Single-sensor double closed-loop urea-selective catalytic reduction (SCR) feedback control method based on observer

Abstract

The invention discloses a single-sensor double closed-loop urea-selective catalytic reduction (SCR) feedback control method based on an observer. According to a calibration test of a relation map between cross-sensitivity factors of an NOx sensor and the exhaust gas temperature and on the basis of a urea-SCR system mathematical model, a non-linear Kalman filtering observation theory is adopted and the diesel engine urea-SCR system C<NOx> and C<NH3> parameter observer based on data / mechanism is designed. Two estimators of C<NOx> and C<NH3> and the difference value of the respective target values are used as inputs of a controller, and a urea injection double closed-loop feedback controller is designed. The observer / controller and the NOx sensor arranged at the exhaust end of a urea-SCR system are used as main parts to establish the urea injection feedback control system. By means of the single-sensor double closed-loop urea-SCR feedback control method based on the observer, the hardware cost is reduced; the compromise control effect can be achieved through a double closed-loop system under the condition of single control input, limits of authority, double-output constraint and mutual contradiction; the observer is simple and reasonable in design; too many calibration processes during development of an engine electronic control unit can be reduced through the data / mechanism observer, and the strategic flexibility and universality are controlled.

Description

technical field [0001] The invention relates to an electronic feedback control method for aftertreatment of diesel engine exhaust, in particular to an observer-based single-sensor double-closed-loop urea-SCR feedback control method. Background technique [0002] Compared with gasoline engines, diesel engines have higher fuel economy and higher power output. However, the emission problem of diesel engine has been a challenge to its development, especially NO x emission. Researchers have proposed many ways to reduce NO x Among them, urea-SCR is the urea selective catalytic reduction emission post-treatment technology, which has certain advantages due to its low cost and high efficiency. Moreover, the urea-SCR system is less sensitive to sulfur. According to the actual national conditions of high sulfur content in fuel oil in my country, this technology has more advantages. The basic principle of the urea-SCR system is to use ammonia (NH 3 ) to reduce the NO produced by th...

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Problems solved by technology

[0010] The purpose of the invention is to solve the existing NO x Errors in the signal measured by the sensor and low NO at the same time x emission and ammonia slip, and an observer-based single-sensor double-closed-loop urea-SCR feedback control method is provided

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