IC Engine Control - the Challenge of Downsizing Dariusz Cieslar* 2nd Workshop on Control of Uncertain Systems: Modelling, Approximation, and Design Department of Engineering, University of Cambridge 23-24/9/2013 * Currently with dspace Ltd
Contents Selected trends in current passenger cars technology development Challenges and control applications Reduction of CO 2 emissions and engine downsizing Concept and implications BREES: turbo-lag reduction system based on compressed gas injections 2
Normalised by Values in 1977 Brief History 1.6 1.4 1.2 Engine Capacity Weight Power Interior Volume CO 2 1 0.8 0.6 1975 1980 1985 1990 1995 2000 2005 2010 2015 Year Electronic Fuel Injection Turbocharging Closed-loop AFR Variable Valvetrains Direct Fuel Injection Fuel Efficient Powertrains and Electrification 3
Selected Current Trends in Passenger Cars Technology CO 2 emissions Toxic emissions Driver Assistance Vehicle-to-Vehicle Vehicle-to-Infrastructure 4
Reduction of CO 2 Emissions How Vehicle Attributes Electrification of Powertrain ICE: Reduction of Losses Downsizing Down-speeding ICE: Advanced Combustion Driver Assistance Vehicle Networks 5
Roles for Control and Challenges Control in production vehicles: Feedback control is a small part of electronic controller code Hierarchical control with mode management Off-line calibration Mainly gain-scheduled PID, some adaptive control System integration (multi ECUs, communication, mode management) System design and analysis: Component selection (sensors, actuators, system architecture) Optimisation, sensitivity analysis 6
Challenges Calibration: Control development separate to calibration Models: Accuracy and complexity of models Calibration has become a major task performed by manufacturers Controllers need to be transferable, extendable Hardware-related: Sensor set is often dictated by cost and diagnostic purposes Control system testing and verification Computational resources 7
Concept of Downsizing Engine downsizing and turbocharging are key technologies which help car manufacturers to achieve CO 2 emissions targets, attractive performance and tolerable on-cost Turbocharged engines suffer from the deficit in torque at low engine speeds The key challenge is the difficulty of accelerating the turbocharger at low air flow conditions 8
Transient Response: Air-Path Control Problem Constraints: Compressor surge limit Mechanical limitations Actuator limits Control task objective: Deliver required torque and power Features: Plant open-loop stable, non-linear and multivariable 9
Engine Downsizing: Selection of System Components Possible approach: Control Actuators Air-path Architecture Sensors 10
Engine Downsizing: Selection of System Components Possible approach: Control Actuators Engine Models Sensors 11
Engine Downsizing: Selection of System Components Possible approach: Control Ideal Actuators Engine Models Ideal Sensors 12
Engine Downsizing: Selection of System Components Possible approach: LPV MPC (simplified model) Ideal Actuators Engine Models Ideal Sensors Model Predictive Control (MPC) is a control framework particularly suited to multi-input multi-output systems with constraints This way a systematic method for evaluating various turbocharging concepts is achieved 13
BREES Concept: Compressed Gas Turbo-Lag Reduction System Modified turbine actuator end-stop is used to reduce vane clearance which generates higher exhaust manifold pressure During braking this allows energy to be captured and stored as compressed gas in a tank attached to the exhaust manifold Stored gas can then be injected into the exhaust manifold to dramatically reduce turbo-lag during high torque demand Control Valve Compressed Gas Tank VGT with modified end-stop Exhaust Manifold 14
Experimental Setup Manoeuvre This manoeuvre allows for charging the tank prior to compressed air injection responding to full-load demand 15
Engine Testing Results Engine operating points during the manoeuvre 16
Concluding Remarks Electronic control has played an essential role in the steady progress of engine technology Technologies offering further reductions in emissions require more control Control engineering is indispensable in the process of engine design Sophisticated control approaches may first find their application at the design stage rather than in immediate on-line application BREES works! 17
Results: Usage of resources Exhaust is best! Injection of the compressed air into the exhaust manifold is significantly more effective than injection into the intake manifold Benchmark Turbocharger electric assist: limited to 0.16 Nm and 2 kw 18