Urea injection volume control methods, devices and electronic equipment

Abstract

This invention provides a method, apparatus, and electronic device for controlling urea injection quantity, relating to the field of automotive exhaust aftertreatment technology. The method is applied to a two-stage SCR aftertreatment system. In this system, the upstream of the downstream SCR uses an iron-based catalyst, and the downstream uses a copper-based catalyst. The method includes: determining a first internal ammonia storage predicted value for the downstream SCR based on kinetic models of the iron-based and copper-based catalysts; determining a first ammonia storage corrected urea injection quantity for the downstream SCR based on the first internal ammonia storage predicted value and the downstream SCR's internal ammonia storage setpoint; and determining the total urea injection quantity for the downstream SCR based on the feedforward urea injection quantity and the first ammonia storage corrected urea injection quantity. This invention can precisely control the urea injection quantity, reducing N2O emissions from the aftertreatment system.

Description

Technical Field

[0001] This invention relates to the field of automotive exhaust aftertreatment technology, specifically to a urea injection quantity control method, device, and electronic equipment. Background Technology

[0002] Nitrogen oxides (NOx) are a potent greenhouse gas with a global warming potential 298 times that of CO2, and they are also detrimental to the ozone layer. Currently, diesel engine aftertreatment systems primarily reduce NOx emissions through selective catalytic reduction (SCR), but N2O is also generated during the SCR reaction. As diesel vehicle emission regulations tighten restrictions on non-CO2 greenhouse gases, N2O emissions are now also subject to limits, making it a significant challenge for aftertreatment systems to effectively suppress N2O formation. Summary of the Invention

[0003] In view of this, embodiments of the present invention aim to provide a method, apparatus and electronic device for controlling urea injection volume, so as to suppress the generation of N2O in the after-treatment system.

[0004] A first aspect of the present invention provides a method for controlling urea injection volume, the method being applied to a two-stage SCR aftertreatment system; wherein the upstream of the downstream SCR in the two-stage SCR aftertreatment system employs an iron-based catalyst and the downstream employs a copper-based catalyst; the method includes:

[0005] Based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model of the subsequent SCR, the first internal ammonia storage prediction value of the subsequent SCR is determined; the iron-based catalyst kinetic model and the copper-based catalyst kinetic model both include ammonia adsorption-desorption reaction, standard reaction, fast reaction, slow reaction, ammonia oxidation reaction and N2O generation reaction;

[0006] Based on the first internal ammonia storage prediction value and the internal ammonia storage setting value of the subsequent SCR, the first ammonia storage correction urea injection amount of the subsequent SCR is determined.

[0007] The total urea injection amount of the subsequent SCR is determined based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage corrected urea injection amount.

[0008] In some embodiments, determining the first internal ammonia storage prediction value of the subsequent SCR based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model includes:

[0009] Based on the kinetic model of the iron-based catalyst and the kinetic model of the copper-based catalyst, the predicted value of the first internal ammonia storage and the predicted value of the first NOx concentration downstream of the subsequent SCR are determined.

[0010] The determination of the total urea injection amount of the subsequent SCR based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage corrected urea injection amount includes:

[0011] Based on the first predicted NOx concentration and the actual first NOx concentration upstream of the subsequent SCR, the model conversion efficiency of the subsequent SCR is determined.

[0012] Based on the set conversion efficiency of the subsequent SCR and the model conversion efficiency, the model feedforward urea injection amount of the subsequent SCR is determined.

[0013] The sum of the feedforward urea injection rate of the subsequent SCR, the first ammonia storage corrected urea injection rate, and the model feedforward urea injection rate is determined, and the total urea injection rate of the subsequent SCR is determined based on the sum of the sums.

[0014] As an example, determining the model feedforward urea injection amount of the subsequent SCR based on the set conversion efficiency of the subsequent SCR and the model conversion efficiency includes:

[0015] Determine a first difference between the set conversion efficiency and the model conversion efficiency;

[0016] Based on the first difference, the model feedforward urea injection amount is determined.

[0017] In some embodiments, determining the total urea injection amount of the subsequent SCR based on the summation result includes:

[0018] Based on the model conversion efficiency and the actual conversion efficiency of the subsequent SCR, a closed-loop correction factor is determined.

[0019] The product of the summation result and the closed-loop correction factor is determined as the total urea injection amount of the subsequent SCR.

[0020] As one possible implementation, the determination of the first internal ammonia storage prediction value of the subsequent SCR based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model includes:

[0021] The inlet temperature of the downstream SCR, the urea injection rate at the previous moment, the actual value of the first NOx concentration upstream of the downstream SCR, and the exhaust gas flow rate are input into the iron-based catalyst kinetic model to obtain the predicted values ​​of the second NOx concentration, NH3 concentration, temperature, and iron-based internal ammonia storage downstream of the iron-based catalyst output by the iron-based catalyst kinetic model.

[0022] The second NOx concentration prediction value, the NH3 concentration prediction value, the temperature prediction value, and the waste gas flow rate are input into the copper-based catalyst kinetic model to obtain the copper-based internal ammonia storage prediction value output by the copper-based catalyst kinetic model.

[0023] The sum of the predicted internal ammonia storage value of the iron-based system and the predicted internal ammonia storage value of the copper-based system is determined as the first predicted internal ammonia storage value.

[0024] In some embodiments, the method further includes:

[0025] Based on the kinetic model of the pre-stage SCR in the dual-stage SCR post-treatment system, the second internal ammonia storage prediction value of the pre-stage SCR is determined; wherein, the kinetic model of the pre-stage SCR includes ammonia adsorption-desorption reaction, standard reaction, fast reaction, slow reaction, ammonia oxidation reaction and N2O generation reaction;

[0026] Based on the second internal ammonia storage prediction value and the internal ammonia storage setting value of the preceding SCR, the second ammonia storage correction urea injection amount of the preceding SCR is determined;

[0027] The total urea injection amount of the pre-stage SCR is determined based on the feedforward urea injection amount of the pre-stage SCR and the second ammonia storage corrected urea injection amount.

[0028] In some embodiments, determining the second internal ammonia storage prediction value of the pre-stage SCR based on the kinetic model of the pre-stage SCR within the two-stage SCR aftertreatment system includes:

[0029] Based on the kinetic model of the pre-stage SCR, the predicted value of the second internal ammonia storage and the predicted value of the third NOx concentration downstream of the pre-stage SCR are determined.

[0030] The determination of the total urea injection rate of the pre-stage SCR based on the feedforward urea injection rate of the pre-stage SCR and the second ammonia storage corrected urea injection rate includes:

[0031] Based on the actual value of the first NOx concentration upstream of the downstream SCR and the predicted value of the third NOx concentration, the closed-loop corrected urea injection amount of the upstream SCR is determined.

[0032] The total urea injection amount of the pre-stage SCR is determined by summing the feedforward urea injection amount, the second ammonia storage corrected urea injection amount, and the closed-loop corrected urea injection amount.

[0033] A second aspect of the present invention provides a urea injection quantity control device, the device being applied to a two-stage SCR aftertreatment system; wherein the upstream of the downstream SCR in the two-stage SCR aftertreatment system employs an iron-based catalyst and the downstream employs a copper-based catalyst; the device comprises:

[0034] The first determining module is used to determine the first internal ammonia storage prediction value of the subsequent SCR based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model of the subsequent SCR; the iron-based catalyst kinetic model and the copper-based catalyst kinetic model both include ammonia adsorption-desorption reaction, standard reaction, fast reaction, slow reaction, ammonia oxidation reaction and N2O generation reaction;

[0035] The second determining module is used to determine the first ammonia storage correction urea injection amount of the subsequent SCR based on the first internal ammonia storage prediction value and the internal ammonia storage setting value of the subsequent SCR.

[0036] The third determining module is used to determine the total urea injection amount of the subsequent SCR based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage corrected urea injection amount.

[0037] A third aspect of the present invention provides an electronic device including a processor and a memory storing a computer program, wherein the processor executes the computer program to implement the urea injection quantity control method described in the first aspect above.

[0038] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, the computer program being executable by a processor to implement the urea injection quantity control method described in the first aspect above.

[0039] According to the urea injection control method, apparatus, and electronic equipment of the present invention, the front end of the subsequent SCR in the two-stage SCR aftertreatment system uses an iron-based catalyst, and the rear end uses a copper-based catalyst. The first internal ammonia storage prediction value of the subsequent SCR is determined by using kinetic models of the iron-based catalyst and the copper-based catalyst based on the subsequent SCR. Based on the first internal ammonia storage prediction value and the internal ammonia storage setpoint of the subsequent SCR, the first ammonia storage-corrected urea injection rate of the subsequent SCR is determined. Based on the feedforward urea injection rate of the subsequent SCR and the first ammonia storage-corrected urea injection rate, the total urea injection rate of the subsequent SCR is determined. This invention uses a combination of iron-based and copper-based catalysts in the subsequent SCR, and determines the ammonia storage-corrected urea injection rate based on the internal ammonia storage prediction value determined by the iron-based catalyst kinetic model and the copper-based catalyst kinetic model, thereby determining the total urea injection rate of the subsequent SCR. This allows for precise control of the urea injection rate and reduces N2O emissions from the aftertreatment system. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0041] Figure 1This is a schematic diagram of the structure of the two-stage SCR post-processing system in an embodiment of the present invention.

[0042] Figure 2 This is a schematic flowchart of a urea injection control method provided in an embodiment of the present invention.

[0043] Figure 3 This is a schematic flowchart of another urea injection volume control method provided in an embodiment of the present invention.

[0044] Figure 4 This is a flowchart illustrating another method for controlling urea injection volume provided in an embodiment of the present invention.

[0045] Figure 5 This is an example diagram of the urea injection quantity control logic for a downstream SCR in an embodiment of the present invention.

[0046] Figure 6 This is a flowchart illustrating another method for controlling urea injection volume provided in an embodiment of the present invention.

[0047] Figure 7 This is a flowchart illustrating another method for controlling urea injection volume provided in an embodiment of the present invention.

[0048] Figure 8 This is an example diagram of the urea injection volume control logic of a pre-stage SCR in an embodiment of the present invention.

[0049] Figure 9 This is a schematic diagram of a urea injection volume control device provided in an embodiment of the present invention.

[0050] Figure 10 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] For ease of description, some of the nouns or terms used in the embodiments of the present invention are explained below:

[0053] DPF: Diesel Particulate Filter, used to capture particulate matter in exhaust gas. When the mass of captured particulate matter reaches a certain level, passive or active regeneration is required to restore the DPF's ability to capture particulate matter.

[0054] DOC: Diesel Oxide Catalyst, installed before the DPF, is used to oxidize NO in the exhaust gas to NO2, while also increasing the exhaust gas temperature and assisting the normal operation of the DPF and SCR.

[0055] SCR: Selectively Catalytic Reduction. Urea is injected before the SCR to reduce nitrogen oxides in the exhaust gas. The SCR is located far from the turbine.

[0056] ccSCR: Tightly Coupled SCR.

[0057] ASC: Ammonia Slip Catalyst, used to oxidize excess ammonia.

[0058] It should be noted that existing post-treatment systems do not consider the side reaction of N2O generation during SCR, and the control of urea injection volume does not take into account the occurrence of N2O side reactions during SCR, resulting in environmental impacts from the generated N2O. To reduce the amount of N2O generated during SCR, this invention provides a urea injection volume control method, apparatus, and electronic device.

[0059] The urea injection quantity control method provided by this invention is applied to a diesel engine exhaust aftertreatment system, and the applicable diesel engine exhaust aftertreatment system can be a two-stage SCR aftertreatment system. Figure 1 This is a schematic diagram of the structure of the two-stage SCR post-processing system in an embodiment of the present invention. Figure 1 As shown, this two-stage SCR aftertreatment system may include ccSCR&ASC, DOC, DPF, and SCR&ASC. The system is equipped with NOx sensors NOx1, NOx2, and NOx3, and temperature sensors T4, T5, T6, T7, and T8. In the bipolar SCR aftertreatment system designed in this invention, the front end of the subsequent SCR stage uses an iron-based catalyst, and the rear end uses a copper-based catalyst. The front-stage SCR can be ccSCR, i.e.,... Figure 1 The middle stage SCR, the subsequent SCR is Figure 1 In SCR & ASC, SCR refers to iron-based catalysts. Figure 1 CAT1, a copper-based catalyst, is... Figure 1 CAT2 in the middle.

[0060] To ensure sufficient conversion efficiency at low temperatures and reduce N2O formation on ASC, Figure 1In the ccSCR&ASC process, the ccSCR (pre-stage SCR) catalyst can be a copper-based catalyst, while the ASC catalyst can be a copper-based catalyst plus a noble metal, with a ccSCR to ASC volume ratio between 3 and 4.5. To reduce NO2 formation in DOC and prevent N2O formation from the SCR catalyst, a low concentration of noble metal, such as 10 g / cm³ of pure Pt, can be used as the DOC catalyst. The SCR (post-stage SCR) catalyst in the SCR&ASC process uses an iron-based catalyst + copper-based catalyst scheme. The pre-stage SCR uses an iron-based catalyst, and the adjacent post-stage uses a copper-based catalyst, with a volume ratio between 0.25 and 0.4. The use of an iron-based catalyst can reduce N2O formation to some extent. Specifically, the iron-based catalyst can reduce N2O formation at the pre-stage of the post-stage SCR while reacting NO2, further reducing N2O formation by the copper-based catalyst.

[0061] This invention determines the first internal ammonia storage prediction value of the subsequent SCR by using kinetic models of iron-based catalysts and copper-based catalysts. Based on the first internal ammonia storage prediction value and the internal ammonia storage setpoint of the subsequent SCR, the first ammonia storage-corrected urea injection rate of the subsequent SCR is determined. Based on the feedforward urea injection rate of the subsequent SCR and the first ammonia storage-corrected urea injection rate, the total urea injection rate of the subsequent SCR is determined. This invention employs a combination of iron-based and copper-based catalysts in the subsequent SCR, and determines the ammonia storage-corrected urea injection rate based on the internal ammonia storage prediction value determined by the iron-based catalyst kinetic model and the copper-based catalyst kinetic model, thereby determining the total urea injection rate of the subsequent SCR. This allows for precise control of the urea injection rate and reduces N2O emissions from the aftertreatment system.

[0062] The urea injection quantity control method, device, and electronic equipment provided by the present invention will now be described in detail with reference to the accompanying drawings.

[0063] Figure 2 This is a schematic flowchart illustrating a urea injection control method provided in an embodiment of the present invention. Figure 2 As shown, the method may include the following steps:

[0064] Step 201: Based on the kinetic models of the iron-based catalyst and the copper-based catalyst of the subsequent SCR, determine the predicted value of the first internal ammonia storage of the subsequent SCR.

[0065] Both the iron-based catalyst kinetic model and the copper-based catalyst kinetic model include ammonia adsorption-desorption reactions, standard reactions, fast reactions, slow reactions, ammonia oxidation reactions, and N₂O generation reactions. In some embodiments, due to the different chemical reaction rates of the iron-based and copper-based catalysts, separate kinetic models are constructed to predict the internal ammonia reserves of the subsequent SCR stage. As an example, the iron-based catalyst kinetic model and the copper-based catalyst kinetic model can be constructed based on the rate equations of the SCR chemical reactions, the conservation of ammonia reserves, and the forward Eulerian method.

[0066] In some embodiments, the inputs to the iron-based catalyst kinetic model may include the exhaust gas flow rate, the inlet temperature of the subsequent SCR stage (e.g., ... Figure 1 (T7 temperature), based on the NOx sensor upstream of the subsequent SCR (such as...) Figure 1 The NOx concentration obtained from the NOx2 sensor (in the middle stage) and the urea injection rate at the previous moment of the subsequent SCR stage are used as inputs. The output of the iron-based catalyst kinetic model can include the predicted value of the internal ammonia storage of the iron-based catalyst, as well as the predicted values ​​of temperature and NOx concentration downstream of the iron-based catalyst. The input of the copper-based catalyst kinetic model can include the predicted values ​​of temperature, NOx concentration, and exhaust gas flow rate output from the iron-based catalyst kinetic model, and the output is the predicted value of the internal ammonia storage of the copper-based catalyst. The sum of the predicted values ​​of the internal ammonia storage of the iron-based catalyst and the internal ammonia storage of the copper-based catalyst is used as the predicted value of the internal ammonia storage of the subsequent SCR stage.

[0067] Step 202: Based on the first internal ammonia storage prediction value and the internal ammonia storage setting value of the subsequent SCR, determine the first ammonia storage correction urea injection amount of the subsequent SCR.

[0068] The internal ammonia storage setpoint of the downstream SCR can be determined by looking up a table. For example, the internal ammonia storage setpoint of the downstream SCR can be obtained by looking up a table based on the exhaust gas flow rate of the aftertreatment system and the temperature of the downstream SCR. The downstream SCR temperature used when looking up the table can be the average temperature of the downstream SCR, which can be calculated by weighted averaging the upstream and downstream temperatures of the downstream SCR.

[0069] As one possible implementation, the process of determining the first ammonia storage-corrected urea injection amount of the subsequent SCR based on the first internal ammonia storage prediction value and the internal ammonia storage set value of the subsequent SCR may include: determining the difference between the first internal ammonia storage prediction value and the internal ammonia storage set value of the subsequent SCR, and dividing the difference by the calibration time to obtain the first ammonia storage-corrected urea injection amount.

[0070] As another possible implementation, the process of determining the first ammonia storage correction urea injection amount of the subsequent SCR based on the first internal ammonia storage prediction value and the internal ammonia storage set value of the subsequent SCR may include: determining the difference between the first internal ammonia storage prediction value and the internal ammonia storage set value of the subsequent SCR, and calculating the first ammonia storage correction urea injection amount based on the difference through a PI controller.

[0071] Step 203: Determine the total urea injection amount of the subsequent SCR based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage corrected urea injection amount.

[0072] The feedforward urea injection rate of the subsequent SCR can be determined based on the set ammonia-to-nitrogen ratio of the subsequent SCR and the actual NOx concentration upstream of the subsequent SCR. The actual NOx concentration upstream of the subsequent SCR can be determined by... Figure 1 The NOx2 concentration is measured by the NOx sensor in the system. The set ammonia-nitrogen ratio for the downstream SCR can be obtained by looking up a table based on the temperature and exhaust gas flow rate of the downstream SCR. The product of the set ammonia-nitrogen ratio and the actual NOx concentration upstream of the downstream SCR is used to obtain the feedforward urea injection rate for the downstream SCR.

[0073] In some embodiments, the sum of the feedforward urea injection rate of the subsequent SCR and the first ammonia storage correction urea injection rate can be determined as the total urea injection rate of the subsequent SCR.

[0074] According to the urea injection control method of this invention, the front end of the subsequent SCR in the two-stage SCR aftertreatment system uses an iron-based catalyst, and the rear end uses a copper-based catalyst. A first internal ammonia storage prediction value for the subsequent SCR is determined using kinetic models of the iron-based catalyst and the copper-based catalyst based on the subsequent SCR. Based on the first internal ammonia storage prediction value and the internal ammonia storage setpoint of the subsequent SCR, a first ammonia storage-corrected urea injection rate for the subsequent SCR is determined. Based on the feedforward urea injection rate of the subsequent SCR and the first ammonia storage-corrected urea injection rate, the total urea injection rate of the subsequent SCR is determined. This invention uses a combination of iron-based and copper-based catalysts in the subsequent SCR, and determines the ammonia storage-corrected urea injection rate based on the internal ammonia storage prediction value determined by the iron-based catalyst kinetic model and the copper-based catalyst kinetic model, thereby determining the total urea injection rate of the subsequent SCR. This allows for precise control of the urea injection rate and reduces N2O emissions from the aftertreatment system.

[0075] To improve the accuracy of urea injection volume control, the present invention provides another embodiment.

[0076] Figure 3 This is a schematic flowchart of another urea injection volume control method provided in an embodiment of the present invention. Figure 3 As shown, the method may include the following steps:

[0077] Step 301: Based on the kinetic models of iron-based catalysts and copper-based catalysts, determine the predicted value of the first internal ammonia storage and the predicted value of the first NOx concentration downstream of the subsequent SCR stage.

[0078] In some embodiments, based on the kinetic models of iron-based catalysts and copper-based catalysts, not only can the first internal ammonia storage prediction value be obtained, but also the first NOx concentration prediction value downstream of the subsequent SCR can be obtained. For example, the kinetic model of iron-based catalysts outputs the NOx concentration prediction value downstream of the iron-based catalyst, and the kinetic model of copper-based catalysts outputs the first NOx concentration prediction value downstream of the subsequent SCR based on the NOx concentration prediction value downstream of the iron-based catalyst.

[0079] Step 302: Based on the first internal ammonia storage prediction value and the internal ammonia storage setting value of the subsequent SCR, determine the first ammonia storage correction urea injection amount of the subsequent SCR.

[0080] Step 303: Based on the predicted value of the first NOx concentration and the actual value of the first NOx concentration upstream of the subsequent SCR, determine the model conversion efficiency of the subsequent SCR.

[0081] The model conversion efficiency refers to the NOx conversion efficiency calculated based on the predicted NOx concentration output by the model.

[0082] As an example, the ratio of the difference between the actual value and the predicted value of the first NOx concentration to the actual value of the first NOx concentration can be determined as the model conversion efficiency of the subsequent SCR.

[0083] Step 304: Determine the model feedforward urea injection amount of the subsequent SCR based on the set conversion efficiency and model conversion efficiency of the subsequent SCR.

[0084] To compensate for the discrepancy between the model prediction and the set value, a model feedforward urea injection rate can be introduced to make the final total urea injection rate more accurate.

[0085] In some embodiments, the ratio between the set conversion efficiency and the model conversion efficiency can be determined first, and then a proportional calculation can be performed based on the ratio to obtain the model feedforward urea injection amount of the subsequent SCR.

[0086] In other embodiments, a first difference between the set conversion efficiency and the model conversion efficiency can be determined first, and the model feedforward urea injection amount can be determined based on the first difference. The process of determining the model feedforward urea injection amount based on the first difference can be by multiplying the first difference by a preset coefficient to obtain the model feedforward urea injection amount, or it can be calculated by the P controller based on the first difference.

[0087] Step 305: Determine the sum of the feedforward urea injection amount of the subsequent SCR, the first ammonia storage corrected urea injection amount, and the model feedforward urea injection amount, and determine the total urea injection amount of the subsequent SCR based on the sum.

[0088] In some embodiments, the calculated summation result can be directly determined as the total urea injection amount of the subsequent SCR, or the calculated summation result can be multiplied by a preset coefficient to obtain the total urea injection amount of the subsequent SCR.

[0089] According to the urea injection rate control method of this invention, the predicted value of the first NOx concentration downstream of the subsequent SCR is obtained based on the kinetic models of iron-based catalysts and copper-based catalysts. Based on the model conversion efficiency and the set conversion efficiency, a model-feedforward urea injection rate is introduced. The total urea injection rate of the subsequent SCR is determined based on the sum of the model-feedforward urea injection rate, the first ammonia storage-corrected urea injection rate, and the model-feedforward urea injection rate. This invention, by introducing a model-feedforward urea injection rate, can compensate for the deviation between the model prediction and the set conversion efficiency, improve the accuracy of urea injection rate control, and reduce N2O generation.

[0090] Figure 4 This is a schematic flowchart illustrating another urea injection volume control method provided in an embodiment of the present invention. Figure 4 As shown, based on the above embodiments, Figure 3 Step 305, which determines the total urea injection amount of the subsequent SCR based on the summation results, may include the following steps:

[0091] Step 401: Determine the closed-loop correction factor based on the model conversion efficiency and the actual conversion efficiency of the subsequent SCR.

[0092] The closed-loop correction factor is used to correct the discrepancy between the model's predicted NOx concentration downstream of the subsequent SCR and the actual NOx concentration, making the model prediction closer to reality. The actual conversion efficiency of the subsequent SCR can be calculated based on the actual NOx concentration downstream of the subsequent SCR and the actual NOx concentration upstream of the subsequent SCR. Figure 1 The NOx3 was measured by the NOx3 sensor in the post-processing system shown.

[0093] In some embodiments, the difference between the actual conversion efficiency of the subsequent SCR and the model conversion efficiency can be calculated first, and the difference can be calculated through a PI controller to obtain a closed-loop correction factor.

[0094] Step 402: The summation result is multiplied by the closed-loop correction factor to determine the total urea injection amount of the subsequent SCR.

[0095] According to the urea injection quantity control method of the present invention, a closed-loop correction factor is determined by combining the model conversion efficiency and the actual conversion efficiency, and the product of the summation result and the closed-loop correction factor is determined as the total urea injection quantity of the subsequent SCR, so as to correct the deviation between the NOx concentration predicted by the model and the actual NOx concentration, realize the closed-loop control of NOx, improve the accuracy of urea injection quantity control, ensure the conversion efficiency of NOx, and reduce the generation of N2O.

[0096] for Figure 2 The implementation process of step 201 may include: inputting the inlet temperature of the downstream SCR, the urea injection rate at the previous moment, the actual value of the first NOx concentration upstream of the downstream SCR, and the exhaust gas flow rate into the iron-based catalyst kinetic model to obtain the predicted values ​​of the second NOx concentration, NH3 concentration, temperature, and iron-based internal ammonia storage downstream of the iron-based catalyst output by the iron-based catalyst kinetic model; inputting the second NOx concentration, NH3 concentration, and temperature prediction values, as well as the exhaust gas flow rate, into the copper-based catalyst kinetic model to obtain the predicted value of copper-based internal ammonia storage output by the copper-based catalyst kinetic model; and summing the predicted value of iron-based internal ammonia storage and the predicted value of copper-based internal ammonia storage to determine the first internal ammonia storage prediction value. The copper-based catalyst kinetic model can also output the predicted value of the first NOx concentration downstream of the downstream SCR.

[0097] Figure 5 This is an example diagram of urea injection quantity control logic for a downstream SCR in an embodiment of the present invention, which can be combined with... Figure 5 The urea injection quantity control method of the above embodiments will be understood.

[0098] Since the two-stage SCR aftertreatment system also includes a pre-stage SCR, the urea injection control method of this embodiment of the invention may also include the control of the urea injection amount of the pre-stage SCR. Please refer to the following embodiments.

[0099] Figure 6 This is a schematic flowchart illustrating another urea injection volume control method provided in an embodiment of the present invention. Figure 6 As shown, based on the above embodiments, the method may further include the following steps:

[0100] Step 601: Based on the kinetic model of the pre-stage SCR in the two-stage SCR post-treatment system, determine the second internal ammonia storage prediction value of the pre-stage SCR.

[0101] The kinetic models for pre-SCR include ammonia adsorption-desorption reactions, standard reactions, fast reactions, slow reactions, ammonia oxidation reactions, and N₂O generation reactions. As an example, the kinetic model for pre-SCR can be constructed based on the rate equations of the aforementioned SCR chemical reactions, the conservation of ammonia storage mass, and the forward Eulerian method.

[0102] In some embodiments, the inputs to the kinetic model of the pre-stage SCR may include exhaust gas flow rate, inlet temperature of the pre-stage SCR (e.g., ...), and other parameters. Figure 1 Temperature at T4), based on the NOx sensor upstream of the pre-stage SCR (such as... Figure 1 The NOx concentration obtained from the NOx1 sensor in the system, as well as the urea injection rate at the previous moment of the upstream SCR, can be used to calculate the NOx concentration. The output of the kinetic model of the upstream SCR can include the predicted value of the second internal ammonia storage, as well as the predicted value of the NOx concentration downstream of the upstream SCR and the predicted value of the NH3 concentration downstream of the upstream SCR.

[0103] Step 602: Based on the predicted value of the second internal ammonia storage and the set value of the internal ammonia storage of the upstream SCR, determine the second ammonia storage correction urea injection amount of the upstream SCR.

[0104] The internal ammonia storage setpoint of the pre-stage SCR can be determined by looking up a table. For example, the internal ammonia storage setpoint of the pre-stage SCR can be obtained by looking up a table based on the exhaust gas flow rate of the aftertreatment system and the inlet temperature of the pre-stage SCR.

[0105] As one possible implementation, the process of determining the second ammonia storage-corrected urea injection amount based on the second internal ammonia storage prediction value and the internal ammonia storage set value of the preceding SCR may include: determining the difference between the second internal ammonia storage prediction value and the internal ammonia storage set value of the preceding stage, and dividing the difference by the calibration time to obtain the second ammonia storage-corrected urea injection amount.

[0106] As another possible implementation, the process of determining the second ammonia storage-corrected urea injection amount based on the second internal ammonia storage prediction value and the internal ammonia storage set value of the preceding SCR may include: determining the difference between the second internal ammonia storage prediction value and the internal ammonia storage set value of the preceding SCR, and calculating the second ammonia storage-corrected urea injection amount based on the difference through a PI controller.

[0107] Step 603: Determine the total urea injection amount of the pre-stage SCR based on the feedforward urea injection amount of the pre-stage SCR and the second ammonia storage-corrected urea injection amount.

[0108] The feedforward urea injection rate of the pre-stage SCR can be determined based on the set ammonia-to-nitrogen ratio of the pre-stage SCR and the actual NOx concentration upstream of the pre-stage SCR. The actual NOx concentration upstream of the pre-stage SCR can be determined by... Figure 1 The NOx concentration is measured by the NOx sensor in the system. The set ammonia-nitrogen ratio for the pre-stage SCR can be obtained by looking up a table based on the inlet temperature and exhaust gas flow rate of the pre-stage SCR. The product of the set ammonia-nitrogen ratio and the actual NOx concentration upstream of the pre-stage SCR is used to obtain the feedforward urea injection rate for the pre-stage SCR.

[0109] In some embodiments, the sum of the feedforward urea injection rate of the pre-stage SCR and the second ammonia storage-corrected urea injection rate can be determined as the total urea injection rate of the pre-stage SCR.

[0110] According to the urea injection rate control method of this invention, based on the kinetic model of the pre-stage SCR, a second internal ammonia storage prediction value of the pre-stage SCR is determined. Based on the second internal ammonia storage prediction value and the internal ammonia storage setpoint, a second ammonia storage corrected urea injection rate is determined. Based on the feedforward urea injection rate of the pre-stage SCR and the second ammonia storage corrected urea injection rate, the total urea injection rate of the pre-stage SCR is determined. This invention, by introducing control of the SCR, can more accurately control the urea injection rate, ensuring NOx conversion efficiency and reducing N2O generation.

[0111] To further improve the accuracy of urea injection volume control, the present invention also provides the following embodiments.

[0112] Figure 7 This is a schematic flowchart illustrating another urea injection volume control method provided in an embodiment of the present invention. Figure 7 As shown, based on the above embodiments, the urea injection quantity control process for the pre-stage SCR may include the following steps:

[0113] Step 701: Based on the kinetic model of the pre-stage SCR, determine the predicted value of the second internal ammonia storage and the predicted value of the third NOx concentration downstream of the pre-stage SCR.

[0114] Step 702: Based on the predicted value of the second internal ammonia storage and the set value of the internal ammonia storage of the upstream SCR, determine the second ammonia storage correction urea injection amount of the upstream SCR.

[0115] Step 703: Based on the actual value of the first NOx concentration and the predicted value of the third NOx concentration upstream of the downstream SCR, determine the closed-loop corrected urea injection amount of the upstream SCR.

[0116] Among them, the closed-loop correction of urea injection rate in the pre-stage SCR is used to correct the deviation between the NOx concentration predicted by the model and the actual NOx concentration.

[0117] In some embodiments, the difference between the actual value of the first NOx concentration and the predicted value of the third NOx concentration can be determined first, and the closed-loop corrected urea injection amount can be obtained by calculating the difference through the P controller.

[0118] Step 704: The sum of the feedforward urea injection rate of the pre-stage SCR, the second ammonia storage correction urea injection rate, and the closed-loop correction urea injection rate is determined as the total urea injection rate of the pre-stage SCR.

[0119] According to the urea injection quantity control method of the present invention, the closed-loop corrected urea injection quantity is determined based on the predicted and actual NOx concentration values. Then, the total urea injection quantity of the front-stage SCR is determined by summing the feedforward urea injection quantity of the front-stage SCR, the second ammonia storage corrected urea injection quantity, and the closed-loop corrected urea injection quantity. Through closed-loop control, the accuracy of urea injection quantity control is improved, the NOx conversion efficiency is guaranteed, and the generation of N2O is reduced.

[0120] In some embodiments, to prevent NH3 leakage from the pre-stage SCR into the DOC to generate N2O, NH3 leakage judgment logic can be added before the urea injection control process of the pre-stage SCR in the above embodiments. This prevents the cross-sensitivity of NOx to NH3 from affecting the closed-loop control and continuously increasing the urea injection amount. As an example, the leakage judgment method may include: monitoring the actual conversion efficiency of the pre-stage SCR; if the actual conversion efficiency is less than a preset threshold, increasing the ammonia-nitrogen ratio at a preset rate, that is, increasing the feedforward urea injection amount of the pre-stage SCR to increase the total urea injection amount of the pre-stage SCR; when the ammonia-nitrogen ratio increases and the actual conversion efficiency decreases, it is determined that NH3 leakage has occurred, and then the ammonia-nitrogen ratio is reduced at a preset rate, that is, the total urea injection amount of the pre-stage SCR is reduced, until the actual conversion efficiency is greater than or equal to the threshold, and then the urea injection control process of the pre-stage SCR in the above embodiments is executed.

[0121] Figure 8 This is an example diagram of urea injection quantity control logic for a pre-stage SCR in an embodiment of the present invention, which can be combined with... Figure 8 The urea injection quantity control method of the above embodiments will be understood.

[0122] To achieve the above embodiments, the present invention also provides a urea injection quantity control device.

[0123] Figure 9 This is a schematic diagram of a urea injection quantity control device provided in an embodiment of the present invention. This device is applied to a two-stage SCR aftertreatment system. In the two-stage SCR aftertreatment system, the front end of the subsequent SCR stage uses an iron-based catalyst, and the rear end uses a copper-based catalyst. Figure 9 As shown, the device may include: a first determining module 901, a second determining module 902, and a third determining module 903.

[0124] The first determining module 901 is used to determine the first internal ammonia storage prediction value of the subsequent SCR based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model of the subsequent SCR; the iron-based catalyst kinetic model and the copper-based catalyst kinetic model both include ammonia adsorption-desorption reaction, standard reaction, fast reaction, slow reaction, ammonia oxidation reaction and N2O generation reaction;

[0125] The second determining module 902 is used to determine the first ammonia storage correction urea injection amount of the subsequent SCR based on the first internal ammonia storage prediction value and the internal ammonia storage setting value of the subsequent SCR.

[0126] The third determining module 903 is used to determine the total urea injection amount of the subsequent SCR based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage corrected urea injection amount.

[0127] In some embodiments, the first determining module 901 is specifically used for:

[0128] Based on the kinetic model of the iron-based catalyst and the kinetic model of the copper-based catalyst, the predicted value of the first internal ammonia storage and the predicted value of the first NOx concentration downstream of the subsequent SCR are determined.

[0129] The third determination module is specifically used for:

[0130] Based on the first predicted NOx concentration and the actual first NOx concentration upstream of the subsequent SCR, the model conversion efficiency of the subsequent SCR is determined.

[0131] Based on the set conversion efficiency of the subsequent SCR and the model conversion efficiency, the model feedforward urea injection amount of the subsequent SCR is determined.

[0132] The sum of the feedforward urea injection rate of the subsequent SCR, the first ammonia storage corrected urea injection rate, and the model feedforward urea injection rate is determined, and the total urea injection rate of the subsequent SCR is determined based on the sum of the sums.

[0133] As one possible implementation, the third determining module 903 is also used for:

[0134] Determine a first difference between the set conversion efficiency and the model conversion efficiency;

[0135] Based on the first difference, the model feedforward urea injection amount is determined.

[0136] In some embodiments, the third determining module 903 is further configured to:

[0137] Based on the model conversion efficiency and the actual conversion efficiency of the subsequent SCR, a closed-loop correction factor is determined.

[0138] The product of the summation result and the closed-loop correction factor is determined as the total urea injection amount of the subsequent SCR.

[0139] As one possible implementation, the first determining module 901 is specifically used for:

[0140] The inlet temperature of the downstream SCR, the urea injection rate at the previous moment, the actual value of the first NOx concentration upstream of the downstream SCR, and the exhaust gas flow rate are input into the iron-based catalyst kinetic model to obtain the predicted values ​​of the second NOx concentration, NH3 concentration, temperature, and iron-based internal ammonia storage downstream of the iron-based catalyst output by the iron-based catalyst kinetic model.

[0141] The second NOx concentration prediction value, the NH3 concentration prediction value, the temperature prediction value, and the waste gas flow rate are input into the copper-based catalyst kinetic model to obtain the copper-based internal ammonia storage prediction value output by the copper-based catalyst kinetic model.

[0142] The sum of the predicted internal ammonia storage value of the iron-based system and the predicted internal ammonia storage value of the copper-based system is determined as the first predicted internal ammonia storage value.

[0143] In some embodiments, the device further includes:

[0144] The fourth determining module 904 is used to determine the second internal ammonia storage prediction value of the pre-stage SCR based on the kinetic model of the pre-stage SCR in the dual-stage SCR post-treatment system; wherein, the kinetic model of the pre-stage SCR includes ammonia adsorption-desorption reaction, standard reaction, fast reaction, slow reaction, ammonia oxidation reaction and N2O generation reaction;

[0145] The fifth determining module 905 is used to determine the second ammonia storage correction urea injection amount of the front-stage SCR based on the second internal ammonia storage prediction value and the internal ammonia storage setting value of the front-stage SCR.

[0146] The sixth determining module 906 is used to determine the total urea injection amount of the pre-stage SCR based on the feedforward urea injection amount of the pre-stage SCR and the second ammonia storage corrected urea injection amount.

[0147] In some embodiments, the fourth determining module 904 is further configured to:

[0148] Based on the kinetic model of the pre-stage SCR, the predicted value of the second internal ammonia storage and the predicted value of the third NOx concentration downstream of the pre-stage SCR are determined.

[0149] In some embodiments, the sixth determining module 906 is further configured to:

[0150] Based on the actual value of the first NOx concentration upstream of the downstream SCR and the predicted value of the third NOx concentration, the closed-loop corrected urea injection amount of the upstream SCR is determined.

[0151] The total urea injection amount of the pre-stage SCR is determined by summing the feedforward urea injection amount, the second ammonia storage corrected urea injection amount, and the closed-loop corrected urea injection amount.

[0152] According to the urea injection control device of the present invention, the front end of the subsequent SCR in the two-stage SCR aftertreatment system uses an iron-based catalyst and the rear end uses a copper-based catalyst. The first internal ammonia storage prediction value of the subsequent SCR is determined by using kinetic models of the iron-based catalyst and the copper-based catalyst based on the subsequent SCR. Based on the first internal ammonia storage prediction value and the internal ammonia storage setpoint of the subsequent SCR, the first ammonia storage-corrected urea injection rate of the subsequent SCR is determined. Based on the feedforward urea injection rate of the subsequent SCR and the first ammonia storage-corrected urea injection rate, the total urea injection rate of the subsequent SCR is determined. This invention uses a combination of iron-based and copper-based catalysts in the subsequent SCR, and determines the ammonia storage-corrected urea injection rate based on the internal ammonia storage prediction value determined by the iron-based catalyst kinetic model and the copper-based catalyst kinetic model, thereby determining the total urea injection rate of the subsequent SCR. This allows for precise control of the urea injection rate and reduces N2O emissions from the aftertreatment system.

[0153] It should be noted that the explanations and descriptions in the above embodiments of the urea injection quantity control method can also be applied to the urea injection quantity control device in the embodiments of the present invention, and will not be repeated here.

[0154] Figure 10 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 10 As shown, the electronic device may include a processor 1010, a communication interface 1020, a memory 1030, and a communication bus 1040, wherein the processor 1010, the communication interface 1020, and the memory 1030 communicate with each other via the communication bus 1040. The processor 1010 can call the computer program in the memory 1030 to execute the steps of the urea injection quantity control method provided in the above embodiment.

[0155] For example, the method includes: determining the first internal ammonia storage prediction value of the subsequent SCR based on the kinetic models of the iron-based catalyst and the copper-based catalyst; both the iron-based catalyst kinetic model and the copper-based catalyst kinetic model include ammonia adsorption-desorption reaction, standard reaction, fast reaction, slow reaction, ammonia oxidation reaction, and N2O generation reaction; determining the first ammonia storage correction urea injection amount of the subsequent SCR based on the first internal ammonia storage prediction value and the internal ammonia storage setpoint of the subsequent SCR; and determining the total urea injection amount of the subsequent SCR based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage correction urea injection amount.

[0156] Furthermore, the logical instructions in the aforementioned memory 1030 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, 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 the present invention. 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.

[0157] On the other hand, embodiments of the present invention also provide a computer program product, the computer program product including a computer program, the computer program being able to be stored on a computer-readable storage medium, and when the computer program is executed by a processor, the computer is able to perform the steps of the urea injection quantity control method provided in the above embodiments.

[0158] On the other hand, embodiments of the present invention also provide a computer-readable storage medium storing a computer program for causing a processor to execute the urea injection quantity control method provided in the above embodiments.

[0159] The computer-readable storage medium can be any available medium or data storage device that the processor can access, including but not limited to magnetic storage (e.g., floppy disk, hard disk, magnetic tape, magneto-optical disk (MO)), optical storage (e.g., CD, DVD, BD, HVD), and semiconductor storage (e.g., ROM, EPROM, EEPROM, non-volatile memory (NAND FLASH), solid-state drive (SSD)).

[0160] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0161] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling the amount of urea injected, characterized in that, The method is applied to a two-stage SCR aftertreatment system; the front end of the two-stage SCR aftertreatment system uses an iron-based catalyst, and the rear end uses a copper-based catalyst; the method includes: Based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model of the subsequent SCR, the first internal ammonia storage prediction value of the subsequent SCR is determined; the iron-based catalyst kinetic model and the copper-based catalyst kinetic model both include ammonia adsorption-desorption reaction, standard reaction, fast reaction, slow reaction, ammonia oxidation reaction and N2O generation reaction; Based on the first internal ammonia storage prediction value and the internal ammonia storage setting value of the subsequent SCR, the first ammonia storage correction urea injection amount of the subsequent SCR is determined. The total urea injection amount of the subsequent SCR is determined based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage corrected urea injection amount. The determination of the first internal ammonia storage prediction value of the subsequent SCR based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model includes: Based on the kinetic model of the iron-based catalyst and the kinetic model of the copper-based catalyst, the predicted value of the first internal ammonia storage and the predicted value of the first NOx concentration downstream of the subsequent SCR are determined. The determination of the total urea injection amount of the subsequent SCR based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage corrected urea injection amount includes: Based on the first predicted NOx concentration and the actual first NOx concentration upstream of the subsequent SCR, the model conversion efficiency of the subsequent SCR is determined. Based on the set conversion efficiency of the subsequent SCR and the model conversion efficiency, the model feedforward urea injection amount of the subsequent SCR is determined. The sum of the feedforward urea injection rate of the subsequent SCR, the first ammonia storage corrected urea injection rate, and the model feedforward urea injection rate is determined, and the total urea injection rate of the subsequent SCR is determined based on the sum of the sums.

2. The method according to claim 1, characterized in that, The step of determining the model feedforward urea injection amount of the subsequent SCR based on the set conversion efficiency of the subsequent SCR and the model conversion efficiency includes: Determine a first difference between the set conversion efficiency and the model conversion efficiency; Based on the first difference, the model feedforward urea injection amount is determined.

3. The method according to claim 1, characterized in that, The determination of the total urea injection amount of the subsequent SCR based on the summation result includes: Based on the model conversion efficiency and the actual conversion efficiency of the subsequent SCR, a closed-loop correction factor is determined. The product of the summation result and the closed-loop correction factor is determined as the total urea injection amount of the subsequent SCR.

4. The method according to claim 1, characterized in that, The determination of the first internal ammonia storage prediction value of the subsequent SCR based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model includes: The inlet temperature of the downstream SCR, the urea injection rate at the previous moment, the actual value of the first NOx concentration upstream of the downstream SCR, and the exhaust gas flow rate are input into the iron-based catalyst kinetic model to obtain the predicted values ​​of the second NOx concentration, NH3 concentration, temperature, and iron-based internal ammonia storage downstream of the iron-based catalyst output by the iron-based catalyst kinetic model. The second NOx concentration prediction value, the NH3 concentration prediction value, the temperature prediction value, and the waste gas flow rate are input into the copper-based catalyst kinetic model to obtain the copper-based internal ammonia storage prediction value output by the copper-based catalyst kinetic model. The sum of the predicted internal ammonia storage value of the iron-based system and the predicted internal ammonia storage value of the copper-based system is determined as the first predicted internal ammonia storage value.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: Based on the kinetic model of the pre-stage SCR in the dual-stage SCR post-treatment system, the second internal ammonia storage prediction value of the pre-stage SCR is determined; wherein, the kinetic model of the pre-stage SCR includes ammonia adsorption-desorption reaction, standard reaction, fast reaction, slow reaction, ammonia oxidation reaction and N2O generation reaction; Based on the second internal ammonia storage prediction value and the internal ammonia storage setting value of the preceding SCR, the second ammonia storage correction urea injection amount of the preceding SCR is determined; The total urea injection amount of the pre-stage SCR is determined based on the feedforward urea injection amount of the pre-stage SCR and the second ammonia storage corrected urea injection amount.

6. The method according to claim 5, characterized in that, The kinetic model based on the pre-stage SCR within the two-stage SCR aftertreatment system determines the second internal ammonia storage prediction value of the pre-stage SCR, including: Based on the kinetic model of the pre-stage SCR, the predicted value of the second internal ammonia storage and the predicted value of the third NOx concentration downstream of the pre-stage SCR are determined. The determination of the total urea injection rate of the pre-stage SCR based on the feedforward urea injection rate of the pre-stage SCR and the second ammonia storage corrected urea injection rate includes: Based on the actual value of the first NOx concentration upstream of the downstream SCR and the predicted value of the third NOx concentration, the closed-loop corrected urea injection amount of the upstream SCR is determined. The total urea injection amount of the pre-stage SCR is determined by summing the feedforward urea injection amount, the second ammonia storage corrected urea injection amount, and the closed-loop corrected urea injection amount.

7. A urea injection quantity control device, characterized in that, The device is used in a two-stage SCR post-treatment system; the front end of the subsequent SCR stage in the two-stage SCR post-treatment system uses an iron-based catalyst, and the rear end uses a copper-based catalyst; the device includes: The first determining module is used to determine the first internal ammonia storage prediction value of the subsequent SCR based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model of the subsequent SCR; the iron-based catalyst kinetic model and the copper-based catalyst kinetic model both include ammonia adsorption-desorption reaction, standard reaction, fast reaction, slow reaction, ammonia oxidation reaction and N2O generation reaction; The second determining module is used to determine the first ammonia storage correction urea injection amount of the subsequent SCR based on the first internal ammonia storage prediction value and the internal ammonia storage setting value of the subsequent SCR. The third determining module is used to determine the total urea injection amount of the subsequent SCR based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage corrected urea injection amount. The determination of the first internal ammonia storage prediction value of the subsequent SCR based on the iron-based catalyst kinetic model and the copper-based catalyst kinetic model includes: Based on the kinetic model of the iron-based catalyst and the kinetic model of the copper-based catalyst, the predicted value of the first internal ammonia storage and the predicted value of the first NOx concentration downstream of the subsequent SCR are determined. The determination of the total urea injection amount of the subsequent SCR based on the feedforward urea injection amount of the subsequent SCR and the first ammonia storage corrected urea injection amount includes: Based on the first predicted NOx concentration and the actual first NOx concentration upstream of the subsequent SCR, the model conversion efficiency of the subsequent SCR is determined. Based on the set conversion efficiency of the subsequent SCR and the model conversion efficiency, the model feedforward urea injection amount of the subsequent SCR is determined. The sum of the feedforward urea injection rate of the subsequent SCR, the first ammonia storage corrected urea injection rate, and the model feedforward urea injection rate is determined, and the total urea injection rate of the subsequent SCR is determined based on the sum of the sums.

8. An electronic device comprising a processor and a memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the urea injection quantity control method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, It stores a computer program that can be executed by a processor to implement the urea injection quantity control method as described in any one of claims 1 to 6.

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