Nonlinear Model Predictive Control of a Turbocharged Diesel Engine

This paper discusses the control challenges of a parallel evaporator organic Rankine cycle (ORC) waste heat recovery (WHR) system for a diesel engine. A nonlinear model predictive control (NMPC) is proposed to regulate the mixed working fluid outlet temperature of both evaporators, ensuring efficient and safe ORC system operation. The NMPC is designed using a reduced order control model of the moving boundary heat exchanger system. In the NMPC formulation, the temperature difference between evaporator outlets is penalized so that the mixed temperature can be controlled smoothly without exceeding maximum or minimum working fluid temperature limits in either evaporator. The NMPC performance is demonstrated in simulation over an experimentally validated, high fidelity, physics based ORC plant model. NMPC performance is further validated through comparison with a classical PID control for selected high load and low load engine operating conditions. Compared to PID control, NMPC provides significantly improved performance in terms of control response time, overshoot, and temperature regulation.

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Nonlinear Model Predictive Control of a Diesel Engine Airpath*

IFAC Proceedings Volumes ◽

10.3182/20090506-3-sf-4003.00017 ◽

2009 ◽

Vol 42 (2) ◽

pp. 91-96 ◽

Cited By ~ 13

Author(s):

P. Ortner ◽

R. Bergmann ◽

H.J. Ferreau ◽

L. del Re

Keyword(s):

Diesel Engine ◽

Model Predictive Control ◽

Predictive Control ◽

Nonlinear Model ◽

Nonlinear Model Predictive Control

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Two-Level Nonlinear Model Predictive Control for Lean NOx Trap Regenerations

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4001710 ◽

2010 ◽

Vol 132 (4) ◽

Cited By ~ 27

Author(s):

Ming-Feng Hsieh ◽

Junmin Wang ◽

Marcello Canova

Keyword(s):

Diesel Engine ◽

Model Predictive Control ◽

Predictive Control ◽

Nonlinear Model ◽

Nox Reduction ◽

Nonlinear Model Predictive Control ◽

Lean Nox Trap ◽

Nox Trap ◽

Profile Control ◽

Lean Nox

This paper describes a two-level nonlinear model predictive control (NMPC) scheme for diesel engine lean NOx trap (LNT) regeneration control. Based on the physical insights into the LNT operational characteristics, a two-level NMPC architecture with the higher-level for the regeneration timing control and the lower-level for the regeneration air to fuel ratio profile control is proposed. A physically based and experimentally validated nonlinear LNT dynamic model is employed to construct the NMPC control algorithms. The control objective is to minimize the fuel penalty induced by LNT regenerations while keeping the tailpipe NOx emissions below the regulations. Based on the physical insights into the LNT system dynamics, different choices of cost function were examined in terms of the impacts on fuel penalty and tailpipe NOx slip amount. The designed control system was evaluated on an experimentally validated vehicle simulator, cX-Emissions, with a 1.9 l diesel engine model through the FTP75 driving cycle. Compared with a conventional LNT control strategy, 31.9% of regeneration fuel penalty reduction was observed during a single regeneration. For the entire cold-start FTP75 test cycle, a 28.1% of tailpipe NOx reduction and 40.9% of fuel penalty reduction were achieved.

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