m (t)+Δu m ;u o (t+1)=u o (t)+Δu o ;u T (t+1)=u T (t)+Δu T ;

[0183] Explanation: In the multivariable control algorithm, Δu m Represents the control increment of methanol flow. It is achieved by adjusting the control error (i.e., the difference between the actual output and the target output). Specifically, the control system calculates the methanol flow that needs to be adjusted based on the dynamic characteristics of the system and the error feedback to make the system closer to the set target.

[0184] When executing the current methanol flow to update the control variable of the next control timing node, real-time judgment u m Is (t+1) greater than the maximum methanol flow rate u? m,max ; if u m (t+1)> Maximum methanol flow rate u m,max , then u m (t+1) = Maximum methanol flow rate u m,max .

[0185] In the multivariable control algorithm, the control increments are described using the following matrix equation:

[0186]

[0187] Here G is a dynamic matrix that includes the coupling effect of the system on each control variable. By solving this equation, the adjustment amount of each control variable (such as Δu m ). This indicates the adjustments that need to be made to each control variable in order to eliminate the error e.

[0188] In another synchronous specific implementation, each control variable can also be adjusted by a comprehensive performance index function; after step S44, it also includes: further determining whether a comprehensive control operation instruction is received, and if a comprehensive control operation instruction is received, setting a comprehensive performance index function F;

[0189] By maximizing the comprehensive performance index function F, the optimal control parameters of the exhaust gas recirculation rate EGR at the next control timing node are solved.

[0190] Preferably, as an implementable embodiment; the setting of the comprehensive performance index function F; utilizing the above-mentioned comprehensive performance index function F to maximize and solve the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node, specifically includes:

[0191] S45: Setting comprehensive performance index function F:

[0192] F = w1*η exhaust methanol detection side combustion efficiency + w2*(1-|φ-φopt|)+w3*(1-|T-Topt| / Tmax)-w4*(NOx(t) / NOx,target)-w5*(FC / FCbaseline)+w6*(1-|EGR-EGRopt| / EGRmax);

[0193] η is the combustion efficiency of the exhaust methanol detection side;

[0194] φ: current equivalence ratio;

[0195] φ opt : Optimal equivalence ratio;

[0196] T: current combustion chamber temperature;

[0197] T opt : Optimal combustion chamber temperature;

[0198] T max : Maximum permissible combustion chamber temperature;

[0199] NOx(t): current nitrogen oxide emissions;

[0200] NOx target : Target nitrogen oxide emissions;

[0201] FC: current fuel consumption rate;

[0202] FC bascline : Baseline fuel consumption rate;

[0203] EGR: current exhaust gas recirculation rate;

[0204] EGR opt : Optimal exhaust gas recirculation rate;

[0205] EGR max : Maximum allowable exhaust gas recirculation rate;

[0206] S46: Define the calculation method of each parameter:

[0207] First, define η tail gas methanol detection side combustion efficiency = (LHVin-LHV_out) / LHVin;

[0208] Among them, LHV_in is the lower heating value of methanol entering the combustion chamber, and LHV_out is the lower heating value of unburned methanol in the tail gas;

[0209] Then define the equivalence ratio φ:

[0210] Equivalence ratio φ=(m f uel / m o xygen) / (m f uel / m o xygen)stoich iometric;

[0211] Where: φ: represents the equivalent ratio; m f uel: represents the fuel mass; m o xygen: represents the mass of oxygen;

[0212] (m f uel / m o xygen)stoich iometric: represents the theoretical stoichiometric ratio;

[0213] Then directly obtain the actual combustion chamber temperature T and the actual nitrogen oxide emission N0x(t); obtain the optimal combustion chamber temperature T opt and the maximum permissible combustion chamber temperature Tmax and the target nitrogen oxide emissions NOx target

[0214] Get the base fuel consumption rate, and then calculate the fuel consumption rate FC: FC = m f uel / Poweroutput;

[0215] Where, FC: represents fuel consumption rate; m f uel: represents fuel quality; Poweroutput: represents engine output power;

[0216] mfuel: represents the fuel mass, usually expressed in grams per second (g / s) or kilograms per hour (kg / h)

[0217] Poweroutput: represents the engine output power, usually expressed in kilowatts (kW);

[0218] This formula calculates the amount of fuel consumed per unit of power output, usually expressed in grams per kilowatt-hour (g / kWh). It is an important indicator of engine fuel efficiency, and the lower the value, the higher the fuel efficiency of the engine.

[0219] Calculate the EGR rate: EGR = m_recirculated / m_total_intake;

[0220] Among them, EGR: represents the exhaust gas recirculation rate; m_recirculated: represents the mass of recirculated exhaust gas; m_total_intake: represents the total mass of intake air (including fresh intake air and recirculated exhaust gas);

[0221] This formula calculates the percentage of total intake air that is recirculated. EGR is usually expressed as a percentage and is used to control the engine's combustion temperature and nitrogen oxide (NOx) emissions. Higher EGR rates can reduce combustion temperatures, thereby reducing NOx formation, but may also affect engine performance and efficiency.

[0222] Obtain the specific values ​​of the matching weight coefficients w1-w6, and substitute all parameters into the formula comprehensive performance index function F to calculate the F value under the current working conditions;

[0223] S46. Optimizing the EGR rate to solve the output maximization comprehensive performance index F: First, obtain the search range and step size that define the EGR rate;

[0224] EGRmin=x1%, EGRmax=x2%, step length ΔEGR=n%;

[0225] According to the above EGRmin, EGRmax, and ΔEGR, the gradient descent method is used to optimize EGR. During the specific optimization, the set learning rate learning_rate, the maximum number of iterations max_iterations, and the tolerance tolerance are obtained to iteratively update the EGR value.

[0226] In each iteration, the gradient of the maximum comprehensive performance index F with respect to EGR is calculated, the EGR value is updated, and it is checked whether the termination condition is met. At the same time, the EGR value is iteratively adjusted in this process until a local maximum value is found and recorded as the optimal EGR value;

[0227] The optimal EGR value is taken as the target value, and the optimal actuator control parameters corresponding to the current target value are analyzed and applied to the engine control system.

[0228] In the process of executing a specific case, determine the weight coefficient: obtain the corresponding weight coefficient according to the engine type matching. For example, determine the values ​​of w1 to w6 through experiments and expert experience. For example:

[0229] w1=0.3,w2=0.15,w3=0.15,w4=0.2,w5=0.1,w6=0.1

[0230] Calculate the F value: Substitute all parameters into the formula comprehensive performance index function F and calculate the F value under the current working conditions.

[0231] S46. Optimize EGR rate to maximize the comprehensive performance index F:

[0232] Define the search range and step size for the EGR rate:

[0233] EGRmin=0%,EGRmax=30%,step length ΔEGR=0.5%;

[0234] For example, the code to implement the golden section search algorithm:

[0235] defgolden_section_search(f,a,b,tol=1e-5):

[0236] gr=Sqrt(5)+1) / 2#Golden ratio c=b-(ba) / gr

[0237] d=a+(ba) / grawhileabs(ba)>tol:iff(c)>f(d):b=d

[0238] else:

[0239] a=c

[0240] c=b-(ba) / gr

[0241] d = a + (ba) / grreturn (b + a) / 2 # define the objective function (negative F, because this embodiment is to maximize F) defobjective (EGR):

[0242] return-calculate_F(EGR)#calculate_F function implements F calculation in S45#

[0243] Use golden section search to find the optimal EGREGR_optimal=

[0244] golden_section_search(objective,EGRmin,EGRmax)

[0245] Real-time EGR control strategy:

[0246] According to the above EGRmin, EGRmax, and ΔEGR, the gradient descent method is used to optimize EGR. During the specific optimization, the set learning rate learning_rate, the maximum number of iterations max_iterations, and the tolerance tolerance are obtained to iteratively update the EGR value.

[0247] In each iteration, the gradient of the maximum comprehensive performance index F with respect to EGR is calculated, the EGR value is updated, and it is checked whether the termination condition is met. At the same time, the EGR value is iteratively adjusted in this process until a local maximum value is found and recorded as the optimal EGR value;

[0248] The optimal EGR value is taken as the target value, and the optimal actuator control parameter (such as valve opening) corresponding to the current target value is analyzed and applied to the engine control system.

[0249] For example: the technical solution sets the EGR search range, such as EGRmin = 0% and EGRmax = 20%. Select an initial EGR value, such as EGR = 5%.

[0250] Use the gradient descent method to optimize EGR. In this embodiment, the learning rate learning_rate=

[0251] 0.01, the maximum number of iterations max_iterations = 100, and a tolerance tolerance =

[0252] 0.001. In each iteration, the gradient of F with respect to EGR is calculated, the EGR value is updated, and the termination condition is checked. This process will iteratively adjust EGR until a local maximum is found. Once the optimal EGR value is found, for example, EGR_optimal = 12%, it is applied to the engine control system, and the current target value is analyzed to correspond to the optimal actuator control parameter (such as valve opening) applied to the engine control system to achieve the control strategy of this optimal value.

[0253] EGR_optimal represents the optimal exhaust gas recirculation rate that can maximize the comprehensive performance index function F under given conditions. After obtaining the EGR_optimal value, the optimal value control strategy is implemented through the actuator control parameters to achieve overall optimization of engine performance. It helps to better balance the control of nitrogen oxide (NOx) emissions and combustion efficiency. The optimal EGR value takes into account the balance of multiple performance indicators.

[0254] For example:

[0255] The current engine parameters are as follows:

[0256] Combustion efficiency η: 85%;

[0257] Equivalence ratio φ: 1.2;

[0258] Combustion chamber temperature T: 1800K;

[0259] Optimal combustion temperature Topt: 1750K;

[0260] Maximum allowable combustion temperature Tmax: 2000K;

[0261] Current nitrogen oxide emissions NOx(t): 100ppm;

[0262] Target nitrogen oxide emission NOx, target: 50ppm;

[0263] Current fuel consumption rate FC: 250g / kWh;

[0264] Baseline fuel consumption rate FCbaseline: 270g / kWh;

[0265] The weight coefficients w1-w5 are set according to actual needs and the judgment of engineers, for example:

[0266] w1 = 0.4 (focus on combustion efficiency);

[0267] w2 = 0.2 (medium emphasis on equivalence ratio);

[0268] w3 = 0.1 (lower emphasis on temperature deviation);

[0269] w4 = 0.2 (focus on nitrogen oxide emissions);

[0270] w5=0.1 (focus on fuel consumption);

[0271] Now, this embodiment applies S45 and S46 to optimize EGR control:

[0272] First, calculate the comprehensive performance index function F:

[0273] F=(0.4*0.85)+(0.2*(1-|1.2-1|))+(0.1*(1-|1800-1750| / 2000))-(0.2*(100 / 50))-(0.1*(250 / 270));

[0274] Then, this embodiment sets the search range of EGR, such as EGRmin=0% and EGRmax=20%. Select an initial EGR value, such as EGR=5%. Use gradient descent to optimize EGR. This embodiment can set the learning rate learning_rate=0.01, the maximum number of iterations max_iterations=100, and a tolerance tolerance=0.001. In each iteration, the gradient of F with respect to EGR is calculated, the EGR value is updated, and the termination condition is checked whether it is met. This process will iteratively adjust EGR until a local maximum is found. Once the optimal EGR value is found, such as EGR_optimal=12%, it is applied to the engine control system and the EGR valve opening is adjusted to achieve this optimal value.

[0275] Based on reality: Research has found that if there is still too much methanol in the exhaust gas, it may cause the following problems: 1. Increased nitrogen oxide (NOx) emissions; 2. Temperature increase: The presence of methanol in the exhaust gas may cause the combustion chamber temperature to increase, increase the generation of NOx, cause environmental pollution and non-compliance with regulations. Engine performance problems; 3. Power loss: Unburned methanol may affect the overall performance and power output of the engine, resulting in slower acceleration and response. 4. Too much unburned methanol may cause carbon deposition, which in turn affects combustion efficiency (comprehensive performance indicator function F). 4. Too much methanol may affect the performance of the catalyst, resulting in a decrease in the efficiency of the catalytic converter, thereby affecting the comprehensive performance indicator function F.

[0276] However, further research found that the above 1-3 problems are long-term problems and will not affect engine performance in the short term. However, carbon deposits and the performance of the catalyst have a greater impact on the comprehensive performance index function F in the short term.

[0277] In the further research process, it is found that even if the methanol flow rate is not limited, excessive methanol flow rate still affects the comprehensive performance index function F of the above steps; an improved design is proposed, and then the improved comprehensive performance index function F' is output;

[0278] In order to more comprehensively consider the impact of introducing too much methanol on the degradation of catalyst performance, the increase of carbon deposits and the attenuation of combustion efficiency, we will redesign step S45, i.e. the modified step S50. The maximum working efficiency of the catalyst, the working efficiency of the current catalyst, and the influence factor of carbon deposits on combustion efficiency are introduced into the comprehensive performance index function. The following is the redesigned content:

[0279] Execute the following step S50: reset the comprehensive performance index function F', and then recalculate and iteratively adjust the EGR:

[0280] The comprehensive performance index function F' is defined as:

[0281]

[0282] Parameter Description:

[0283] w1,w2,w3,w4,w5,w6,w7,w8w_1,w_2,w_3,w_4,w_5,w_6,w_7,w_8w1

[0284] , w2, w3, w4, w5, w6, w7, w8: weight coefficients, used to adjust the influence of each indicator on the comprehensive performance, and need to be set according to the specific application.

[0285] φ: Current equivalence ratio, which indicates the ratio of fuel to oxygen. The ideal value should be close to the theoretical value.

[0286] φ opt : The optimal equivalence ratio is determined through experiments or model analysis.

[0287] T: Current combustion chamber temperature, which affects combustion efficiency and emissions.

[0288] T opt : The optimal combustion chamber temperature is determined through experiments.

[0289] T max : Maximum permissible combustion chamber temperature, above which engine damage or excessive NOx emissions may result.

[0290] NOx(t): Current nitrogen oxide emissions must be controlled within the regulatory range.

[0291] NOx target : Set target nitrogen oxide emissions.

[0292] FC: Current fuel consumption rate, reflecting fuel efficiency.

[0293] EGR: The current exhaust gas recirculation rate, which directly affects the combustion characteristics and emission levels.

[0294] EGRopt : The optimal exhaust gas recirculation rate is determined by the optimization algorithm.

[0295] EGR max : Maximum allowed exhaust gas recirculation rate.

[0296] C max :The maximum working efficiency of the catalyst, determined based on the design and material properties of the catalyst.

[0297] C current :The working efficiency of the current catalyst needs to be monitored regularly to evaluate the catalyst performance.

[0298] S max : The maximum carbon deposit tolerance of the catalyst refers to the maximum amount of carbon deposit that the catalyst can accept while ensuring performance. current :The current carbon deposit level of the catalyst affects the effectiveness and combustion efficiency of the catalyst.

[0299] The technical solution adopted in the embodiment of the present invention takes into account the influence of catalyst performance and carbon deposition;

[0300] In the new comprehensive performance indicator function, two new items are added:

[0301] 1. Impact of catalyst working efficiency:

[0302] Import Item Used to evaluate the impact of catalyst performance degradation. When the current catalyst efficiency is lower than the maximum efficiency, this item will have a negative impact on the comprehensive performance index F, prompting the system to adjust operations to restore catalyst performance.

[0303] 2. Impact of carbon deposition:

[0304] Import Item Used to evaluate the effect of carbon deposits on catalyst performance. Increased carbon deposits can lead to decreased catalyst activity, thus affecting combustion efficiency and emission control.

[0305] In summary, the potential impact of excessive methanol on catalyst performance degradation and increased carbon deposits has been fully considered through the redesign of the comprehensive performance index function FFF. This improvement will help achieve more refined engine control, ensuring that combustion efficiency and catalyst performance are optimized while meeting environmental regulations. By dynamically adjusting the EGR rate and other control parameters, emissions can be effectively reduced and the economy and reliability of the overall system can be improved.

[0306] Then recalculating and iteratively adjusting the EGR means that after executing step S50, returning to execute step S46, that is, optimizing the EGR rate to solve the output maximization comprehensive performance index F, and optimally obtaining the updated optimal EGR target value.

[0307] The control method of the methanol-pure oxygen combustion exhaust gas recirculation internal combustion engine adopted in the embodiment of the present invention improves the engine power and thermal efficiency through the mixed combustion technology of methanol and pure oxygen with the engine's high-temperature exhaust gas, realizes the recycling of the internal combustion engine's high-temperature exhaust gas, and especially carries out in-depth control in a specific direction around the reasonable ratio control of the methanol flow rate, thereby ensuring the comprehensive combustion performance of the engine.

[0308] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0309] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A combustion optimization control system for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine, characterized in that: include: Multiple sensors are used to collect engine operating parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow, oxygen flow and exhaust gas composition; based on the engine operating parameters, calculate the current actual combustion efficiency, and then detect and obtain the actual nitrogen oxide emission concentration; The central control unit is used to set the target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target , calculate the error of the control variable; Under the preset condition of limiting the methanol flow rate, using a multivariable adaptive control algorithm, the adjustment amount of the methanol flow rate, the oxygen flow rate and the combustion chamber temperature is calculated; under the preset condition of not limiting the methanol flow rate, the adjustment amount of the valve opening is calculated by solving the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node; the adjustment amount is executed to adjust the corresponding control device actuator; the control device actuator includes a switch valve and a pump, a flow valve and a combustion temperature controller; Human-computer interaction interface, used to display system operation status and receive operation instructions.

2. The combustion optimization control system of the methanol pure oxygen combustion exhaust gas recirculation internal combustion engine according to claim 1, characterized in that: Also includes: High-precision thermocouples, piezoresistive pressure sensors, Coriolis mass flow meters and infrared spectrometers; The high-precision thermocouple is used to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber and calculate the average temperature as the combustion chamber temperature; The piezoresistive pressure sensor is used to measure the combustion chamber pressure and obtain the combustion chamber pressure; The Coriolis mass flowmeter is used to measure the methanol flow rate and the oxygen flow rate respectively; The infrared spectrometer is used for real-time analysis of exhaust gas components.

3. A combustion optimization control method for a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine, characterized in that: The control process is implemented by using a combustion optimization control system of a methanol pure oxygen combustion exhaust gas recirculation internal combustion engine that implements the method described in any one of claims 1 to 2, and includes the following steps: S1. Collect engine operating parameters, including combustion chamber temperature, combustion chamber pressure, methanol flow rate, oxygen flow rate and exhaust gas composition; S2. Calculating the current actual combustion efficiency based on the engine operating parameters, and then detecting and obtaining the actual nitrogen oxide emission concentration; S3, according to the preset target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target , calculate the error of the control variable; S4. Under the preset condition of limiting the methanol flow rate, use a multivariable adaptive control algorithm to calculate the adjustment amount of the methanol flow rate, oxygen flow rate and combustion chamber temperature; under the preset condition of not limiting the methanol flow rate, use the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node to calculate the adjustment amount of the valve opening; execute the adjustment amount and adjust the corresponding control device actuator; the control device actuator includes a switch valve and a pump, a flow valve and a combustion temperature controller.

4. The method according to claim 3, characterized in that The operating parameters collected in step S1 also include: S11, using a high-precision thermocouple to measure the multi-point combustion chamber temperature, obtain the multi-point combustion chamber temperature of the current combustion chamber and calculate the average temperature as the combustion chamber temperature; S12, measuring the combustion chamber pressure using a piezoresistive pressure sensor to obtain the combustion chamber pressure; S13, using a Coriolis mass flowmeter to measure the methanol flow rate and the oxygen flow rate respectively; S14. Analyze the exhaust gas components in real time by using an infrared spectrometer to obtain exhaust gas component analysis results.

5. The method according to claim 4, characterized in that The method for calculating the combustion efficiency in step S2 includes: S21. Calculate theoretical thermal efficiency based on combustion chamber temperature and combustion chamber pressure; S22, calculating the current actual air-fuel ratio using the detection ratio of the methanol flow rate and the oxygen flow rate; and then calculating the corrected current air-fuel ratio based on the current actual air-fuel ratio, the preset ideal air-fuel ratio and the adjustment parameters; Among them: AFR 实际 : The actual air-fuel ratio calculated in step S22; AFR 理想 : ideal air-fuel ratio; σ: represents a tuning parameter; S23, calculating the proportion of incompletely burned fuel according to the exhaust gas composition analysis result; S24, outputting the actual combustion efficiency by comprehensively calculating the theoretical thermal efficiency, the corrected current air-fuel ratio, and the proportion of fuel that is not completely burned, to obtain the actual combustion efficiency. The calculation formula for actual combustion efficiency is: 实际( =η 理论( ·k 空燃比( ·(1-r 末完全燃烧 ); η 实际 : The actual combustion efficiency finally calculated; η 理论 : Theoretical thermal efficiency; k 空燃比 : Corrected current air-fuel ratio k 空燃比 ; r 末完全燃烧 : Indicates the proportion of fuel that is not completely burned.

6. The method according to claim 5, characterized in that Step S3 is based on the preset target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target , calculate the error of the control variable; the step S4 uses a multivariable adaptive control algorithm to calculate the adjustment amount of methanol flow, oxygen flow and combustion chamber temperature, including the following steps: S41, implement PID control algorithm for each control variable to build a multivariable mathematical model, the control variable includes methanol flow rate u m , oxygen flow u o , combustion chamber temperature u T ; The calculation formula of the multivariate mathematical model is: Among them, i∈m,o,T, respectively represent the methanol flow rate, oxygen flow rate and combustion chamber temperature; S42, performing adaptive control calculation on the multivariable mathematical model: Among them, K p,i (t+1) is the value of the proportional gain of the ith controlled variable (such as methanol flow, oxygen flow or combustion chamber temperature) at time t+1. It is used to control the response of the system to the current error. K i,i (t+1) is the value of the integral gain of the i-th control variable at time t+1t+1t+1. The integral gain is used to eliminate steady-state errors, that is, to adjust the output by accumulating past errors. K d,i (t+1) is the value of the derivative gain of the ith control variable at time t+1. The derivative gain is used to predict future error changes and help reduce the overshoot of the system; α p ,α i ,α d are their respective learning rates, and E is the preset threshold index of the comprehensive performance of fuel saving; Then they are the partial derivatives of the performance index E with respect to the proportional gain, integral gain and differential gain respectively; S43, obtain the current demand input instruction, analyze the current demand input instruction, obtain the setting target combustion chamber temperature T target and target nitrogen oxide emission concentration u o,target And the target methanol flow rate u m,target Instruction information; record the current methanol flow u m (t), oxygen flow u o (t) and combustion chamber temperature u T (t); then calculate the error of the current control variable based on the current record information and instruction information: e m =u m,target -u m (t); e o =u o，target -u o (t); e T =T target -u T (t); Obtain the coupling effect dynamics G of each built-in control variable of the system: the coupling effect matrix G of each built-in control variable of the system is as follows: S44, input the error of the control variable into the coupling effect matrix G, and then calculate the increment of each control variable to adjust the control variable (i.e., the control increment Δu of the output methanol flow rate) m and the control increment Δu of oxygen flow o and the control increment Δu of the combustion chamber temperature T ), adjust the control variables by the increment of each control variable and record the current methanol flow u m (t), oxygen flow u o (t) and combustion chamber temperature u T (t) Perform a sum operation to obtain and update the control variable of the next control timing node: u m (t+1)=u m (t)+△u m ; u o (t+1)=u o (t)+△u o ; u T (t+1)=u T (t)+△u T 。 When executing the current methanol flow to update the control variable of the next control timing node, real-time judgment u m Is (t+1) greater than the maximum methanol flow rate u? m,max ; if u m (t+1)>Maximum methanol flow rate u m,max , then u m (t+1) = Maximum methanol flow rate u m,max .

7. The method according to claim 6, characterized in that After step S44, the method further includes: Further determining whether an unrestricted methanol flow comprehensive control operation instruction is received, and if a restricted methanol flow comprehensive control operation instruction is received, setting a comprehensive performance index function F; A comprehensive performance index function F is set; and the optimal control parameters of the exhaust gas recirculation rate EGR at the next control timing node are solved by maximizing the comprehensive performance index function F.

8. The method according to claim 7, characterized in that The setting of the comprehensive performance index function F; and solving the optimal control parameters of the exhaust gas recirculation rate EGR of the next control timing node by maximizing the comprehensive performance index function F specifically include: S45: Setting comprehensive performance index function F: F = w1*η exhaust methanol detection side combustion efficiency + w2*(1-|φ-φopt|)+w3*(1-|T-Topt| / Tmax)-w4*(NOx(t) / NOx,target)-w5*(FC / FCbaseline)+w6*(1-|EGR-EGRopt| / EGRmax); η is the combustion efficiency of the exhaust gas methanol detection side; φ: current equivalence ratio; φ opt : Optimal equivalence ratio; T: current combustion chamber temperature; T opt : Optimal combustion chamber temperature; T max : Maximum permissible combustion chamber temperature; NOx(t): current nitrogen oxide emissions; NOx target : Target nitrogen oxide emissions; FC: current fuel consumption rate; FC bascline : Baseline fuel consumption rate; EGR: current exhaust gas recirculation rate; EGR opt : Optimal exhaust gas recirculation rate; EGR max : Maximum allowable exhaust gas recirculation rate; S46: Define the calculation method of each parameter: First, define η tail gas methanol detection side combustion efficiency = (LHVin-LHV_out) / LHVin; Among them, LHV_in is the lower heating value of methanol entering the combustion chamber, and LHV_out is the lower heating value of unburned methanol in the tail gas; Then define the equivalence ratio φ: Equivalence ratio φ=(m f uel / m o xygen) / (m f uel / m o xygen)stoichiometric; Among them: φ: represents the equivalent ratio; m f uel: represents the fuel quality; m o xygen: represents the mass of oxygen; (m f uel / m o xygen)stoichiometric: represents the theoretical stoichiometric ratio; Then directly obtain the actual combustion chamber temperature T and the actual nitrogen oxide emission NOx(t); obtain the optimal combustion chamber temperature T opt and the maximum permissible combustion chamber temperature Tmax and the target nitrogen oxide emissions NOx target Get the base fuel consumption rate, and then calculate the fuel consumption rate FC: FC = m f uel / Poweroutput; Among them, FC: represents fuel consumption rate; m f uel: represents the fuel quality; Poweroutput: represents the engine output power; Calculate the EGR rate: EGR = m_recirculated / m_total_intake; Among them, EGR: represents the exhaust gas recirculation rate; m_recirculated: represents the mass of recirculated exhaust gas; m_total_intake: represents the total mass of intake air; Obtain the specific values ​​of the matching weight coefficients w1-w6, and substitute all parameters into the formula comprehensive performance index function F to calculate the F value under the current working conditions; S46. Optimizing the EGR rate to solve the output maximization comprehensive performance index F: First, obtain the search range and step size that define the EGR rate; EGRmin=x1%, EGRmax=x2%, step length ΔEGR=n%; According to the above EGRmin, EGRmax, and ΔEGR, the gradient descent method is used to optimize EGR. During the specific optimization, the set learning rate learning_rate, the maximum number of iterations max_iterations, and the tolerance tolerance are obtained to iteratively update the EGR value. In each iteration, the gradient of the maximum comprehensive performance index F with respect to EGR is calculated, the EGR value is updated, and it is checked whether the termination condition is met. At the same time, the EGR value is iteratively adjusted in this process until a local maximum value is found and recorded as the optimal EGR value; The optimal EGR value is taken as the target value, and the valve opening is adjusted to achieve this optimal target value.

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