Different Vibe function model structures for parameterized diesel engine heat release models are investigated. The work is motivated by the need of such models when closed-loop combustion control is implemented based on torque domain combustion phasing analysis.
Starting from the studied model structures, models are created by estimating the model parameters using a separable least squares approach. After this, the models are evaluated according to two different performance criteria. The first criterion rates the ability of the estimated models to describe reference mass fraction burned traces. The second criterion assesses how accurately the models estimate the reference combustion phasing measure.
As expected, the analysis shows that the models based on the most flexible model structure achieve the best results, both regarding mass fraction burned estimation and combustion phasing estimation. However, even if the less complex models describe the mass fraction burned traces with lower accuracy, these models are able to estimate the combustion phasing measure surprisingly well.