Luenberger-sliding mode observer based ammonia concentration estimation for selective catalyst reduction system

2016 ◽  
Author(s):  
Taixiong Zheng ◽  
Weimin Han ◽  
Yongfu Li ◽  
Bin Yang ◽  
Lichen Shi
Keyword(s):  
Sliding Mode ◽  
Ammonia Concentration ◽  
Sliding Mode Observer ◽  
Selective Catalyst ◽  
Reduction System ◽  
Concentration Estimation ◽  
Catalyst Reduction

Interpretation of the Oscillating Signals of the Smart NOx Sensors Used in Urea Selective Catalyst Reduction Systems via Spectral Analysis

2013 ◽  
Vol 479-480 ◽  
pp. 719-723
Author(s):  
Chih Cheng Chou ◽  
Chia Jui Chiang ◽  
Yu Hsuan Su ◽  
Yong Yuan Ku
Keyword(s):  
Spectral Analysis ◽  
Catalytic Reduction ◽  
Ammonia Concentration ◽  
Nonlinear Characteristic ◽  
Sensor Signal ◽  
Reciprocating Motion ◽  
Selective Catalyst ◽  
Nox Sensor ◽  
Higher Harmonic ◽  
Catalyst Reduction

The oscillating signals of NOx sensor observed in urea selective catalytic reduction (SCR) tests are explained via spectral analysis. The NOx sensor built by NGK / Continental requires decoding following the SAE J1939 protocol and thus higher harmonic induced by the discretization is observed in the spectral analysis. The reciprocating motion of the urea pump induces fluctuation of the ammonia dosage, which combined with the nonlinear characteristic from ammonia dosage to NOx downstream SCR result in oscillating NOx sensor readings with different amplitude. The cross-sensitivity of the NOx sensor to ammonia concentration for higher-than-stoichiometric ammonia dosage also results in oscillating NOx sensor signal at lower frequencies.

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