Extended Kalman Filter Estimator for NH3 Storage, NO, NO2 and NH3 Estimation in a SCR Michigan Technological Univ

Format:

Conference/Event

Author/Creator:

Surenahalli, Surenahalli, author.

Contributor:

Johnson, John H.

Parker, Gordon

Conference Name:

SAE 2013 World Congress & Exhibition (2013-04-16 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2013

Summary:

This paper focuses on the development of an Extended KalmanFilter for estimating internal species concentration and storagestates of an SCR using NOX and NH₃ sensors. The motivation forthis work was twofold. First, knowledge of internal states may beuseful for onboard diagnostic strategy development. In particular,significant errors between the outlet NOX or NH₃ sensors,reconstructed from estimated states, and the measured NOX or NH₃concentrations may aid OBD strategies that attempt to identifyparticular system failure modes. Second, the EKF describedestimates not only stored ammonia but also NO, NO₂ and NH₃ gasconcentrations within and exiting the SCR. Exploiting knowledge ofthe individual species concentrations, instead of lumping themtogether as NOX, can yield improved closed loop urea controllerperformance in terms of reduced urea consumption and better NOXconversion.The model used for EKF development was calibrated to transientengine data using a 2010 Cummins ISB engine with a productionaftertreatment system consisting of a DOC, CPF and SCR. The EKF wasthen exercised for three different SCR outlets, sensorconfigurations: NOX only, NH₃ only and both NOX and NH₃. TheEKF-estimated outlet NO, NO₂, and NH₃ concentrations were comparedto measured experimental data using a mass spectrometer. Notsurprisingly, the case where both NOX and NH₃ were measured atthe SCR outlet and used as input to the EKF yielded the bestresults. The next best performance was achieved using only the NH₃sensor. This was likely due to a better estimate of the NH₃ storagewithin the SCR and thus better estimates of the effect of thereactions. The results of the NOX sensor only case might beimproved by using a better model of the NOX sensor

Notes:

Vendor supplied data

Publisher Number:

2013-01-1581

Access Restriction:

Restricted for use by site license