Control and testing of a free piston engine

The free piston energy converter (FPEC) project aims to develop an efficient energy conversion system for series hybrid vehicles as well as for standalone or distributed power generating application. The principle is based on Cl free-piston concept, comprising of a combustion system integrated with a linear tubular electrical machine. The project was funded by the EC (Project No. GRD2-2001-51813) with a consortium comprised of VTEC/-VOLVO (Sweden), Institut Francais du Per role (France), ABB (Sweden). Chalrners University of Technology (Sweden). Kungliga Tekniska Hogskolan (Sweden) and University of Sheffield (liK). This thesis describes the work undertaken by the author as part of the FPEC project. The principal aim of the work covered by this thesis was to develop and demonstrate novel control strategies required to control the piston motion, and thereby realise optimum combustion conditions. For this purpose, a multi-level control architecture is adopted. The focus of this thesis is, however on the intermediate level of combustion control and the low level of electrical machine control. A computationally efficient. zero-dimensional engine model is established based on the first law of thermodynamics. This is integrated with models of the linear electrical machine and inverter control to form a complete system model which is used as a tool for control law development and performance evaluation. A kinetic energy control strategy is derived for the combustion control and its numeric implement able algorithm for fixed point processing is described together with intake pressure estimation and minimisation of control actions. Robust and reliable position sensing presents a significant challenge for the realisation of the FPEC. A position triggered time varying Kalman filter is derived and its performance analysed and experimentally demonstrated. A prototype FPEC control system has been constructed novel methods were developed for testing the system, and the experimental results are presented and analysed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo