Control method of urea injection in scr system

Abstract

The invention discloses a urea injection control system of an SCR system, and belongs to the technical field of diesel engine control. According to the urea injection control system of the SCR system, a partial differential equation (PDE) model of the system is researched from the aspect of the chemical reaction mechanism of the urea SCR system, an appropriate approach method is selected to simplify the mode, and an SCR system urea injection control method processing time lag and uncertainty through rolling optimization control is utilized. The method includes the steps of a, partial differential modeling of the urea SCR system and b, designing of a partial differential system prediction controller. According to the urea injection control system, on the basis of actual control requirements of the urea SCR system, distributed parameter system modeling and designing of the prediction controller are combined, and the non-linear optimization problem of the system on the constraint condition can be solved on the basis of accurately describing the dynamic property of the system.

Description

technical field [0001] The invention belongs to the technical field of diesel engine control. Background technique [0002] Compared with gasoline engines, diesel engines have higher fuel economy and power output. However, due to its lean burn characteristics, diesel engines produce more NO than gasoline engines x harmful gas. With the worldwide targeting of NO x More and more stringent regulations on emissions have been introduced, and various methods are used to reduce NO x The exhaust aftertreatment system available. These technologies include urea selective catalytic reduction (SCR) systems. The urea SCR system does not require additional fuel when it works, and the urea consumption is relatively low. With these advantages, it has already occupied a certain advantage in the automotive industry. In my country, the current actual national conditions are that the sulfur content in fuel oil is relatively high, and the promotion of many emission control technologies is ...

AI Technical Summary

Problems solved by technology

As a typical distributed parameter system in which multi-substances propagate unevenly along the axial direction of the catalyst and complex chemical reactions occur, the SCR system not only has infinite-dimensional characteristics, but the complex multi-substance axial propagation environment also makes the system have a large hysteresis and uncertainties, the above control method based on the ODE model with concentrated parameters is difficult to achieve the ideal control effect

In addition, there are many constraints on the parameters of the urea SCR system

For example, the system input (urea injector injection volume) has a maximum limit, and the system output (NO x with NH 3 ) are subject to emission regulations, etc.

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