Combustion Control Project

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Combustion Control Project

• Per Tunestål

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Outline

• People
• Papers
• Activities
• FPGA based heat release
• Ultra-bandwidth rapid protoptype system
• Self-tuning heat release
• theHEAT
• Accurate crank angle information

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People involved

• Carl Wilhelmsson, PhD Student CE
• Anders Widd, PhD Student, AC
• Per Tunestål, Assoc. Prof. CE
• Rolf Johansson, Prof. AC

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Papers 2006 2007

• 2006
• The Effect of Displacement on Air-Diluted
  Multi-Cylinder HCCI Engine Performance (SAE)
• FPGA Based Engine Feedback Control Algorithms
  (FISITA)
• Model Based Engine Control using ASICs (IFP)
• 2007
• Operation strategy of a Dual Fuel HCCI Engine
  with VGT (JSAE, SAE)
• IFAC, An Ultra High Bandwidth Automotive Rapid
  Prototype System (AAC, IFAC)
• Self Tuning Cylinder Pressure Based Heat Release
  Computation (AAC, IFAC)

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FPGA implementation ultra rapid Heat Release
analysis
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FPGA Based Engine Control algorithms

• Throughput 50MHz
• Delay 120ns
• Asynchrounous operation
• In cycle HR analysis!

Simulated engine
Oscilloscope
Signal conditioning
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Rapid prototype system
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Rapid prototype goals

• Simulink provides flexibility for control of
  peripheral equipment (turbo, fuel rail pressure
  etc)
• Simulink provides flexibility for between cycle
  combustion control
• Standard COTS components and open communication
  protocols provides flexibility
• FPGA provides less flexible ultra bandwidth
  control possibilities

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Self-tuning heat release

• Self tuning heat release algorithm using
• Fast nonlinear least-squares fit of pressure to
  polytropic curve
• Accurate estimation of polytropic exponent during
  compression and expansion
• Accurate estimation of pressure sensor offset
  during compression and expansion
• Convergence in 4-5 iterations
• Interpolation of polytropic exponent during
  combustion
• Offers implicit correction for losses (heat,
  crevice, )
• Suitable for real-time applications
• To be presented at IFAC-AAC07 in August 2007
• Preliminary patent application submitted
• Final patent application by either Scania or
  Volvo PWT

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Polytropic fits

• Yields
• Pressure offsets
• Polytropic exponents

Both in compressionand expansion strokes
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Linear interpolation
Apply linear interpolationto polytropic
exponentand pressure sensoroffset during
combustionevent
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Calculation of heat release
Calculate net heat releaseusing
interpolatedpolytropic exponent
Well tuned heat release
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Two HCCI cases

• Scania 6-cylinder 12 liter engine
• 2.3 kJ fuel energy
• 1.6 kJ fuel energy

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Exponent 2.3 kJ fuel energy
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Pressure offset 2.3 kJ fuel energy
Pressure impactduring combustionpushes the
sensoroffset downsomewhat
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RMS error 2.3 kJ fuel energy
Somewhat higher RMS error duringexpansion due
topressure oscillation
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Heat release 2.3 kJ fuel energy
Slight over-estimation of theheat release
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Exponent 1.6 kJ fuel energy
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Pressure offset 1.6 kJ fuel energy
Less differencein sensor offsetwith
lesscombustion
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RMS error 1.6 kJ fuel energy
No pressureoscillation at lowerload ? same
RMSerror before andafter combustion
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Heat release 1.6 kJ fuel energy
Slight over-estimation of theheat release
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theHEAT 1.0

• www.theHEAT.nu

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theHEAT

• Intended as a complete combustion analysis
  toolset
• May contain real time implementable software
  components
• Is model based and free of ad-hoc assumptions

www.theHEAT.nu
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Accurate crank angle information(work in
progress)

• Desirable to sample pressure time based
• A/D converters handle this better
• Pressure sensor has limit frequency in time
  domain
• Crank angle information not synchronized with
  time
• ?Use phase locking frequency multiplier to obtain
  extremely accurate crank angle information in
  real time