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An ammonia coverage ratio observing and tracking controller: stability analysis and simulation evaluation

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Abstract

In urea selective catalytic reduction (urea-SCR) systems, the ammonia coverage ratio is an important parameter for satisfying emission regulations. However, this parameter cannot be directly measured by onboard sensors. Most of observers and tracking controllers for the ammonia coverage ratio in the existing literature were designed separately and lacked an overall robustness analysis. In this paper, an observing and tracking controller (AOTC), along with its overall design and stability analysis, is proposed under inputto-state stability (ISS) theory. The proposed AOTC strategy consists of a sliding mode observer based on NH3 concentration dynamics and a tracking controller based on the observer dynamics. The stability is discussed considering the uncertainties about the conversion of urea to NH3 and the cross-sensitivity of the NOx sensor, and the principle for adjusting the control parameters is provided. A few transient simulations are conducted to evaluate the effectiveness of the proposed AOTC strategy.

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Acknowledgements

This work was supported by National Nature Science Foundation of China (Grant Nos. 61773009, U1864201, 61703177) and Jilin Province Science and Technology Development Plan (Grant Nos. 20180101067JC, 201903021 05GX, JJKH20180144KJ, JJKH20190999KJ).

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Correspondence to Yunfeng Hu.

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Zhao, J., Gong, X., Hu, Y. et al. An ammonia coverage ratio observing and tracking controller: stability analysis and simulation evaluation. Sci. China Inf. Sci. 62, 62201 (2019). https://doi.org/10.1007/s11432-018-9638-7

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Keywords

  • diesel emission control
  • urea-SCR system
  • nonlinear control
  • sliding mode observer
  • input-tostate stability