Integration of Free Piston Linear Generator and Battery Pack in Hybrid Vehicles

Free-piston linear generator (FPLG) is based on a cylindrical combustion chamber connected on the axis with a linear electric generator. The system allows the conversion of the mechanical energy produced by the combustion into electrical energy available on board the vehicle. The FREE-MOST project aims to model, simulate, control and experimentally validate a laboratory-scale FPLG configuration, with particular attention to the electrical subsystem. Within the project a model for the integration of a FPLG with a vehicle battery pack has been developed, which is the contribution of this paper. Starting from the force and velocity profiles generated by the combustion, the model of the linear generator allows one to construct the power electronics interface to the battery, which ultimately will power the vehicle. By modeling the individual components and the mathematical description of the dynamics involved, a modular lumped parameters model useful for steady state and transients analysis at the electrical time-scale is presented.