Unlike a traditional internal combustion engine, which propels a drive shaft, a free piston engine linear generator (FPEG) is designed to generate electricity directly. Magnets attached to the piston move within a linear coil, converting kinetic energy to electrical energy.
A team from Toyota Central R&D Labs presented a prototype FPEG in 2014. Now the Toyota researchers have developed a new FPEG control method that improves the stability and flexibility of the piston motion control.
These are a kind of mini generators - very small and light - they could provide a continuous re-charge of electric vehicle batteries while driving...