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 V

flat (boxer) 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

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- 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

Designing of the simple model, which allow study of the 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

Phases of LCE research

Model of the LCE

nonlinear scavenging, non homogenous mixture3 order

Model of Electric motor-generator

Model of Combustion Engine

Block diagram of the control system

PC with dSpace DSP board

Interface board

IGBT bridge

Injection control

unit

Ignition unit

Ignition coil

Throttle regulator

MAF

Position senzor

Power supply

3-phase network

On system variable

measurement

Power switch

Load resistor

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

Time [s]

Po

sit

ion

[m

]

Long term steady operation was achieved

Max. drained electric power: 400 W at 1200 rpm

Experimental results

Position [m]

Vel

ocity

[m

]

Experimental results

0.5 1 1.5 2 2.5 3 3.5 4 4.5

x 10-5

0

0.5

1

1.5

2

2.5

3x 10

6

V [m3]

p [P

a]p-V diagram comparison

SimulatedExperimental (filtered)

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