Engine air-fuel ratio control method

Abstract

The application discloses an engine air-fuel ratio control method, and relates to the technical field of engine control, and comprises the following steps: obtaining the accurate value of a first actuator adjustment increment and the accurate value of a second actuator adjustment increment through the accurate value of a mixer outlet pressure deviation value, the accurate value of a change rate of the mixer outlet pressure deviation value and the accurate value of an air flow and fuel flow ratio deviation value; and adjusting the air flow and fuel flow ratio according to the accurate value of the first actuator adjustment increment and the accurate value of the second actuator adjustment increment. The application adjusts the first actuator opening degree and the second actuator opening degree through fuzzy inference rules and fuzzy algorithms, and realizes the control of the engine air-fuel ratio.

Description

Technical Field

[0001] This application relates to the field of engine control technology, and more specifically, to an engine air-fuel ratio control method. Background Technology

[0002] Low-calorific-value gas refers to gas with a low calorific value, typically derived from associated gas from coal mining, industrial waste gas, landfill gas, biomass gas, etc. It can be used as fuel for gas engines to drive synchronous AC generators, achieving cascaded energy utilization and improving energy efficiency. Gas must be mixed with air in a specific ratio before entering the engine cylinder for combustion and power generation. The mass ratio of air to gas entering the cylinder is the engine's air-fuel ratio, a key factor affecting combustion efficiency and performance. Low-calorific-value gas engines differ significantly from engines using high-concentration gaseous fuels such as natural gas and biogas. Firstly, low-calorific-value gas is transported through pipelines at lower pressures. Secondly, the gas-to-air flow ratio covers a wide range during engine operation, making conventional mechanical or Venturi mixers unsuitable. The industry commonly uses dual-butterfly valve mixers, where the gas and air flow rates are regulated separately by their respective electronically controlled butterfly valves. Air-fuel ratio control is challenging, requiring coordinated control of the two butterfly valves to ensure both the correct air-to-gas flow ratio and that the total gas and air flow meets the engine's requirements. Low-calorific-value gas engines are complex nonlinear systems, and real-time closed-loop control of the air-fuel ratio involves multiple control objectives and multiple actuators, which cannot be solved by traditional control methods, making it a technical challenge for the gas-fired power generation industry. Summary of the Invention

[0003] The technical problem to be solved by this application is the instability of airflow and gas flow intake when the gas pressure fluctuates or the load changes suddenly in a low-calorific-value gas engine.

[0004] The technical solution adopted by this application to solve its technical problem is:

[0005] In a first aspect, this application provides an engine air-fuel ratio control method, which includes the following steps:

[0006] S1. Calculate the precise value of the deviation value of the air flow rate and gas flow rate ratio based on the precise value of the target value of the air flow rate and gas flow rate ratio and the precise value of the actual value of the air flow rate and gas flow rate ratio. Obtain the precise value of the deviation value of the mixer outlet pressure based on the precise value of the target value of the mixer outlet pressure and the precise value of the actual value of the mixer outlet pressure.

[0007] S2. Based on the precise value of the mixer outlet pressure deviation value, the precise value of the rate of change of the mixer outlet pressure deviation value is obtained. Through the precise value of the mixer outlet pressure deviation value, the precise value of the rate of change of the mixer outlet pressure deviation value, and the precise value of the deviation value of the air flow rate and the gas flow rate ratio, the precise value of the first actuator adjustment increment and the precise value of the second actuator adjustment increment are obtained.

[0008] S3. Adjust the air flow rate and gas flow rate ratio according to the precise value of the adjustment increment of the first actuator and the precise value of the adjustment increment of the second actuator.

[0009] Based on the first aspect, further, in step S2 above, obtaining the precise values ​​of the first actuator adjustment increment and the second actuator adjustment increment through the precise values ​​of the mixer outlet pressure deviation value, the rate of change of the mixer outlet pressure deviation value, and the deviation value of the air flow rate and gas flow rate ratio includes the following steps:

[0010] Membership functions are used to map the precise value of the mixer outlet pressure deviation to a fuzzy set of the mixed gas outlet pressure deviation values, obtaining the fuzzy value of the mixed gas outlet pressure deviation value corresponding to the precise value of the mixer outlet pressure deviation value; membership functions are also used to map the precise value of the rate of change of the mixer outlet pressure deviation to a fuzzy set of the rate of change of the mixed gas outlet pressure deviation value, obtaining the fuzzy value of the rate of change of the mixed gas outlet pressure deviation value corresponding to the precise value of the rate of change of the mixed gas outlet pressure deviation value; finally, membership functions are used to map the precise value of the deviation value of the air flow rate and gas flow rate ratio to a fuzzy set of the deviation values ​​of the air flow rate and gas flow rate ratio, obtaining the fuzzy value of the deviation value of the air flow rate and gas flow rate ratio corresponding to the precise value of the deviation value of the air flow rate and gas flow rate ratio.

[0011] Based on fuzzy inference rules, a fuzzy algorithm is used to map the fuzzy values ​​of the mixture outlet pressure deviation, the rate of change of the mixture outlet pressure deviation, and the deviation of the air flow rate to the fuzzy set of the first actuator adjustment increment, thus obtaining the fuzzy value of the first actuator adjustment increment; the fuzzy values ​​of the mixer outlet pressure deviation, the rate of change of the mixture outlet pressure deviation, and the deviation of the air flow rate to the fuzzy set of the second actuator adjustment increment are then mapped to the fuzzy set of the second actuator adjustment increment, thus obtaining the fuzzy value of the second actuator adjustment increment.

[0012] A de-sharpening algorithm is used to convert the fuzzy value of the adjustment increment of the first actuator into the precise value of the adjustment increment of the first actuator, and the de-sharpening algorithm is used to convert the fuzzy value of the adjustment increment of the second actuator into the precise value of the adjustment increment of the second actuator.

[0013] Furthermore, based on the first aspect, the precise value of the target value for the air flow rate and gas flow rate ratio can be preset.

[0014] Based on the first aspect, the precise value of the target value for the air flow rate to gas flow rate ratio can also be obtained by the following calculation formula:

[0015] K req =L th λ req c f -c a ;

[0016] Among them, K req λ is the precise value of the target ratio of air flow rate to gas flow rate. req For the target excess air coefficient, c f c is the mass concentration of combustible gas in the gas. a L represents the air mass concentration in the fuel gas. th This is the theoretical air-fuel ratio of the combustible gas.

[0017] Based on the first aspect, further, the fuzzy set of the above-mentioned gas mixture outlet pressure deviation value is {NB1, NS1, Z1, PS1, PB1}, and the universe of discourse of the gas mixture outlet pressure deviation value is [-10, +10].

[0018] The fuzzy set of the rate of change of the outlet pressure deviation of the mixture is {NB2, NS2, Z2, PS2, PB2}, and the universe of discourse of the rate of change of the outlet pressure deviation of the mixture is [-100, +100].

[0019] The fuzzy set of the deviation values ​​of the air flow rate and gas flow rate ratio is {NB3, NS3, Z3, PS3, PB3}, and the universe of discourse of the deviation values ​​of the air flow rate and gas flow rate ratio is [-0.1, +0.1].

[0020] The fuzzy set of the first actuator adjustment increment is {NB4, NS4, Z4, PS4, PB4}, and the universe of discourse of the first actuator adjustment increment is [-1.0, +1.0].

[0021] The fuzzy set of the second actuator adjustment increment is {NB5, NS5, Z5, PS5, PB5}, and the universe of discourse of the second actuator adjustment increment is [-1.0, +1.0].

[0022] Based on the first aspect, further, the above-mentioned fuzzy inference rules include a first inference rule, which is:

[0023] If the outlet pressure deviation of the gas mixture is NB1, the rate of change of the outlet pressure deviation of the gas mixture is NB2, and the deviation of the air flow rate and gas flow rate ratio is NB3, then the adjustment increment of the first actuator is NB4, and the adjustment increment of the second actuator is Z5.

[0024] Based on the first aspect, the above-mentioned fuzzy inference rule further includes a second inference rule, which is as follows:

[0025] If the outlet pressure deviation of the gas mixture is NB1, the rate of change of the outlet pressure deviation of the gas mixture is NB2, and the deviation of the air flow rate and gas flow rate ratio is NS3, then the adjustment increment of the first actuator is NB4, and the adjustment increment of the second actuator is NS5.

[0026] Based on the first aspect, the above-mentioned fuzzy inference rules further include a third inference rule, which is as follows:

[0027] If the outlet pressure deviation of the mixture is NB1, the rate of change of the outlet pressure deviation is NB2, and the deviation of the air flow rate to gas flow rate ratio is Z3, then the adjustment increment of the first actuator is NB4, and the adjustment increment of the second actuator is NB5.

[0028] Based on the first aspect, the above-mentioned fuzzy inference rules further include a fourth inference rule, which is as follows:

[0029] If the outlet pressure deviation of the mixture is NB1, the rate of change of the outlet pressure deviation is NB2, and the deviation of the air flow rate to gas flow rate ratio is PS3, then the adjustment increment of the first actuator is NS4, and the adjustment increment of the second actuator is NB5.

[0030] Based on the first aspect, the above-mentioned fuzzy inference rules further include a fifth inference rule, which is as follows:

[0031] If the outlet pressure deviation of the mixed gas is PB1, the rate of change of the outlet pressure deviation of the mixed gas is PB2, and the deviation of the air flow rate and gas flow rate ratio is PS3, then the adjustment increment of the first actuator is PB4, and the adjustment increment of the second actuator is PS5.

[0032] Based on the first aspect, the above-mentioned fuzzy inference rules further include a sixth inference rule, which is as follows:

[0033] If the outlet pressure deviation of the mixed gas is PB1, the rate of change of the outlet pressure deviation of the mixed gas is PB2, and the deviation of the air flow rate and gas flow rate ratio is PB3, then the adjustment increment of the first actuator is PB4, and the adjustment increment of the second actuator is Z5.

[0034] Based on the first aspect, the aforementioned fuzzy algorithm can further be the Mamdani inference method.

[0035] In a second aspect, this application also provides an electronic device including a memory and a processor; the memory is used to store one or more programs; when the one or more programs are executed by the processor, they implement the method as described in any of the first aspects above.

[0036] Thirdly, this application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method as described in any of the first aspects above.

[0037] The beneficial effects of this application are:

[0038] This application achieves control of the engine air-fuel ratio by adjusting the opening degree of the first actuator and the second actuator through fuzzy inference rules and fuzzy algorithms. Attached Figure Description

[0039] Figure 1 A flowchart of an engine air-fuel ratio control method provided in an embodiment of this application.

[0040] Figure 2 This is a structural diagram of the engine air-fuel ratio control system provided in an embodiment of this application.

[0041] Figure 3 This is a schematic diagram of the target power-mixed outlet pressure calibration curve provided for an embodiment of this application.

[0042] Figure 4 A structural block diagram of an electronic device provided in an embodiment of this application.

[0043] The attached figures are labeled as follows: 1, methane concentration sensor; 2, air butterfly valve; 3, gas butterfly valve; 4, air flow meter; 5, gas flow meter; 6, pressure sensor; 7, throttle valve; 8, air-fuel ratio controller; 9, ECU; 101, memory; 102, processor; 103, communication interface. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0046] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0048] In the description of the embodiments of this application, "a plurality of" means at least two.

[0049] Firstly, such as Figure 1 As shown, an embodiment of this application provides an engine air-fuel ratio control method, which includes the following steps:

[0050] S1, calculate the accurate value of the deviation value of the air flow rate and gas flow rate ratio based on the accurate value of the target value of the air flow rate and gas flow rate ratio and the accurate value of the actual value of the air flow rate and gas flow rate ratio, and obtain the accurate value of the deviation value of the mixer outlet pressure based on the accurate value of the target value of the mixer outlet pressure and the accurate value of the actual value of the mixer outlet pressure.

[0051] S2, based on the precise value of the mixer outlet pressure deviation value, the precise value of the rate of change of the mixer outlet pressure deviation value is obtained. Through the precise value of the mixer outlet pressure deviation value, the precise value of the rate of change of the mixer outlet pressure deviation value, and the precise value of the deviation value of the air flow rate and the gas flow rate ratio, the precise value of the first actuator adjustment increment and the precise value of the second actuator adjustment increment are obtained.

[0052] S3 adjusts the air flow rate and gas flow rate ratio based on the precise value of the first actuator adjustment increment and the precise value of the second actuator adjustment increment.

[0053] In one embodiment of this application, such as Figure 2 As shown, an embodiment of this application provides an engine air-fuel ratio control system, which includes an ECU (electronic controller) 9, an air-fuel ratio controller 8, an air butterfly valve 2, a gas butterfly valve 3, a speed governor 5, a methane concentration sensor 1, an air flow meter 4, a gas flow meter 5, and a pressure sensor 6, wherein:

[0054] The air butterfly valve 2 is installed on the air intake pipe and is used to adjust the air intake flow rate;

[0055] The gas butterfly valve 3 is installed on the gas inlet pipe and is used to adjust the gas inlet flow rate;

[0056] The air intake pipe and the gas intake pipe are connected to the mixer. The outlet of the mixer is connected to the engine through the engine intake pipe. The throttle valve 7 is installed on the engine intake pipe and is used to adjust the intake flow rate of the mixture.

[0057] The methane concentration sensor 1 is used to measure the methane concentration in the fuel gas;

[0058] The air flow meter 4 is used to measure the air intake flow rate in real time.

[0059] The gas flow meter 5 is used to measure the gas intake flow rate in real time.

[0060] The pressure sensor 6 is used to measure the mixer outlet pressure in real time.

[0061] The input signals of ECU9 are air intake flow rate, gas intake flow rate, methane concentration of gas, and mixer outlet pressure. The output signals of ECU9 are the opening values ​​of air butterfly valve 2 and gas butterfly valve 3. The air-fuel ratio controller is used to adjust the opening of air butterfly valve 2 and gas butterfly valve 3 according to the output signals of ECU9.

[0062] In one embodiment of this application, the first actuator is an air butterfly valve 2.

[0063] In one embodiment of this application, the second actuator is a gas butterfly valve 3.

[0064] When the load changes, in order to maintain a constant speed, the governor (not shown in the figure) will change the air-fuel mixture flow by controlling the throttle valve 7 in a closed loop.

[0065] In one embodiment of this application, the precise value of the aforementioned mixer outlet pressure deviation is the difference between the precise value of the target value of the mixer outlet pressure and the precise value of the actual value of the mixer outlet pressure.

[0066] In another embodiment of this application, the precise value of the target value of the mixer outlet pressure is obtained from the target power-mixing outlet pressure calibration curve. The target power-mixing outlet pressure calibration curve is shown below. Figure 3 As shown.

[0067] In one embodiment of this application, the precise value of the rate of change of the mixer outlet pressure deviation value can be obtained from the precise value of the mixer outlet pressure deviation value using the following method:

[0068] The first value of the mixer outlet pressure is collected. After a first time interval, the second value of the mixer outlet pressure is collected again. The accurate value of the mixer outlet pressure deviation is obtained by subtracting the first value of the mixer outlet pressure from the second value. The accurate value of the rate of change of the mixer outlet pressure deviation is obtained by dividing the accurate value of the mixer outlet pressure deviation by the first time interval.

[0069] In one embodiment of this application, the first time is 0.01s.

[0070] In one embodiment of this application, the precise values ​​of the first actuator adjustment increment and the second actuator adjustment increment obtained in step S2 above through the precise values ​​of the mixer outlet pressure deviation, the rate of change of the mixer outlet pressure deviation, and the deviation of the air flow rate and gas flow rate ratio, include the following steps:

[0071] Membership functions are used to map the precise value of the mixer outlet pressure deviation to a fuzzy set of the mixed gas outlet pressure deviation values, obtaining the fuzzy value of the mixed gas outlet pressure deviation value corresponding to the precise value of the mixer outlet pressure deviation value; membership functions are also used to map the precise value of the rate of change of the mixer outlet pressure deviation to a fuzzy set of the rate of change of the mixed gas outlet pressure deviation value, obtaining the fuzzy value of the rate of change of the mixed gas outlet pressure deviation value corresponding to the precise value of the rate of change of the mixed gas outlet pressure deviation value; finally, membership functions are used to map the precise value of the deviation value of the air flow rate and gas flow rate ratio to a fuzzy set of the deviation values ​​of the air flow rate and gas flow rate ratio, obtaining the fuzzy value of the deviation value of the air flow rate and gas flow rate ratio corresponding to the precise value of the deviation value of the air flow rate and gas flow rate ratio.

[0072] Based on fuzzy inference rules, a fuzzy algorithm is used to map the fuzzy values ​​of the mixture outlet pressure deviation, the rate of change of the mixture outlet pressure deviation, and the deviation of the air flow rate to the fuzzy set of the first actuator adjustment increment, thus obtaining the fuzzy value of the first actuator adjustment increment; the fuzzy values ​​of the mixer outlet pressure deviation, the rate of change of the mixture outlet pressure deviation, and the deviation of the air flow rate to the fuzzy set of the second actuator adjustment increment are then mapped to the fuzzy set of the second actuator adjustment increment, thus obtaining the fuzzy value of the second actuator adjustment increment.

[0073] A de-sharpening algorithm is used to convert the fuzzy value of the adjustment increment of the first actuator into the precise value of the adjustment increment of the first actuator, and the de-sharpening algorithm is used to convert the fuzzy value of the adjustment increment of the second actuator into the precise value of the adjustment increment of the second actuator.

[0074] In one embodiment of this application, the membership function described above may be a triangular membership function.

[0075] In one embodiment of this application, the membership function may also be a Gaussian membership function, a trapezoidal membership function, a bell-shaped membership function, or a sigmoid membership function.

[0076] In one embodiment of this application, the precise value of the target value of the air flow rate and gas flow rate ratio can be preset.

[0077] In one embodiment of this application, the precise value of the target value for the air flow rate to gas flow rate ratio can also be obtained by the following calculation formula:

[0078] K req =L th λ req c f -c a ;

[0079] Among them, K req λ is the precise value of the target ratio of air flow rate to gas flow rate. req For the target excess air coefficient, c f c is the mass concentration of combustible gas in the gas. a L represents the air mass concentration in the fuel gas. th This is the theoretical air-fuel ratio of the combustible gas.

[0080] In one embodiment of this application, the fuzzy set of the above-mentioned gas mixture outlet pressure deviation value is {NB1, NS1, Z1, PS1, PB1}, and the universe of discourse of the gas mixture outlet pressure deviation value is [-10, +10].

[0081] The fuzzy set of the rate of change of the outlet pressure deviation of the mixture is {NB2, NS2, Z2, PS2, PB2}, and the universe of discourse of the rate of change of the outlet pressure deviation of the mixture is [-100, +100].

[0082] The fuzzy set of the deviation values ​​of the air flow rate and gas flow rate ratio is {NB3, NS3, Z3, PS3, PB3}, and the universe of discourse of the deviation values ​​of the air flow rate and gas flow rate ratio is [-0.1, +0.1].

[0083] The fuzzy set of the first actuator adjustment increment is {NB4, NS4, Z4, PS4, PB4}, and the universe of discourse of the first actuator adjustment increment is [-1.0, +1.0].

[0084] The fuzzy set of the second actuator adjustment increment is {NB5, NS5, Z5, PS5, PB5}, and the universe of discourse of the second actuator adjustment increment is [-1.0, +1.0].

[0085] NB1, NB2, NB3, NB4, and NB5 all indicate negative values. NB1 indicates that the actual value of the mixed gas outlet pressure is less than the target value, and the difference between the two is large. NB2 indicates that the rate of change of the mixed gas outlet pressure deviation is less than zero, and the difference between the two is large. NB3 indicates that the actual value of the air flow rate to gas flow rate ratio is less than the target value, and the difference between the two is large. NB4 indicates that the decrease in the adjustment increment of the first actuator is large. NB5 indicates that the decrease in the adjustment increment of the second actuator is large.

[0086] NS1, NS2, NS3, NS4, and NS5 all represent negative values. NS1 indicates that the actual value of the mixed gas outlet pressure is less than the target value, and the difference between the two is small. NS2 indicates that the rate of change of the mixed gas outlet pressure deviation is less than zero, and the difference between the two is small. NS3 indicates that the actual value of the air flow rate to gas flow rate ratio is less than the target value, and the difference between the two is small. NS4 indicates that the decrease in the adjustment increment of the first actuator is small. NS5 indicates that the decrease in the adjustment increment of the second actuator is small.

[0087] In one embodiment of this application, Z1, Z2, Z3, Z4, and Z5 all represent zero. Z1 indicates that the actual value of the gas mixture outlet pressure is the same as the target value of the gas mixture outlet pressure; Z2 indicates that the rate of change of the gas mixture outlet pressure deviation is zero; Z3 indicates that the actual value of the air flow rate to gas flow rate ratio is the same as the target value of the air flow rate to gas flow rate ratio; Z4 indicates that the adjustment increment of the first actuator is zero; and Z5 indicates that the adjustment increment of the second actuator is zero.

[0088] In one embodiment of this application, PS1, PS2, PS3, PS4, and PS5 all represent positive and negative values. PS1 indicates that the actual value of the mixed gas outlet pressure is greater than the target value of the mixed gas outlet pressure, and the difference between the two is small. PS2 indicates that the rate of change of the mixed gas outlet pressure deviation is greater than zero, and the difference between the two is small. PS3 indicates that the actual value of the air flow rate to gas flow rate ratio is greater than the target value of the air flow rate to gas flow rate ratio, and the difference between the two is small. PS4 indicates that the increase in the adjustment increment of the first actuator is small. PS5 indicates that the increase in the adjustment increment of the second actuator is small.

[0089] In one embodiment of this application, PB1, PB2, PB3, PB4, and PB5 all represent positive values. PB1 indicates that the actual value of the mixed gas outlet pressure is greater than the target value of the mixed gas outlet pressure, and the difference between the two is large. PB2 indicates that the rate of change of the mixed gas outlet pressure deviation is greater than zero, and the difference between the two is large. PB3 indicates that the actual value of the air flow rate to gas flow rate ratio is greater than the target value of the air flow rate to gas flow rate ratio, and the difference between the two is large. PB4 indicates that the increase in the adjustment increment of the first actuator is large. PB5 indicates that the increase in the adjustment increment of the second actuator is large.

[0090] In one embodiment of this application, the main principle of the fuzzy inference rule definition is as follows: When the actual value of the mixer outlet pressure is the same as the target value of the mixer outlet pressure, that is, when the total intake air flow and gas flow meet the requirements, it is only necessary to adjust the ratio of air flow and gas flow based on the feedback of the air flow and gas flow ratio. The one with a larger air flow and gas flow decreases, while the one with a smaller air flow and gas flow increases. When the mixer outlet pressure is low, that is, when the actual value of the mixer outlet pressure is less than the target value of the mixer outlet pressure, it is necessary to increase the total intake air flow and gas flow, prioritizing the increase of the relatively insufficient air flow and gas flow based on the feedback of the air flow and gas flow ratio. When the mixer outlet pressure is high, that is, when the actual value of the mixer outlet pressure is greater than the target value of the mixer outlet pressure, it is necessary to decrease the total intake air flow and gas flow, prioritizing the decrease of the relatively excessive air flow and gas flow based on the feedback of the air flow and gas flow ratio. The rule base typically contains multiple rules presented in the form of "if-then" to comprehensively cover various possible operating conditions.

[0091] In one embodiment of this application, the above-mentioned fuzzy inference rule includes a first inference rule, which is:

[0092] If the outlet pressure deviation of the gas mixture is NB1, the rate of change of the outlet pressure deviation of the gas mixture is NB2, and the deviation of the air flow rate and gas flow rate ratio is NB3, then the adjustment increment of the first actuator is NB4, and the adjustment increment of the second actuator is Z5.

[0093] In one embodiment of this application, the first inference rule is presented in the rule base as follows:

[0094] If(e p is NB1)and(de p is NB2)and(e Q isNB3)then(dy-air isNB4)(dy-gasisZ5);e p The deviation value of the outlet pressure of the mixture, de p e is the rate of change of the outlet pressure deviation of the mixture. Q dy-air represents the deviation between the air flow rate and the gas flow rate, dy-air represents the adjustment increment of the first actuator, and dy-gas represents the adjustment increment of the second actuator.

[0095] In one embodiment of this application, the above-mentioned fuzzy inference rule further includes a second inference rule, which is:

[0096] If the outlet pressure deviation of the gas mixture is NB1, the rate of change of the outlet pressure deviation of the gas mixture is NB2, and the deviation of the air flow rate and gas flow rate ratio is NS3, then the adjustment increment of the first actuator is NB4, and the adjustment increment of the second actuator is NS5.

[0097] In one embodiment of this application, the second inference rule is presented in the rule base as follows:

[0098] If(e p is NB1)and(de p is NB2)and(e Q is NS3)then(dy-air isNB4)(dy-gasisNS5);e p The deviation value of the outlet pressure of the mixture, de p e is the rate of change of the outlet pressure deviation of the mixture. Q dy-air represents the deviation between the air flow rate and the gas flow rate, dy-air represents the adjustment increment of the first actuator, and dy-gas represents the adjustment increment of the second actuator.

[0099] In one embodiment of this application, the above-mentioned fuzzy inference rule further includes a third inference rule, which is:

[0100] If the outlet pressure deviation of the mixture is NB1, the rate of change of the outlet pressure deviation is NB2, and the deviation of the air flow rate to gas flow rate ratio is Z3, then the adjustment increment of the first actuator is NB4, and the adjustment increment of the second actuator is NB5.

[0101] In one embodiment of this application, the third inference rule is presented in the rule base as follows:

[0102] If(e p is NB1)and(de p is NB2)and(e Q is Z3)then(dy-air isNB4)(dy-gas isNB5); e p The deviation value of the outlet pressure of the mixture, de p e is the rate of change of the outlet pressure deviation of the mixture. Q dy-air represents the deviation between the air flow rate and the gas flow rate, dy-air represents the adjustment increment of the first actuator, and dy-gas represents the adjustment increment of the second actuator.

[0103] In one embodiment of this application, the above-mentioned fuzzy inference rule further includes a fourth inference rule, which is:

[0104] If the outlet pressure deviation of the mixture is NB1, the rate of change of the outlet pressure deviation is NB2, and the deviation of the air flow rate to gas flow rate ratio is PS3, then the adjustment increment of the first actuator is NS4, and the adjustment increment of the second actuator is NB5.

[0105] In one embodiment of this application, the fourth inference rule is presented in the rule base as follows:

[0106] If(e p is NB1)and(de p is NB2)and(e Q is PS3)then(dy-air isNS4)(dy-gasisNB5);e p The deviation value of the outlet pressure of the mixture, de p e is the rate of change of the outlet pressure deviation of the mixture. Q dy-air represents the deviation between the air flow rate and the gas flow rate, dy-air represents the adjustment increment of the first actuator, and dy-gas represents the adjustment increment of the second actuator.

[0107] In one embodiment of this application, the above-mentioned fuzzy inference rule further includes a fifth inference rule, which is:

[0108] If the outlet pressure deviation of the mixed gas is PB1, the rate of change of the outlet pressure deviation of the mixed gas is PB2, and the deviation of the air flow rate and gas flow rate ratio is PS3, then the adjustment increment of the first actuator is PB4, and the adjustment increment of the second actuator is PS5.

[0109] In one embodiment of this application, the fifth inference rule is presented in the rule base as follows:

[0110] If(e p is PB1)and(de p is PB2)and(e Q is PS3)then(dy-air isPB4)(dy-gasisPS5);e p The deviation value of the outlet pressure of the mixture, de p e is the rate of change of the outlet pressure deviation of the mixture. Q dy-air represents the deviation between the air flow rate and the gas flow rate, dy-air represents the adjustment increment of the first actuator, and dy-gas represents the adjustment increment of the second actuator.

[0111] In one embodiment of this application, the above-mentioned fuzzy inference rule further includes a sixth inference rule, which is:

[0112] If the outlet pressure deviation of the mixed gas is PB1, the rate of change of the outlet pressure deviation of the mixed gas is PB2, and the deviation of the air flow rate and gas flow rate ratio is PB3, then the adjustment increment of the first actuator is PB4, and the adjustment increment of the second actuator is Z5.

[0113] In one embodiment of this application, the sixth inference rule is presented in the rule base as follows:

[0114] If(e p is PB1)and(de p is PB2)and(e Q isPB3)then(dy-air isPB4)(dy-gasisZ5);e p The deviation value of the outlet pressure of the mixture, de p e is the rate of change of the outlet pressure deviation of the mixture. Q dy-air represents the deviation between the air flow rate and the gas flow rate, dy-air represents the adjustment increment of the first actuator, and dy-gas represents the adjustment increment of the second actuator.

[0115] In one embodiment of this application, the fuzzy algorithm described above may be the Mamdani inference method.

[0116] In one embodiment of this application, the above-mentioned fuzzy algorithm can also be the Zadeh inference method or the Mizumoto algorithm.

[0117] In one embodiment of this application, the declarative algorithm may be the maximum membership method, the centroid method, or the weighted average method.

[0118] Secondly, such as Figure 4 As shown, embodiments of this application also provide an electronic device, which includes a memory 101 and a processor 102; the memory 101 is used to store one or more programs; when the one or more programs are executed by the processor 102, they implement the method as described in any of the first aspects above.

[0119] The electronic device may further include a communication interface 103. The memory 101, processor 102, and communication interface 103 are directly or indirectly electrically connected to each other to realize data transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines. The memory 101 can be used to store software programs and modules, and the processor 102 executes various functional applications and data processing by executing the software programs and modules stored in the memory 101. The communication interface 103 can be used for signaling or data communication with other node devices.

[0120] The memory 101 may be, but is not limited to, random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.

[0121] The processor 102 can be an integrated circuit chip with signal processing capabilities. The processor 102 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0122] Thirdly, embodiments of this application also provide a computer-readable storage medium storing a computer program that, when executed by processor 102, implements the methods described in any of the first aspects above. If the functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0123] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0124] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for controlling the air-fuel ratio of an engine, characterized in that, Includes the following steps: S1, calculate the accurate value of the deviation value of the air flow rate and gas flow rate ratio based on the accurate value of the target value of the air flow rate and gas flow rate ratio and the accurate value of the actual value of the air flow rate and gas flow rate ratio, and obtain the accurate value of the deviation value of the mixer outlet pressure based on the accurate value of the target value of the mixer outlet pressure and the accurate value of the actual value of the mixer outlet pressure. S2, based on the precise value of the mixer outlet pressure deviation value, the precise value of the rate of change of the mixer outlet pressure deviation value is obtained. Through the precise value of the mixer outlet pressure deviation value, the precise value of the rate of change of the mixer outlet pressure deviation value, and the precise value of the deviation value of the air flow rate and the gas flow rate ratio, the precise value of the first actuator adjustment increment and the precise value of the second actuator adjustment increment are obtained. S3 adjusts the air flow rate and gas flow rate ratio based on the precise value of the first actuator adjustment increment and the precise value of the second actuator adjustment increment.

2. The engine air-fuel ratio control method according to claim 1, characterized in that, In step S2, the precise values ​​of the first actuator adjustment increment and the second actuator adjustment increment are obtained by using the precise values ​​of the mixer outlet pressure deviation, the rate of change of the mixer outlet pressure deviation, and the deviation of the air flow rate and gas flow rate ratio. This includes the following steps: Membership functions are used to map the precise value of the mixer outlet pressure deviation to a fuzzy set of the mixed gas outlet pressure deviation values, obtaining the fuzzy value of the mixed gas outlet pressure deviation value corresponding to the precise value of the mixer outlet pressure deviation value; membership functions are also used to map the precise value of the rate of change of the mixer outlet pressure deviation to a fuzzy set of the rate of change of the mixed gas outlet pressure deviation value, obtaining the fuzzy value of the rate of change of the mixed gas outlet pressure deviation value corresponding to the precise value of the rate of change of the mixed gas outlet pressure deviation value; finally, membership functions are used to map the precise value of the deviation value of the air flow rate and gas flow rate ratio to a fuzzy set of the deviation values ​​of the air flow rate and gas flow rate ratio, obtaining the fuzzy value of the deviation value of the air flow rate and gas flow rate ratio corresponding to the precise value of the deviation value of the air flow rate and gas flow rate ratio. Based on fuzzy inference rules, a fuzzy algorithm is used to map the fuzzy values ​​of the mixture outlet pressure deviation, the rate of change of the mixture outlet pressure deviation, and the deviation of the air flow rate to the fuzzy set of the first actuator adjustment increment, thus obtaining the fuzzy value of the first actuator adjustment increment; the fuzzy values ​​of the mixer outlet pressure deviation, the rate of change of the mixture outlet pressure deviation, and the deviation of the air flow rate to the fuzzy set of the second actuator adjustment increment are then mapped to the fuzzy set of the second actuator adjustment increment, thus obtaining the fuzzy value of the second actuator adjustment increment. A de-sharpening algorithm is used to convert the fuzzy value of the adjustment increment of the first actuator into the precise value of the adjustment increment of the first actuator, and the de-sharpening algorithm is used to convert the fuzzy value of the adjustment increment of the second actuator into the precise value of the adjustment increment of the second actuator.

3. The engine air-fuel ratio control method according to claim 2, characterized in that, The precise value of the target airflow to gasflow ratio is obtained by the following calculation formula: K req =L th l req c f -c a ; Among them, K req λ is the precise value of the target ratio of air flow rate to gas flow rate. req For the target excess air coefficient, c f c is the mass concentration of combustible gas in the gas. a L represents the air mass concentration in the fuel gas. th This is the theoretical air-fuel ratio of the combustible gas.

4. The engine air-fuel ratio control method according to claim 2, characterized in that, The fuzzy set of the outlet pressure deviation value of the mixed gas is {NB1, NS1, Z1, PS1, PB1}, and the universe of discourse of the outlet pressure deviation value of the mixed gas is [-10, +10]. The fuzzy set of the rate of change of the outlet pressure deviation of the mixture is {NB2, NS2, Z2, PS2, PB2}, and the universe of discourse of the rate of change of the outlet pressure deviation of the mixture is [-100, +100]. The fuzzy set of the deviation values ​​of the air flow rate and gas flow rate ratio is {NB3, NS3, Z3, PS3, PB3}, and the universe of discourse of the deviation values ​​of the air flow rate and gas flow rate ratio is [-0.1, +0.1]. The fuzzy set of the first actuator adjustment increment is {NB4, NS4, Z4, PS4, PB4}, and the universe of discourse of the first actuator adjustment increment is [-1.0, +1.0]. The fuzzy set of the second actuator adjustment increment is {NB5, NS5, Z5, PS5, PB5}, and the universe of discourse of the second actuator adjustment increment is [-1.0, +1.0].

5. The engine air-fuel ratio control method according to claim 2, characterized in that, The fuzzy inference rules include a first inference rule, which is: If the outlet pressure deviation of the gas mixture is NB1, the rate of change of the outlet pressure deviation of the gas mixture is NB2, and the deviation of the air flow rate and gas flow rate ratio is NB3, then the adjustment increment of the first actuator is NB4, and the adjustment increment of the second actuator is Z5.

6. The engine air-fuel ratio control method according to claim 2, characterized in that, The fuzzy inference rule also includes a second inference rule, which is: If the outlet pressure deviation of the gas mixture is NB1, the rate of change of the outlet pressure deviation of the gas mixture is NB2, and the deviation of the air flow rate and gas flow rate ratio is NS3, then the adjustment increment of the first actuator is NB4, and the adjustment increment of the second actuator is NS5.

7. The engine air-fuel ratio control method according to claim 2, characterized in that, The fuzzy inference rule also includes a third inference rule, which is: If the outlet pressure deviation of the mixture is NB1, the rate of change of the outlet pressure deviation is NB2, and the deviation of the air flow rate to gas flow rate ratio is Z3, then the adjustment increment of the first actuator is NB4, and the adjustment increment of the second actuator is NB5.

8. The engine air-fuel ratio control method according to claim 2, characterized in that, The fuzzy inference rules also include a fourth inference rule, which is: If the outlet pressure deviation of the mixture is NB1, the rate of change of the outlet pressure deviation is NB2, and the deviation of the air flow rate to gas flow rate ratio is PS3, then the adjustment increment of the first actuator is NS4, and the adjustment increment of the second actuator is NB5.

9. The engine air-fuel ratio control method according to claim 2, characterized in that, The fuzzy inference rules also include a fifth inference rule, which is: If the outlet pressure deviation of the mixed gas is PB1, the rate of change of the outlet pressure deviation of the mixed gas is PB2, and the deviation of the air flow rate and gas flow rate ratio is PS3, then the adjustment increment of the first actuator is PB4, and the adjustment increment of the second actuator is PS5.

10. The engine air-fuel ratio control method according to claim 2, characterized in that, The fuzzy inference rules also include a sixth inference rule, which is as follows: If the outlet pressure deviation of the mixed gas is PB1, the rate of change of the outlet pressure deviation of the mixed gas is PB2, and the deviation of the air flow rate and gas flow rate ratio is PB3, then the adjustment increment of the first actuator is PB4, and the adjustment increment of the second actuator is Z5.

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