ic engine control - the challenge of downsizing

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