Upload
pascale-cameron
View
43
Download
1
Tags:
Embed Size (px)
DESCRIPTION
Physics-based Modeling and Control of Homogeneous Charge Compression Ignition (HCCI) Engines. Gregory M. Shaver Dynamic Design Lab May 6 th , 2005 Department of Mechanical Engineering Stanford University. Outline. What is residual-affected HCCI? What are its benefits? - PowerPoint PPT Presentation
Citation preview
Physics-based Modeling and Control of Homogeneous Charge Compression Ignition
(HCCI) Engines
Gregory M. Shaver
Dynamic Design Lab
May 6th, 2005
Department of Mechanical Engineering
Stanford University
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 2
Dynamic Design Lab.
Outline
What is residual-affected HCCI? What are its benefits?
Hurdles to practically implementing HCCI Lack of combustion trigger Cyclic coupling
Dynamic modeling of HCCI
Making HCCI practical with feedback control
Conclusions and future work
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 3
Dynamic Design Lab.
What is Residual-Affected HCCI?
Residual-Affected Homogeneous Charge Compression Ignition Advanced combustion strategy for piston engines
Combustion due to uniform auto-ignition using compression alone
Hot exhaust gases reinducted using Variable Valve Actuation (VVA)
Main benefits 1. Increased efficiency compared to SI
2. Modest compression ratios
3. Drastic reduction in NOx emissions (i.e. smog)
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 4
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 5
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Reactants (fuel & air) & previously exhausted gases (residual) inducted
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 6
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Reactants (fuel & air) & previously exhausted gases (residual) inducted
Compression of mixture
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 7
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Reactants (fuel & air) & previously exhausted gases (residual) inducted
Compression of mixture causes auto-ignition uniform, fast & uncontrolled
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 8
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Reactants (fuel & air) & previously exhausted gases (residual) inducted
Compression of mixture causes auto-ignition uniform, fast & uncontrolled
Useful work from expansion
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 9
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Reactants (fuel & air) & previously exhausted gases (residual) inducted
Compression of mixture causes auto-ignition uniform, fast & uncontrolled
Useful work from expansion
Hot combustion products exhausted
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 10
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Reactants (fuel & air) & previously exhausted gases (residual) inducted
Compression of mixture causes auto-ignition uniform, fast & uncontrolled
Useful work from expansion
Hot combustion products exhausted, portion reinducted
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 11
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Valve motions from VVA determine: inducted gas composition amount of compression
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 12
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 13
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Sudden rise in pressure combustion initiation
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 14
Dynamic Design Lab.
HCCI with Variable Valve Actuation
Sudden rise in pressure combustion initiation
Work output: PdVW
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 15
Dynamic Design Lab.
HCCI with VVA -Challenges
Goal: achieve desired combustion timing & work output
Challenges No direct initiator of combustion Cycle-to-cycle coupling through exhaust gas
Significantly complicate transient load operation
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 16
Dynamic Design Lab.
HCCI with VVA -Challenges
Goal: achieve desired combustion timing & work output
Challenges No direct initiator of combustion Cycle-to-cycle coupling through exhaust gas
Significantly complicate transient load operation To date – HCCI impractical!!
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 17
Dynamic Design Lab.
Research Goals
Make HCCI practical through closed-loop control Stabilize process & control work output
Modeling Objective: Simple physical models that capture behavior most relevant for control Cyclic coupling Combustion timing In-cylinder pressure evolution (work output)
Control Objective - Control of: Combustion timing – make combustion sure happens! Work output – the key output of the engine
efficiency & reduced emissions come as result of process
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 18
Dynamic Design Lab.
Previous Work – Simulation Modeling
Ogink and Golovitchev 2002, Babajimopoulos et al. 2002 Multi-zone modeling of HCCI
Kong et al. 2002 Multi-dimensional CFD models using detailed chemistry
Many others
Complex flow and chemical kinetics models Capture general steady state behavior
Ignore cycle-to-cycle coupling
Exhibit long run times - ~12 hours per engine cycle
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 19
Dynamic Design Lab.
Contributions – Simulation Modeling
Developed a simulation model of residual-affected HCCI that:
Captures the cyclic couplingPredicts behavior during steady state & transients
Captures ignition via kinetics with a simple, intuitive model runtimes: ~ 15 seconds per engine cycle (amenable to
use as a control testbed)
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 20
Dynamic Design Lab.
Previous Work - Control
Agrell et al. 2003, Haraldsson et al. 2003, Bengtsson et al. 2004, Olsson et al. 2001, Matthews et al. 2005, others Various approaches to control combustion timing or work
output
In all cases: controller hand-tuned or synthesized from black-box models
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 21
Dynamic Design Lab.
Contributions - Control
Physics-based control model of HCCI The first physics-based approach to control of HCCI
Generalizable Enables use of control engineering tools:
Theoretical control designStability analysis
Control strategies for:Combustion timingPeak pressure or work output
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 22
Dynamic Design Lab.
Outline - Modeling Strategies
Simulation model Gain some intuition of the process
What are key features?What are relevant control inputs & outputs?
Control model Need a slightly simpler physical description for synthesis The launching point for developing control strategies
…..making HCCI practical!!
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 23
Dynamic Design Lab.
Experimental Apparatus
Single cylinder engine With VVA
Fuel used: Propane
Compression ratio Variable: 13-15.5
Engine speed Fixed: 1800 rpm
In-cylinder pressure transducer Combustion timing Peak pressure Work output
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 24
Dynamic Design Lab.
1st law analysis of cylinder and exhaust manifold
HCCI Simulation Model
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 25
Dynamic Design Lab.
1st law analysis of cylinder and exhaust manifold Steady state 1D compressible flow relations
HCCI Simulation Model
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 26
Dynamic Design Lab.
1st law analysis of cylinder and exhaust manifold Steady state 1D compressible flow relations
Heat transfer In-cylinder (modified Woschni)
Ref: Chang et al. 2004 Exhaust manifold
HCCI Simulation Model
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 27
Dynamic Design Lab.
1st law analysis of cylinder and exhaust manifold Steady state 1D compressible flow relations
Heat transfer In-cylinder (modified Woschni)
Ref: Chang et al. 2004 Exhaust manifold
Combustion model Wiebe function What do we use as a combustion trigger?
HCCI Simulation Model
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 28
Dynamic Design Lab.
1st law analysis of cylinder and exhaust manifold Steady state 1D compressible flow relations
Heat transfer In-cylinder (modified Woschni)
Ref: Chang et al. 2004 Exhaust manifold
Combustion model Wiebe function What do we use as a combustion trigger?
Resulting Model – 9 nonlinear ODEs
HCCI Simulation Model
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 29
Dynamic Design Lab.
Temperature Threshold
Assume HCCI occurs at a threshold temperature A fit at one temperature…
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 30
Dynamic Design Lab.
Temperature Threshold
Assume HCCI occurs at a threshold temperature Fit at one temperature… doesn’t hold at others!
Increasing residual
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 31
Dynamic Design Lab.
What Happened?
Simulation model: earlier timing for increasing residual More residual means mixture temperature Higher temperature leads to early timing
Experiments show more constant timing
Is some physical effect missing? Yes! Concentration of reactants More residual means lower reactant concentration
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 32
Dynamic Design Lab.
Integrated Arrhenius Rate Equation
Simple model for start of combustion Integrated Arrhenius rate
Constant threshold, a, b and Ea from published experiments
Contributions from temperature & reactant concentration captured
dOHCRTEAK ba
VC ath
th
283/exp
thK
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 33
Dynamic Design Lab.
Integrated Arrhenius Rate
Set threshold at one operating point…
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 34
Dynamic Design Lab.
Set threshold at one operating point… …and pressure, timing & work output at all points is captured
Increasing residual
Integrated Arrhenius Rate
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 35
Dynamic Design Lab.
Integrated Arrhenius Rate
Note: can vary composition without much change in timing
Increasing residual
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 36
Dynamic Design Lab.
Steady state behavior with propane captured
What about transients?Changes in load
Can the model capture these?
Simulation Model: Can it be extended?
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 37
Dynamic Design Lab.
Simulation Model: Transients
1st operating point has higher steady state temperature than 2nd
The elevated exhaust temperature advances combustion process during transition
As exhaust temperature decreases, behavior reaches new steady state
Cycle 1
Cycle 2
Cycle 6
EVC 180IVO 70EVC 185
IVO 50
Valve Profiles1 2-6
Experiment
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 38
Dynamic Design Lab.
Simulation Model: Transients
Simple model captures the coupling and ignition behavior during transition
Cycle 1
Cycle 2
Cycle 6
Cycle 1Cycle 2Cycle 6
EVC 180IVO 70EVC 185
IVO 50
Valve Profiles1 2-6
Simulation
Experiment
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 39
Dynamic Design Lab.
Results from Simulation modeling
Aspects most relevant for control captured with simple simulation model: Cyclic coupling & combustion timing In-cylinder pressure evolution
Approach can handle: Steady-state behavior Transients
A valuable virtual testbed for control
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 40
Dynamic Design Lab.
Motivation for Control Model
Simulation model has a lot of benefits
Still, too complex for synthesizing control strategies
Motivates a simpler dynamic model1. Enabled through additional physical assumptions
2. Discretizing the process (induction, compression, etc.)
3. Linking processes
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 41
Dynamic Design Lab.
Control Model Assumptions
Assumptions: Induction: atmospheric pressure Isentropic compression & expansion HCCI is fast: constant volume combustion In-cylinder heat transfer:% of combustion energy
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 42
Dynamic Design Lab.
Control Model Assumptions
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 43
Dynamic Design Lab.
A Simple Control Model
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 44
Dynamic Design Lab.
A Simple Control Model
Step through process to develop model of dynamics
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 45
Dynamic Design Lab.
A Simple Control Model
Step through process to develop model of dynamics
dynamics
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 46
Dynamic Design Lab.
Peak Pressure Dynamics
The peak pressure dynamics takes the form:
Fairly complex nonlinear dynamic model
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 47
Dynamic Design Lab.
Peak Pressure Dynamics
The peak pressure dynamics takes the form:
Fairly complex nonlinear dynamic model Can see dependence on:
Control inputs
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 48
Dynamic Design Lab.
Peak Pressure Dynamics
The peak pressure dynamics takes the form:
Fairly complex nonlinear dynamic model Can see dependence on:
Control inputsCyclic coupling
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 49
Dynamic Design Lab.
Peak Pressure Dynamics
The peak pressure dynamics takes the form:
Fairly complex nonlinear dynamic model Can see dependence on:
Control inputsCyclic couplingCombustion timing
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 50
Dynamic Design Lab.
Peak Pressure Dynamics
The peak pressure dynamics takes the form:
Fairly complex nonlinear dynamic model Can see dependence on:
Control inputsCyclic couplingCombustion timing
How do we model initiation of combustion, comb
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 51
Dynamic Design Lab.
Combustion Timing Dynamics
Recall the integrated Arrhenius rate model:
dOHCRTEAK ba
ath
th
vc283/exp
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 52
Dynamic Design Lab.
Combustion Timing Dynamics
Recall the integrated Arrhenius rate model:
Integrand takes on largest value at TDC
dOHCRTEAK ba
ath
th
vc283/exp
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 53
Dynamic Design Lab.
Combustion Timing Dynamics
Recall the integrated Arrhenius rate model:
Integrand takes on largest value at TDC Simplify: begin integration at TDC with values at TDC
dOHCRTEAK ba
ath
th
vc283/exp
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 54
Dynamic Design Lab.
Combustion Timing Dynamics
Recall the integrated Arrhenius rate model:
Integrand takes on largest value at TDC Simplify: begin integration at TDC with values at TDC
dOHCRTEAK b
TDC
a
TDCTDCath
th
TDC283/exp
~
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 55
Dynamic Design Lab.
Combustion Timing Dynamics
Recall the integrated Arrhenius rate model:
Integrand takes on largest value at TDC Simplify: begin integration at TDC with values at TDC
TDCthb
TDC
a
TDCTDCa
b
TDC
a
TDCTDCath
OHCRTEA
dOHCRTEAKth
TDC
283
283
/exp
/exp~
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 56
Dynamic Design Lab.
Combustion Timing Dynamics
Recall the integrated Arrhenius rate model:
Integrand takes on largest value at TDC Simplify: begin integration at TDC with values at TDC Algebraic expression exists for each variable
TDCthb
TDC
a
TDCTDCa
b
TDC
a
TDCTDCath
OHCRTEA
dOHCRTEAKth
TDC
283
283
/exp
/exp~
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 57
Dynamic Design Lab.
Combustion Timing Dynamics
Recall the integrated Arrhenius rate model:
Integrand takes on largest value at TDC Simplify: begin integration at TDC with values at TDC Algebraic expression exists for each variable
TDCthb
TDC
a
TDCTDCa
b
TDC
a
TDCTDCath
OHCRTEA
dOHCRTEAKth
TDC
283
283
/exp
/exp~
),,,,,( 1,,1,11, kvckvckcombkkkkcomb Pf
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 58
Dynamic Design Lab.
Control Model
Peak pressure and combustion timing dynamics together give:
A nonlinear 2-state, dynamic, discrete system model
),,,,,(
),,,,,(
1,,1,11,
1,,1,11
kvckvckcombkkkkcomb
kvckvckcombkkkpk
Pf
PfP
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 59
Dynamic Design Lab.
Control Model Validation
Control model captures Steady state & transient
Peak pressure Combustion Timing
Captures Cyclic coupling Ignition via kinetics
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 60
Dynamic Design Lab.
Control Modeling Summary
HCCI is difficult to control: Cyclic coupling No direct combustion trigger
Control model captures these phenomena!! Simple model tells us how dynamics are affected by
control inputs Is a launching point for:
Synthesizing control strategiesAssessing system stability
Generalizable
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 61
Dynamic Design Lab.
Outline of Control Implementations
From control model
1. Peak-pressure control at constant combustion timing
2. Work output control at constant combustion timing
3. Simultaneous peak pressure and combustion timing control
Many other approaches possible
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 62
Dynamic Design Lab.
Peak Pressure Control w/ Constant timing
Fix final valve closure
Vary composition to control peak pressure A “static” approach to controlling timing
A large number of control approaches can be utilized
),,,,,(
),,,,,(
1,,1,11,
1,,1,11
kvckvckcombkkkkcomb
kvckvckcombkkkpk
Pf
PfP
),,( 11 kkkk PfP
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 63
Dynamic Design Lab.
Peak Pressure Control w/ Constant timing Linear Controller Synthesis
A common control approach is to linearize the system model Linearizing about an operating point yields:
Simple linear control laws can be synthesized
kk
k
k
k
cP
c
c
c
cP
c
~
1~00~
20
22
1
1
20
21
20
23
P
PPkk kk
~where:
,P
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 64
Dynamic Design Lab.
Peak Pressure Control w/ Constant timing
In closed-loop:
Controller synthesized from linearized version of model
Is controller stable in closed-loop with nonlinear model?
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 65
Dynamic Design Lab.
Peak Pressure Control w/ Constant timing Nonlinear Stability Analysis
Using: Lyapunov
stability theory Convex
optimization
Shows: Simple linear
controller stabilizes entire operating regime
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 66
Dynamic Design Lab.
Peak Pressure Control w/ Constant timing Experimental Implementation
Accurate control of peak pressure Mean tracking Fluctuation reduction
Increases robustness
Little change in phase
What about direct control of work output (IMEP)?
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 67
Dynamic Design Lab.
Experimental Work Output Control
Rapid mean tracking & fluctuation reduction
We can control work output, while keeping timing roughly constant
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 68
Dynamic Design Lab.
Experimental Work Output Control
Positive and negative load transients
What about simultaneous control of combustion timing and work output?
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 69
Dynamic Design Lab.
Combustion Timing & Work Output Control
Add other control input: final valve closure Significant control knob for combustion timing
Simple approach Separate linear controllers for peak pressure and timing
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 70
Dynamic Design Lab.
Decoupled Peak Pressure and Phase Control
Maintain cycle-to-cycle peak pressure controller, vary phase more slowly
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 71
Dynamic Design Lab.
Approach works
Simultaneous control of timing and peak
pressure
Experiments with Decoupled Control
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 72
Dynamic Design Lab.
Comments on Control Experiments
Simple physics-based controllers works well Implementation is straightforward Mean tracking & fluctuation reduction of
peak pressure work output
Combustion timing fairly constant
Independent control of peak pressure & combustion timing
Many others possible
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 73
Dynamic Design Lab.
Conclusion
HCCI has a promising future as a cleaner, more efficient strategy Hurdle: controlling the process No combustion initiator & cycle-to-cycle coupling
The good news: HCCI is amenable to model-based control Key behaviors captured in both simulation and control models
Simulation & control models capture: Steady-state Transients
Physics-based control of: Peak pressure Work output Combustion timing
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 74
Dynamic Design Lab.
Future Work
Study different control approaches
Control of multi-cylinder HCCI engines Results to date with single-cylinder engines
Cylinder-to-cylinder dynamics now play a key role!
Change the world!
Stanford UniversityPhysics-based Modeling and Control of Homogeneous Charge Compression
Ignition (HCCI) Engines
- 75
Dynamic Design Lab.
Acknowledgments
Chris Gerdes
The Dynamic Design Lab
Partners in crime: Matt Roelle & Nikhil Ravi
A great sponsor – Robert Bosch Corporation Jean-Pierre Hathout, Jasim Ahmed, Aleks Kojic & Sungbae Park
The defense Committee Chris Edwards, Sanjay Lall, Matt Franchek & Steve Rock
Stanford University