Modelling and Control of Linear
Combustion Engine (LCE)
Pavel Němeček, Ondřej Vysoký, Michal Šindelka
Czech Technical University in Prague
Faculty of Electrical Engineering
Department of Control Engineering
Internal Combustion Engines
 inline
 flat (boxer)
V
Crank shaft
turns the piston's
up and down motion
into circular motion
Series Hybrid Car
 Gasoline engine turns a generator
 Generator can either charge the batteries or
power an electric motor that drives the
transmission
 Thus, the gasoline
engine never directly
powers the vehicle
 and no rotation
needed ?!
Linear Combustion Engines
 single hit – easy
 industrial staplers
 how to achieve repetitive (periodic) motion???
 by proper configuration and control
LCE – animation
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Two-stroke, Two opposite cylinders (2x50 ccm)
Pistons directly connected by rod (no crankshaft)
Direct air assisted fuel injection
Contains linear electric motor-generator
- enable starting of LCE
- provide conversion to electric energy
- enable intervention when misfire occurs
 No mechanical output, application for serial hybrid vehicles
 Control, control, control !
Schematic diagram of LCE
Advantages of the LCE
 Elimination of friction losses
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- associated with the crankshaft and it’s accessories
- piston friction reduction (no angular loading)
=> higher efficiency
High power density
Compact shape (allow non-standard inbuilt)
Reduced amount of moving parts
- increase durability
- simplify mechanical construction
- simplify lubrication
Compression ration is not fixed =>
theoretically multi-fuel operation is enabled
Phases of LCE research
 Designing of the simple model, which allow study of the
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basic LCE behavior
Building up of an experimental prototype of the LCE and
validation of the model
Control algorithm design for achieving a steady
operation
Controller’s optimization with respect some criteria of
quality (efficiency, emission, power etc.)
Design of a power management strategy of a serial
hybrid vehicle with the LCE as the main power unit
Model of the LCE
nonlinear scavenging,
non homogenous mixture
3 order
Model of Electric motor-generator
Model of Combustion Engine
Block diagram of the control system
PC with dSpace
DSP board
Interface
board
On system
variable
measurement
MAF
IGBT
bridge
Position
senzor
Load
resistor
Throttle
regulator
Ignition
coil
Ignition
unit
Power
switch
Power
supply
3-phase
network
Injection
control
unit
Linear-motorgenerator
Requirements for the control system
of the linear electric motor-generator
 Collision avoiding
between the piston and the cylinder head
 Maximization of drained electric power in each cycle
 Prevention of the LCE from stopping
when a misfire occurs
 Starting of the LCE (with respect to a actual LCE state)
Experimental results
 Long term steady operation was achieved
Position [m]
 Max. drained electric power: 400 W at 1200 rpm
Time [s]
Velocity [m]
Experimental results
Position [m]
Experimental results
6
3
p-V diagram comparison
x 10
Simulated
Experimental (filtered)
2.5
p [Pa]
2
1.5
1
0.5
0
0.5
1
1.5
2
2.5
3
V [m ]
3
3.5
4
4.5
-5
x 10
Video – LCE prototype in operation
Conclusion and further work
Conclusion
 Long term steady operation was achieved
 Efficiency of the present experimental prototype is low,
but it allow study of the system behavior
Further work
 Optimization of the thermodynamical cycle
 Design and construction of a new prototype in
cooperation with mechanical engineers
to increase efficiency and durability of the LCE