Starting a free-piston linear engine-generator consists of reciprocating a freely moving piston-magnet-translator assembly between two oppositely placed engine cylinders to initiate combustion. To provide for the reciprocating force, the machine is operated as a brushless linear motor. A starting strategy is proposed which utilizes the air-spring quality of the engine cylinders prior to combustion: by energizing the coils with fixed DC voltage and by open-loop, rectangular commutation of injected current, sufficiently high motor force is produced to reciprocate the piston-magnet assembly in small amplitudes initially. Due to repeated compression-expansion of the engine cylinders and constant application of motoring force in the direction of natural bouncing motion, the translatorpsilas amplitude and compression pressure is expected to grow - due to mechanical resonance - to finally reach the required parameters for combustion. This work discusses the electrical aspects of the starting strategy, considers control possibilities, builds a model of the electrical subsystem and presents simulation and validation tests of the integrated model for starting investigation.
[1]
Hamzah Arof,et al.
ON THE ISSUES OF STARTING AND COGGING FORCE REDUCTION OF A TUBULAR PERMANENT MAGNET LINEAR GENERATOR
,
2004
.
[2]
W. M. Arshad.
A Low-Leakage Linear Transverse-Flux Machine for a Free-Piston Generator
,
2003
.
[3]
Němeček Pavel,et al.
Modeling and Control of Linear Combustion Engine
,
2004
.
[4]
Subhash Nandkumar,et al.
Two-stroke linear engine
,
1998
.
[5]
M.N. Karsiti,et al.
Starting of a free-piston linear engine-generator by mechanical resonance and rectangular current commutation
,
2008,
2008 IEEE Vehicle Power and Propulsion Conference.
[6]
K.M. Nor,et al.
Design of a 5 kW tubular permanent magnet linear generator
,
2004,
39th International Universities Power Engineering Conference, 2004. UPEC 2004..
[7]
Dal Y. Ohm.
ABOUT COMMUTATION AND CURRENT CONTROL METHODS FOR BRUSHLESS MOTORS
,
2000
.