Different Approaches to Soot Estimation as Key Requirement for DPF Applications

The accuracy of soot estimation is - besides thermal management – one of the key requirements for successful DPF applications. With the implementation of more stringent emissions regulations and requirements for fuel efficiency the importance of high quality soot mass estimation becomes even more relevant. The durability targets for T2B5 and Euro 6 require accurate soot load detection under all driving profiles and customer specific environments – from low speed delivery cycles to high speed extra urban driving profiles. The most fuel and CO₂ efficient regeneration strategy relies on knowledge of the current soot mass in the DPF. This paper describes several options of soot mass estimation: From an empirical engine out emissions model, combined with a physical soot oxidation model to a physical model in which the pressure drop signal combined with other parameters is used to determine the filter load. Matlab/Simulink models were developed and evaluated for this study using test bench and real world vehicle driving data. This paper describes simple models used as well as the benefits and trade offs for each of the methods. It also provides data on the achieved accuracy in soot mass estimation for commercial diesel particulate filters used in light duty diesel applications.