CN114810296B

CN114810296B - Stability control method and device of closed-loop controller

Info

Publication number: CN114810296B
Application number: CN202210497183.7A
Authority: CN
Inventors: 张竞菲; 张军; 谭治学; 杨新达; 王云
Original assignee: Weichai Power Co Ltd
Current assignee: Weichai Power Co Ltd
Priority date: 2022-05-09
Filing date: 2022-05-09
Publication date: 2023-07-18
Anticipated expiration: 2042-05-09
Also published as: CN114810296A

Abstract

The application provides a stability control method and device of a closed loop controller, the method calculates an ammonia leakage risk factor according to an aging factor, ammonia leakage detection and urea injection detection of a catalyst of an SCR (selective catalytic reduction), estimates a target ammonia leakage value downstream of the SCR based on the ammonia leakage risk factor, an ammonia feedforward control amount, an actual ammonia injection amount and an ammonia efficiency injection amount, calculates a target NOx correction value based on the target ammonia leakage value and the ammonia leakage factor downstream of the SCR, and corrects a downstream NOx value of an SCR model included in the SCR based on the NOx correction value. The downstream NOx value of the SCR model is corrected, so that the stability of the closed-loop controller is improved, and the overspray and ammonia leakage of urea are reduced.

Description

Stability control method and device of closed-loop controller

Technical Field

The application relates to the technical field of vehicle tail gas treatment, in particular to a stability control method and device of a closed-loop controller.

Background

In the prior art, during the control process of an SCR (selectively catalytic reduction, selective catalytic conversion device) included in an aftertreatment system, the actual conversion efficiency of the catalyst is continuously reduced due to the influence of thermal aging, irreversible chemistry and the like of the catalyst of the SCR, and an SCR model in the SCR still outputs NOx calibrated in advance as downstream NOx of the SCR model, so that a closed loop controller in the SCR is unstable, thereby causing a large amount of overspray of urea injection and generating large ammonia leakage.

Disclosure of Invention

The application provides a stability control method and device of a closed-loop controller, and aims to solve the problems that the closed-loop controller in SCR is unstable, urea is injected in a large amount to be oversprayed and larger ammonia leakage is generated in the prior art.

In order to achieve the above object, the present application provides the following technical solutions:

a stability control method of a closed loop controller, comprising:

acquiring a temperature value detected by a temperature sensor in the aftertreatment system;

calculating an aging factor of a catalyst of an SCR of a selective catalytic conversion device in the aftertreatment system based on the temperature value;

performing ammonia leakage detection and urea injection detection on the aftertreatment system;

calculating an ammonia slip factor based on the results of the ammonia slip detection and the urea injection detection;

calculating a target ammonia slip risk factor based on the aging factor and the ammonia slip factor;

acquiring an ammonia feedforward control amount, an actual ammonia injection amount and an ammonia efficiency injection amount;

estimating a target ammonia slip value downstream of the SCR based on the ammonia slip risk factor, the ammonia feed-forward control amount, the actual ammonia injection amount, and the ammonia efficiency injection amount;

A target NOx correction value is calculated based on the ammonia slip factor and a target ammonia slip value downstream of the SCR, and a downstream NOx value of an SCR model included in the SCR is corrected based on the NOx correction value.

The method, optionally, the calculating, based on the temperature value, an aging factor of a catalyst of an SCR of a selective catalytic conversion device in the aftertreatment system includes:

determining a temperature coefficient corresponding to the temperature value;

integrating the temperature coefficient by utilizing an integral controller to obtain a thermal ageing coefficient of a catalyst of a selective catalytic conversion device SCR in the aftertreatment system;

and obtaining the aging factor of the catalyst of the SCR through a leakage factor curve based on the thermal aging coefficient.

The method, optionally, of performing ammonia leak detection on the aftertreatment system, includes:

under the condition that the engine is determined to be reversed, if the NOx value detected by a NOx sensor at the downstream of the SCR is larger than a preset threshold value, a detection result representing that ammonia leakage exists in the aftertreatment system is generated;

under the condition that the normal operation of the engine is determined, calculating a NOx difference value based on the NOx value detected by an upstream NOx sensor of the SCR and the NOx value detected by a downstream NOx sensor of the SCR, and if the NOx difference value is larger than a preset difference value, generating a detection result representing that ammonia leakage exists in the aftertreatment system;

Urea injection detection is performed on the aftertreatment system, including:

controlling a urea nozzle in the aftertreatment system to stop spraying, and detecting an ammonia storage value of the SCR in real time;

under the condition that the ammonia storage value of the SCR is smaller than a preset ammonia storage value, controlling the urea nozzle to spray urea based on a preset nitrogen-ammonia ratio, and calculating the actual conversion efficiency after a preset time period passes based on the NOx value detected by an upstream NOx sensor of the SCR and the NOx value detected by a downstream NOx sensor of the SCR;

if the actual conversion efficiency is greater than a preset conversion efficiency value, generating a result representing that urea overspray exists in the aftertreatment system;

and if the actual conversion efficiency is smaller than the preset conversion efficiency value, generating a result which indicates that the post-treatment system has urea underspray.

The method, optionally, the calculating the ammonia leakage factor based on the result of the ammonia leakage detection and the result of the urea injection detection includes:

judging whether the ammonia leakage detection result represents that the post-treatment system has ammonia leakage or whether the urea injection detection result represents that the post-treatment system has urea overspray;

if the ammonia leakage detection result indicates that the post-treatment system has ammonia leakage, or the urea injection detection result indicates that the post-treatment system has urea overspray, performing count increment treatment on a preset count accumulator;

Judging whether the current counting result of the counter is smaller than a preset counting threshold value or not;

if the current counting result of the counting accumulator is not smaller than a preset counting threshold value, taking the current counting result of the counting accumulator as an ammonia leakage factor;

if the current counting result of the counting accumulator is smaller than a preset counting threshold value, returning to execute the steps of ammonia leakage detection and urea injection detection on the aftertreatment system;

if the ammonia leakage detection result indicates that the post-treatment system does not have ammonia leakage, and the urea injection detection result indicates that the post-treatment system does not have urea overspray, judging whether the urea injection detection result indicates that the post-treatment system has urea underspray;

if the urea injection detection result indicates that the post-treatment system does not have urea underspray, returning to execute the steps of ammonia leakage detection and urea injection detection on the post-treatment system;

and if the urea injection detection result represents that the post-treatment system has urea underspray, resetting the counting accumulator, and taking the current counting result of the counting accumulator as an ammonia leakage factor.

The method, optionally, the calculating a target ammonia leakage risk factor based on the aging factor and the ammonia leakage factor, includes:

summing the aging factor and the ammonia leakage factor to obtain an initial ammonia leakage risk factor;

if the initial ammonia leakage risk factor is larger than a preset first limit value, taking the preset first limit value as a target ammonia leakage risk factor;

if the initial ammonia leakage risk factor is smaller than a preset second limit value, taking the preset second limit value as a target ammonia leakage risk factor; the preset first limit value is larger than the preset second limit value;

and if the initial ammonia leakage risk factor is not smaller than a preset second limit value and is not larger than a preset first limit value, determining the initial ammonia leakage risk factor as a target ammonia leakage risk factor.

The method, optionally, wherein estimating the target ammonia slip value downstream of the SCR based on the ammonia slip risk factor, the ammonia feedforward control amount, the actual ammonia injection amount, and the ammonia efficiency injection amount includes:

calculating the actual ammonia injection amount and the ammonia efficiency injection amount under the condition that the actual ammonia injection amount is larger than the ammonia efficiency injection amount, so as to obtain an initial overspray ammonia coefficient;

Determining a correction factor corresponding to the ammonia slip risk factor;

calculating the correction factor and the initial ammonia overspray coefficient to obtain a target ammonia overspray coefficient;

based on the target ammonia overspray coefficient and the ammonia feedforward control quantity, obtaining an initial ammonia leakage value at the downstream of the SCR through oxidation correction treatment;

and performing low-pass filtering and delay filtering on the initial ammonia leakage value to obtain a target ammonia leakage value at the downstream of the SCR.

The method, optionally, wherein calculating the target NOx correction value based on the ammonia slip factor and a target ammonia slip value downstream of the SCR comprises:

determining a NOx value corresponding to an ammonia slip value downstream of the SCR;

calculating a NOx value corresponding to the ammonia slip value at the downstream of the SCR and a correction factor corresponding to the ammonia slip risk factor to obtain an initial NOx correction value;

if the initial NOx correction value is larger than a preset third limit value, determining the preset third limit value as a target NOx correction value;

and if the initial NOx correction value is not greater than a preset third limit value, determining the initial NOx correction value as a target NOx correction value.

A stability control device of a closed loop controller, comprising:

A first acquisition unit configured to acquire a temperature value detected by a temperature sensor in the post-processing system;

a first calculation unit configured to calculate an aging factor of a catalyst of an SCR of a selective catalytic conversion device in the aftertreatment system based on the temperature value;

the detection unit is used for detecting ammonia leakage and urea injection of the aftertreatment system;

a second calculation unit configured to calculate an ammonia slip factor based on a result of the ammonia slip detection and a result of the urea injection detection;

a third calculation unit configured to calculate a target ammonia leakage risk factor based on the aging factor and the ammonia leakage factor;

a second acquisition unit configured to acquire an ammonia feedforward control amount, an actual ammonia injection amount, and an ammonia efficiency injection amount;

an estimation unit configured to estimate a target ammonia slip value downstream of the SCR based on the ammonia slip risk factor, the ammonia feedforward control amount, the actual ammonia injection amount, and the ammonia efficiency injection amount;

and the correction unit is used for calculating a target NOx correction value based on the ammonia slip factor and a target ammonia slip value downstream of the SCR and correcting a downstream NOx value of an SCR model included in the SCR based on the NOx correction value.

The above apparatus, optionally, the first computing unit is specifically configured to:

determining a temperature coefficient corresponding to the temperature value;

The above device, optionally, the detecting unit is specifically configured to, when detecting ammonia leakage of the aftertreatment system:

the detection unit is specifically configured to, when performing urea injection detection on the aftertreatment system:

A storage medium storing a set of instructions that when executed by a processor implement a method of controlling stability of a ring controller as described above.

An electronic device, comprising:

a memory for storing at least one set of instructions;

and the processor is used for executing the instruction set stored in the memory, and realizing the stability control method of the ring controller by executing the instruction set.

Compared with the prior art, the application has the following advantages:

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present application, and that other drawings may be obtained according to the provided drawings without inventive effort to a person skilled in the art.

FIG. 1 is a schematic diagram of a system architecture of an aftertreatment system provided herein;

FIG. 2 is a method flow chart of a control process method of an SCR provided herein;

FIG. 3 is a flow chart of a method for controlling stability of a closed loop controller according to the present application;

FIG. 4 is a flow chart of a method of controlling the stability of a closed loop controller according to the present application;

FIG. 5 is a flow chart of a method of controlling the stability of a closed loop controller according to the present application;

FIG. 6 is a flow chart of a method of controlling the stability of a closed loop controller according to the present application;

FIG. 7 is a flow chart of a method of controlling the stability of a closed loop controller according to the present application;

FIG. 8 is an exemplary diagram of a method of controlling stability of a closed loop controller provided herein;

FIG. 9 is a diagram of yet another example of a method of controlling stability of a closed loop controller provided herein;

FIG. 10 is a diagram of yet another example of a method of stability control for a closed loop controller provided herein;

FIG. 11 is a schematic structural diagram of a stability control device of a closed loop controller provided in the present application;

fig. 12 is a schematic structural diagram of an electronic device provided in the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

The term "including" and variations thereof as used herein are intended to be open-ended, i.e., including, but not limited to. The term "based on" is based at least in part on. The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments. Related definitions of other terms will be given in the description below.

It should be noted that the terms "first," "second," and the like herein are merely used for distinguishing between different systems, modules, or units and not for limiting the order or interdependence of the functions performed by such systems, modules, or units.

It should be noted that the references to "one" or "a plurality" in this disclosure are intended to be illustrative rather than limiting, and those of ordinary skill in the art will appreciate that "one or more" is intended to be construed as "one or more" unless the context clearly indicates otherwise.

In the closed-loop control stability control method provided in the embodiment of the present application, a schematic structural diagram of a post-processing system is shown in fig. 1, and includes:

an oxidation-catalytic converter DOC, a particulate matter trap DPF, a selective catalytic reduction conversion device SCR, an ammonia trap ASC, a first temperature sensor T4, a second temperature sensor T5, a third temperature sensor T7, a first NOx sensor NOx1, a second NOx sensor NOx2, an HC nozzle and a urea nozzle DM.

Wherein, DOC (diesel oxide catalyst, oxidation catalytic converter) is used for converting NO in the tail gas into NO2 before DPF, and simultaneously, the temperature of the tail gas is raised to assist the normal operation of DPF and SCR.

The DPF (diesel particulate filter, particulate matter trap) is used for trapping the particulate matters in the tail gas, and when the trapped particulate matters reach a certain level, passive regeneration or active regeneration is required, so that the trapping capacity of the DPF on the particulate matters is restored.

SCR (selectively catalytic reduction, selective catalytic conversion device) for reducing nitrogen oxides in exhaust emissions.

Referring to fig. 2, in the closed-loop control stability control method provided in the embodiment of the present application, the control process of the SCR specifically includes the following steps:

the SCR Pre-control calculates a feed-forward ammonia injection quantity NH3_Pre according to the upstream NOx emission of the SCR, the current temperature, the model ammonia storage of the SCR model, the set efficiency and the like. The ammonia storage correction calculates an ammonia injection correction amount nh3_cor based on the set ammonia storage and the model ammonia storage. The SCR model calculates model ammonia storage and downstream NOx of the SCR model based on upstream NOx, temperature, etc. The closed-loop controller performs closed-loop PI control according to the downstream NOx of the SCR and the actual sensor NOx to obtain an injection correction factor Fac_CL. The self-adaptive control is based on fixed time or SCR low-efficiency triggering, and an over-spray or under-spray state and a correction factor Fac_Adp are obtained through three processes of stopping spray, fixed spray and efficiency detection.

Referring to fig. 3, an embodiment of the present application provides a stability control method of a closed-loop controller, which specifically includes the following steps:

s301, acquiring a temperature value detected by a temperature sensor in the aftertreatment system.

In this embodiment, the post-processing system includes a plurality of temperature sensors, each for detecting a temperature value.

In this embodiment, the temperature value detected by the temperature sensor in the aftertreatment system is obtained, specifically, the temperature value detected by the upstream temperature sensor and the temperature value detected by the downstream temperature sensor of the SCR in the aftertreatment system are obtained, where the upstream temperature sensor of the SCR is the third temperature sensor T6 in fig. 1, and the downstream temperature sensor of the SCR is the fourth temperature sensor T7 in fig. 1.

S302, based on the temperature value, an aging factor of a catalyst of an SCR of the selective catalytic conversion device in the aftertreatment system is calculated.

In this embodiment, an aging factor of a catalyst of an SCR of a selective catalytic conversion device in an aftertreatment system is calculated based on a temperature value.

Referring to fig. 4, a process for calculating an aging factor of a catalyst of an SCR of a selective catalytic conversion device in an aftertreatment system based on a temperature value specifically includes the steps of:

s401, determining a temperature coefficient corresponding to the temperature value.

In this embodiment, a temperature coefficient corresponding to a temperature value is determined, specifically, an average temperature value of a temperature value detected by an upstream temperature sensor and a temperature value detected by a downstream temperature sensor of the SCR is calculated, and a temperature coefficient corresponding to the average temperature value is searched through a preset temperature coefficient table.

The temperature coefficient table is a table of correspondence between temperature values and temperature coefficients, and the temperature coefficients corresponding to the temperature values can be determined from the temperature values.

S402, integrating the temperature coefficient by using an integral controller to obtain the thermal ageing coefficient of the catalyst of the selective catalytic conversion device SCR in the aftertreatment system.

In this embodiment, the temperature coefficient is input to the integral controller, and the integral controller integrates the temperature coefficient, so as to obtain the thermal aging coefficient of the catalyst of the selective catalytic reduction device SCR in the aftertreatment system.

S403, based on the thermal ageing coefficient, obtaining the ageing factor of the SCR catalyst through a leakage factor curve.

In this embodiment, the aging factor of the catalyst of the SCR corresponding to the thermal aging coefficient is found by the leakage factor curve.

S303, ammonia leakage detection and urea injection detection are carried out on the aftertreatment system.

In the implementation, ammonia leakage detection is performed on the post-treatment system to obtain a result of whether the post-treatment system has ammonia leakage or not, urea injection detection is performed on the post-treatment system to obtain a result of whether the post-treatment system has urea overspray, urea underspray or normal urea injection or not.

In this embodiment, the process of detecting ammonia leakage in the aftertreatment system specifically includes the following steps:

under the condition that the engine is determined to be reversed, if the NOx value detected by a downstream NOx sensor of the SCR is larger than a preset threshold value, a detection result representing that ammonia leakage exists in the aftertreatment system is generated;

under the condition that the engine is determined to normally run, calculating a NOx difference value based on the NOx value detected by an upstream NOx sensor of the SCR and the NOx value detected by a downstream NOx sensor of the SCR, and if the NOx difference value is larger than a preset difference value, generating a detection result representing that the after-treatment system has ammonia leakage.

In this embodiment, whether the engine is reversed is determined, if the engine is reversed, a NOx value detected by a downstream NOx sensor of the SCR is obtained, that is, a NOx value detected by a second NOx sensor NOx2 is obtained, if the NOx value is greater than a preset threshold, a detection result indicating that ammonia leakage exists in the aftertreatment system is generated, and if the NOx value is not greater than the preset threshold, a detection result indicating that ammonia leakage does not exist in the aftertreatment system is generated; preferably, the preset threshold is a value of 0.

It should be noted that, because the engine emits NOx of 0 when the engine is reversed, and the NOx value detected by the downstream NOx sensor of the SCR is greater than the preset threshold, that is, the NOx value detected by the downstream NOx sensor of the SCR is not 0 when the engine is reversed, it is indicated that there is ammonia slip.

In this embodiment, if the engine does not slip, that is, if the engine is running normally, the NOx difference is calculated based on the NOx value detected by the upstream NOx sensor of the SCR and the NOx value detected by the downstream NOx sensor of the SCR, that is, the difference between the NOx value detected by the first NOx sensor NOx1 and the NOx value detected by the second NOx sensor NOx2 is calculated, so as to obtain the NOx difference, if the NOx difference is greater than the preset difference, a detection result indicating that the aftertreatment system has ammonia slip is generated, and if the NOx difference is not greater than the preset difference, a detection result indicating that the aftertreatment system has no ammonia slip is generated.

In this embodiment, the urea injection detection process for the aftertreatment system specifically includes the following steps:

controlling a urea nozzle in the aftertreatment system to stop spraying, and detecting an ammonia storage value of SCR in real time;

under the condition that the ammonia storage value of the SCR is smaller than the preset ammonia storage value, controlling a urea nozzle to spray urea based on the preset nitrogen-ammonia ratio, and after a preset time period, calculating the actual conversion efficiency based on the NOx value detected by an upstream NOx sensor of the SCR and the NOx value detected by a downstream NOx sensor of the SCR;

if the actual conversion efficiency is greater than the preset conversion efficiency value, generating a result representing that the post-treatment system has urea overspray;

In this embodiment, the urea nozzle of the aftertreatment system is controlled to stop spraying, and the ammonia storage value of the SCR is detected in real time, that is, the ammonia storage value of a model of the SCR included in the SCR is detected, whether the ammonia storage value of the SCR is smaller than a preset ammonia storage value is determined, under the condition that the ammonia storage value of the SCR is smaller than the preset ammonia storage value, the urea nozzle is controlled to spray urea based on a preset nitrogen-ammonia ratio, after a preset period of time elapses, the actual conversion efficiency is calculated based on the NOx value detected by an upstream NOx sensor of the SCR and the NOx value detected by a downstream NOx sensor of the SCR, that is, the actual conversion efficiency is calculated based on the NOx value detected by NOx1 and the NOx value detected by NOx2, whether the actual conversion efficiency is smaller than the preset conversion efficiency value is determined, if the actual conversion efficiency is larger than the preset conversion efficiency value, a result indicating that urea overspray exists in the aftertreatment system is generated, if the actual conversion efficiency is smaller than the preset conversion efficiency value, and if the actual conversion efficiency is equal to the preset conversion efficiency is not equal to the preset conversion efficiency, the urea overspray result indicating that neither urea overspray exists in the aftertreatment system is generated.

In this embodiment, the predetermined nitrogen to ammonia ratio may be preferably 0.7.

In this embodiment, the preset conversion efficiency value may be preferably 0.7.

S304, calculating an ammonia leakage factor based on the ammonia leakage detection result and the urea injection detection result.

In this embodiment, the ammonia leakage factor is calculated based on the result of ammonia leakage detection and the result of urea injection, specifically, the method includes the steps of:

judging whether an ammonia leakage detection result represents that the after-treatment system has ammonia leakage or whether a urea injection detection result represents that the after-treatment system has urea overspray;

if the result of the ammonia leakage detection indicates that the post-treatment system has ammonia leakage, or the result of the urea injection detection indicates that the post-treatment system has urea overspray, performing count increasing treatment on a preset count accumulator;

if the current counting result of the counting accumulator is not smaller than the preset counting threshold value, taking the current counting result of the counting accumulator as an ammonia leakage factor;

if the current counting result of the counting accumulator is smaller than the preset counting threshold value, returning to execute the steps of ammonia leakage detection and urea injection detection on the aftertreatment system;

If the result of the ammonia leakage detection indicates that the aftertreatment system does not have ammonia leakage, and the result of the urea injection detection indicates that the aftertreatment system does not have urea overspray, judging whether the result of the urea injection detection indicates that the aftertreatment system has urea underspray;

if the result of the urea injection detection indicates that the post-treatment system does not have urea underspray, returning to execute the steps of ammonia leakage detection and urea injection detection on the post-treatment system;

if the urea injection detection result represents that the post-treatment system has urea underspray, resetting the counting accumulator, and taking the current counting result of the counting accumulator as an ammonia leakage factor.

In this embodiment, if the result of the ammonia leakage detection indicates that the post-processing system has ammonia leakage, or the result of the urea injection detection indicates that the post-processing system has urea overspray, the counting increment processing is performed on the preset counting accumulator, and preferably, the counting increment processing may be performed on the preset counting accumulator.

In this embodiment, if the current count result of the count accumulator is greater than the threshold of the design number, the ammonia leakage factor is output, that is, the current count result of the count accumulator is taken as the ammonia leakage factor, and if the current count result of the count accumulator is not greater than the preset threshold, the execution step S303 is returned until the ammonia leakage factor or the ammonia leakage factor is output.

In this embodiment, when the result of the ammonia leakage detection indicates that the post-processing system does not have ammonia leakage, and when the result of the urea injection detection indicates that the post-processing system does not have urea overspray, if the result of the urea injection detection indicates that the post-processing system has urea underspray, the counting accumulator is reset, and an ammonia leakage factor is output, that is, when the current counting result of the counting accumulator is taken as the ammonia leakage factor, that is, when the value of the ammonia leakage factor is 0, the ammonia leakage factor is considered to be the ammonia leakage factor, and if the result of the urea injection detection indicates that the post-processing system does not have urea underspray, step S303 is executed again until the ammonia leakage factor or the ammonia leakage factor is output.

S305, calculating a target ammonia leakage risk factor based on the aging factor and the ammonia leakage factor.

In this embodiment, the target ammonia slip risk factor is calculated based on the aging factor and the ammonia slip factor.

It should be noted that the target ammonia slip risk factor is between 0 and 1, 0 represents no risk of ammonia slip, and 1 represents the maximum risk of ammonia slip.

Specifically, referring to fig. 5, the method includes the following steps:

and S501, summing the aging factor and the ammonia leakage factor to obtain an initial ammonia leakage risk factor.

In this embodiment, the aging factor and the ammonia slip factor are accumulated to obtain an initial ammonia slip risk factor.

S502, judging whether the initial ammonia leakage factor is larger than a preset first limit value, if so, executing S503, and if not, executing S504.

In this embodiment, a limiting interval is preset, and the preset first limiting value is the maximum value of the preset limiting interval.

Judging whether the initial ammonia leakage factor is larger than a preset first limit value, namely judging whether the initial ammonia leakage factor is larger than the maximum value of a preset limit interval.

S503, taking a preset first limit value as a target ammonia leakage risk factor.

In this embodiment, if the initial ammonia leakage factor is greater than the preset first limit value, the preset first limit value is taken as the target ammonia leakage risk factor.

S504, judging whether the initial ammonia leakage factor is smaller than a preset second limit value, if so, executing S505, and if not, executing S506.

In this embodiment, the preset second limit value is the minimum value of the preset limit interval, that is, the preset first limit value is greater than the preset second limit.

In this embodiment, if the initial ammonia leakage factor is not greater than the preset first limit value, it is further determined whether the initial ammonia leakage factor is less than the preset second limit value.

S505, taking a preset second limiting value as a target ammonia leakage risk factor.

In this embodiment, if the initial leakage factor is smaller than the preset second limit value, the preset second limit value is used as the target ammonia leakage risk factor.

S506, determining the initial ammonia leakage risk factor as a target ammonia leakage risk factor.

In this embodiment, the initial leakage factor is not greater than the preset first limit value, but not less than the second limit value, that is, the initial leakage factor is within the preset limit interval, and the initial ammonia leakage risk factor is directly determined as the target ammonia leakage risk factor.

In the method provided by the embodiment of the application, the initial ammonia leakage risk factor is limited based on the preset first limit and the preset second limit, so that the obtained target ammonia leakage risk factor is in a limit interval formed by the preset first limit and the preset second limit.

S306, acquiring an ammonia feedforward control quantity, an actual ammonia injection quantity and an ammonia efficiency injection quantity.

In this embodiment, the ammonia feedforward control amount, that is, the feedforward ammonia injection amount nh3_pre is obtained, specifically, the feedforward ammonia injection amount nh3_pre output by the SCR Pre-control is obtained, where the SCR Pre-control calculates the feedforward injection amount nh3_pre according to the upstream NOx emission of the SCR, the current temperature, the model ammonia storage and the set efficiency, and the like.

In the present embodiment, the actual ammonia injection amount is acquired.

In the present embodiment, the ammonia-efficiency injection amount is acquired, specifically, the correction factor fac_adapter is acquired, and the ammonia-efficiency injection amount is determined based on the correction factor fac_adapter and the feed-forward ammonia injection amount nh3_pre.

S307, estimating a target ammonia slip value downstream of the SCR based on the ammonia slip risk factor, the ammonia feedforward control amount, the actual ammonia injection amount and the ammonia efficiency injection amount.

In this embodiment, the target ammonia slip value downstream of the SCR is estimated based on the ammonia slip risk factor, the ammonia feedforward control amount, the actual ammonia injection amount, and the ammonia efficiency injection amount, and specifically, referring to fig. 6, the method includes the steps of:

s601, calculating the actual ammonia injection quantity and the ammonia efficiency injection quantity to obtain an initial overspray ammonia coefficient under the condition that the actual ammonia injection quantity is larger than the ammonia efficiency injection quantity.

In this embodiment, it is determined whether the actual ammonia injection amount is greater than the ammonia efficiency injection amount, and if the actual ammonia injection amount is greater than the ammonia efficiency injection amount, the actual ammonia injection amount and the ammonia efficiency injection amount are calculated to obtain an initial overspray ammonia coefficient, and specifically, a ratio of the time ammonia injection amount to the ammonia efficiency injection amount is calculated to obtain the initial overspray ammonia coefficient.

S602, determining a correction factor corresponding to the ammonia leakage risk factor.

In this embodiment, based on the ammonia leakage factor, a correction factor corresponding to the ammonia leakage factor in a preset correction factor table is searched.

S603, calculating the correction factor and the initial overspray ammonia coefficient to obtain a target overspray ammonia coefficient.

In this embodiment, the correction factor and the initial overspray ammonia coefficient are calculated to obtain a target ammonia coefficient, specifically, a difference between the initial overspray ammonia coefficient and the correction factor is calculated, and the difference is used as the target ammonia coefficient.

S604, obtaining an initial ammonia leakage value at the downstream of the SCR through oxidation correction processing based on the target ammonia overspray coefficient and the ammonia feedforward control quantity.

In this embodiment, based on the target ammonia overspray coefficient and the ammonia feedforward control amount, an initial ammonia slip value downstream of the SCR is obtained through oxidation correction processing, specifically including the following steps:

calculating the product of the target ammonia overspray coefficient and the ammonia feedforward control quantity to obtain a product result, and performing oxidation correction treatment on the product result to obtain an initial ammonia leakage value at the downstream of the SCR;

or alternatively, the first and second heat exchangers may be,

and (3) performing oxidation correction treatment on the target ammonia overspray coefficient to obtain an oxidation correction result, and calculating the product of the oxidation correction result and the ammonia feedforward control quantity to obtain an initial ammonia leakage value at the downstream of the SCR.

S605, performing low-pass filtering and delay filtering on the initial ammonia leakage value to obtain a target ammonia leakage value at the downstream of the SCR.

In this embodiment, the low-pass filtering process and the delay filtering process are performed on the initial ammonia slip value to obtain a target ammonia slip value downstream of the SCR.

S308, calculating a target NOx correction value based on the ammonia slip factor and a target ammonia slip value downstream of the SCR, and correcting a downstream NOx value of an SCR model included in the SCR based on the NOx correction value.

In this embodiment, the target NOx correction value is calculated based on the ammonia slip factor and the target ammonia slip value downstream of the SCR, specifically referring to fig. 7, including the steps of:

s701, determining a NOx value corresponding to the ammonia slip value downstream of the SCR.

In this embodiment, the ammonia slip value downstream of the SCR is input to a preset NOx sensor model, and a NOx value corresponding to the ammonia slip value downstream of the SCR is obtained.

S702, calculating a NOx value corresponding to the ammonia slip value downstream of the SCR and a correction factor corresponding to the ammonia slip risk factor to obtain an initial NOx correction value.

In this embodiment, based on the ammonia leakage factor, a correction factor corresponding to the ammonia leakage factor in a preset correction factor table is searched. And calculating the product of the NOx value corresponding to the ammonia slip value downstream of the SCR and the correction factor corresponding to the ammonia slip risk factor to obtain an initial NOx correction value.

S703, judging whether the initial NOx correction value is larger than a preset third limit value, if so, executing S704, and if not, executing S705.

In this embodiment, a third limit value is preset, the third limit value is determined based on a working condition MAP, where the working condition MAP is a MAP related to exhaust gas flow and temperature, and a corresponding value may be determined based on exhaust gas flow and temperature of the aftertreatment system, and the value is used as the third limit value.

In this embodiment, it is determined whether the initial NOx correction value is greater than a preset third limit value.

S704, determining a preset third limiting value as a target NOx correction value.

In this embodiment, if the initial NOx correction value is greater than the preset third limit, the preset third limit value is determined as the target NOx correction value.

S705, determining the initial NOx correction value as the target NOx correction value.

In this embodiment, if the initial NOx correction value is not greater than the preset third limit value, the initial NOx correction value is determined as the target NOx correction value.

According to the method provided by the embodiment of the application, the initial NOx is corrected through the preset third limiting value, so that the target NOx correction value is controlled within the range not larger than the preset third limiting value.

In this embodiment, after the target NOx correction value is determined, the downstream NOx value of the SCR model included in the SCR is corrected based on the NOx correction value. That is, the downstream NOx value output by the SCR model is controlled to be the target NOx correction value.

According to the stability control method of the closed loop controller, according to the aging factor, ammonia leakage detection and urea injection detection of the catalyst of the SCR, the ammonia leakage risk factor is calculated, and the target ammonia leakage value downstream of the SCR is estimated based on the ammonia leakage risk factor, the ammonia feedforward control quantity, the actual ammonia injection quantity and the ammonia efficiency injection quantity, so that the target NOx correction value is calculated based on the target ammonia leakage value and the ammonia leakage factor downstream of the SCR, and the downstream NOx value of an SCR model included in the SCR is corrected based on the NOx correction value. The downstream NOx value of the SCR model is corrected, so that the stability of the closed-loop controller is improved, and the overspray and ammonia leakage of urea are reduced.

The stability control method of the closed-loop controller provided by the embodiment of the application is illustrated as follows:

and calculating an ammonia slip risk factor, calculating an ammonia slip amount (namely, a target ammonia slip value downstream of the SCR) and a NOx model correction (namely, a target NOx correction value) downstream of the SCR, and correcting a downstream NOx value of an SCR model included in the SCR based on the NOx model correction.

Wherein, the process of calculating the ammonia leakage risk factor comprises:

step one, referring to the a diagram in fig. 8, the aging factor calculation process is as follows: the SCR temperature coefficients are determined from the SCR temperatures, i.e. the inverse of the time for aging at each SCR temperature to a final aging state (a predefined thermal aging time, e.g. 200 hours at 600 ℃) is put into the SCR temperature coefficients, so that the aging time is checked in real time. The heat aging effect can be accumulated through the I integral controller, and the final aging factor to be accumulated is obtained through the leakage factor curve. This factor is updated to the subsequent NH3 slip risk factor calculation after the aftertreatment regeneration is successful.

Step two, referring to the b diagram in fig. 8, the ammonia leakage factor calculation process is as follows: and through the ammonia leakage detection and the overspray detection states, the number of ammonia leakage is calculated in an accumulated manner, and when the number exceeds a preset limit value, the ammonia leakage factor is triggered and output. The ammonia leakage detection method mainly comprises the following steps: and (3) detecting backward and comparing the values of the upstream NOx sensor and the downstream NOx sensor. When the engine is in reverse towing, the NOx discharged by the engine is 0, and the NOx value detected in the downstream is regarded as NH3 leakage; during engine operation, ammonia slip is considered to occur if the downstream NOx sensor value is greater than the upstream NOx sensor value by more than a limit. And (3) overspray detection: the SCR ammonia storage is reduced by stopping injection, then injection with a low ammonia-nitrogen ratio (such as 0.7) is fixed, efficiency detection is started after a period of time, actual conversion efficiency is calculated according to downstream NOx and upstream NOx, and if the efficiency exceeds 0.7, the excessive injection is considered. And (3) underspray detection: the SCR ammonia storage is reduced by stopping injection, then injection with a low ammonia-nitrogen ratio (such as 0.7) is fixed, efficiency detection is started after a period of time, actual conversion efficiency is calculated according to downstream NOx and upstream NOx, and the efficiency is lower than 0.7, so that insufficient injection is considered. When the underinjection state occurs, the frequency accumulator is reset on one hand, and the ammonia leakage-free factor is directly output on the other hand.

Step three, referring to the graph c in fig. 8, the NH3 slip risk factor (i.e., ammonia slip risk factor) is obtained by accumulating the aging factor, the ammonia slip factor, and the ammonia slip-free factor, and by the upper and lower limit values (e.g., minimum 0, maximum 1).

Referring to fig. 9, a process for calculating ammonia slip downstream of an SCR includes:

the product of the feedforward control amount nh3_pre and fac_adapter is considered as the NH3 injection amount necessary to achieve the target SCR conversion efficiency, which is the NH3 efficiency injection amount. When the actual injection amount is larger than the NH3 efficiency injection amount, the excess portion is considered to be the maximum NH3 slip amount. The ammonia coefficient of the over-injection is determined from the ratio of the actual NH3 injection amount (slip filter process based on the period of time) to the NH3 efficiency injection amount (slip filter process based on the period of time), with the normal value around 1. Meanwhile, considering the influence of NH3 leakage risk factors on the ammonia coefficient, and obtaining the coefficient of the overspray after subtraction, wherein the coefficient is FAC1. The coefficient is subjected to temperature-based oxidation correction and then multiplied by NH3_Pre to obtain the original NH3 leakage. And obtaining the final estimated NH3 leakage after the original NH3 leakage is subjected to low-pass filtering and delay filtering.

Referring to fig. 10, a process of calculating a NOx model correction amount includes:

The calculated NH3 leakage amount is converted into a NOx value through a NOx sensor model, then corrected through the product based on the NH3 leakage risk factor, and then limited by MAP based on working conditions (flow and temperature), so as to obtain a NOx correction amount, and the NOx correction amount is added to a downstream NOx model value to obtain a corrected downstream NOx model value.

It should be noted that although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order. In certain circumstances, multitasking and parallel processing may be advantageous.

It should be understood that the various steps recited in the method embodiments disclosed herein may be performed in a different order and/or performed in parallel. Furthermore, method embodiments may include additional steps and/or omit performing the illustrated steps. The scope of the present disclosure is not limited in this respect.

Corresponding to the method shown in fig. 1, the embodiment of the present application further provides a stability control device of a closed loop controller, which is used for implementing the method in fig. 1, and the schematic structural diagram of the stability control device is shown in fig. 11, and specifically includes:

a first acquisition unit 1101 for acquiring a temperature value detected by a temperature sensor in the post-processing system;

A first calculation unit 1102 for calculating an aging factor of a catalyst of an SCR of a selective catalytic conversion device in the aftertreatment system based on the temperature value;

a detection unit 1103 for performing ammonia leakage detection and urea injection detection on the aftertreatment system;

a second calculation unit 1104 for calculating an ammonia slip factor based on a result of the ammonia slip detection and a result of the urea injection detection;

a third calculation unit 1105 for calculating a target ammonia leakage risk factor based on the aging factor and the ammonia leakage factor;

a second acquisition unit 1106 for acquiring an ammonia feedforward control amount, an actual ammonia injection amount, and an ammonia efficiency injection amount;

an estimation unit 1107 for estimating a target ammonia slip value downstream of the SCR based on the ammonia slip risk factor, the ammonia feedforward control amount, the actual ammonia injection amount, and the ammonia efficiency injection amount;

a correction unit 1108, configured to calculate a target NOx correction value based on the ammonia slip factor and a target ammonia slip value downstream of the SCR, and correct a downstream NOx value of an SCR model included in the SCR based on the NOx correction value.

According to the stability control device of the closed loop controller, the ammonia leakage risk factor is calculated according to the aging factor, ammonia leakage detection and urea injection detection of the catalyst of the SCR, and the target ammonia leakage value of the downstream of the SCR is estimated based on the ammonia leakage risk factor, the ammonia feedforward control quantity, the actual ammonia injection quantity and the ammonia efficiency injection quantity, so that the target NOx correction value is calculated based on the target ammonia leakage value and the ammonia leakage factor of the downstream of the SCR, and the downstream NOx value of an SCR model included in the SCR is corrected based on the NOx correction value. The downstream NOx value of the SCR model is corrected, so that the stability of the closed-loop controller is improved, and the overspray and ammonia leakage of urea are reduced.

In one embodiment of the present application, based on the foregoing scheme, the first calculating unit 1102 is specifically configured to:

determining a temperature coefficient corresponding to the temperature value;

In one embodiment of the present application, based on the foregoing scheme, the detection unit 1103 is specifically configured to, when performing ammonia leakage detection on the aftertreatment system:

the detecting unit 1103 is specifically configured to, when performing urea injection detection on the aftertreatment system:

In one embodiment of the present application, based on the foregoing scheme, the second computing unit 1104 is specifically configured to:

In one embodiment of the present application, based on the foregoing scheme, the third calculation unit 1105 is specifically configured to:

In one embodiment of the present application, based on the foregoing scheme, the estimation unit 1107 is specifically configured to:

determining a correction factor corresponding to the ammonia slip risk factor;

In one embodiment of the present application, based on the foregoing scheme, the correction unit 1108 is specifically configured to, when calculating the target NOx correction value based on the ammonia slip factor and the target ammonia slip value downstream of the SCR:

The embodiment of the application also provides a storage medium, wherein the storage medium stores an instruction set, and the stability control method of the closed-loop controller as disclosed in any embodiment above is executed when the instruction set runs.

The embodiment of the application further provides an electronic device, the structure of which is shown in fig. 12, and specifically includes a memory 1201, configured to store at least one set of instructions; a processor 1202 for executing a set of instructions stored in the memory, by executing the set of instructions, to implement a method of controlling the stability of a closed loop controller as disclosed in any of the embodiments above.

It should be noted that, in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described as different from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other. For the apparatus class embodiments, the description is relatively simple as it is substantially similar to the method embodiments, and reference is made to the description of the method embodiments for relevant points.

Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above describes in detail a method and apparatus for controlling stability of a closed-loop controller provided in the present application, and specific examples are applied herein to illustrate principles and embodiments of the present application, where the above description of the examples is only for helping to understand the method and core ideas of the present application; meanwhile, as those skilled in the art will have modifications in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.

Claims

1. A method for controlling stability of a closed loop controller, comprising:

determining a temperature coefficient corresponding to the temperature value;

based on the thermal ageing coefficient, obtaining an ageing factor of the catalyst of the SCR through a leakage factor curve;

if the initial ammonia leakage risk factor is not smaller than a preset second limit value and is not larger than a preset first limit value, determining the initial ammonia leakage risk factor as a target ammonia leakage risk factor;

acquiring an ammonia feedforward control amount, an actual ammonia injection amount and an ammonia efficiency injection amount; calculating an ammonia feedforward control amount according to the upstream NOx emission, the current temperature, the model ammonia storage and the set efficiency; the ammonia efficiency injection quantity is the product of the ammonia feedforward control quantity and the correction factor;

determining a correction factor corresponding to the ammonia slip risk factor;

performing low-pass filtering and delay filtering on the initial ammonia leakage value to obtain a target ammonia leakage value at the downstream of the SCR;

if the initial NOx correction value is not greater than a preset third limit value, determining the initial NOx correction value as a target NOx correction value;

the calculating an ammonia slip factor based on the results of the ammonia slip test and the urea injection test, comprising:

2. The method of claim 1, wherein said performing ammonia leak detection on said aftertreatment system comprises:

urea injection detection is performed on the aftertreatment system, including:

3. A stability control device for a closed loop controller, comprising:

a second acquisition unit configured to acquire an ammonia feedforward control amount, an actual ammonia injection amount, and an ammonia efficiency injection amount; calculating an ammonia feedforward control amount according to the upstream NOx emission, the current temperature, the model ammonia storage and the set efficiency; the ammonia efficiency injection quantity is the product of the ammonia feedforward control quantity and the correction factor;

a correction unit for calculating a target NOx correction value based on the ammonia slip factor and a target ammonia slip value downstream of the SCR, and correcting a downstream NOx value of an SCR model included in the SCR based on the NOx correction value;

the first computing unit is specifically configured to:

determining a temperature coefficient corresponding to the temperature value;

the second computing unit is specifically configured to:

if the urea injection detection result represents that the post-treatment system has urea underspray, resetting the counting accumulator, and taking the current counting result of the counting accumulator as an ammonia leakage factor;

The third computing unit is specifically configured to:

the estimation unit is specifically configured to:

determining a correction factor corresponding to the ammonia slip risk factor;

the correction unit is specifically configured to, when calculating a target NOx correction value based on the ammonia slip factor and a target ammonia slip value downstream of the SCR:

4. The apparatus according to claim 3, wherein the detection unit is configured to, when performing ammonia leak detection on the aftertreatment system: