Double-SCR (Selective Catalytic Reduction) pumping pressure control method and system based on physical model

Abstract

The invention belongs to the technical field of engine aftertreatment systems. The invention provides a double-SCR pump pressure control method and system based on a physical model, and the method comprises the steps: calculating a first pressure deviation value between a set urea pump pressure and a model urea pump pressure, obtaining a dynamic feed-forward correction duty ratio through a proportional controller, and taking the sum of a steady state duty ratio and the dynamic feed-forward correction duty ratio as a feed-forward duty ratio; a second pressure deviation value between the actual pump pressure of the urea pump and the pressure of the model urea pump is calculated, a feedback correction duty ratio is obtained through a proportional controller, and the sum of the feedback correction duty ratio and the steady-state duty ratio serves as the feedback duty ratio; and taking the sum of the feedforward duty ratio and the feedback duty ratio as the duty ratio of the urea pump, and controlling the urea pump according to the duty ratio of the urea pump. According to the invention, cooperative control of urea input pressure in the front and rear SCR injection systems is realized, so that higher injection precision and purification effect are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine aftertreatment systems, and in particular to a dual SCR pump pressure control method and system based on a physical model. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] With the increasing emphasis on environmental protection, people are paying more and more attention to the control of diesel engine emission pollutants. Diesel engine emissions mainly include nitrogen oxides, particulate matter, HC and CO. Among them, nitrogen oxides are the most concerned pollutants in diesel engine emission control due to their emission proportion and harm to the human body. The current mainstream diesel engine after-treatment technology route is DOC+DPF+SCR+ASC, and the emission limits of pollutants such as nitrogen oxides will be further tightened in the future. Therefore, more advanced after-treatment technology is needed to address the problem of excessive NOx emissions in cold start conditions under the current after-treatment equipment configuration.

[0004] Among the many new emission control technologies, the technical route of installing a tightly coupled SCR upstream of the after-treatment system is highly favored. This technology requires the installation of two upstream and downstream SCRs (the front Lo-SCR and the rear SCR) to expand the temperature range for efficient removal of nitrogen oxides. Accordingly, urea nozzles need to be set in the front and rear SCRs respectively (a urea nozzle is set in the front space of the Lo-SCR and SCR) to form a single urea pump and dual urea nozzle system. Due to the different working conditions of the two SCRs, the injection states of the corresponding nozzles are also very different, which in turn produces large pressure fluctuations. The traditional single nozzle technology uses PID closed-loop control to make it difficult to cope with the pressure fluctuations under the dual injection system, which is not conducive to precise injection during SCR operation. Summary of the invention

[0005] In order to address the deficiencies of the prior art, the present invention provides a dual SCR pump pressure control method and system based on a physical model, which realizes the coordinated control of urea input pressure in the front and rear SCR injection systems, thereby achieving higher injection accuracy and NOx purification effect.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: In a first aspect, the present invention provides a dual SCR pump pressure control method based on a physical model.

[0007] A dual SCR pump pressure control method based on a physical model includes the following processes: Calculating a first pressure deviation value between a set urea pump pressure and a model urea pump pressure, using a proportional controller to obtain a dynamic feedforward correction duty cycle, and taking the sum of the steady-state duty cycle and the dynamic feedforward correction duty cycle as the feedforward duty cycle; Calculate the second pressure deviation value between the actual pump pressure of the urea pump and the model urea pump pressure, obtain the feedback correction duty cycle through the proportional controller, and use the sum of the feedback correction duty cycle and the steady-state duty cycle as the feedback duty cycle; The sum of the feedforward duty cycle and the feedback duty cycle is taken as the urea pump duty cycle, and the urea pump is controlled according to the urea pump duty cycle.

[0008] In a second aspect, the present invention provides a dual SCR pump pressure control system based on a physical model.

[0009] A dual SCR pump pressure control system based on a physical model, comprising: A feedforward control unit is configured to: calculate a first pressure deviation value between a set urea pump pressure and a model urea pump pressure, obtain a dynamic feedforward correction duty cycle using a proportional controller, and take the sum of the steady-state duty cycle and the dynamic feedforward correction duty cycle as the feedforward duty cycle; The feedback control unit is configured to: calculate a second pressure deviation value between the actual pump pressure of the urea pump and the model urea pump pressure, obtain a feedback correction duty cycle through a proportional controller, and use the sum of the feedback correction duty cycle and the steady-state duty cycle as the feedback duty cycle; The urea pump control unit is configured to: take the sum of the feedforward duty cycle and the feedback duty cycle as the urea pump duty cycle, and control the urea pump according to the urea pump duty cycle.

[0010] In a third aspect, the present invention provides a computer device, comprising: a processor and a computer-readable storage medium; a processor adapted to execute a computer program; A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by the processor, the physical model-based dual SCR pump pressure control method as described in the first aspect of the present invention is implemented.

[0011] In a fourth aspect, the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program is suitable for being loaded by a processor and executing the physical model-based dual SCR pump pressure control method as described in the first aspect of the present invention.

[0012] In a fifth aspect, the present invention provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the dual SCR pump pressure control method based on the physical model as described in the first aspect of the present invention.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, a pressure flow model of the urea injection system is established, and calculations are performed periodically, which can more accurately describe the real-time changes in the pressure in the urea injection system and provide a reference for pump pressure control.

[0014] 2. In the present invention, a two-stage SCR pump pressure control strategy is established based on the pressure model, which has feedforward control, model control and feedback control. The three control paths realize stable regulation of the front and rear injection pressures. Feedforward control includes steady state and dynamic. The process is simple to calibrate and can respond quickly. Through feedforward control, it can quickly respond to the impact of nozzle injection on the urea pump pressure, increase the urea pump duty cycle in advance, and increase the urea amount to maintain the pressure; feedback control can combine the actual injection situation and the model calculation situation to realize accurate pump pressure control of the dual injection system and maintain the injection system pressure stability.

[0015] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0017] Figure 1 A schematic diagram of the layout of the dual-spray system provided in Example 1 of the present invention; Figure 2 A schematic diagram of the control principle of a dual-spray system based on a model provided in Example 1 of the present invention; Among them, 1. control unit; 2. urea tank; 3. urea pump motor; 4. pump pressure chamber; 5. reflux valve. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0020] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0021] Embodiment 1: This implementation proposes a dual SCR pump pressure control method based on a physical model, using a dual-stage SCR urea injection system with pump pressure self-regulation, such as Figure 1 As shown, it includes: a control unit 1, a urea tank 2, a urea pump motor 3, a pump pressure chamber 4, a reflux valve 5, an upstream Lo-SCR nozzle (i.e., a first nozzle), a downstream SCR nozzle (i.e., a second nozzle), and a pressure sensor (i.e., arranged in a urea supply system and in a post-treatment device) Figure 1 In ) and gas concentration sensors (i.e. Figure 1 Each of ).

[0022] According to the working principle of the urea injection system, for the urea in the pump pressure chamber 4 and the urea pipe, the input is the urea pump supply, and the output includes urea injection and urea reflux of two urea nozzles. By controlling the duty cycle of the urea pump motor 3 and the injection time and injection amount of the injector, the input and output of urea in the system are controlled; at the same time, a reflux valve 5 for regulating the pressure in the pipe is set in the urea injection pipeline (the reflux valve 5 is connected to the urea tank 2. When the pressure in the pipe is too high, the reflux valve 5 is opened to maintain the pipeline pressure constant by discharging a certain flow of urea solution), and the negative feedback is used to regulate and stabilize the pressure in the pipe; the nozzle injection duty cycle depends on the engine exhaust condition (there is a linear relationship between the duty cycle and the pump speed, and the pump speed directly affects the urea supply flow of the pump. Therefore, when the exhaust volume increases, the speed is increased accordingly by increasing the duty cycle, thereby increasing the urea supply amount, and realizing the required effective conversion of pollutants in the exhaust gas). The present invention establishes a urea pump pressure calculation pressure physical model for the urea pump input, and calculates the urea pump pressure value in real time.

[0023] The control method described in this implementation is as follows: Figure 2 As shown, three control paths including feedforward control, model control and feedback control are used to achieve stable regulation of the pressure of the urea injection system.

[0024] The pressure physical model in this implementation is obtained based on the flow calculation formula. The input is the operating state parameters such as the duty cycle of the urea pump, and the output is the urea pump model pressure at the current moment. The input and output of urea in the system are controlled by controlling the duty cycle of the urea pump motor 3 and the injection time and injection amount of each nozzle. The duty cycle of the nozzle injection depends on the engine exhaust condition. A urea pump pressure calculation physical model is established for urea input, and the urea pump pressure value is calculated in real time.

[0025] Pressure differential equation: (1); Urea pump supply flow calculation formula: (2); (3).

[0026] The output flow characteristics adopt the throttling orifice formula of pressure flow control. When the flow is turbulent, its flow pressure characteristics are as follows: Urea output formula of the first nozzle: (4); The second nozzle urea input formula: (5).

[0027] Return flow formula: (6); is the space pressure of urea tank 2, It is the pressure value set for opening the reflux valve 5. When the pressure in the pipeline is too high, the reflux valve 5 opens to discharge a certain flow of urea solution to maintain a constant pipeline pressure.

[0028] Flow coefficient formula: (7); In the above formula: is the pressure value of the space at the SCR inlet after the first nozzle; is the pressure value at the SCR inlet after the second nozzle; is the outlet flow of urea pump; is the reflux flow of reflux valve 5; The first nozzle sprays a flow rate; spraying flow for the second nozzle; is the pump speed; is the pump displacement; is the pump volumetric efficiency; D is the actual duty cycle of the urea pump, with a value range of 0-1; K is the 3 coefficient of the urea pump motor, which is provided by the manufacturer's technical parameters; is the nozzle flow coefficient; is the effective flow area of ​​the nozzle; is the urea pump pressure; is the density of urea solution; is the flow coefficient of reflux valve 5; is the spring stiffness coefficient of the return valve 5; is the inlet diameter of the reflux valve 5; is the bulk elastic modulus of urea solution; is the pipe volume (the pipe containing urea in front of the two nozzles, connecting the input of the urea pump and the urea output of the two nozzles).

[0029] In the urea pump pressure model, the flow coefficient parameters and elastic bulk modulus of the model are calibrated by the actual urea injection system structural parameters and measurement data, and the model performs calculations periodically.

[0030] In this implementation, the feedforward control includes static feedforward control and dynamic feedforward control. In the steady-state control, the set urea pump pressure is converted into the urea pump supply flow rate according to the pressure-flow characteristic curve of the urea pump set by the manufacturer in the calculation unit, and then the supply flow rate is converted into the steady-state control duty cycle of the static feedforward through formula (2) and formula (3).

[0031] During the dynamic feedforward control process, the deviation between the set urea pump pressure and the model urea pump pressure is calculated and converted into a flow deviation according to the characteristic curve. A proportional controller is used to convert the deviation into a duty cycle change output (i.e., the dynamic feedforward correction duty cycle) and added to the steady-state control duty cycle of the static feedforward.

[0032] (8); (9); in, is the first pressure deviation value; is the model pressure; To set the pressure; is the first duty cycle deviation value; It is the first proportional coefficient, which is factory set according to the urea pump characteristic curve.

[0033] In this way, the final output duty cycle includes the steady-state control duty cycle and the dynamic feedforward correction duty cycle. This control method has a fast response and simple calibration. Through feedforward control, it can quickly respond to the impact of nozzle injection on the urea pump pressure, increase the urea pump duty cycle in advance, and increase the urea amount to maintain pressure.

[0034] The closed-loop control is performed based on the deviation between the urea pump model pressure and the actual urea pump pressure. The closed-loop pressure change is obtained through the PI controller. The correction is added to the feedforward pressure change, and then the urea pump duty cycle is obtained through the pressure-flow model and the urea pump characteristic model to achieve precise control of the pump pressure.

[0035] (10); (11); in, is the second pressure deviation value; is the model pressure; is the actual pressure; is the second duty cycle deviation value; It is the second proportional coefficient, which is factory set according to the urea pump characteristic curve.

[0036] Through the coordination of the above three control paths, the urea pump can quickly respond to the pump pressure fluctuations caused by intermittent or simultaneous injection of the two urea nozzles, and realize stable and precise control of the pump pressure of a single pump and two nozzles.

[0037] In this implementation, during the urea injection process, each sensor collects state parameters such as pressure and concentration in real time, feeds them back to the control unit 1 for pressure model calculation, and inputs the calculation results into the above-mentioned pump pressure control model. Combined with the feedforward and feedback control paths, the urea pump pressure is accurately and quickly regulated, thereby making the urea injection more accurate and controllable.

[0038] Specifically, the control unit 1 obtains the actual driving duty cycle of the urea pump, uses the pressure sensor to collect the pressure in the supply pipeline and the urea pump, and at the same time, uses the nitrogen oxide sensor in the post-treatment equipment and the real-time operating parameters at that moment to calculate and control the injection volume of the upstream and downstream nozzles; the above operating parameters are input into the pressure flow model to calculate the urea pump model pressure at that moment; the calculated model pressure is input into the dynamic control system in the feedforward control, the deviation between the set pressure and the model pressure is calculated, and converted into a duty cycle output to achieve dynamic regulation. At the same time, the actual urea pump pressure value is collected by the pressure sensor, and the pressure is calculated and compared with the above output model pressure in the control unit 1 to obtain the pressure deviation between the model calculation and the actual output, and the duty cycle is corrected by feedback to achieve precise control of the pump pressure.

[0039] The actual injection conditions of the two nozzles depend on the calculation of the engine exhaust nitrogen oxides and the internal ammonia storage of the SCR, and are precisely controlled by the control unit 1. Specifically, the calculation process of the urea injection flow rate based on the nitrogen oxide emission concentration is as follows: Molar flow rate of nitrogen oxides: (12); The calculation formula for the injection mass flow rate of the first urea nozzle is: (13); Ammonia storage correction factor: (14); in, is the molar flow rate of nitrogen oxides at the upstream end of the first nozzle, is the mass flow rate of nitrogen oxides at the upstream end of the first nozzle; is the proportion of nitric oxide at the upstream end of the first nozzle; is the density of urea solution; is the ammonia storage correction factor at the upstream end of the first nozzle; setting an ammonia storage amount for the upstream end of the first nozzle; is the target ammonia storage amount at the upstream end of the first nozzle; storing a maximum allowable value for ammonia at the upstream end of the first nozzle; A minimum allowed value is stored for ammonia upstream of the first nozzle.

[0040] At the same time, the downstream urea injection flow rate is calculated based on the downstream data ,Right now: (15); (16); (17); in, is the molar flow rate of nitrogen oxides at the upstream end of the second nozzle, is the nitrogen oxide mass flow rate at the upstream end of the second nozzle; is the proportion of nitric oxide at the upstream end of the second nozzle; is the density of urea solution; is the ammonia storage correction factor at the upstream end of the second nozzle; setting an ammonia storage amount for the upstream end of the second nozzle; is the target ammonia storage amount at the upstream end of the second nozzle; storing a maximum allowable value for ammonia at the upstream end of the second nozzle; A minimum allowed value is stored for ammonia upstream of the second nozzle.

[0041] Embodiment 2: This implementation provides a dual SCR pump pressure control system based on a physical model, including: A feedforward control unit is configured to: calculate a first pressure deviation value between a set urea pump pressure and a model urea pump pressure, obtain a dynamic feedforward correction duty cycle using a proportional controller, and take the sum of the steady-state duty cycle and the dynamic feedforward correction duty cycle as the feedforward duty cycle; The feedback control unit is configured to: calculate a second pressure deviation value between the actual pump pressure of the urea pump and the model urea pump pressure, obtain a feedback correction duty cycle through a proportional controller, and use the sum of the feedback correction duty cycle and the steady-state duty cycle as the feedback duty cycle; The urea pump control unit is configured to: take the sum of the feedforward duty cycle and the feedback duty cycle as the urea pump duty cycle, and control the urea pump according to the urea pump duty cycle.

[0042] It is understandable that the above-mentioned units can be separately or completely combined into one or several other units to constitute, or one (some) of the units can be further divided into multiple smaller units in function to constitute, which can achieve the same operation without affecting the realization of the technical effects of the embodiments of the present application. The above-mentioned units are divided based on logical functions. In practical applications, the functions of one unit can also be implemented by multiple units, or the functions of multiple units can be implemented by one unit. In other embodiments of the present application, the system may also include other units. In practical applications, these functions can also be implemented with the assistance of other units, and can be implemented by the collaboration of multiple units.

[0043] According to another embodiment of the present application, the system described in this embodiment can be constructed, and the method of Example 1 of the present application can be implemented by running a computer program (including program code) capable of executing the steps involved in the corresponding method described in Example 1 on a general-purpose computing device such as a computer, which includes processing elements and storage elements such as a central processing unit (CPU), random access memory (RAM), and read-only memory (ROM). The computer program can be recorded on, for example, a computer-readable recording medium, and loaded into the above-mentioned computing device through the computer-readable recording medium and run therein.

[0044] Embodiment 3: This implementation provides an electronic device, which includes a processor, a communication interface, and a computer-readable storage medium, wherein the processor, the communication interface, and the computer-readable storage medium may be connected via a bus or other means.

[0045] Among them, the communication interface is used to receive and send data, the computer-readable storage medium can be stored in the memory of the electronic device, the computer-readable storage medium is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer-readable storage medium.

[0046] A processor (or CPU (Central Processing Unit)) is the computing core and control core of an electronic device, which is suitable for implementing one or more instructions, and specifically suitable for loading and executing one or more instructions to implement corresponding method flows or corresponding functions.

[0047] The processor is configured to perform the following process: Calculating a first pressure deviation value between a set urea pump pressure and a model urea pump pressure, using a proportional controller to obtain a dynamic feedforward correction duty cycle, and taking the sum of the steady-state duty cycle and the dynamic feedforward correction duty cycle as the feedforward duty cycle; Calculate the second pressure deviation value between the actual pump pressure of the urea pump and the model urea pump pressure, obtain the feedback correction duty cycle through the proportional controller, and use the sum of the feedback correction duty cycle and the steady-state duty cycle as the feedback duty cycle; The sum of the feedforward duty cycle and the feedback duty cycle is taken as the urea pump duty cycle, and the urea pump is controlled according to the urea pump duty cycle.

[0048] The detailed process is described in Example 1 and will not be repeated here.

[0049] Embodiment 4: This implementation provides a computer-readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It is understandable that the computer-readable storage medium here can include both built-in storage media in the electronic device and, of course, extended storage media supported by the electronic device. The computer-readable storage medium provides a storage space that stores the processing system of the electronic device.

[0050] In addition, the storage space also stores one or more instructions suitable for being loaded and executed by the processor, and these instructions may be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here may be a high-speed RAM memory, or a non-volatile memory, such as at least one disk memory; optionally, it may also be at least one computer-readable storage medium located away from the aforementioned processor.

[0051] In one embodiment, the computer-readable storage medium stores one or more instructions; the processor loads and executes the one or more instructions stored in the computer-readable storage medium to implement the following process: Calculating a first pressure deviation value between a set urea pump pressure and a model urea pump pressure, using a proportional controller to obtain a dynamic feedforward correction duty cycle, and taking the sum of the steady-state duty cycle and the dynamic feedforward correction duty cycle as the feedforward duty cycle; Calculate the second pressure deviation value between the actual pump pressure of the urea pump and the model urea pump pressure, obtain the feedback correction duty cycle through the proportional controller, and use the sum of the feedback correction duty cycle and the steady-state duty cycle as the feedback duty cycle; The sum of the feedforward duty cycle and the feedback duty cycle is taken as the urea pump duty cycle, and the urea pump is controlled according to the urea pump duty cycle.

[0052] The detailed process is described in Example 1 and will not be repeated here.

[0053] Embodiment 5: The present implementation provides a computer program product or a computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the electronic device performs the following process: Calculating a first pressure deviation value between a set urea pump pressure and a model urea pump pressure, using a proportional controller to obtain a dynamic feedforward correction duty cycle, and taking the sum of the steady-state duty cycle and the dynamic feedforward correction duty cycle as the feedforward duty cycle; Calculate the second pressure deviation value between the actual pump pressure of the urea pump and the model urea pump pressure, obtain the feedback correction duty cycle through the proportional controller, and use the sum of the feedback correction duty cycle and the steady-state duty cycle as the feedback duty cycle; The sum of the feedforward duty cycle and the feedback duty cycle is taken as the urea pump duty cycle, and the urea pump is controlled according to the urea pump duty cycle.

[0054] The detailed process is described in Example 1 and will not be repeated here.

[0055] A person skilled in the art can appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0056] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from a website site, a computer, a server or a data center to another website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by the computer or a data processing device such as a server, a data center, etc. that includes one or more available media integrated. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dual SCR pump pressure control method based on a physical model, characterized in that: The process includes: Calculating a first pressure deviation value between a set urea pump pressure and a model urea pump pressure, using a proportional controller to obtain a dynamic feedforward correction duty cycle, and taking the sum of the steady-state duty cycle and the dynamic feedforward correction duty cycle as the feedforward duty cycle; Calculate the second pressure deviation value between the actual pump pressure of the urea pump and the model urea pump pressure, obtain the feedback correction duty cycle through the proportional controller, and use the sum of the feedback correction duty cycle and the steady-state duty cycle as the feedback duty cycle; The sum of the feedforward duty cycle and the feedback duty cycle is taken as the urea pump duty cycle, and the urea pump is controlled according to the urea pump duty cycle.

2. The dual SCR pump pressure control method based on the physical model according to claim 1, characterized in that: The model urea pump pressure is calculated according to the urea pump pressure model, including: ； in, is the outlet flow of the urea pump, is the reflux flow of the reflux valve, is the injection flow rate of the first nozzle, is the injection flow rate of the second nozzle, is the bulk elastic modulus of urea solution, is the pipe volume, is the model urea pump pressure.

3. The dual SCR pump pressure control method based on physical model according to claim 2, characterized in that: The spray flow rate of the first nozzle and the injection flow rate of the second nozzle ,include: ， ； in, is the first nozzle flow coefficient, is the effective flow area of ​​the first nozzle, is the density of urea solution, is the flow coefficient of the second nozzle, is the effective flow area of ​​the second nozzle, is the density of urea solution, is the pressure value of the SCR inlet space after the first nozzle, is the pressure value at the SCR inlet after the second nozzle.

4. The dual SCR pump pressure control method based on physical model according to claim 2, characterized in that: Backflow valve backflow flow ,include: ； in, is the flow coefficient, , is the reflux valve flow coefficient, is the spring stiffness coefficient of the return valve, is the inlet diameter of the reflux valve, is the space pressure of the urea tank, is the density of urea solution.

5. The dual SCR pump pressure control method based on physical model according to claim 1, characterized in that: Calculate the first pressure deviation value between the set urea pump pressure and the model urea pump pressure , a proportional controller is used to convert the deviation into a dynamic feedforward correction duty cycle, including: , ,in, is the first pressure deviation value; is the model pressure; To set the pressure; Correct the duty cycle for dynamic feedforward; is the first proportionality coefficient.

6. The dual SCR pump pressure control method based on physical model according to claim 1, characterized in that: Calculate the second pressure deviation value between the actual pump pressure of the urea pump and the model urea pump pressure , the feedback duty cycle is obtained through the proportional controller, including: , ,in, is the second pressure deviation value; is the model urea pump pressure; is the actual pump pressure of the urea pump; is the second duty cycle deviation value; is the second proportionality coefficient.

7. A dual SCR pump pressure control system based on a physical model, characterized in that: include: A feedforward control unit is configured to: calculate a first pressure deviation value between a set urea pump pressure and a model urea pump pressure, obtain a dynamic feedforward correction duty cycle using a proportional controller, and take the sum of the steady-state duty cycle and the dynamic feedforward correction duty cycle as the feedforward duty cycle; The feedback control unit is configured to: calculate a second pressure deviation value between the actual pump pressure of the urea pump and the model urea pump pressure, obtain a feedback correction duty cycle through a proportional controller, and use the sum of the feedback correction duty cycle and the steady-state duty cycle as the feedback duty cycle; The urea pump control unit is configured to: take the sum of the feedforward duty cycle and the feedback duty cycle as the urea pump duty cycle, and control the urea pump according to the urea pump duty cycle.

8. A computer device, characterized in that: include: A processor and a computer readable storage medium; a processor adapted to execute a computer program; A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by the processor, the physical model-based dual SCR pump pressure control method according to any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is suitable for being loaded by a processor and executing the dual SCR pump pressure control method based on a physical model as described in any one of claims 1 to 6.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the dual SCR pump pressure control method based on a physical model as claimed in any one of claims 1 to 6 is implemented.

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