SIMPLIFIED MODELS OF ENGINE HC EMISSIONS, EXHAUST TEMPERATURE AND CATALYST TEMPERATURE FOR AUTOMOTIVE COLDSTART

The initial 1-2 minutes of operation of an automotive spark-ignition engine, commonly called as the “coldstart” period, produces more than 75-80 % of the hydrocarbon (HC) emissions in a typical drive cycle. Model-based controller development requires accurate, yet simple, models that can run in realtime. Simple, intuitive models are developed to predict both tailpipe hydrocarbon (HC) emissions and exhaust temperature during coldstart. Each of the models is chosen to be sum of first order linear systems based on the observation of experimental data and on the notion that such structure is suitable for controller synthesis. Inputs to these models are AFR, spark timing and engine crankshaft speed. A reduced order thermodynamic model for the catalyst temperature is also developed. The parameters are identified using least squares technique. The model estimates for the coldstart are compared with the experimental results with good agreement. Submitted to Fifth IFAC Symposium on Advances in Automotive Control