Estimation of the distributed temperature of a SI engine catalyst for light-off strategy

This paper proposes a model for the internal temperature of a SI engine catalyst, aiming at designing a prediction-based light-off strategy. Due to its elongated geometry where a gas stream is in contact with a spatially distributed monolith, the system under consideration is inherently a distributed parameter system. This paper advocates an approach which is based on a one-dimensional distributed parameter model, coupled with an advection-diffusion equation accounting for the distributed heat generation resulting from pollutant conversion. Following recent works, this heat supply is shown here to be equivalent to an inlet temperature entering the system at a virtual entry point inside the catalyst. This new input has a static gain depending on the state of the system, which introduced a coupling. Taking advantage of the low-pass filter characteristic of the system, an estimate of this model is designed and results into a time-varying input-delay system whose dynamics parameters (time constant, delay, gains) are obtained through a simple analytic reduction procedure. A corresponding prediction-based light-off strategy is proposed and illustrated in simulations exploiting experimental data.