Operating characteristics of a linear range extender with different energy consumption topologies

The free-piston linear generator is a new energy transformation technology with compact structure, multi-fuel adaptability, low friction loss, and simple modular configuration. To advance the practical process of the free-piston linear generator, several different topologies of electrical energy consumption are applied to the system, and the generating performance of the system is investigated in three-phase resistive load topology, uncontrolled rectification-resistive load topology, uncontrolled rectification-battery topology, and uncontrolled rectification-direct current to direct current converter -battery topology. The influence of the different topologies on the generator is mainly in the output type and output power (periodic, fluctuating). Furthermore, the impact of the topology on the operating characteristics of the free-piston linear generator, which mainly brings about changes in the characteristics of the current amplitude current fluctuations and generator force near the dead center, is explored. The current amplitude can influence the frequency and damp properties significantly and may cause system shutdown because of the improper matching of the generator and the load terminal. Changes in the generator force in the low-velocity region near the dead center have less impact on the output and thermodynamic processes of the system. The impact on system performance increases as the changes expand to the high-velocity region.