Rectangular current commutation and open-loop control for starting of a free-piston linear engine-generator

• Main Authors: S.A., Zulkifli, M.N., Karsiti, A.R.A., Aziz
• Format: Conference or Workshop Item
• Published: 2008
• Subjects: TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.utp.edu.my/276/1/paper.pdf; http://www.scopus.com/inward/record.url?eid=2-s2.0-63049128041&partnerID=40&md5=85f217832da7b7db690a267bf07013e3; http://eprints.utp.edu.my/276/
• Institution: Universiti Teknologi Petronas

Starting a free-piston linear engine-generator consists of reciprocating a freely moving piston-magnettranslator 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 translator's 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. © 2008 IEEE.