SCR Additive Supply Control Under Injector Variation and Sensor Error
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Solution Overview
Problem
Existing after-treatment systems face challenges in accurately supplying additives due to hardware variations and sensor errors, leading to reduced conversion performance of harmful substances like NOx in SCR catalysts.
Innovation Solution
A control device that uses machine learning models and physical models to estimate the adsorption amount of additives in SCR catalysts, considering variations in supply portions and sensor errors, to optimize additive supply and enhance conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a supply portion is used to supply additive to SCR catalyst, then additive supply is enabled, but hardware variation causes inaccurate supply amount
Solution Approach 1:
The control device uses feedback from outlet NOx concentration measurements to continuously adjust and correct the additive supply amount. By comparing actual outlet NOx levels with target levels, the system compensates for hardware variations in the supply portion, ensuring accurate additive delivery despite manufacturing tolerances in injection valves or pump units.
Solution Approach 2:
The system dynamically changes the supply amount parameter based on measured outlet NOx concentration and estimated catalyst adsorption amount. Instead of using fixed supply rates, the control device adjusts the additive supply in real-time to account for hardware variations and changing operating conditions, thereby maintaining precise control over the actual supply amount.
2Measurement precision
If outlet NOx concentration is measured to determine command value, then conversion performance is monitored, but sensor error reduces estimation accuracy
Solution Approach 1:
The system uses feedback from outlet NOx measurements combined with a catalyst state estimation model to continuously refine the estimated adsorption amount. The estimation model processes the measured NOx concentration along with other operating parameters to derive accurate state quantities, compensating for sensor errors through systematic calculation and correction.
Solution Approach 2:
The catalyst state estimation model acts as an intermediary between the raw sensor measurement and the control decision. Instead of directly using the measured outlet NOx concentration for control, the system processes it through the estimation model which considers multiple factors including adsorption dynamics and operating conditions, thereby filtering out sensor errors and producing more reliable state estimates.
3Object-generated harmful factors
If SCR catalyst is used to convert NOx, then harmful substance conversion is achieved, but supply portion variation lowers conversion rate
Solution Approach 1:
The control device continuously monitors outlet NOx concentration and uses this feedback to adjust additive supply, compensating for supply portion variations. By maintaining closed-loop control, the system ensures that despite hardware variations in different supply portions, the actual additive delivery achieves the required level for optimal NOx conversion.
Solution Approach 2:
The system dynamically adjusts the supply amount parameter based on real-time measurements and catalyst state estimation. This parameter adaptation compensates for variations between different supply portions, ensuring that each supply portion operates at its optimal performance level and maintains high NOx conversion rates despite manufacturing differences.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise control of additive supply, improving the NOx conversion rate by accounting for hardware variations and sensor inaccuracies, thereby enhancing the performance of after-treatment systems.
Implementation Method 1
use an SCR catalyst (Selective Catalytic Reduction catalyst) to convert NOx (nitrogen oxides) as harmful substances
Implementation Method 2
a hydrolysis catalyst is provided upstream of an SCR catalyst
Implementation Method 3
estimate an adsorption amount of NH3 by the SCR catalyst
Data Source
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AI summary
In an after-treatment system configured to convert a harmful substance in exhaust emission using an additive, an object is to allow for supply of the additive by taking into account a variation in a supply portion serving to supply the additive. There is provided a control device of an after-treatment system, comprising: an outlet concentration acquirer configured to obtain a concentration of a harmful substance at an outlet of a main flow path; a first estimator configured to estimate a first adsorption amount that is an adsorption amount of an additive adsorbed to a catalyst, by using a mathematical model; a second estimator configured to estimate a second adsorption amount that is an adsorption amount of the additive in the catalyst in consideration of the concentration of the harmful substance obtained by the outlet concentration acquirer, and a gain value that indicates a variation in a supply portion in consideration of the concentration of the harmful substance obtained by the outlet concentration acquirer, from the first adsorption amount and a gain value indicating a variation in the supply portion, by using a state estimation theory; and a supply controller configured to control supply of the additive in the supply portion by using the second adsorption amount and the gain value estimated by the second estimator.