Control of a Urea SCR Catalytic Converter System for a Mobile Heavy Duty Diesel Engine 2003-01-0776
An advanced controller for a urea SCR (Selective Catalytic Reduction) catalytic converter system for a mobile heavy-duty diesel engine is presented. The after-treatment system is composed of the injecting device for urea solution and a single SCR catalytic converter. The control strategy consists of three parts: A primary feedforward controller, a surface coverage observer, and a feedback controller. A nitrogen oxide (NOx) gas sensor with non-negligible cross-sensitivity to ammonia (NH3) is used for a good feedback control performance. The control strategy is validated with ESC and ETC cycles: While the average NH3 slip is kept below 10 ppm, the emission of NOx is reduced by 82%.