A Linear Magnetic-geared Free-piston Generator for Range-extended Electric Vehicles

Abstract

This paper proposes a novel linear magnetic-geared machine for the free-piston generator in range-extended electric vehicles. The key is to integrate a linear magnetic gear into a linear permanent magnet synchronous machine to form a single machine, which can offer high efficiency and high power density for electricity generation. The low-speed mover of the proposed machine is directly coupled with the pistons of the internal combustion engine and reciprocates with the pistons. Due to the magnetic gear effect, the high-speed mover which is also the translator of the synchronous machine can travel at high speeds, hence offering high power density design and generating electricity with a high voltage. By using finite element analysis, the machine performance is analyzed and verified.