ic engine control - the challenge of downsizing
TRANSCRIPT
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
I.C. Engines Group – Emissions, Measurement and Control
* Currently with dSPACE Ltd
Contents
• Selected trends in current passenger cars technology development
• Challenges and control applications
• Reduction of CO2 emissions and engine downsizing
• Concept and implications
• BREES: turbo-lag reduction system based on compressed gas
injections
2 I.C. Engines Group – Emissions, Measurement and Control
Brief History
3
1975 1980 1985 1990 1995 2000 2005 2010 2015
0.6
0.8
1
1.2
1.4
1.6
Year
No
rma
lise
d b
y V
alu
es in
19
77
Engine Capacity
Weight
Power
Interior Volume
CO2
3
Turbocharging
Electronic Fuel Injection
Closed-loop AFR
Variable Valvetrains
Direct Fuel Injection
Fuel Efficient Powertrains
and Electrification
I.C. Engines Group – Emissions, Measurement and Control
Selected Current Trends in Passenger Cars Technology
4
CO2 emissions Toxic emissions
Driver Assistance Vehicle-to-Vehicle
Vehicle-to-Infrastructure
I.C. Engines Group – Emissions, Measurement and Control
Reduction of CO2 Emissions
5
How
Vehicle Attributes
Electrification of
Powertrain
ICE: Reduction of
Losses
ICE: Advanced
Combustion
Driver Assistance
Vehicle Networks
Downsizing
Down-speeding
I.C. Engines Group – Emissions, Measurement and Control
Roles for Control and Challenges
6
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
I.C. Engines Group – Emissions, Measurement and Control
Challenges
7
Calibration:
• Control development separate to calibration
• Calibration has become a major task performed
by manufacturers
• Controllers need to be transferable, extendable
I.C. Engines Group – Emissions, Measurement and Control
Models:
• Accuracy and complexity of models
Hardware-related:
• Sensor set is often dictated by cost and
diagnostic purposes
• Computational resources
Control system testing and
verification
Concept of Downsizing
• Engine downsizing and turbocharging
are key technologies which help car
manufacturers to achieve CO2
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
I.C. Engines Group – Emissions, Measurement and Control 8
Transient Response: Air-Path Control Problem
• Constraints:
• Compressor surge limit
• Mechanical limitations
• Actuator limits
9
• Control task objective:
• Deliver required torque and power
• Features:
• Plant open-loop stable, non-linear
and multivariable
I.C. Engines Group – Emissions, Measurement and Control
Engine Downsizing: Selection of System Components
10
Air-path
Architecture Sensors
Control
Actuators
• Possible approach:
I.C. Engines Group – Emissions, Measurement and Control
Engine Downsizing: Selection of System Components
11
Sensors
Control
Actuators Engine Models
• Possible approach:
I.C. Engines Group – Emissions, Measurement and Control
Engine Downsizing: Selection of System Components
12
Control
Engine Models Ideal Sensors Ideal Actuators
• Possible approach:
I.C. Engines Group – Emissions, Measurement and Control
• Possible approach:
Engine Downsizing: Selection of System Components
13
LPV MPC
(simplified model)
• 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
Engine Models Ideal Sensors Ideal Actuators
I.C. Engines Group – Emissions, Measurement and Control
BREES Concept:
Compressed Gas Turbo-Lag Reduction System
Compressed Gas Tank
Control
Valve
Exhaust
Manifold
VGT
with modified
end-stop
14 14
• 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
I.C. Engines Group – Emissions, Measurement and Control
Experimental Setup – Manoeuvre
15 15
• This manoeuvre allows for charging the tank prior to compressed air
injection responding to full-load demand
I.C. Engines Group – Emissions, Measurement and Control
Engine Testing Results
16 16
• Engine operating points during the manoeuvre
I.C. Engines Group – Emissions, Measurement and Control
Concluding Remarks
17 17
• 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!
I.C. Engines Group – Emissions, Measurement and Control
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 18 I.C. Engines Group – Emissions, Measurement and Control