Model-Based Gain Scheduling Strategy for an Internal Model Control-Based Boost Pressure Controller in Variable Geometric Turbocharger System of Diesel Engines

Hong, Seungwoo; Park, Inseok; Sunwoo, Myoungho

doi:10.1115/1.4032283

Cited by 5 publications

(1 citation statement)

References 30 publications

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“…The inlet air mass flow ( MAF ) and the boost pressure ( P b ) are the most common feedback signals used for diesel engine air path control, significantly important for the aforementioned performance variables. 1–5 Due to problems such as sign change for DC gains and nonlinearity in input–output relations observed for an MAF − P b controller, new architectures have been proposed for manipulation of the exhaust gas recirculation (EGR) and variable geometry turbine (VGT) control valves. 6–8 In the work by Park et al, 6 for example, it is shown that the cylinder oxygen ratio, χ cyl , has a close and monotonic correlation to diesel engine-out NO x emissions and is used as a feedback-estimated signal to be managed by controlling the EGR valve.…”

Section: Introductionmentioning

confidence: 99%

Diesel air path control using pressure difference: Pumping loss and aging considerations

Salehi

Stefanopoulou

Vernham³

2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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Pressure difference across the exhaust and intake manifolds ([Formula: see text] P) is a crucial variable to control the pumping loss and cylinder charge dilution through the exhaust gas recirculation in a diesel engine. This paper presents a novel architecture for controlling [Formula: see text] P and the engine-out NO x emissions, which increases the controller tolerance to engine components aging. The architecture has an internal control loop, designed as a two-input two-output controller, to coordinate the exhaust gas recirculation and variable geometry turbine valves. Using feedback from [Formula: see text] P and the estimated cylinder oxygen ratio [Formula: see text] cyl, the two-input two-output controller regulates the pumping loss and the engine NO x emissions. To reduce high turbo lag and its associated slow air–fuel ratio ([Formula: see text]) response, which are inherent features of a [Formula: see text] P-based control strategy, the two-input two-output linear quadratic controller is tuned such that [Formula: see text] is also regulated, but only during fast transients. An external loop is supplementing the core two-input two-output controller correcting the internal loop set points to reduce the effects of [Formula: see text] cyl estimation errors on NO x control and ensure [Formula: see text] stays above a minimum value, [Formula: see text] min, critical for smoke emissions. As a feature of the proposed control system, direct feedback from [Formula: see text] P increases pumping loss robustness to common degradation in diesel engines, namely, turbine efficiency and diesel particulate filter blockage due to ash deposit, compared to a conventional boost pressure–based controller. Also, it is shown that the input–output coupling structure of the proposed two-input two-output controller and use of the NO x feedback mitigate effects of exhaust gas recirculation fouling and associated exhaust gas recirculation valve saturation on increase in NO x emission.

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Section: Introductionmentioning

confidence: 99%

Diesel air path control using pressure difference: Pumping loss and aging considerations

Salehi

Stefanopoulou

Vernham³

2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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Simplified Decoupler-Based Multivariable Controller With a Gain Scheduling Strategy for the Exhaust Gas Recirculation and Variable Geometry Turbocharger Systems in Diesel Engines

Hong

Park

Shin

et al. 2017

Journal of Dynamic Systems, Measurement, and Control

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This paper presents a simplified decoupler-based multivariable controller with a gain scheduling strategy in order to deal with strong nonlinearities and cross-coupled characteristics for exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems in diesel engines. A feedback controller is designed with the gain scheduling strategy, which updates control gains according to engine operating conditions. The gain scheduling strategy is implemented by using a proposed scheduling variable derived from indirect measurements of the EGR mass flow, such as the pressure ratio of the intake, exhaust manifolds, and the exhaust air-to-fuel ratio. The scheduling variable is utilized to estimate static gains of the EGR and VGT systems; it has a large dispersion in various engine operating conditions. Based on the estimated static gains of the plant, the Skogestad internal model control (SIMC) method determines appropriate control gains. The dynamic decoupler is designed to deal with the cross-coupled effects of the EGR and VGT systems by applying a simplified decoupler design method. The simplified decoupler is beneficial for compensating for the dynamics difference between two control loops of the EGR and VGT systems, for example, slow VGT dynamics and fast EGR dynamics. The proposed control algorithm is evaluated through engine experiments. Step test results of set points reveal that root-mean-square (RMS) error of the gain-scheduled feedback controller is reduced by 47% as compared to those of the fixed gain controller. Furthermore, the designed simplified decoupler decreased the tracking error under transients by 14–66% in various engine operating conditions.

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Decentralized Feedback Control of Pumping Losses and NOx Emissions in Diesel Engines

Salehi

Martz

Stefanopoulou

et al. 2018

Journal of Engineering for Gas Turbines and Power

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A novel decentralized control architecture is developed based on a feedback from the pressure difference across the engine which is responsible for the pumping losses and the exhaust gas recirculation (EGR) flow in diesel engines. The controller is supplemented with another feedback loop based on NOx emissions measurement. Aiming for simple design and tuning, the two control loops are designed and discussed: one manipulates the variable geometry turbine (VGT) actuator and the other manipulates the EGR valve. An experimentally validated mean-value diesel engine model is used to analyze the best pairing of actuators and set points. Emphasis is given to the robustness of this pairing based on gain changes across the entire operating region, since swapping the pairing needs to be avoided. The VGT loop is designed to achieve fast cylinder air charge increase in response to a rapid pedal tip-in by a feedforward term based on the real-time derivative of the desired boost pressure. The EGR loop relies on a feedback measurement from a NOx sensor and a real-time estimation of cylinder oxygen ratio, χcyl. The engine model is used for evaluating the designed controllers over the federal test procedure (FTP) for heavy duty (HD) vehicles. Results indicate that the control system meets all targets, namely fast air charge and χcyl control during torque transients, robust NOx control during steady-state operation, and controlled pumping losses in all conditions.

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Model-Based Gain Scheduling Strategy for an Internal Model Control-Based Boost Pressure Controller in Variable Geometric Turbocharger System of Diesel Engines

Cited by 5 publications

References 30 publications

Diesel air path control using pressure difference: Pumping loss and aging considerations

Diesel air path control using pressure difference: Pumping loss and aging considerations

Simplified Decoupler-Based Multivariable Controller With a Gain Scheduling Strategy for the Exhaust Gas Recirculation and Variable Geometry Turbocharger Systems in Diesel Engines

Decentralized Feedback Control of Pumping Losses and NOx Emissions in Diesel Engines

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